KR100748734B1 - Fuel gas supply system of lng carrier being attached engine using double fuel - Google Patents

Abstract

A fuel gas supply system of an LNG carrier to which a dual fuel using engine is provided to install a one speed type compressor by installed a return line extending from a low capacity compressor to a liquid separator. A fuel gas supply system of an LNG carrier includes a liquid separator(3), a low capacity compressor(4), an after cooler/heater, and high capacity compressor bypass line, and a high capacity heater(9). The gas naturally evaporated in a cargo tank is supplied to the liquid separator. The low capacity compressor compresses the evaporated gas discharged from the liquid separator. The after cooler/heater cools and heat the gas discharged through the low capacity compressor. The high capacity compressor bypass line introduced the evaporated gas before the evaporated gas is introduced into the liquid separator. The high capacity heater controls the gas detouring the high capacity compressor to a temperature suitable for an engine. A line is installed from the low capacity compressor to the liquid separator so that a one speed type motor can be used in the low capacity compressor. The motor in the low capacity compressor is changed from two speed to one speed until the temperature of the evaporated gas reach a predetermined value by circulating the evaporated gas.

Description

Fuel gas supply system of LNG carrier being attached engine using double fuel}

1 is a schematic diagram showing a fuel gas supply system of a liquefied natural gas carrier equipped with a dual fuel engine according to the present invention;

2 is a schematic diagram showing a fuel gas supply system of a liquefied natural gas carrier equipped with a general dual fuel use engine;

<Explanation of symbols for main parts of the drawings>

1: cargo tank 2: inline mixer

3: liquid phase separator 4: low volume compressor

5: cooler / heater 6: forced carburetor

8: High Capacity Compressor 9: High Capacity Heater

10: Bypass Line 11: Control Valve

12: Return Line 13: Bypass Line

V: Valve L: Basic Line

The present invention relates to a fuel gas system of a liquefied natural gas carrier equipped with a dual fuel engine, and more particularly, to a liquefaction with a dual fuel engine that can simplify the configuration of the fuel gas system and achieve cost reduction. A fuel gas system for a natural gas carrier.

In general, liquefied natural gas, that is, LNG (LIQUIFIED PETROLEUM GAS) is a natural gas (NG; NATURAL GAS) based on methane is cooled to a very low temperature of minus 162 ℃ to reduce the volume to approximately 1/600.

In order to use the liquefied natural gas as an energy source, a large amount of liquefied natural gas (LNG) needs to be transported from the production base to the consumer, and for this, a liquefied natural gas carrier is required.

That is, liquefied natural gas in a gaseous state at the loading port, which is a natural gas production area, is stored in a storage tank of a liquefied natural gas carrier, and after arriving at the unloading port, liquefied natural gas at low temperature. The gas is converted into natural gas and then supplied to the consumer through piping.

The liquefied natural gas carrier is equipped with a spherical independent tank type or a membrane type tank to store the liquefied natural gas. In the case of the membrane type, the liquefied natural gas is stored and transported in the cargo hold of the carrier.

The boil-off gas is discharged into the atmosphere or burned in a boiler in a ship without a reliquefaction system, and in a ship equipped with a reliquefaction system, the boil-off gas is re-liquefied and returned to the cargo hold.

Here, if a dual type engine that uses vaporized gas and a diesel engine as fuel for the vessel is installed, that is, a dual fuel engine is used, the vaporized gas is used as the fuel of the engine. It is mounted on the gas system.

As shown in FIG. 2, the first liquid phase separator 51 is connected to a natural vaporization line so as to remove water from the natural vaporized liquefied natural gas in the cargo tank 50, and the first liquid phase separator. Two low-capacity compressors 52 installed to pressurize the gas passing through the 51, an after-cooler 53 provided to lower the temperature of the gas passing through the low-capacity compressor 52, and the after-sales unit. It consists of a low-capacity heater 54 installed to match the temperature of the gas passing through the cooler 53 to the required temperature of the engine, and a buffer tank 55 for temporarily storing the gas and returning the gas to the cargo tank 50 when overloaded. .

Here, the low-capacity compressor 52 uses a 2 SPEED type motor to facilitate starting when the gas temperature is low, and the after cooler 53 uses an LNG SPRAY TYPE for cooling by injecting liquefied natural gas. do.

Further, a forced vaporizer 56 and a line are connected to the low capacity heater 54 through a second liquid phase separator (forced liquid phase separator) 57 to forcibly vaporize the gas in the cargo tank 50, The high capacity compressor 58 and the high capacity heater 59 are installed in the natural vaporization line so as to be selected and used according to the capacity of the gas.

Of course, the low- and high-capacity heaters 54 and 59 are connected to a gas combustion unit (GCU) to combust gas.

However, when the two liquid phase separators are installed as described above and the low volume and high capacity heaters are used, the devices having the same function are duplicated and thus the configuration of the device is unnecessarily complicated and the material cost and installation cost are increased. .

In addition, since there is no return line to the liquid phase separator, a low-capacity compressor uses a two-speed feeder as an initial starting problem, causing unnecessary equipment cost increase. Accordingly, an object of the present invention is to solve the above problems, and by using only one liquid separator and a high capacity heater, and to install a return line to the liquid phase separator so that a low capacity compressor can use a 1 SPEED type motor, the device is constructed. To provide a fuel gas supply system for a LNG carrier equipped with a dual fuel engine that can simplify the cost of materials and reduce installation and installation costs.

In addition, the control valve 7 and the bypass line 8 are provided at the front end of the forced vaporizer and the high capacity heater so as to supply fuel gas in the entire range required by the engine, thereby expanding the flow control range of the gas.

In order to achieve the above object, the present invention, through the liquid separator is installed so that the vaporized gas evaporated from the cargo tank, a low capacity compressor installed to compress the evaporated gas discharged from the liquid separator, and the low capacity compressor After cooler / heater that cools or heats the discharged gas and supplies it to a gas combustor or engine, and a high capacity compressor and its bypass installed to bypass the boil-off gas before the boil-off gas enters the liquid phase separator. In the fuel gas supply system of a liquefied natural gas carrier ship equipped with a dual-fuel engine comprising a pass line and a high capacity heater to allow the gas passed through the high capacity compressor to be adjusted to a temperature suitable for the engine,

In order to expand the flow control range, a control valve and a thatch bypass line are installed at the introduction portion of the forced vaporizer and the high capacity heater, and the liquid phase separator 7 of the forced vaporizer is removed in FIG. Incorporating a liquid phase separator, in consideration of the control of the compressor and various system operating modes, a separate line / valve 13 is installed for the purpose of load division of the low volume compressor, and the low speed compressor is equipped with a 1 speed type motor. And a return line which circulates the gas discharged from the low capacity compressor back into the liquid phase separator to control the temperature of the gas.

The present invention provides a liquid separator installed to supply a vaporized gas evaporated from a cargo tank, a low capacity compressor installed to compress the evaporated gas discharged from the liquid separator, and cooling the temperature of the gas discharged through the low capacity compressor. The after cooler for supplying the gas combustor or engine, the high capacity compressor bypass line installed to bypass the evaporation gas before the evaporation gas enters the liquid phase separator, and the gas bypassing the high capacity compressor is suitable for the engine. In a fuel gas supply system of a LNG carrier equipped with a dual-fuel engine including a high capacity heater to be controlled by temperature,

In order to use the 1-speed type motor in the low-capacity compressor described above, the low-capacity compressor is changed from 2 speeds to 1 speed by installing a line from the low-capacity compressor to the liquid separator and circulating until the temperature becomes appropriate. do.

The present invention also includes a bypass line / valve 13 installed to improve the load distribution efficiency of the gas discharged from the low volume compressor.

In addition, the present invention provides a control valve and an additional bypass line at the introduction portion of the forced vaporizer and the high capacity heater, and a control valve having a different flow control range than the control valve described above.

In addition, the present invention uses an aftercooler of the type for cooling / heating the gas using fresh water instead of the LNG injection after cooler.

In addition, the present invention deletes the liquid phase separator (7) for the forced vaporizer to separate the liquid phase in the gas from the forced vaporizer, the liquid phase separator (3) is composed of two liquid phase separators.

1 is a schematic view showing a fuel gas supply system of a liquefied natural gas carrier equipped with a dual fuel use engine according to the present invention, in which a natural vaporized evaporated gas is supplied through an inline mixer 2 in a cargo tank 1. Two low-capacity compressors 4 installed so as to compress the vaporized gas discharged from the liquid-phase separator 3 and the one-speed motor, and the low-capacity compressor 4 4) the gas discharged through the cargo tank 1 and the after cooler / heater 5 for cooling the temperature of the gas discharged through the water by spraying water and supplying the gas to the GCU or the engine. A forced vaporizer 6 provided to supply the liquid phase separator 3, a high capacity compressor 8 bypass line installed to bypass the boil-off gas before the boil-off gas enters the liquid phase separator 3, and the high-capacity compressor described above. Consists of a high capacity heater (9) for the gas bypass (8) to be adjusted to a temperature suitable for the engine.

Of course, a plurality of valves are installed to control when the gas is introduced or discharged into each of the above components and when they are merged or branched with each other, and in the after cooler / heater 5, the heater portion is formed of a forced vaporized gas. To increase the temperature, the temperature control range of the gas can be expanded more.

The bypass line 10 is installed at the inlet of the forced vaporizer 6 and the inlet of the high capacity heater 9, and the control valve 11 having a different capacity from that of the valve V installed at the basic line L. It is possible to increase the flow control range of the gas supplied to the engine and the gas combustion apparatus, so that full range control is possible.

That is, the capacity control of the gas flowing into the forced vaporizer 6 and the gas flowing into the high-capacity heater 9 is performed by the control valve V and the bypass line 10 installed in the base line L having different flow rate control capacities. It is controlled by the control valve 11 installed in the double.

For example, since the valve V is a valve for controlling a very small amount of gas, and the control valve 11 is configured as a valve capable of controlling a large amount of gas, very fine gas control is possible. The flow control range of the gas can be maximized.

In particular, a return line 12 is provided to facilitate the starting of the compressor motor by introducing the gas discharged from the low-capacity compressor 4 back into the liquid phase separator 3 to lower the temperature of the gas. By controlling the temperature of the compressor by the return line 12 described above, one-speed type motor can be used.

In addition, the bypass line 13 is provided to disperse the gas discharged from the low-capacity compressor 4, which makes it possible to distribute the load of the discharged gas to facilitate the distribution of the load.

Referring to the operation and effect of the present invention as described above, when the natural vaporized evaporated gas is generated in the cargo tank 1, the evaporated gas is introduced into the liquid phase separator 3 through the pipe and the in-line mixer (2).

The boil-off gas introduced into the liquid phase separator 3 is introduced into the low volume compressor 4 with water removed therethrough and adjusted to a suitable temperature in the cooler / heater 5 of the water spray type.

At this time, in the initial starting of the low-capacity compressor 4, if the temperature of the boil-off gas passing through the low-capacity compressor is too high, it is circulated back through the return line 12 to the liquid phase separator 3 to be a proper temperature. .

When the temperature of the gas is adjusted to an appropriate temperature, it passes through the heater and the cooler 5 to supply the engine or the gas combustion device.

Of course, the control of each valve, such as the operation of the heater and cooler 5 and the operation such that the boil-off gas is introduced into the return line 12 is performed in a separate control device.

Here, when the gas is forced to vaporize in the forced vaporizer 6 in addition to the natural vaporized gas, the valve (V) and the control valve 11 is operated, the gas flowing into the forced vaporizer (6) By more precisely controlling the amount of, the flow rate control width of the gas is greatly increased to allow full range control.

The gas forcibly vaporized by the forced vaporizer 6 is introduced into the liquid phase separator 3 to be supplied to the engine through the low capacity compressor 4 and the heater / cooler 5 in a state where water is removed.

When the natural vaporized gas is introduced into the high capacity compressor 8 without passing through the liquid phase separator 3 and the inline mixer 2, the bypass line 10 and the control valve 11 installed in the high capacity heater 9 are provided. The supply width of the flow rate can be adjusted in a larger range.

As described above, in the present invention, the bypass line and the control valve are installed at the inlet of the forced vaporizer and the high capacity heater to expand the control range of the flow rate so that the full range control is possible, and the return line is installed as the liquid separator in the low capacity compressor. 1 By installing a SPEED type compressor and converting the LNG SPRAY TYPE After Cooler into a fresh water-based after cooler / heater, it can be used in various operating modes of the ship, and prevents excessive evaporation gas generation. The installation of only one installed heater and liquid phase separator has the advantage of simplifying the fuel gas system of the LNG carrier equipped with the entire dual fuel engine and reducing the installation cost.

Claims (5)

A gas combustor which cools the temperature of the gas discharged through the low volume compressor installed in the cargo tank, a low capacity compressor installed to compress the evaporated gas discharged from the liquid separator, and the low volume compressor. Alternatively, the after-cooler supplied to the engine, the high capacity compressor bypass line installed to bypass the evaporation gas before the evaporation gas is introduced into the liquid phase separator, and the gas bypassing the high capacity compressor are adjusted to a temperature suitable for the engine. In a fuel gas supply system of a liquefied natural gas carrier equipped with a dual-fuel engine including a high capacity heater, In order to use the 1-speed type motor in the low-capacity compressor described above, the low-capacity compressor is changed from 2 speeds to 1 speed by installing a line from the low-capacity compressor to the liquid separator and circulating until the temperature becomes appropriate. Fuel gas supply system of the LNG carrier. The fuel of the LNG carrier according to claim 1, further comprising a bypass line / valve (13) installed to improve the load distribution efficiency of the gas discharged from the low capacity compressor. Gas supply system. 2. The dual fuel engine according to claim 1, wherein a control valve, an additional bypass line, and a control valve having a different flow control range than the control valve are installed at the introduction portion of the forced vaporizer and the high capacity heater. Fuel gas supply system of this LNG carrier. The LNG carrier according to any one of claims 1 to 3, wherein an aftercooler of a type for cooling / heating gas by using fresh water instead of an LNG injection after cooler is used. Fuel gas supply system. The liquefied natural gas carrier according to claim 1, wherein the liquid phase separator (7) for the forced vaporizer that separates the liquid phase in the gas from the forced vaporizer is removed, but the two liquid phase separators are integrated into one liquid phase separator (3). Fuel gas supply system.

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