KR101280152B1 - Fuel gas supply system of the indirect heat exchange form using heat of intake air - Google Patents

Abstract

The present invention relates to a fuel gas supply apparatus of an indirect heat exchange method using intake heat. The fuel gas supply device of the present invention, the fuel gas supply line (L1) connected from the LNG tank 20 to the engine 10; A feed pump 22 installed in the middle of the fuel gas supply line L1 and pumping LNG from the LNG tank 20 to the engine 10; A vaporizer 23 installed on the fuel gas supply line L1 between the feed pump 22 and the engine 10 to vaporize LNG; An intake bypass line 30 formed by branching the intake line 13 connected to the engine 10 from the supercharger 12; An intake heat using heat exchanger (40) installed on the intake bypass line (30) to allow heat exchange between the intake air flowing through the intake bypass line (30) and the heat exchange medium; The heat exchange medium is formed to circulate through the intake heat using heat exchanger 40 and the vaporizer 23, and the heat exchange medium exchanges heat with the intake air in the intake heat using heat exchanger 40 to extract heat from the intake air. A heat exchange medium circulation line 50 which enters 23 and heat exchanges again with LNG passing through the vaporizer 23 to vaporize the LNG; And a circulation pump 52 installed on the heat exchange medium circulation line 50 to circulate the heat exchange medium. The present invention utilizes a high temperature intake air supplied from the supercharger to the engine as a heat source for LNG vaporization, there is no need to install a separate heating device for vaporization of LNG, reducing the installation cost and power loss, the efficiency of the entire power system Will be improved.

Description

FUEL GAS SUPPLY SYSTEM OF THE INDIRECT HEAT EXCHANGE FORM USING HEAT OF INTAKE AIR}

The present invention relates to a fuel gas supply apparatus for a ship, an offshore floating structure, or an onshore power plant using LNG as an engine fuel, and more particularly, a separate heating device for a heat source for vaporizing LNG supplied from an LNG tank. Indirect heat exchange fuel gas supply system utilizing intake heat to reduce system maintenance cost and improve energy efficiency by obtaining from intake air (intake air) supplied to engine combustion chamber instead of supply from .

Vessels handling (storing, transporting) LNG (Liquefied Natural Gas) (e.g., LNG carriers), offshore floating structures (e.g., Floating Storage Regasification Units (FSRUs)), or onshore power generation The facility is equipped with a series of vaporization facilities for vaporizing the LNG stored in the LNG tank to maximize utilization by the engine power.

In recent years, LNG carriers tend to use diesel engines rather than turbine engines due to steam driving. Therefore, gaseous gas recovered in the LNG tank is recovered, liquefied into LNG, and then sent back to the LNG tank. Liquefaction equipment is being applied to LNG carriers.

However, such a reliquefaction apparatus has an unreasonable problem in that the expenditure of the expense of the facility and operation of the reliquefaction apparatus is much greater than the advantage of reliquefaction of the vaporized gas.

In this situation, recently, a dual (or heterogeneous) fuel engine has been used in which LNG can be alternately used as an auxiliary fuel of an engine together with heavy oil that is a main fuel of a diesel engine. This dual fuel engine has two combustion modes. As an example of two combustion modes, the secondary fuel (eg Marine Diesel Oil, Marine Gas Oil) is injected before the main fuel (eg, Heavy Fuel Oil, Marine Diesel Oil) is injected in the diesel fuel mode to control the combustion environment of the combustion chamber. Improves soot, NOx improvement and combustion performance. In addition, in the gas fuel mode, only the auxiliary fuel is injected by adjusting the fuel injection amount control device (governor) to achieve stable ignition of the gas fuel introduced through the gas admission valve.

In addition, the development of an engine (for example, MAN Diesel & Turbo's ME-GI engine) that burns and burns LNG gas fuel as a main fuel under high pressure injection and uses it as a propulsion engine or a main engine, fueling LNG again. have.

1 is a system diagram showing a configuration of an engine and a vaporization gas supply apparatus using a conventional LNG gas as a fuel.

The conventional vaporization gas supply apparatus includes the LNG tank 2, the pump 3 for LNG supply, the vaporizer 4, the heating apparatus 5, and the pump 7 for heat exchange medium supply.

Specifically, the fuel gas supply line between the LNG tank 2 and the engine 1 vaporizes a supply pump 3 for pumping LNG stored in the LNG tank 2 and fuel supplied from the supply pump 4. The vaporizer | carburetor 4 sent to the engine 1 is provided. In addition, a separate heat exchange medium circulation line 6 is provided in the vaporizer 4, and a heating device 5 and a heat exchange medium supply pump 7 are installed on the heat exchange medium circulation line 6. The heat exchange medium heated to a constant temperature in the heating device (5) enters the vaporizer (4) by the supply pump (7), heat exchanges with LNG passing through the vaporizer (4), and then circulates back to the heating device (5). . As a result, in the vaporizer | carburetor 4, LNG is vaporized through the heat exchange between a heat exchange medium and LNG, and this vaporized LNG is supplied as a fuel of the engine 1.

However, such a conventional vaporized gas supply device has the following problems.

First, since a heating device 5 which is a heating source of the heat exchange medium is additionally required to vaporize LNG, a part of the power energy generated from the engine 1 is consumed by the heating device 5 which heats the heat exchange medium again. Thus, considering the energy aspect of the overall power system, it is impossible to expect great efficiency.

In addition, in order to satisfy the requirements of the heating apparatus 5 and the vaporizer 4 for vaporizing LNG, facilities such as the vaporizer 4, the heating apparatus 5, and the engine 1 equipment need to be enlarged. This results in increased maintenance costs.

In addition, ethylene glycol (Ethylene Glycol), which is a kind of antifreeze called glycol water, is mainly used as the heat exchange medium for circulating the heat exchange medium circulation line 6 to provide vaporization heat to LNG. This ethylene glycol is a highly viscous colorless liquid having a molecular weight of 62.07, melting point −12.6 ° C., boiling point 197.7 ° C., and specific gravity 1.1131, which exchange heat with LNG liquefied under high pressure and cryogenic temperature (about -163 ° C.), even though the melting point is relatively low. Freezing may occur during the process. In particular, if a failure occurs in the heating device 5, the low temperature of LNG may cause a great risk of freezing of the piping of the heat exchange medium circulation line 6, as well as the surrounding vaporization equipment, or being damaged by freezing. There is.

Therefore, an object of the present invention, by utilizing the heat energy of the high temperature intake supplied to the engine as a heat source for vaporizing LNG, to prevent the loss of power generated in the engine, and additional installation of a heating device for heating the heat exchange medium Therefore, to provide an indirect heat exchange fuel gas supply unit fuel gas supply unit using intake heat that can improve the efficiency of the entire power system accordingly.

Another object of the present invention is to utilize the intake air that is compressed through the supercharger before reaching the supercharged air cooler to vaporize LNG, thereby increasing the cooling efficiency of the cooler by primarily cooling the intake air entering the combustion chamber of the engine, It is possible to reduce the load or reduce the capacity of the cooling system to minimize operating costs and maximize system efficiency.

It is still another object of the present invention to provide a system in which heat of intake heat and LNG are indirectly exchanged, thereby eliminating the concern about intake of intake gas from the vaporized gas as compared to the direct heat exchange method.

In order to achieve the above object, the indirect heat exchange fuel gas supply apparatus using the intake heat according to the present invention, the fuel gas supply line is connected to the engine from the LNG tank; A supply pump installed in the middle of the fuel gas supply line and pumping LNG from the LNG tank to the engine side; A vaporizer installed on a fuel gas supply line between the feed pump and the engine to vaporize LNG; An intake bypass line formed by branching an intake line connected to the engine from the supercharger; An intake heat using heat exchanger installed on the intake bypass line to perform heat exchange between the intake flowing through the intake bypass line and the heat exchange medium; A heat exchange medium is circulated between the intake heat using heat exchanger and the vaporizer, and the heat exchange medium first exchanges heat with the intake in the intake heat using heat exchanger to extract heat from the intake, and then passes through the carburetor with the LNG; A heat exchange medium circulation line for vaporizing the LNG by second heat exchange; And a circulation pump installed on the heat exchange medium circulation line to circulate the heat exchange medium.

It is preferable that the intake bypass line branches on an upstream side of the charge air cooler that cools the intake air that has passed through the supercharger before being supplied to the engine.

It is preferable to install a three-way valve at the branch point of the intake bypass line, so that the three-way valve adjusts some or all of the intake air from the supercharger to flow into the intake bypass line.

On the fuel gas supply line between the LNG tank and the feed pump, a buffer tank for temporarily storing LNG and discharging the stored LNG by internal pressure may be installed.

According to the fuel gas supply device of the indirect heat exchange method using the intake heat of the present invention, by using a high temperature intake air supplied from the supercharger to the engine as a heat source for LNG vaporization, it is necessary to install a separate heating device for vaporization of LNG There will be no. Therefore, according to the present invention, the loss of power is reduced, and the efficiency of the entire power system is improved.

In addition, according to the fuel gas supply apparatus utilizing the intake heat of the present invention, the intake air entering the engine combustion chamber by heat exchange between the intake and the LNG is utilized by utilizing the intake air before being compressed through the supercharger to vaporize the LNG. By first cooling the coolant before reaching the cooler, the load on the cooler can be reduced and the cooling efficiency can be increased. According to this, it is possible to reduce the capacity of the cooling installation, as well as to minimize the maintenance cost and to maximize the overall system efficiency.

1 is a system diagram of a conventional vaporization gas supply apparatus.
2 is a system diagram of a vaporization gas supply apparatus utilizing intake heat according to the present invention.

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

2 is a schematic diagram of a vaporization gas supply apparatus utilizing intake heat according to the present invention.

Referring to Figure 2, in the vaporization gas supply apparatus using the intake heat according to the present invention, the engine 10 is provided with a charger (12) for increasing the engine output by compressing the intake air to a high pressure, the supercharger The engine is provided with a charge air cooler (cooler or inter cooler) 14 for cooling the intake air compressed in 12 to increase the density and increase the charging efficiency.

The supercharger 12 shown in FIG. 2 drives the turbine by the flow energy of the engine exhaust gas discharged to the exhaust gas line 11, and exhaust gas turbo-charger which compresses the intake air by the rotation of the turbine. ), But may be a mechanical super charger system driven by the power of the engine.

The present invention, by utilizing the heat of the intake (air) of the high temperature and high pressure flowing through the intake line 13 through the supercharger 12 is already installed and operated in the existing engine as a heat source for vaporizing LNG, It is to be able to vaporize LNG without heating device.

Specifically, the fuel gas supply apparatus of the indirect heat exchange method using intake heat according to the present invention includes a fuel gas supply line L1 connected from the LNG tank 20 to the engine 10, and a fuel gas supply line L1. Is installed in the middle of the feed pump 22 to pump the LNG from the LNG tank 20 to the engine 10 side, and is installed on the fuel gas supply line L1 between the feed pump 22 and the engine 10. On the intake bypass line 30 and the intake bypass line 30 formed by branching the vaporizer 23 which vaporizes LNG, the intake line 13 connected to the engine 10 from the supercharger 12, The heat exchange medium is circulated through the intake heat using heat exchanger 40 and the intake heat using heat exchanger 40 and the vaporizer 23 which are installed to allow heat exchange between the intake air flowing through the intake bypass line 30 and the heat exchange medium. And a heat exchange medium to the intake heat utilizing heat exchanger 40. Heat exchange with the intake air to remove the heat of the intake, the heat exchange medium circulation line 50 to enter the vaporizer 23 and heat exchange again with the LNG passing through the vaporizer 23 to vaporize the LNG, and a heat exchange medium circulation line ( 50 is installed on the circulation pump 52 for circulating the heat exchange medium.

Accordingly, the intake air flows along the intake air bypass line 30 branching the intake line 13 of the engine to the intake heat using heat exchanger 40 to exchange heat with the heat exchange medium, and in the intake heat using heat exchanger 40 The heat exchange medium which takes heat from the intake air is circulated back to the vaporizer 23 to exchange heat with LNG passing through the vaporizer 23 to vaporize the LNG.

Here, the intake bypass line 30 branches on the upstream side of the charge air cooler 14 which cools the intake air passing through the supercharger 12 before being supplied to the engine.

By doing so, the heat exchange efficiency in the intake heat utilizing heat exchanger 40 is increased by utilizing the intake heat of high temperature and high pressure before being cooled by the charge air cooler 14 as it is.

In addition, by allowing the intake air to be primarily cooled in the intake heat using heat exchanger 40 before entering the charge air cooler 14, the cooling efficiency in the charge air cooler 14 can be maximized, and the charge air cooler ( As the efficiency of 14 increases, the charge air cooler 14 having a small capacity may be used.

In addition, a three-way valve 32 is provided at the branch point of the intake air bypass line 30. The three-way valve 32 adjusts a portion of the intake air from the supercharger 12 to enter the intake bypass line 30 or a portion of the intake air from the supercharger 12 flows into the intake bypass line 30. You can adjust it.

In addition, on the fuel gas supply line L1 between the LNG tank 20 and the feed pump 22, a buffer tank 21 for temporarily storing LNG and discharging the stored LNG by internal pressure is provided.

The buffer tank 21 is also referred to as a so-called 'suction drum', and the LNG is temporarily pumped from the LNG tank 20 to the supply pump 22 instead of being temporarily pumped to the buffer tank 21. After storage, the LNG can be supplied to feed pump 22 at a stable (constant) pressure.

If LNG, which is compressed at low temperature (-163 ° C.) in the LNG tank 20, is directly supplied to the supply pump 22, LNG is not easily controlled. Therefore, LNG having an appropriate pressure and capacity is supplied to the vaporizer 23. It is not easy to supply.

For this reason, the buffer tank 21 is provided between the LNG tank 20 and the feed pump 22 so that LNG of a stable pressure and capacity can always be supplied to the feed pump 102.

Although not shown in FIG. 2, the buffer tank 21 includes means for adjusting a storage pressure and a storage capacity of the LNG flowing into the LNG tank 21, so that the LNG having a constant pressure and capacity is always provided toward the LNG supply pump 102. Can be supplied stably.

For example, the storage pressure regulating means in the buffer tank 21 may include a pressure controller, a pressure regulating valve and a pressure sensor. The pressure controller receives pressure information from the pressure sensor located in the buffer tank 21, opens and closes the pressure control valve, and returns the natural vaporized gas located above the LNG level in the buffer tank 21 to the LNG tank 20. Accordingly, the pressure inside the buffer tank 21 can be kept constant at a predetermined pressure.

The storage capacity adjusting means of the buffer tank 21 may include a capacity controller, a capacity sensor, and a capacity control valve. The capacity controller receives the capacity (level) information of the LNG from the capacity sensor in the buffer tank 21 to open and close the capacity control valve to keep the level of LNG constant.

On the other hand, as the heat exchange medium flowing through the heat exchange medium circulation line 50, an antifreeze and a coolant mixed solution are suitable. Ethylene glycol is suitable as an antifreeze solution and other antifreeze solutions can be used.

As described above, even if an antifreeze and a coolant mixed solution are used as the heat exchange medium, in the present invention, since the heat exchange medium is heated by using the intake of the engine, as in the conventional case of using a separate heating device, the failure of the heating device and the piping accordingly There is no need to worry about freezing of the back.

In addition, since the indirect heat exchange system heats the heat exchange medium primarily by using the heat of intake air supplied to the engine, and circulates the heat exchange medium back to the vaporizer to exchange heat with LNG, high-pressure LNG gas flows into the engine together with the intake air. There is no concern. For example, in the case of using a direct heat exchange method in which the bypass pipe 30 is directly connected to the vaporizer 23 to directly heat exchange the intake gas and LNG, the bypass pipe 30 is formed to extend in the vaporizer 23. If micro-cracks occur in the process of heat shrink bundles repeating heat shrink and expansion, high-pressure LNG gas may penetrate the bypass pipe 30 and enter the engine intake tube, causing an accident. There is. However, if the indirect heat exchange method is used as in the present invention, the LNG gas may be displaced as much as the concern about the accident of entering the intake cylinder.

The foregoing is a description of certain preferred embodiments of the present invention. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein, but may be modified and altered without departing from the spirit and scope of the invention as defined in the appended claims.

10: Engine
11: exhaust gas line
12: supercharger
13: intake line
14: supercharged air cooler
20: LNG tank
21: buffer tank
22: feed pump
23: carburetor
30: intake bypass line
40: heat exchanger
50: heat exchange medium circulation line
52: circulation pump

Claims (4)

A fuel gas supply line L1 connected to the engine 10 from the LNG tank 20;
A feed pump 22 installed in the middle of the fuel gas supply line L1 and pumping LNG from the LNG tank 20 to the engine 10;
A vaporizer 23 installed on the fuel gas supply line L1 between the feed pump 22 and the engine 10 to vaporize LNG;
An intake bypass line 30 formed by branching the intake line 13 of the engine connected to the engine 10 from the supercharger 12;
An intake heat using heat exchanger (40) installed on the intake bypass line (30) to heat the heat exchange medium by intake air flowing through the intake bypass line (30);
The heat exchange medium is circulated through the intake heat using heat exchanger 40 and the vaporizer 23, and the heat exchange medium is primarily heat exchanged with the intake in the intake heat using heat exchanger 40 to heat the intake air. A heat exchange medium circulation line (50) which enters the vaporizer (23) and then heat-exchanges with LNG passing through the vaporizer (23) to vaporize the LNG; And
Indirect heat exchange fuel gas supply apparatus using the intake heat, characterized in that it comprises a circulating pump (52) installed on the heat exchange medium circulation line (50) for circulating the heat exchange medium. The method of claim 1,
The intake bypass line 30 is branched from an upstream side of the charge air cooler 14 for cooling the intake air from the supercharger 12 before being supplied to the engine. Fuel gas supply. The method of claim 1,
A three-way valve 32 is installed at the branch point of the intake bypass line 30, and the three-way valve 32 introduces a part or all of the intake air from the supercharger 12 into the intake bypass line 30. Indirect heat exchange fuel gas supply apparatus using intake heat, characterized in that to be adjusted to. The method of claim 1, wherein
On the fuel gas supply line L1 between the LNG tank 20 and the feed pump 22, a buffer tank 21 for temporarily storing LNG and discharging the stored LNG by internal pressure is installed. Indirect heat exchanger fuel gas supply system using intake heat.

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