KR101394841B1 - A fuel gas supply system of liquefied natural gas and a method for the same - Google Patents

Abstract

The present invention relates to an LNG fuel supply system which includes: a fuel supply line which is connected from an LNG storage tank to an engine; a pump which is arranged on the fuel supply line and pressurizes LNG which is discharged from the LNG storage tank at a high pressure; a heat exchanger which is arranged on the fuel supply line between the engine and the pump and supplies the LNG which is supplied from the pump to the engine by exchanging the heat of the LNG with glycol water; a glycol heater which supplies the glycol water to the heat exchanger after heating the glycol water with steam; a steam supply line which supplies steam to the glycol heater; and a steam valve which controls the supply quantity of the steam by being arranged on the steam supply line and heats the steam supply line by supplying the steam under a preset pressure at a predetermined time when initializing the driving of the engine or restarting the engine after a stop of the engine. The system and a method of the system for supplying LNG fuel according to the present invention are able to prevent a hammering phenomenon which hits the steam supply line in advance by suddenly expanding cold air which exists in the steam supply line by the high temperature of steam since the temperature of the steam supply line is increased by supplying the steam at a low pressure for a predetermined time when operating initially or restarting after a stop.

Description

[0001] The present invention relates to an LNG fuel supply system,

The present invention relates to a LNG fuel supply system and method.

A ship is a means of transporting large quantities of minerals, crude oil, natural gas, or more than a thousand containers. It is made of steel and buoyant to float on the water surface. ≪ / 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.

In recent years, however, LNG fuel supply systems for driving an engine using LNG as a fuel have been used in an LNG carrier carrying Liquefied Natural Gas (LNG) It is also applied to other ships.

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

However, the temperature and pressure required to drive the engine may be different from the state of the LNG stored in the tank. Therefore, in recent years, research and development have been made on the technology of controlling the temperature and pressure of the LNG stored in the liquid state and supplying the engine to the engine.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the prior art, and it is an object of the present invention to provide a method and apparatus for heating LNG to a required engine temperature using heated glycol water by heating the glycol water with steam, And to provide an LNG fuel supply system capable of increasing heating efficiency.

It is a further object of the present invention to provide a steam heating system and a steam heating system which are equipped with a steam control valve and a steam block valve in a steam supply line for supplying steam to a glycol heater and control the flow rate of steam with a steam block valve when leakage occurs in the steam control valve, And to provide an LNG fuel supply system capable of preventing leakage.

It is another object of the present invention to provide a steam heating system and a steam heating system which are capable of supplying steam to the glycol heater at an initial operation, And to provide a LNG fuel supply system and method that can prevent the occurrence of a hamming phenomenon.

It is another object of the present invention to provide a steam generator which has a condensate discharge valve and a condensate control valve downstream of a condensate tank for storing condensed water discharged from a glycol heater and controls each valve according to the level of the condensate tank, And to provide an LNG fuel supply system capable of preventing steam from being discharged together with condensed water.

An LNG fuel supply system according to an aspect of the present invention includes a fuel supply line connected from an LNG storage tank to an engine; A pump provided on the fuel supply line for pressurizing the LNG discharged from the LNG storage tank to a high pressure; A heat exchanger provided on the fuel supply line between the engine and the pump, for heat-exchanging the LNG supplied from the pump with glycol water to supply the LNG to the engine; A glycol heater for heating the glycol water with steam and supplying the glycol water to the heat exchanger; A steam supply line for supplying steam to the glycol heater; And a steam valve provided on the steam supply line to control the supply amount of the steam and to supply steam for a predetermined time at a time of restarting the engine at the time of starting or stopping the engine to stop the steam supply line .

Specifically, the steam valve can supply the steam for 5 to 10 minutes at a pressure within a preset range.

Specifically, the steam valve may raise the supply pressure of the steam after the lapse of the predetermined time.

Specifically, the steam valve may supply the steam at a pressure of 5 to 10 bar after the lapse of the predetermined time.

Specifically, the steam valve includes: a steam control valve provided on the steam supply line; And a steam block valve provided upstream of the steam control valve on the steam supply line.

Specifically, the steam control valve and the steam block valve may be arranged in series on the steam supply line.

Specifically, the apparatus further includes a glycol tank for storing the glycol water, and the glycol heater can heat the glycol water discharged from the glycol tank.

Specifically, the apparatus may further include a glycol pump for supplying the glycol water stored in the glycol tank to the glycol heater.

According to an aspect of the present invention, there is provided a method of supplying LNG fuel to an engine by supplying steam to a glycol heater through a steam supply line to heat the glycol water, heat-exchanging LNG with the heated glycol water, Sensing a temperature of the steam supply line when the engine is restarted after an initial operation or after stopping the engine; Heating the steam supply line by supplying steam for a predetermined time less than a preset pressure when the temperature is lower than a preset temperature; And increasing the supply pressure of the steam after a predetermined time has elapsed.

Specifically, in the step of heating the steam supply line, the steam may be supplied for 5 to 10 minutes under a predetermined range of pressure.

Specifically, the step of raising and supplying the steam supply pressure may supply the steam at a pressure of 5 bar to 10 bar.

The LNG fuel supply system according to the present invention can heat the glycol water through the steam generated by using the boiler and allow the glycol water to heat the LNG to efficiently raise the temperature of the LNG to the engine required temperature.

Further, the LNG fuel supply system according to the present invention is characterized in that the steam control valve and the steam block valve are arranged in series in the steam supply line and the steam block valve can control the inflow amount of steam even if leakage occurs in the steam control valve. .

Further, the system and method for supplying LNG fuel according to the present invention enable the steam to be supplied at a low pressure for a predetermined time during the initial operation or after restarting to raise the temperature of the steam supply line, It is possible to prevent the hamming phenomenon in which the cold air existing in the line is rapidly expanded and strikes the steam supply line.

In the LNG fuel supply system according to the present invention, a condensate discharge valve and a condensate control valve are arranged in series in a condensate tank connected to the glycol heater, and the condensate discharge valve discharges condensed water according to the level of the condensate tank, And the condensate discharge valve prevents the condensate and steam from being discharged together with the condensate control valve, so that the steam supply and the condensed water discharge can be smoothly performed.

1 is a conceptual diagram of a conventional LNG fuel supply system.
2 is a conceptual diagram of an LNG fuel supply system according to an embodiment of the present invention.
3 is a cross-sectional view of an LNG storage tank in an LNG fuel supply system according to an embodiment of the present invention.
4 is a flowchart of a method of supplying LNG fuel according to an embodiment of the present invention.
5 is a conceptual diagram of an LNG fuel supply system according to another embodiment of the present invention.

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

1 is a conceptual diagram of a conventional LNG fuel supply system.

1, a conventional LNG fuel supply system 1 includes an LNG storage tank 10, an engine 20, a pump 30, and an electric heater 40. [ In the present specification, LNG can be used to encompass both NG, which is a liquid state, and NG, which is a supercritical state, for the sake of convenience.

In the conventional LNG fuel supply system 1, an electric heater 40, which receives the electric energy and directly heats the LNG, is used. However, since the electric energy necessary for driving the electric heater 40 can be obtained only by driving a generator (not shown) by using fuel, there is a problem of cost due to fuel consumption, Environmental pollution problems and the like may occur.

FIG. 2 is a conceptual diagram of an LNG fuel supply system according to an embodiment of the present invention, and FIG. 3 is a sectional view of an LNG storage tank in an LNG fuel supply system according to an embodiment of the present invention.

2, an LNG fuel supply system 2 according to an embodiment of the present invention includes an LNG storage tank 10, an engine 20, a pump 30, a heat exchanger 50, A glycol pump 62, a glycol heater 63, a steam supply line 70, and steam valves 71 and 72. [ In an embodiment of the present invention, the LNG storage tank 10, the engine 20, the pump 30, and the like are denoted by the same reference numerals as those in the conventional LNG fuel supply system 1, ≪ / RTI >

The LNG storage tank 10 stores the LNG to be supplied to the engine 20. The LNG storage tank 10 must store the LNG in a liquid state, and the LNG storage tank 10 may have a pressure tank form.

3, the LNG storage tank 10 includes an outer tank 11, an inner tank 12, and a heat insulating portion 13. As shown in Fig. The outer tank 11 is formed as an outer wall of the LNG storage tank 10, and may be formed of steel, and may have a polygonal cross section.

The tanks 12 are provided inside the tanks 11 and can be supported and supported inside the tanks 11 by means of a support 14. At this time, the support 14 may be provided at the lower end of the inner tank 12, and may be provided at the side of the inner tank 12 in order to suppress the lateral movement of the inner tank 12. [

The bath tank 12 may be made of stainless steel and designed to withstand a pressure of 5 bar to 10 bar (for example 6 bar). The reason why the inner tank 12 is designed to withstand such a constant pressure is that the inner pressure of the inner tank 12 can be raised as the LNG provided in the inner tank 12 is evaporated to generate the evaporation gas Because.

A baffle 15 may be provided in the inner tank 12. [ The baffle 15 means a plate in the form of a lattice and the baffle 15 is installed so that the pressure inside the tank 12 can be evenly distributed to prevent the tank 12 from being subjected to concentrated pressure .

The heat insulating portion 13 is provided between the inner tank 12 and the outer tank 11 and can prevent the external heat energy from being transmitted to the inner tank 12. [ At this time, the heat insulating portion 13 may be in a vacuum state. By forming the adiabatic portion 13 in a vacuum, the LNG storage tank 10 can more efficiently withstand higher pressures as compared to a conventional tank. For example, the LNG storage tank 10 may sustain a pressure of 5 to 20 bar through the vacuum insulation 13.

As described above, the present embodiment uses the pressure tank LNG storage tank 10 having the vacuum insulation unit 13 between the outer tank 11 and the inner tank 12 to minimize the generation of the evaporated gas And it is possible to prevent the LNG storage tank 10 from being damaged even if the internal pressure is increased.

The engine 20 is driven through the LNG supplied from the LNG storage tank 10 to generate thrust. The engine 20 may be a MEGI engine 20 or a dual fuel engine 20.

When the engine 20 is the dual fuel engine 20, the LNG and the oil may be selectively supplied without mixing the LNG and the oil. This is to prevent the mixture of two materials having different combustion temperatures from being mixed and to prevent the efficiency of the engine 20 from being lowered.

As the piston 20 (not shown) in the cylinder (not shown) reciprocates due to the combustion of the LNG, the engine 20 rotates the crank shaft (not shown) connected to the piston, (Not shown) can be rotated. Therefore, as the propeller (not shown) connected to the shaft finally rotates when the engine 20 is driven, the hull is moved forward or backward.

Of course, in the present embodiment, the engine 20 may be an engine 20 for driving a propeller, but it may be an engine 20 for generating electricity or an engine 20 for generating other power. That is, the present embodiment does not specifically limit the type of the engine 20. However, the engine 20 may be an internal combustion engine that generates a driving force by combustion of the LNG.

A fuel supply line 21 for transferring LNG can be installed between the LNG storage tank 10 and the engine 20 and the pump 30 and the heat exchanger 50 are provided in the fuel supply line 21 So that the LNG is supplied to the engine 20.

At this time, the fuel supply line 21 is provided with a fuel supply valve (not shown) so that the supply amount of the LNG can be adjusted according to the opening degree adjustment of the fuel supply valve.

The pump 30 is provided on the fuel supply line 21 and pressurizes the LNG discharged from the LNG storage tank 10 to a high pressure. The pump 30 includes a boosting pump 31 and a high pressure pump 32.

The boosting pump 31 may be provided on the fuel supply line 21 between the LNG storage tank 10 and the high pressure pump 32 or in the LNG storage tank 10 and may be sufficient for the high pressure pump 32 So that positive LNG is supplied to prevent cavitation of the high-pressure pump 32. Also, the boosting pump 31 can pressurize the LNG from the LNG storage tank 10 to a pressure of several to several tens of bar, and the LNG through the boosting pump 31 can be pressurized to 1 to 25 bar.

The LNG stored in the LNG storage tank 10 is in a liquid state. At this time, the boosting pump 31 may pressurize the LNG discharged from the LNG storage tank 10 to slightly increase the pressure and the temperature, and the LNG pressurized by the boosting pump 31 may still be in a liquid state.

The high-pressure pump 32 pressurizes the LNG discharged from the boosting pump 31 to a high pressure so that the LNG is supplied to the engine 20. The LNG is discharged from the LNG storage tank 10 at a pressure of about 10 bar and then primarily pressurized by the boosting pump 31. The high pressure pump 32 is supplied with the LNG in the liquid state pressurized by the boosting pump 31 And is supplied to the heat exchanger 50 to be described later.

At this time, the high-pressure pump 32 may pressurize the LNG to the engine 20 at a pressure required by the engine 20, for example, 200 to 400 bar, thereby causing the engine 20 to produce thrust through the LNG .

The high pressure pump 32 is capable of phase-changing the LNG discharged from the boosting pump 31 to a supercritical state having a higher temperature and a higher pressure than the LNG at a high pressure have. At this time, the temperature of the supercritical LNG may be lower than -20 ° C, which is relatively higher than the critical temperature.

Or the high-pressure pump 32 can pressurize the LNG in a liquid state to a super-cooled liquid state by pressurizing it with a high pressure. Here, the LNG in the subcooled liquid state is a state in which the pressure of the LNG is higher than the critical pressure and the temperature is lower than the critical temperature.

Specifically, the high-pressure pump 32 pressurizes the liquid LNG discharged from the boosting pump 31 to a high pressure of 200 to 400 bar so that the temperature of the LNG becomes lower than the critical temperature, Phase change. Here, the temperature of the LNG in the subcooled liquid state may be -140 캜 to -60 캜, which is relatively lower than the critical temperature.

The heat exchanger 50 is provided on the fuel supply line 21 between the engine 20 and the pump 30 and exchanges the LNG supplied from the pump 30 with the glycol water and supplies the LNG to the engine 20 . The pump 30 for supplying the LNG to the heat exchanger 50 may be the high pressure pump 32 and the heat exchanger 50 may supply the LNG in the supercooled liquid state or the supercritical state to the high pressure pump 32 Heated to 200 to 400 bar, converted into LNG in a supercritical state of 30 to 60 degrees, and then supplied to the engine 20.

The heat exchanger 50 in the present embodiment can heat the LNG using the glycol water supplied from the glycol heater 63. [ The glycol water is a fluid obtained by mixing ethylene glycol and water. The glycol water is heated in the glycol heater 63, cooled in the heat exchanger 50, and circulated.

The temperature of the glycol water discharged after the heat exchange with the LNG in the heat exchanger 50 may vary depending on the LNG phase change of the high-pressure pump 32 mentioned above. That is, when the high-pressure pump 32 changes the phase of the LNG into the subcooled liquid state and then supplies it to the heat exchanger 50, the glycol water can be cooled while heating the subcooled LNG from 30 to 60 degrees, When the pump 32 phase-changes the LNG to a supercritical state and then supplies the LNG to the heat exchanger 50, the glycol water heats the supercritical LNG having a temperature higher than the supercooled liquid state to the required temperature of the engine 20 . At this time, the glycol water in the case of heat exchange with the LNG in the supercooled liquid state can be cooled to a lower temperature than the glycol water in the case of heat exchange with the LNG in the supercritical state, and then circulated to the glycol tank 61.

The glycol tank 61 can store the glycol water. The glycol tank 61 can store the glycol water at a temperature that can prevent cracking of the glycol water (a phenomenon in which water and ethylene glycol are separated due to a phase change of water).

A glycol pump 62 is provided downstream of the glycol tank 61 so that a predetermined amount of glycol water can be introduced into the glycol heater 63 from the glycol tank 61 by the glycol pump 62. A heat exchanger (50) is connected upstream of the glycol tank (61) to supply heat to the LNG, and the cooled glycol water can be reintroduced into the glycol tank (61).

The glycol tank 61 and the glycol pump 62, the glycol heater 63 and the heat exchanger 50 may be connected by a glycol circulation line 64. That is, the glycol water can be heated or cooled by moving in the order of the glycol tank 61, the glycol pump 62, the glycol heater 63, and the heat exchanger 50 while flowing along the glycol circulation line 64.

The glycol pump 62 supplies the glycol water stored in the glycol tank 61 to the glycol heater 63. The glycol pump 62 may be provided downstream of the glycol tank 61 and may transfer the glycol water from the glycol tank 61 to the glycol heater 63 in consideration of the amount of glycol water discharged from the heat exchanger 50 .

The glycol heater (63) heats the glycol water discharged from the glycol tank (61) and supplies it to the heat exchanger (50). The glycol heater 63 can heat the glycol water to a predetermined temperature so that the glycol water can supply the LNG with sufficient heat in the heat exchanger 50. [

The glycol heater 63 may use electric energy to heat the glycol water, but this embodiment can use steam. That is, the glycol heater 63 is supplied with steam generated by a boiler (not shown), the steam supplies heat to the glycol water, and the glycol water cools the steam so that the glycol water is heated and the steam is condensed into the condensed water .

At this time, the condensed water may be re-introduced into the boiler through the condensate tank 81, changed into steam, and then may be introduced into the glycol heater 63. The glycol water heated by the steam is discharged from the glycol heater 63, (50).

The steam supply line (70) supplies steam to the glycol heater (63). One end of the steam supply line 70 may be connected to the boiler and the other end may be connected to the glycol heater 63. The steam supply line 70 may be insulated so that the steam is smoothly supplied to the glycol heater 63.

The LNG fuel supply system 2 according to the present invention can be driven under various conditions, for example, the engine 20 can be stopped and restarted. When the steam is supplied at a pressure for sufficiently heating the glycol water, air is heated by the steam. In this case, The inner surface of the steam supply line 70 can be struck strongly.

That is, when the engine 20 is restarted at the time of initial operation or after stopping, steam is supplied to the steam supply line 70 at a normal pressure (which means that the steam is supplied to the steam supply line 70 in an environment in which LNG is supplied to the engine 20) There is a risk that a hammer phenomenon occurs in which the air that has been cooled suddenly expands and impacts the steam supply line 70.

Therefore, in this embodiment, it is possible to prevent damage to the steam supply line 70 by preventing the occurrence of the hammering phenomenon by supplying the steam for a predetermined time less than the preset pressure. The steam valves 71 and 72 will be described in detail below.

The steam valves 71 and 72 are provided on the steam supply line 70 to control the supply amount of steam. The steam valves 71 and 72 may include a steam control valve 71 and a steam block valve 72.

The steam control valve 71 is a valve for controlling the inflow amount of steam supplied to the glycol heater 63. The steam control valve 71 is not particularly limited in the form. However, the steam control valve 71 may be a valve controlled by a method of varying the area of the steam supply line 70, rather than a valve controlled by the On / Off method.

The steam control valve 71 can heat the steam supply line 70 by supplying steam for a predetermined time at a time when the engine 20 is initially started or after the stoppage is restarted. As described above, if the supply of steam is interrupted for a predetermined time in the steam supply line 70, the air cooled by the external environment may be cold. At this time, when the steam is strongly supplied, the steam suddenly expands and the steam supply line 70 may be damaged by an impact. Therefore, the steam control valve 71 of this embodiment can preheat the steam supply line 70. [

Specifically, the steam control valve 71 can supply steam for 5 to 10 minutes at a preset pressure (for example, 2 bar) to prevent the air in the steam supply line 70 from being rapidly expanded. After a predetermined time has elapsed, the steam control valve 71 can increase the supply pressure of steam and supply the steam. For example, the steam control valve 71 can supply steam at a pressure of 5 bar to 10 bar after a certain period of time.

5 bar to 10 bar means the supply pressure of the steam required to sufficiently heat the glycol water that is heat-exchanged with the LNG when the engine 20 is driven in a steady state. Of course, the present invention does not limit the steam supply pressure as described above .

The steam is regulated in pressure by the steam control valve 71. When the LNG is supplied to the engine 20 at the time of initial operation or after restarting the engine 20, Can be supplied to the heater (63). In this case, the cold air existing in the steam supply line 70 is expanded by the steam, but since the present embodiment supplies steam at a pressure lower than the pressure at the time of driving the engine 20, The occurrence of the hammering phenomenon in the line 70 can be prevented.

The steam block valve 72 is provided upstream of the steam control valve 71 on the steam supply line. The steam block valve 72 and the steam control valve 71 may be arranged in series on the steam supply line 70.

The steam block valve 72 is a valve that shields the flow of a fluid such as steam. The steam block valve 72 is not limited in its shape as in the steam control valve 71. That is, the steam block valve 72 may have the form of a butterfly valve, a ball valve, or the like.

The steam block valve 72 is opened to a maximum in operation of the steam control valve 71 and is capable of shielding at least a part of the steam supply line 70 when the steam control valve 71 is stopped to vary the supply amount of steam have. The operation stop of the steam control valve 71 may mean that the steam control valve 71 can not be driven due to breakage or the like.

When the steam control valve 71 is operated, the present embodiment can control the steam supply amount by the steam block valve 72 and adjust the supply amount of the steam through the steam control valve 71. However, if the steam control valve 71 is broken due to an unexpected cause, or if the operation is interrupted, the steam block valve 72 can control the inflow of steam instead of the steam control valve 71.

Therefore, in the present embodiment, even if the steam control valve 71 is not operated, the steam block valve 72 can be used to adjust the flow rate of the steam, and the temperature of the glycol water in the glycol heater 63 can be appropriately adjusted Can be maintained or varied.

4 is a flowchart of a method of supplying LNG fuel according to an embodiment of the present invention.

4, in the LNG fuel supply method according to the embodiment of the present invention, steam is supplied to the glycol heater 63 through the steam supply line 70 to heat the glycol water, and the LNG is heated (S110) of detecting the temperature of the steam supply line (70) when the engine (20) is restarted after the initial operation or after stopping the engine (20) in the heat exchange with the glycol water, A step S120 of heating the steam supply line 70 by supplying steam for a predetermined time less than the predetermined pressure S120, and a step S130 of raising the supply pressure of the steam after a lapse of a predetermined time and supplying the steam.

In step S110, the temperature of the steam supply line 70 is sensed when the engine 20 is initially started or after restarting. The temperature of the steam supply line 70 means the temperature of the space in which the steam supply line 70 is installed or the internal temperature of the steam supply line 70. The temperature of the steam supply line 70 can be sensed by a temperature sensor (not shown), and the temperature sensor is a general configuration, so a detailed description is omitted.

Since the outside temperature is generally lower than the temperature of the steam, the temperature of the steam supply line 70 may drop while the engine 20 is not driven. At this time, the air existing inside the steam supply line 70 can be cooled by the external environment and can remain as cold air.

If the steam is supplied at a pressure required for driving the engine 20 in such a situation, the air can be rapidly expanded by the steam, so that the inner surface of the steam supply line 70 can be strongly hit, Cracks may occur.

In step S120, when the temperature is lower than the predetermined temperature, the steam supply line 70 is heated by supplying steam for a predetermined time less than the preset pressure. As described above, when the temperature of the steam supply line 70 is lower than the preset temperature, if the steam is generally supplied, there is a fear of hamming due to rapid expansion of the cold air. Therefore, at step S120, the steam supply line 70 can be preheated by supplying the steam at a level lower than the predetermined pressure.

Through the preheating of the steam supply line 70, the cold air can gradually change to warm air, and the expansion of the air can also be gradual. In this case, the hammering phenomenon can be greatly reduced, and therefore the steam supply line 70 can smoothly supply the steam.

The predetermined temperature may be a temperature at which the hammering phenomenon may be fatal when the steam is supplied. For example, the predetermined temperature may be 10 degrees. However, the preset temperature is not particularly limited.

The preset pressure may be a preset range of 2 bar. And the period of time may be 5 to 10 minutes. This can be determined differently depending on specifications such as the diameter, length, etc. of the steam supply line 70.

In step S130, the supply pressure of the steam is increased after a predetermined time has elapsed. If it is determined that the predetermined time has elapsed, it can be determined that the steam supply line 70 is fully preheated, and that the cold air in the steam supply line 70 is removed to some extent, .

At this time, in this embodiment, for example, steam is supplied at a pressure of 5 bar to 10 bar so that steam can heat the glycol water in the glycol heater 63, so that the engine 20 can be smoothly driven.

Thus, in the present embodiment, when the steam supply line 70 is cooled by the external temperature, the steam supply line 70 is preheated, so that the cold air existing in the steam supply line 70 meets the steam, It is possible to prevent the supply line 70 from being impacted. Also, even if the steam leaks due to failure of the steam control valve 71 to operate, the steam block valve 72 can be used to supply a proper amount of steam to the glycol heater 63 smoothly.

5 is a conceptual diagram of an LNG fuel supply system according to another embodiment of the present invention.

The LNG storage tank 10, the engine 20, the pump 30, the heat exchanger 50, the glycol tank 61, the glycol pump 62 A glycol heater 63, a condensate discharge line 80, a condensate tank 81, a condensate discharge valve 82, and a condensate control valve 83. Except for the condensate discharge line 80, the condensate tank 81, the condensate discharge valve 82, and the condensate control valve 83, the other configurations are the same as those described in the foregoing embodiment, do.

The condensate discharge line (80) discharges the condensed water generated in the glycol heater (63). The glycol heater 63 is supplied with steam. As the steam and the glycol water heat-exchange, the glycol water is heated and the steam is cooled. The cooled steam condenses into the condensed water, and the condensed water can be discharged from the glycol heater 63 along the condensate discharge line 80.

The condensate discharge line 80 may be connected at one end to the glycol heater 63 and at the other end to a boiler (not shown). The condensed water condensed in the glycol heater 63 flows into the boiler along the condensate discharge line 80, and can be heated in the boiler to be converted into steam and then reintroduced into the glycol heater 63.

The condensate tank 81 stores condensed water. The condensate tank 81 may be provided downstream of the glycol heater 63 to temporarily store the condensed water discharged from the glycol heater 63. The condensate stored in the condensate tank 81 flows into the boiler through the condensate discharge valve 82 and the condensate control valve 83 and can be heated.

The condensate discharge valve 82 is provided on the condensate discharge line 80 and controls the discharge amount of the condensed water according to the level of the condensed water stored in the condensate tank 81. Condensate water is temporarily stored in the condensate water tank 81, and the internal pressure of the condensate water tank 81 may vary depending on the level of the condensed water. Since the internal pressure of the condensate tank 81 affects the inflow amount of the condensed water, the condensed water level finally determines the inflow amount of the glycol heater 63 of steam.

At this time, the condensate discharge valve 82 senses the level of the condensate stored in the condensate tank 81 and discharges the condensed water so that more steam can be introduced into the glycol heater 63. Or the condensate discharge valve 82 may reduce the amount of steam entering the glycol heater 63 by closing the condensate discharge line 80 or lowering the amount of condensate discharge so that the condensate can not be discharged from the condensate tank 81 have. That is, the condensate discharge valve 82 can control the discharge of the condensed water stored in the condensate tank 81 to control the amount of steam flowing into the glycol heater 63.

The condensate discharge valve 82 can be opened by the pressure of the condensed water stored in the condensate tank 81. That is, the condensate discharge valve 82 can be automatically opened and closed by the condensed water pressure. In this case, the amount of steam supplied to the glycol heater 63 can be controlled within a certain range.

However, when the condensate discharge valve 82 is opened by the condensed water pressure, the steam which has been introduced into the glycol heater 63 together with the condensed water can escape from the condensate discharge valve 82. In this case, as the steam is discharged from the glycol heater 63, the glycol water and the steam are not heat-exchanged properly, so that the glycol water can not be heated to a sufficient temperature, and therefore the LNG can not be heated to the temperature required by the engine . However, the present embodiment can prevent the steam from escaping through the condensate discharge valve 82 by providing the condensate control valve 83. [

A condensate control valve 83 is provided downstream of the condensate discharge valve 82 on the condensate discharge line 80. The condensate discharge valve 82 and the condensate control valve 83 may be disposed in series on the condensate discharge line 80.

The condensate control valve 83 can block the steam discharged to the outside by the condensate discharge valve 82. That is, if the condensate discharge valve 82 is opened due to the pressure of the condensed water, the condensate control valve 83 can be closed to prevent the discharge of steam from the outside.

The condensate control valve 83 can be opened when the condensate stored in the condensate tank 81 is above a predetermined level. When the condensate water is stored in the condensate tank 81 for a minimum amount of opening the condensate discharge valve 82, the condensed water can be discharged while opening the condensate discharge valve 82, And can be discharged.

However, if a sufficient amount of condensed water is stored in the condensate tank 81, the condensate discharge valve 82 can be automatically opened, and even if the condensate control valve 83 is opened, the steam can not be discharged together, have. Therefore, the condensate water control valve 83 can be opened or closed according to the level of the condensed water stored in the condensate water tank 81. In this case, the predetermined level means a level at which the flow rate of the condensed water is sufficient to the extent that the steam can not escape with the condensed water even if the valves 82 and 83 are opened. In this embodiment, Do not. The predetermined level may vary depending on the specification of the glycol heater 63, the size and shape of the condensate discharge valve 82, and the like.

In this way, according to the present embodiment, the condensate water discharge valve 82 is provided downstream of the condensate water tank 81 so that the condensed water can be discharged when a predetermined amount of condensed water is stored in the condensate water tank 81, It is possible to vary the amount to be introduced into the glycol heater 63.

In the case where the condensed water discharge valve 82 is automatically opened and closed by the condensed water, the present embodiment is provided with the condensed water control valve 83 to discharge the condensed water only when the condensed water is stored in the condensed water tank 81 in a sufficient amount , It is possible to prevent the steam from being mixed and discharged when the condensed water is discharged.

As described above, according to the present invention, by using the glycol water heated by the steam, the LNG is heated up to the required temperature of the engine 20, thereby reducing the amount of electric energy used, saving energy and building an environmentally friendly system.

The present invention can also prevent the cold air of the steam supply line (70) from hitting the steam supply line (70) due to the rapid expansion of the cold air in the steam supply line (70) by preheating the steam supply line (70) By providing the steam lines 71 and 72 in the supply line 70, the steam can be stably supplied.

The present invention also allows the condensed water stored in the condensate tank 81 to be discharged by the condensate discharge valve 82 or the condensate control valve 83 to control the inflow amount of the steam through the adjustment of the discharge amount of the condensed water, And can be prevented from being discharged along the condensate discharge line (80).

1: conventional LNG fuel supply system 2, 3: LNG fuel supply system of the present invention
10: LNG storage tank 11: outer tank
12: inner tank 13:
14: Support 15: Baffle
20: engine 21: fuel supply line
30: Pump 31: Boosting pump
32: high pressure pump 40: electric heater
50: heat exchanger 61: glycol tank
62: Glycol pump 63: Glycol heater
64: glycol circulation line 70: steam supply line
71: Steam control valve 72: Steam block valve
80: Condensate discharge line 81: Condensate tank
82: Condensate discharge valve 83: Condensate control valve

Claims (11)

A fuel supply line connected from the LNG storage tank to the engine;
A pump provided on the fuel supply line for pressurizing the LNG discharged from the LNG storage tank to a high pressure;
A heat exchanger provided on the fuel supply line between the engine and the pump, for heat-exchanging the LNG supplied from the pump with glycol water to supply the LNG to the engine;
A glycol heater for heating the glycol water with steam and supplying the glycol water to the heat exchanger;
A steam supply line for supplying steam to the glycol heater; And
And a steam valve provided on the steam supply line for heating the steam supply line,
The steam valve includes:
A steam control valve provided on the steam supply line for controlling the supply amount of the steam and heating the steam supply line by supplying steam for a predetermined time at a time of starting or stopping the engine at the time of restarting the engine; And
A steam supply line for supplying steam to the steam supply line; a steam supply line for supplying steam to the steam supply line; a steam supply line for supplying steam to the steam supply line; And a steam block valve for varying a supply amount of the steam. The steam generator according to claim 1,
And the steam is supplied for 5 to 10 minutes at a pressure in a predetermined range. The steam generator according to claim 1,
And the supply pressure of the steam is increased after the lapse of the predetermined time. The steam generator according to claim 1,
And the steam is supplied at a pressure of 5 bar to 10 bar after the lapse of the predetermined time. delete 2. The steam generator according to claim 1, wherein the steam control valve and the steam block valve comprise:
Wherein the steam supply line is arranged in series on the steam supply line. The method according to claim 1,
Further comprising a glycol tank for storing the glycol water,
Wherein the glycol heater heats the glycol water discharged from the glycol tank. 8. The method of claim 7,
Further comprising a glycol pump for supplying the glycol water stored in the glycol tank to the glycol heater. delete delete delete

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