KR20160076206A - LNG Vaporizing System and Method - Google Patents

Abstract

The present invention relates to an LNG vaporizing system and an LNG vaporizing method, and more specifically, to an LNG vaporizing system for vaporizing an LNG supplied to an engine of an LNG fuelled drillship, and an LNG vaporizing method. The LNG vaporizing system comprises: a vaporizer which is supplied with an LNG for a fuel and vaporizes the LNG; and a seawater supply passage which supplies, to the vaporizer, seawater heated by waste heat generated in an engine room, wherein the heated seawater is supplied to the vaporizer at a flow rate of 50-100 m^3/hr and is circulated as a heat medium to vaporized the LNG. According to the present invention, since the LNG for the fuel is vaporized by using the seawater heated by the waste heat generated in the engine room of the LNG fuelled drillship, it is possible to minimize a design change of the LNG fuelled drillship, which is necessary for installing equipment for producing a heat medium used to vaporize the LNG for the fuel, and it is possible to improve energy efficiency.

Description

[0001] LNG Vaporization System and Method [0002]

The present invention relates to an LNG vaporization system and method, and more particularly, to an LNG vaporization system and method, which uses heated seawater using waste heat generated in an engine room of a drill ship as a heating medium for vaporizing LNG for fuel. And methods.

In recent years, consumption of liquefied gas such as LNG (Liquefied Natural Gas) and LPG (Liquefied Petroleum Gas) has been rapidly increasing worldwide. The liquefied gas is transported in a gaseous state through land or sea gas pipelines, or in a liquefied state and stored in a liquefied gas carrier and transported to a distant consumer. Liquefied gas such as LNG or LPG is obtained by cooling natural gas or petroleum gas at cryogenic temperature (approximately -163 ° C in the case of LNG), and its volume is considerably reduced compared to when it is in a gaseous state, so it is suitable for long distance transportation through sea.

Particularly, in a marine suspension or ship using liquefied gas as fuel, a vaporizer for converting liquefied gas stored in the fuel tank into a fuel gas capable of being combusted inside the engine is used.

The vaporizer vaporizes the cryogenic liquefied gas by heat exchange with the heat medium.

In order to use glycol water as a heating medium of a vaporizer, a heating medium used in a vaporizer provided in a general fuel gas supply (FGS: Fuel Gas Supply) system is separately required for manufacturing, supplying and recovering glycol water. Of the system.

For example, in a fuel supply system for supplying fuel gas to a ship's Dual Fuel Engine, which includes an LNG fuel tank, a vaporizer, and a fuel gas supply valve, as shown in Fig. 1, A glycol water can be used as a heating medium for vaporizing LNG.

The glycol water may be prepared in an IHM (Intermediate Heating Medium) system, and the IHM system may include an expansion tank for storing glycol water produced by mixing glycol and water, a glycol tank for circulating the glycol water stored in the expansion tank A circulation pump for feeding, and a heater for heating the glycol water. At this time, the heater may be a steam heater or an electric heater.

When the glycol water is used as the heating medium of the vaporizer for vaporizing the liquefied gas in the fuel supply system of the ship, a separate system such as an IHM system should be additionally constructed.

Therefore, in order to apply the IHM system to the ship, it is necessary to provide additional space for arranging the IHM system related equipment and the piping, and the cost is also considerable.

However, in the case of the drill ship, its linearity and arrangement are standardized, so it is not easy to flexibly modify the structure to apply the IHM system, and the price competitiveness may be lowered.

In addition, there are three engine rooms to satisfy DP (Dynamic Positioning) requirements, and an independent fuel supply system is applied to each engine room.

Therefore, in order to use glycol water as the heating medium of the carburetor included in the fuel supply system of the drill rig, the IHM system should be reflected. Also, since the IHM system should be included in each engine room, Should be secured.

The heater for heating the glycol water produced by mixing the glycol and the water should be equipped with a steam heater or an electric heater. Since the steam system is not included in the case of the drill rig, the heater of the IHM system applied to the drill rig An electric heater should be used. An electric heater may have a situation where the generator capacity needs to be increased if the required electric load is high.

Thus, a liquefied gas vaporization system capable of vaporizing a liquefied gas at a low cost with simple equipment arrangement can be constructed without using glycol water as a heating medium of a vaporizer necessary for vaporizing liquefied gas in a fuel supply system of a drill rig and supplying it as fuel gas Technology development that can be done is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide an LNG vaporization system for vaporizing an LNG supplied to an engine of an LNG fueled drillship using LNG as fuel, To provide a LNG vaporizing system with a simple structure which does not require a separate apparatus for producing a heating medium for vaporizing LNG for fuel by using seawater heated by waste heat generated in an engine room.

According to an aspect of the present invention, there is provided an LNG vaporization system for vaporizing an LNG supplied to an engine of an LNG fired drillship using LNG as fuel, carburetor; And a seawater supply channel for supplying the heated seawater heated by the waste heat generated in the engine room to the vaporizer, wherein the heated seawater is supplied to the vaporizer at a flow rate of 50 to 100 m3 / hr, An LNG vaporization system characterized by vaporizing LNG is provided.

The seawater supply channel includes a heat exchanger that uses seawater to cool fresh water circulating the fresh water cooling cycle for cooling the engine room; And a booster pump for cooling the fresh water in the heat exchanger and then supplying the heated seawater heated to the vaporizer.

The heated seawater supplied to the vaporizer may be at a temperature of 38 to 48 DEG C and a pressure of 1.0 to 4.0 barg.

In the vaporizer, the LNG for fuel vaporized by heated seawater supplied at a temperature of 38 to 48 DEG C and a pressure of 1.4 to 2.4 barg may be at a temperature of 12 to 18 DEG C and a pressure of 5.0 to 6.0 barg.

The engine may be a Dual Fuel Engine.

According to another aspect of the present invention, there is provided an LNG vaporization method for vaporizing LNG for fuel supplied to an engine of a drilling rig using LNG as fuel, comprising the steps of: heating seawater using waste heat generated in an engine room; And heating the LNG for fuel using heated seawater.

According to the present invention, it is possible to provide a facility for producing a heating medium for vaporizing LNG for fuel by vaporizing LNG for fuel by using seawater heated using waste heat generated in the engine room of the drill ship, The design change can be minimized.

In addition, the energy efficiency can be improved in terms of recycling the waste heat generated in the engine room of the drill rig.

1 is a schematic diagram of a liquefied gas vaporization system using glycol water as a heating medium according to the prior art.
2 is a schematic diagram of an LNG vaporization system according to an embodiment of the present invention.
3 is a graph showing a correlation between temperatures of seawater discharged to a rear end of a vaporizer according to a flow rate of heated seawater supplied to a vaporizer of an LNG vaporization system according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the following examples can be modified in various forms, and the scope of the present invention is not limited to the following examples.

FIG. 2 is a schematic diagram illustrating a generator operation mode of a drill rig according to an embodiment of the present invention.

2, the present invention is an LNG vaporization system 1 for vaporizing an LNG supplied to an engine of an LNG-fueled drillship using LNG as fuel. The LNG vaporization system 1 includes a vaporizer 10 ); And a seawater supply channel (20) for supplying heated seawater heated using waste heat generated in an engine room to the vaporizer (10), wherein the heated seawater is supplied to the vaporizer (10 To the LNG vaporization system (1), characterized in that the LNG is vaporized while circulating in the heat medium.

The vaporizer 10 is a device for vaporizing the LNG for fuel stored in the LNG storage tank 11 to supply it to the engine, and seawater can be used as a heating medium for vaporizing the LNG for fuel.

The LNG for fuel vaporized in the vaporizer 10 can be supplied to the engine, and the cooled seawater after vaporizing the LNG for fuel can be discharged to the outside of the hull.

The seawater used as the heating medium in the vaporizer 10 may be supplied to the vaporizer 10 through the seawater supply channel 20 as heated seawater heated by the waste heat generated in the engine room.

The seawater supply passage 20 includes a heat exchanger 21 for cooling the fresh water circulating in the fresh water cooling cycle 30 for cooling the engine room using seawater; And a booster pump 22 for cooling the fresh water in the heat exchanger 21 and then supplying the heated seawater heated to the vaporizer 10. The booster pump 22 can also adjust the pressure of the heated seawater used as the heating medium in the vaporizer 10 to the required pressure of the vaporizer 10.

The fresh water cooling cycle 30 is for cooling the equipment installed in the engine room, and seawater can be used to remove the heat load from the fresh water cooling cycle 30. That is, the fresh water FW which is a refrigerant circulating in the fresh water cooling cycle 30 is heat-exchanged with the seawater SW in a heated state, and then cooled and circulated again through the fresh water cooling cycle 30, Some of the heated seawater heated after the heat exchange is discharged outboard, and a part of the heated seawater can be supplied to the vaporizer 10 by the booster pump 22. The seawater SW may be supplied to the heat exchanger 21 from a sea chest.

3, the flow rate of the seawater supplied to the vaporizer 10 by the booster pump 22 in the heated seawater heated by the heat exchanger 21 is 50 to 100 m3 / Will be described in more detail.

3 is a graph showing a correlation between the flow rate of the heated seawater supplied to the vaporizer and the temperature of the seawater discharged to the rear end of the vaporizer.

Referring to FIG. 3, when the flow rate of the heated seawater supplied to the vaporizer is 50 to 100 m 3 / hr, the temperature of the discharged seawater after vaporizing the LNG for fuel may be 30 to 39 ° C. When the flow rate of the heated seawater exceeds 100 m3 / hr, the temperature of the seawater discharged to the downstream of the vaporizer is constant. Therefore, when the flow rate of the heated seawater supplied to the vaporizer is 50 to 100 m3 / hr, And can be used most efficiently.

On the other hand, the heated seawater supplied to the vaporizer may have a temperature of 38 to 48 DEG C and a pressure of 1.0 to 4.0 barg. By supplying the heated seawater having such temperature and pressure to the vaporizer at a flow rate of 50 to 100 m 3 / hr, the LNG for fuel can be vaporized to be suitable as fuel for the engine. The engine may be a dual fuel engine.

The LNG for fuel vaporized in the vaporizer by the heated seawater has a temperature and a pressure at a front end of the vaporizer of -150 to -130 ° C and 6.0 to 7.0 barg respectively and a temperature and a pressure at the rear end of the vaporizer of 12 to 18 ° C and 5.0 To 6.0 barg, and the flow rate of the LNG for fuel in the vaporizer may be 6.1 to 7.3 m3 / hr.

Table 1 shows changes in physical properties of seawater and LNG in a vaporizer according to an embodiment of the present invention.

Working Fluid Properties in a Vaporizer Heat Capa. (Mcal / hr) 517.6 SW LNG Flow rate (m3 / hr) 50 6.84 Inlet temperature (캜) 43.34 -140 Outlet temperature (캜) 32.6 15 Inlet pressure (barg) 1.90 6.50 Outlet pressure (barg) 1.00 5.70

The physical properties of the heated seawater supplied to the vaporizer 10, for example, the temperature, the pressure and the flow rate may be optimized by heat exchange with fresh water in the heat exchanger 21 and also by the booster pump 22.

The physical properties of clean water for optimizing the physical properties of the heated seawater supplied to the vaporizer 10, for example, the temperature and the pressure at the front end of the heat exchanger 21 are 43 to 53 ° C and 2.5 to 4.0 barg, respectively, 21 and the temperature and pressure at the rear end may be 31 to 41 ° C and 2.0 to 3.5 barg respectively and the flow rate of clean water in the heat exchanger 21 may be 636 m3 / hr.

Table 2 shows changes in physical properties of seawater and fresh water in a heat exchanger according to an embodiment of the present invention.

Working Fluid Properties in Heat Exchangers Heat Capa. (Mcal / hr) 7760.7 SW FW Flow rate (m3 / hr) 710 636 Inlet temperature (캜) 32 48.2 Outlet temperature (캜) 43.34 36 Inlet pressure (barg) 3.30 3.00 Outlet pressure (barg) 2.30 2.41

The present invention also provides a method for LNG vaporization for vaporizing LNG for fuel supplied to an engine of a drilling rig using LNG as fuel, comprising the steps of: heating seawater using waste heat generated in an engine room; And a step of vaporizing the LNG for fuel using heated seawater.

As described above, the present invention is an LNG vaporization system for vaporizing an LNG supplied to an engine of a drill rig using LNG as a fuel, and more particularly to a LNG vaporization system in which a LNG for fuel is used as a fuel for a dual- The temperature, pressure and flow rate of the seawater for vaporizing the fuel LNG are optimized so that the pressure and the flow rate can be adjusted. The temperature, the pressure and the flow rate of the seawater vaporizing the fuel LNG are optimized by using the waste heat generated in the engine room of the drill ship. And the flow rate can be optimized.

Thus, by using the seawater heated using the waste heat generated in the engine room of the drill ship without the facility for separately producing the heating medium of the LNG vaporization system for vaporizing the LNG for fuel, it is possible to simplify the facility, Saving and energy efficiency can be expected.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention will be.

10: Carburetor
11: LNG storage tank
20: Sea water supply channel
21: Heat exchanger
22: Booster pump
23: Seed Chest
24: Seawater cooling pump
30: fresh water cooling cycle
40: Gas valve unit
FW: fresh water
SW: Seawater

Claims (6)

An LNG vaporization system for vaporizing an LNG supplied to an engine of a LNG fired drillship using LNG as fuel,
A vaporizer for supplying and vaporizing LNG for fuel; And
And a seawater supply channel for supplying the heated seawater heated using the waste heat generated in the engine room to the vaporizer,
Wherein the heated seawater is supplied to the vaporizer at a flow rate of 50 to 100 m < 3 > / hr to vaporize the LNG while circulating through the heating medium. The method according to claim 1,
The seawater supply channel
A heat exchanger that uses seawater to cool fresh water circulating a fresh water cooling cycle for cooling the engine room; And
And a booster pump for cooling the fresh water in the heat exchanger and then supplying the heated seawater heated to the vaporizer. The method according to claim 1,
Wherein the heated seawater supplied to the vaporizer has a temperature of 38 to 48 DEG C and a pressure of 1.0 to 4.0 barg. The method according to claim 1,
In the vaporizer,
Characterized in that the LNG for fuel vaporized by heated seawater supplied at a temperature of 38 to 48 DEG C and a pressure of 1.4 to 2.4 barg has a temperature of 12 to 18 DEG C and a pressure of 5.0 to 6.0 barg. The method according to claim 1,
Characterized in that the engine is a Dual Fuel Engine. A method of LNG vaporization for vaporizing LNG for fuel supplied to an engine of a drilling rig using LNG as fuel,
Heating seawater using waste heat generated in an engine room; And
And vaporizing the LNG for fuel using heated seawater.

Images