KR101957091B1 - Lng fuel supply system utilizing phase changing fluid - Google Patents

Abstract

The present invention relates to an LNG fuel supply system, and more specifically, to an LNG supply system using fluid causing a phase change, which uses fluid causing a phase change as a heat source of vaporization to vaporize LNG and supplies the same for propulsion of an LNG propulsion ship and fuel of an auxiliary engine. The present invention, which is the fuel supply system of LNG propulsion ships, vaporizing the LNG to supply the same for the fuel of the engine, is characterized by using the fluid causing a phase change as the heat source for vaporizing the LNG.

Description

TECHNICAL FIELD [0001] The present invention relates to an LNG fuel supply system using a fluid for causing a phase change,

The present invention relates to an LNG fuel supply system using a fluid that causes phase change in which LNG is vaporized and supplied as fuel to an engine for propulsion and monitoring of an LNG propulsion vessel.

Liquefied natural gas (LNG) is a liquefied natural gas cooled at atmospheric pressure below the boiling point of methane (-162 ° C), which is the main component, and is reduced to about 1/600 compared with the volume at 0 ° C It is easy to store and transport, and there is no sulfur dioxide gas when it is burned.

An LNG propulsion vessel engine using such LNG as a fuel is separately provided in an LNG fuel supply system for supplying LNG stored in a fuel tank with a high pressure gas to the engine in response to high pressure gas demand.

The LNG fuel supply system includes a pump for pressurizing the LNG and a vaporizer for vaporizing and uses seawater or glycol water as a heat source for vaporization.

However, both of the seawater and glycol water have a disadvantage in that the amount of energy consumption is relatively large because the heat capacity within the allowable operating temperature range is small. In addition, seawater and glycol water are corrosive to metals, and there is a disadvantage that they must be accompanied by a design for corrosion prevention in a vaporizer and piping which are in contact with each other.

In order to solve the drawbacks of using seawater or glycol water as a heat source for vaporizing LNG as described above, development of a technology capable of effectively vaporizing LNG and supplying it as fuel using a heat source having a large heat capacity and no corrosiveness to metal need.

Korean Registered Patent No. 10-1368796, Registered as a Registered Person on Feb. 24, 2014. Korean Registered Patent Publication No. 10-1302006, 2013.08.26 Registration. Korean Registered Patent No. 10-1681716, November 25, 2016.

Disclosure of Invention Technical Problem [8] The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a fluid for causing a phase change that can reduce energy consumption by a large heat capacity and is not corrosive to metals, The present invention provides a LNG fuel supply system using a fluid which causes phase change by supplying LNG as fuel to the engine for propulsion and monitoring of LNG propulsion vessel by vaporizing LNG by using it as a heat source of vaporization.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood from the following description.

In order to achieve the above object, according to the present invention, there is provided an LNG fuel supply system using a fluid for causing a phase change, comprising: a fuel supply system for an LNG propulsion vessel that vaporizes LNG to supply fuel to the engine, Is used as a heat source for vaporization.

A vaporizer for vaporizing the LNG into heat of the fluid; A compensation tank for storing the fluid liquefied in the vaporizer; A transfer pump for transferring the fluid stored in the compensation tank; A heat exchanger for vaporizing the fluid transferred by the transfer pump; And a high-pressure storage tank connected in parallel between the transfer pump and the heat exchanger to store the liquefied fluid in a liquid state at normal temperature.

And a heater for raising the liquefied LNG using the heat of the fluid vaporized by the heat exchanger.

And temperature adjusting means connected between the vaporizer and the heat exchanger in parallel with the heater to adjust the temperature of the vaporized LNG to the heat of the vaporized fluid.

And the fluid causing the phase change is CO ₂ .

And a separator connected to a rear end of the heater to separate and remove moisture that may be contained in the vaporized LNG.

A control valve installed on a bypass pipe connected to the heater in parallel with the heater to control the fluid supplied by the heater to be supplied to the bypass pipe or the heater in accordance with the opening / closing operation; A temperature sensor for sensing the temperature of the LNG vaporized by the vaporizer; And a controller for controlling the opening and closing operation of the control valve according to a result of comparing the temperature of the LNG detected by the temperature sensor with a predetermined required temperature.

And the heat exchanger is configured to vaporize the fluid by receiving heat from the coolant-cooled cooling water of the engine.

The following effects can be expected in the LNG fuel supply system using the fluid that causes the phase change according to the present invention having the above-described configuration.

First, by using a fluid that causes a phase change as a heat source for LNG vaporization, a flow rate of a heat source necessary for LNG vaporization is reduced, and energy consumption is greatly reduced, thereby reducing operating costs.

When the temperature of the vaporized LNG is raised to correspond to the required temperature of the engine, the energy consumption for regulating the temperature of the LNG is greatly reduced by using the phase-changed gas through the heat of the engine to further reduce the operating cost .

In addition, since a high-pressure storage tank for storing high-pressure fluid existing in a liquid state at room temperature is separately provided, the fluid is bypassed to the high-pressure storage tank when the pressure of the fluid rises, .

1 is a configuration diagram of an LNG fuel supply system using a fluid for causing a phase change according to a preferred embodiment of the present invention.
2 is a block diagram of a control system for an LNG fuel supply system using a fluid for causing a phase change according to a preferred embodiment of the present invention.

The present invention relates to an LNG fuel supply system using a fluid that causes phase change to vaporize LNG and supply it as fuel for propulsion and viewing engines of LNG PS vessels.

Particularly, the LNG fuel supply system using the fluid to cause the phase change according to the present invention uses a fluid that causes phase change without using seawater, glycol water or the like as a heat source for LNG vaporization, It can reduce energy consumption greatly and is not corrosive to metal, so it can exclude corrosion prevention design for vaporizer and piping.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an LNG fuel supply system using a fluid for causing a phase change according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1, the LNG storage tank 10, the booster pump 20, the vaporizer 30, the compensation tank 40, and the recovery tank 40 are connected to the LNG storage tank 10, A transfer pump 50, a heat exchanger 60, a heater 70, a temperature control means, and a pressure maintaining means.

First, the LNG storage tank 10 is configured to store and supply LNG in a liquid state that can be used as fuel for an engine for propulsion and monitoring of an LNG propulsion vessel.

At this time, the LNG in the liquid state stored in the LNG storage tank 10 may have a pressure of 5 to 7 bar and a temperature of -160 ° C. or less.

The booster pump 20 is connected to the rear end of the LNG storage tank 10 through a first connection pipe L1 to increase the pressure of the LNG supplied from the LNG storage tank 10. [

That is, the booster pump 20 pressurizes the LNG to correspond to a predetermined required pressure so that the LNG can be used as the fuel of the engine.

At this time, the booster pump 20 may pressurize the LNG to 14 to 18 bar to correspond to a predetermined required pressure.

Next, the vaporizer 30 is connected to the rear end of the booster pump 20 through a second connection pipe L2 to vaporize the LNG in the liquid state, which is pressurized by the booster pump 20.

That is, the vaporizer 30 passes LNG in a liquid state to be vaporized to the inside and at the same time, heat exchange between a liquid LNG and a heat source necessary for vaporization is performed in passing the heat source necessary for LNG vaporization, .

At this time, the carburetor 30 includes an LNG input end into which the LNG in the liquid state is input, an LNG output end from which the vaporized LNG is discharged, a heat source inlet through which the heat source necessary for vaporization is input, .

The LNG input end is connected to the second connection pipe L2. The third connection pipe L3 for discharging the vaporized LNG is connected to the LNG discharge end, and the heat source inlet pipe And a heat source discharge pipe L5 for discharging a heat source may be connected to the heat source discharge end.

Here, as a heat source necessary for LNG vaporization in the vaporizer 30, a phase change occurs due to a temperature change such as CO _2, and a fluid which is not corrosive to metals can be used.

Unlike conventional seawater or glycol water, the fluid that causes a phase change such as CO ₂ has a relatively large heat capacity within a permissible operation temperature range, and can not significantly corrode metals, thereby greatly reducing energy consumption. The cost of manufacture and operation can be greatly reduced.

That is, the vaporizer 30 receives the liquid LNG having a pressure of 14-18 bar and a temperature below -160 ° C. through the LNG inlet and discharges it to the LNG outlet end. At the same time, the pressure of 16-22 bar and the pressure of 18-22 The LNG can be vaporized by heat exchange between the liquid LNG and the gaseous CO ₂ in the process of entering the gaseous CO ₂ at a temperature of about ₂₀₀ ° C. through the inlet of the heat source and discharging it to the heat source outlet.

At this time, as the heat of the gaseous CO ₂ delivered to the LNG in a liquid state depending on the heat exchange between the CO ₂ and CO ₂ is LNG With a pressure of 16 to 22 bar and a liquid temperature of -45 to -55 ° C, the LNG is phase-changed with a pressure of 14-18 bar and a temperature of -27 to -33 ° C.

The vaporized LNG can be discharged to the third connecting pipe L3 through the LNG discharge end of the vaporizer 30 and the liquefied CO ₂ flows to the heat source discharge pipe L5 through the heat source discharge end of the vaporizer 30 Can be discharged.

Next, the compensation tank 40 is connected to the end of the heat source discharge pipe L5 connected to the heat source discharge end of the vaporizer 30 to store the CO ₂ that has been changed to the liquid state in the vaporizer 30.

At this time, the compensation tank 40 may include means for separating and removing gas components contained in CO ₂ stored in a liquid state.

Next, the transfer pump 50 is connected to the rear end of the compensation tank 40 through a transfer pipe L6 to transfer the liquid CO ₂ stored in the compensation tank 40.

That is, the transfer pump 50 is for circulating the liquid CO ₂ stored in the compensation tank 40 in the LNG fuel supply system so as to be continuously used as a heat source for LNG vaporization.

Next, the heat exchanger 60 is connected to the rear end of the transfer pump 50 through a heat source transfer pipe L7 to vaporize the liquid CO ₂ circulating in the LNG fuel supply system by the transfer pump 50 .

That is, the heat exchanger 60 heats CO ₂ in the liquid state so that the LNG is vaporized and the CO ₂ , which has been changed into the liquid state, can be used again as a heat source for LNG vaporization, thereby causing a phase change to the gaseous state.

At this time, the heat source for vaporizing CO ₂ in the liquid state may use waste heat generated in the engine or the like of the ship. That is, means for indirectly receiving the heat of the engine from the cooling water cooled the engine and heating the CO ₂ in the liquid state to cause a phase change to the gaseous state may be included.

Next, the heater 70 is connected to the end of the third connection pipe L3 to heat the gaseous LNG discharged through the third connection pipe L3 to raise the temperature corresponding to a predetermined required temperature .

The heater 70 is connected to the heat source supply pipe L8 connected to the rear end of the heat exchanger 60 and the heat source inlet pipe L4 connected to the heat source inlet end of the evaporator 30 by the heat exchanger 60, Lt; RTI ID = 0.0 > CO ₂ < / RTI >

That is, the heater 70 receives heat from the gaseous CO ₂ supplied through the heat source supply pipe L 8 and supplied through the heat source inlet pipe L 4, and transfers the LNG to a predetermined temperature of 35 to 45 ° C. The temperature can be raised.

And an LNG supply pipe L9 may be connected to a rear end of the heater 70. [ Therefore, the gaseous LNG heated to a temperature of 35 to 45 DEG C by the heater 70 can be supplied to the fuel of the propulsion and viewing engine of the ship through the LNG supply pipe L9.

The separator 90 may be further provided at an end of the LNG supply pipe L9 to separate and remove moisture that may be contained in the gaseous LNG passing through the vaporizer 30 and the heater 70 in order.

The high pressure storage tank 80 is connected to the first bypass pipe L10 bypassed from the heat source transfer pipe L7 between the transfer pump 50 and the heat exchanger 60 as shown in FIG. And bypasses and stores CO ₂ in the liquid state transferred along the heat source transfer pipe L7.

At this time, the first control valve (V1) may be installed in the first bypass pipe (L10) in the upstream of the high-pressure storage tank (80). The second control valve V2 may be installed in the heat source transfer pipe L7 at the downstream end of the branch point between the first bypass pipe L10 and the heat source transfer pipe L7.

That is, when the operation of the LNG fuel supply system is stopped, the first control valve V1 is opened and the second control valve V2 is closed, so that the liquid CO ₂ , which rises at a high pressure of 90 to 110 bar at room temperature, It can be safely stored in the high-pressure storage tank 80 by bypassing from the transfer pipe L7 to the first bypass pipe L10.

At the initial stage of operation of the LNG fuel supply system, CO ₂ , which is a high-pressure liquid state stored in the high-pressure storage tank 80, is supplied to the heat source transfer pipe L 7 so that the total pressure of the LNG fuel supply system corresponds to a predetermined required pressure .

When the CO ₂ circulated through the LNG fuel supply system supplied from the high-pressure storage tank 80 is stored in the compensation tank 40 at a predetermined reference capacity or more, the first control valve V 1 is closed and the second control valve V2 is opened so that the supply of CO ₂ through the high-pressure storage tank 80 is stopped so that the transfer pump 50 can be switched to the normal operation mode of the operating LNG fuel supply system.

On the other hand, if the amount of circulation of CO _{2 in} the LNG fuel supply system is larger or smaller than the preset reference circulation amount, CO ₂ in the LNG fuel supply system is increased in accordance with opening / closing operations of the first control valve V 1 and the second control valve V ₂ CO ₂ stored in the storage tank or stored in the high-pressure storage tank may be supplied to the LNG fuel supply system.

The temperature control means is provided on the second bypass pipe L11 connected in parallel with the heater 70 between the vaporizer 30 and the heat exchanger 60 to supply the LNG vaporized by the vaporizer 30 Is controlled through the temperature of CO ₂ vaporized by the heat exchanger (60).

2, the temperature control means includes a third control valve V3 installed on the second bead deflection pipe L11, and a third control valve V3 installed on the LNG supply pipe L9 to adjust the temperature of the vaporized LNG A first controller (not shown) for controlling opening and closing operations of the third control valve V3 in accordance with the temperature of the LNG sensed by the temperature sensor S1 and a result of comparing the temperature of the LNG with a predetermined required temperature, Time).

That is, when the temperature of the LNG sensed by the temperature sensor S1 is lower than the preset required temperature, the temperature control means closes the third control valve V3 to supply the vaporized CO ₂ to the heater 70, The temperature can be raised.

Alternatively, if the temperature of the LNG sensed by the temperature sensor S1 meets the preset required temperature, the third control valve V3 is opened to bypass the vaporized CO ₂ to the second bypass pipe L11, Can be maintained.

Lastly, the pressure maintaining means is configured to maintain the total pressure in the LNG fuel supply system at 18 to 22 bar in order to prevent frost-induced icing due to low pressure and low temperature of CO ₂ circulated in the LNG fuel supply system .

2, the pressure maintaining means includes a pressure sensor S2 for sensing the pressure of CO ₂ supplied along the heat source supply pipe L8, a pressure sensor S2 for detecting the pressure of the CO ₂ supplied to the heat exchanger 60, A fourth control valve V4 provided at the third bypass pipe L12 and a first bypass deflection pipe L10 at the rear end of the pressure tank 80. The third bypass pipe L12 connects the front ends of the pressure tank 80, A fourth control valve V4 and a fifth control valve V5 according to a result of comparing the pressure of CO ₂ sensed by the pressure sensor S2 with a predetermined required pressure, And a second controller (not shown) for controlling the opening and closing operations of the first and second switches V5 and V5.

That is, the pressure holding means to close a pressure sensor (S2) the pressure of the CO ₂ group is higher than the set pressure required opening of the fourth control valve (V4) and fifth control valve (V5) detected by the pressure of the CO ₂ Can be maintained.

Alternatively, if the pressure of the CO ₂ sensed through the pressure sensor S2 is lower than the preset required pressure, the fifth control valve V5 is opened and the fourth control valve V4 is closed to set the pressure of the CO ₂ It can be raised to the required pressure.

As described above, according to the present invention, the LNG is vaporized by using the fluid causing the phase change as a heat source, so that the flow rate of the heat source required by the system can be greatly reduced, so that the energy consumption can be reduced and the system operation cost can be reduced.

The above-described embodiments are merely illustrative, and various modifications may be made by those skilled in the art without departing from the scope of the present invention.

Therefore, the true technical protection scope of the present invention should include not only the above embodiments but also various other modified embodiments according to the technical idea of the invention described in the following claims.

10: LNG storage tank
20: Booster pump
30: vaporizer
40: compensation tank
50: Feed pump
60: heat exchanger
70: heater
80: High pressure storage tank
90: separator
L1: first connection pipe
L2: second connection piping
L3: Third connection piping
L4: Heat source inlet piping
L5: Heat source exhaust pipe
L6: Transfer piping
L7: Heat source transfer pipe
L8: Heat source supply piping
L9: LNG supply piping
L10: First bypass piping
L11: Second bypass piping
L12: Third bypass piping
V1: first control valve
V2: the second control valve
V3: Third control valve
V4: fourth control valve
V5: fifth control valve
S1: Temperature sensor
S2: Pressure sensor

Claims (8)

A fuel supply system for an LNG propulsion vessel in which LNG is vaporized and supplied as fuel to an engine, wherein a fluid causing phase change is used as a heat source for vaporizing the LNG,
A LNG input end into which the LNG is input, an LNG output end from which the vaporized LNG is discharged, a heat input end in which the fluid required for vaporization is input, and a heat source discharge end through which the fluid vaporized by the LNG is discharged, A vaporizer for vaporizing LNG into the heat of the fluid;
A compensation tank connected to the heat source discharge stage by a heat source discharge pipe to store the fluid liquefied in the vaporizer;
A transfer pump connected to the compensation tank by a transfer pipe for transferring the fluid stored in the compensation tank;
A heat exchanger connected to the transfer pump by a heat source transfer pipe to vaporize the fluid transferred by the transfer pump;
A high pressure storage tank connected to the heat source transfer pipe by a first bypass pipe so as to be connected in parallel between the transfer pump and the heat exchanger and storing the fluid in a liquid state at room temperature;
A heater connected to the heat exchanger by a heat source supply pipe to heat the LNG liquefied using the heat of the fluid vaporized by the heat exchanger;
And temperature adjusting means connected between the vaporizer and the heat exchanger in parallel with the heater to adjust the temperature of the vaporized LNG to the heat of the vaporized fluid,
The temperature control means
A control valve installed on a second bypass pipe connected in parallel with the heater to control the fluid vaporized by the heater to be supplied to the vaporizer or the heater through the second bypass pipe in accordance with opening and closing operations;
A temperature sensor for sensing the temperature of the LNG vaporized by the vaporizer; And
And a controller for controlling the opening and closing operation of the control valve according to a result of comparing the temperature of the LNG detected by the temperature sensor with a preset required temperature, wherein the LNG fuel supply system. delete delete delete The method according to claim 1,
The fluid causing the phase change
LNG fuel supply system using a fluid that causes a phase change, characterized in that CO _2. The method according to claim 1,
And a separator connected to a rear end of the heater to separate and remove moisture contained in the vaporized LNG. delete The method according to claim 1,
The heat exchanger
And the fluid is vaporized by receiving heat from the cooling water cooled by the engine.

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