KR101681726B1 - Boil Off Gas Treatment System - Google Patents
Boil Off Gas Treatment System Download PDFInfo
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- KR101681726B1 KR101681726B1 KR1020150095397A KR20150095397A KR101681726B1 KR 101681726 B1 KR101681726 B1 KR 101681726B1 KR 1020150095397 A KR1020150095397 A KR 1020150095397A KR 20150095397 A KR20150095397 A KR 20150095397A KR 101681726 B1 KR101681726 B1 KR 101681726B1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C5/00—Methods or apparatus for filling containers with liquefied, solidified, or compressed gases under pressures
- F17C5/02—Methods or apparatus for filling containers with liquefied, solidified, or compressed gases under pressures for filling with liquefied gases
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B25/00—Load-accommodating arrangements, e.g. stowing, trimming; Vessels characterised thereby
- B63B25/02—Load-accommodating arrangements, e.g. stowing, trimming; Vessels characterised thereby for bulk goods
- B63B25/08—Load-accommodating arrangements, e.g. stowing, trimming; Vessels characterised thereby for bulk goods fluid
- B63B25/12—Load-accommodating arrangements, e.g. stowing, trimming; Vessels characterised thereby for bulk goods fluid closed
- B63B25/16—Load-accommodating arrangements, e.g. stowing, trimming; Vessels characterised thereby for bulk goods fluid closed heat-insulated
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H21/00—Use of propulsion power plant or units on vessels
- B63H21/38—Apparatus or methods specially adapted for use on marine vessels, for handling power plant or unit liquids, e.g. lubricants, coolants, fuels or the like
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
- F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
- F02M21/0203—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels characterised by the type of gaseous fuel
- F02M21/0215—Mixtures of gaseous fuels; Natural gas; Biogas; Mine gas; Landfill gas
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
- F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
- F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M25/00—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture
- F02M25/08—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture adding fuel vapours drawn from engine fuel reservoir
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C7/00—Methods or apparatus for discharging liquefied, solidified, or compressed gases from pressure vessels, not covered by another subclass
- F17C7/02—Discharging liquefied gases
- F17C7/04—Discharging liquefied gases with change of state, e.g. vaporisation
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
- F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
- F25J1/0002—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
- F25J1/0022—Hydrocarbons, e.g. natural gas
- F25J1/0025—Boil-off gases "BOG" from storages
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2265/00—Effects achieved by gas storage or gas handling
- F17C2265/03—Treating the boil-off
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2265/00—Effects achieved by gas storage or gas handling
- F17C2265/06—Fluid distribution
- F17C2265/066—Fluid distribution for feeding engines for propulsion
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
- F17C2270/00—Applications
- F17C2270/01—Applications for fluid transport or storage
- F17C2270/0102—Applications for fluid transport or storage on or in the water
- F17C2270/0105—Ships
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Ocean & Marine Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Filling Or Discharging Of Gas Storage Vessels (AREA)
Abstract
An evaporative gas treatment system is disclosed. The evaporation gas processing system of the present invention comprises an expander for receiving BOG (Boil-Off Gas) generated in an LNG storage tank provided in a ship or a marine structure and compressing the BOG to be thermally expanded and connected to the expander A compander comprising a BOG compressor for compressing the BOG by an inflation force; An HD (High Duty) compressor unit for further compressing the BOG compressed by the BOG compressor of the compander; A precooler in which the BOG compressed by the HD compressor unit is cooled by heat exchange with a BOG to be introduced into the BOG compressor from the LNG storage tank; A main heat exchanger in which the BOG compressed through the HD compressor unit is cooled by heat exchange with the BOG thermally expanded from the expander of the compander; And a fuel consuming unit provided in the ship or the sea structure for receiving BOG compressed by at least a part of the HD compressor unit as fuel, wherein the BOG cooled by the HDC compressor unit and cooled by the precooler is supplied to the expander And is thermally expanded.
Description
The present invention relates to an evaporative gas processing system, and more particularly, to an evaporative gas processing system in which a BOG compressed by an HD compressor unit is cooled by heat exchange with BOG to be introduced into a BOG compressor of a compander, and a BOG compressed by a boost compressor unit, And a main heat exchanger cooled by heat exchange with the BOG cooled by the thermal expansion from the expander of the compander.
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 obtained by liquefying the gas at a low temperature has an advantage of being able to increase the storage and transport efficiency because the volume becomes very small as compared with the gas. In addition, liquefied natural gas (Liquefied Natural Gas) (hereinafter referred to as "LNG") can be used as an eco-friendly fuel which can remove or reduce air pollutants during the liquefaction process,
For example, liquefied natural gas is a colorless transparent liquid which can be obtained by cooling natural gas containing methane as a main component to about -162 ° C and liquefying it, and has a volume of about 1/600 as compared with natural gas. Therefore, it can be transported very efficiently when liquefied by LNG for transporting natural gas.
However, since the liquefaction temperature of natural gas is a cryogenic temperature of -162 ° C at normal pressure, LNG is sensitive to temperature change and is easily evaporated. As a result, the LNG storage tank of the LNG carrier is insulated. However, since the external heat is continuously transferred to the LNG storage tank, the LNG is continuously vaporized in the LNG storage tank during the LNG transportation, BOG) occurs. This also applies to other low temperature liquefied gases such as ethane.
BOG is a kind of loss and an important issue in transportation efficiency. Further, when the evaporation gas accumulates in the storage tank, the internal pressure of the tank may rise excessively, and there is a risk that the tank may be damaged. Therefore, various methods for treating BOG occurring in the storage tank have been studied. Recently, a method of re-liquefying BOG to return to a storage tank for processing BOG, a method of returning BOG to a storage tank, And the like are used.
The present applicant has proposed a re-liquefying apparatus which utilizes the cooling heat of the evaporation gas itself by using the evaporation gas as the cooling fluid on Jul. 10, 2013, No. 10-2013-0081029. The Partial Re-liquefaction System (PRS) proposed in the patent of No. 10-2013-0081029 is a device for re-liquefying the evaporated gas discharged outside the storage tank by using the evaporation gas itself as a refrigerant, It is possible to re-liquefy the evaporated gas without separately installing the re-liquefier, and it is evaluated as an epoch-making technology that can effectively reduce the overall natural evacuation rate (BOR) of the liquefied natural gas storage tank.
1 is a schematic configuration diagram of the redispersion apparatus of the present invention, No. 10-2013-0081029. Referring to FIG. 1, the process of re-liquefying the evaporation gas in the re-liquefier will be briefly described below.
The evaporated gas discharged from the
The evaporated gas (C line) cooled through heat exchange in the
In the case where there is a low-pressure fuel consuming place which is supplied with a gas of lower pressure than the gas which has passed through all the multi-stage compressors in a ship, for example, three of the five
The present applicant's prior art is a device capable of effectively treating evaporative gas generated in a storage tank. In order to constitute such a device, an expensive compressor or the like is constituted, so that a facility cost is high. In particular, And the operating cost was also high.
An object of the present invention is to propose a vaporized gas processing system which can solve the above problems and more effectively compress BOG to be re-liquefied and processed.
According to an aspect of the present invention, there is provided an expander for expanding a boil-off gas (BOG) generated in an LNG storage tank provided in a ship or an offshore structure, A compander including a BOG compressor for compressing BOG by an expansion force;
An HD (High Duty) compressor unit for further compressing the BOG compressed by the BOG compressor of the compander;
A precooler in which a part of the BOG compressed by the HD compressor unit is cooled by heat exchange with a BOG to be introduced from the LNG storage tank to the BOG compressor;
A main heat exchanger in which the remaining BOG not transmitted to the precooler among the BOG compressed through the HD compressor unit is cooled by heat exchange with the BOG thermally expanded from the expander of the compander; And
And a fuel consuming unit which is provided in the ship or the sea structure and receives BOG compressed by at least a part of the HD compressor unit as fuel,
Wherein the BOG cooled by the precooler after being compressed by the HD compressor unit is introduced into the expander and is thermally expanded.
Preferably, the HD compressor unit includes at least one HD compressor for further compressing the BOG compressed by the BOG compressor of the compander, and at least one HD compressor cooler provided at the rear end of the HD compressor for cooling the BOG compressed. The HD compressor and the HD compressor cooler may be alternately provided.
Preferably, the fuel consuming unit may be a marine engine that is supplied with BOG compressed at 3 to 15 bar via at least a part of the HD compressor unit.
Preferably, the boost compressor further comprises a boost compressor for receiving the BOG compressed by the HD compressor and further compressing the BOG to a pressure exceeding a critical pressure; And a boost compressor provided at a rear end of the boost compressor and including a boost compressor cooler for cooling the compressed BOG, wherein the BOG compressed by the boost compressor is compressed by the expander in the main heat exchanger, Lt; RTI ID = 0.0 > BOG < / RTI >
Preferably, expansion means for receiving the BOG or LNG condensed from the BOG cooled by the main heat exchanger after compression in the booster compressor and for thermally expanding the LNG is provided, and the BOG or LNG is supplied from the expansion means, And a flash drum to which the ink is supplied.
Preferably, the liquid LNG separated from the flash drum is restored to the LNG storage tank, and the gaseous flash gas separated from the flash drum is supplied to the BOG compressor introduced into the BOG compressor through the pre- Can join the flow.
The BOG compressor may further include a GCU (Gas Combustion Unit) provided in the ship or the sea structure for supplying and burning the BOG to be introduced to the HD compressor from the BOG compressor of the compander.
According to another aspect of the present invention, there is provided a boiler for an internal combustion engine, comprising: an expander for receiving BOG (Boil-Off Gas) generated in an LNG storage tank provided in a ship or a sea structure and compressing the BOG, A compander comprising a BOG compressor for compressing BOG by an expansion force;
A first stream from which the BOG is supplied from the LNG storage tank to a BOG compressor of the compander;
A second stream supplied from the BOG compressor to the expander of the compander after the compressed BOG is further compressed;
A third stream in which the BOG thermally expanded from the expander is supplied to a front end of the BOG compressor;
A fourth stream that branches from the second stream and is further compressed to a pressure at which the BOG exceeds a critical pressure and then cooled and re-liquefied; And
And a fifth stream that is branched from the second stream and is supplied to a fuel consuming place where the compressed BOG is provided in the ship or the marine structure,
The first stream and the second stream, and the third stream and the fourth stream are mutually heat-exchanged.
Advantageously, the second stream is cooled by heat exchange with the first stream before being fed to the expander after further compression, and the fourth stream is subjected to heat exchange with the third stream after compression to a pressure exceeding the critical pressure, , And can be further cooled by a single thermal expansion.
The BOG generated in the LNG storage tank can be effectively re-liquefied and stored through the evaporative gas processing system of the present invention, thereby securing the safety of the tank and the ship, and improving the transportation efficiency of the LNG. In particular, it is possible to cool the compressed BOG by using BOG without constituting a separate refrigerant system, and to re-liquefy the refrigerant, thereby reducing the cost and contributing to securing the space inside the ship. In addition, it is possible to implement a system that is simple in configuration and operation and high in liquefaction efficiency.
Fig. 1 schematically shows a partial redistribution device capable of treating an evaporative gas according to the applicant's prior patent.
Figure 2 schematically depicts an evaporative gas treatment system according to a basic embodiment of the present invention.
Figure 3 shows the evaporative gas treatment system of the basic embodiment of the present invention in more detail.
Figure 4 schematically shows a vaporized gas processing system of a first embodiment of the present invention extending from a basic embodiment.
Figure 5 schematically shows a vaporization gas treatment system of a second embodiment of the present invention extending from a basic embodiment.
5A schematically shows a system of a second modification extended from the evaporative gas treatment system of the second embodiment.
5B schematically shows a system of the second modification and a control system for controlling the same.
Figure 6 schematically shows a vaporized gas processing system of a third embodiment of the present invention extending from a basic embodiment.
Figure 7 schematically shows a vaporized gas processing system of a fourth embodiment of the present invention extending from a basic embodiment.
Fig. 8 schematically shows a vaporized gas processing system of a fifth embodiment of the present invention extended from the basic embodiment.
Fig. 9 schematically shows a vaporized gas processing system of a sixth embodiment of the present invention extended from the basic embodiment.
In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.
Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. Like reference symbols in the drawings denote like elements.
First, the evaporation gas processing system described below of the present invention is a system for processing all kinds of ships and marine structures such as LNG carriers, Liquefied Ethane Gas (LEG) carriers, LNG RVs and LNG carriers equipped with storage tanks capable of storing low- It can be applied for evaporative gas treatment in marine structures such as LNG FPSO, LNG FSRU, including the same vessel.
In the following embodiments, LNG, which is a representative low-temperature liquid cargo, is described as an example for convenience of explanation, but the present invention is not limited thereto. Liquefied gas stored in such a storage tank may be any liquid cargo that can be transported by liquefaction at a low temperature. For example, in addition to LNG, LEG, LPG, liquefied nitrogen, liquefied gas such as ethylene, acetylene, propylene, and the like may be applicable. The present embodiment can be applied to the treatment of the evaporative gas generated from such liquefied gas.
FIG. 2 schematically shows an evaporative gas treatment system according to an embodiment of the present invention, and FIG. 3 shows this evaporative gas treatment system in more detail.
As shown in FIGS. 2 and 3, in the evaporative gas processing system of the present embodiment, BOG (Boil-Off Gas) generated in an LNG storage tank T provided in a ship or an offshore structure is supplied, And a
The BOG compressed by the BOG compressor of the compander is supplied to the HD (High Duty)
The system of this embodiment includes a
Meanwhile, the system of the present embodiment includes a
The BOG compressed at a pressure exceeding the critical pressure is cooled in the
The LNG that has been condensed from BOG or BOG cooled by the post-compression
The liquid phase LNG separated from the
In the above system, the flow of the BOG supplied from the LNG storage tank to the BOG compressor of the compander is referred to as a first stream, the flow supplied from the BOG compressor to the expander of the compander after the compressed BOG is further compressed is referred to as a second stream, The flow in which BOG thermally expanded from the expander is supplied to the front end of the BOG compressor is referred to as a third stream, and the flow in which the additional compressed BOG is compressed to a pressure exceeding the critical pressure, , The first stream and the second stream, and the third stream and the fourth stream are mutually heat-exchanged. With this configuration, the system of the present embodiment can re-liquefy BOG by cooling BOG through heat exchange between BOG and BOG compressed at different pressures without providing a separate refrigerant system.
Since there is no need to provide a separate refrigerant system, the system construction cost can be reduced and the BOG can be re-liquefied using only the BOG itself, which simplifies the system. In addition, the BOG generated from the LNG storage tank has a low temperature and a high temperature difference with the compressed BOG, so the liquefaction efficiency is high. BOG is re-liquefied and transported to the LNG storage tank for transportation, which can increase transportation efficiency.
As shown in FIG. 3, the HD compressor unit includes a plurality of
The
Next, FIG. 4 schematically shows the evaporative gas treatment system of the first embodiment of the present invention extended from the basic embodiment.
As in the above-described embodiment, the
The first embodiment is characterized in that the BOG compressed through a part of the HD compressor section is supplied through a fuel supply line (FLA) to a fuel consuming destination (E) such as an inboard engine. The fuel consumption point E may be, for example, a power generation engine for a ship, or more specifically, a dual fuel diesel engine (DFDE).
4, the discharge port pressure at the rear end of the first HD compressor 210aA and the HD compressor cooler 220aA set of the
The gas combustion line RMLA may be provided at the front end of the
As described above, the system according to the first embodiment of the present invention is configured such that the BOG passing through only a part of the HD compressor unit composed of multiple stages can be supplied as fuel to the fuel consuming place or sent to the GCU from the front end of the HD compressor unit, These configurations can be supplied. Therefore, it is possible to reduce the amount of BOG to be liquefied while supplying the necessary fuel to the ship, thereby reducing the load on the devices and increasing the energy efficiency.
Other configurations are similar to those of the above-described basic embodiment, so duplicate descriptions are omitted.
5 schematically shows a vaporized gas processing system of a second embodiment of the present invention extended from the basic embodiment.
In the second embodiment shown in FIG. 5, when there is a fuel consuming place using a high-pressure gas as fuel and a fuel consuming place using low-pressure gas as fuel, the compressed gas can be supplied to these devices. This is an extension of the first embodiment described above.
The first fuel consuming party receiving the low-pressure gas may be a marine engine, for example, a DFDE, which receives BOG compressed to 3 to 15 bar through only a part of the HD compressor unit. The second fuel consuming unit may include an HD compressor unit and a boost For example, an ME-GI engine, which is a propulsion engine for a marine vessel that is supplied with a compressed BOG through a compressor section.
Two fuel supply lines are provided in this embodiment for supplying fuel to such consuming places. The first fuel supply line FL1B for supplying fuel to the first fuel consumption destination E1 is connected to the first HD compressor 210aB of the
When the second fuel consuming place is the ME-GI engine, high pressure gas of about 150 to 400 bar, more preferably 300 bar is supplied. In order to supply the high pressure gas in accordance with the fuel supply condition, BOG is added to the second fuel supply line FL2B A high-
The second embodiment of the present invention is configured to supply the fuel required for both the low-pressure and high-pressure gas fuel consumption sites in the ship using the BOG as fuel, thereby reducing the amount of BOG to be liquefied thereby reducing the load of the devices, The efficiency can be increased. In addition, BOG can be supplied or liquefied to each engine depending on the amount of generated BOG or the fuel requirement of the in-vessel fuel consuming party, thus enabling a flexible system operation.
Other configurations are similar to those of the above-described basic embodiment and the first embodiment, so duplicated description will be omitted.
5A schematically shows a system of a second modification extended from the evaporative gas treatment system of the second embodiment described above.
As shown in FIG. 5A, the system of the present modification includes a pre-cooler 300B 'for supplying LNG pumped from the LNG storage tank to the BOG introduced from the LNG storage tank into the pre-cooler, And an LNG cooling unit is provided upstream.
When the temperature of the BOG generated in the LNG storage tank is relatively high and the temperature of various facilities such as the pipeline is relatively high as in the initial operation of the system, when the BOG supplied to the precooler is not sufficiently cooled, The time is delayed until the system can be stably operated, the liquefaction efficiency of the BOG is reduced, and energy waste can occur.
In order to solve such a problem, the present modified embodiment has constituted an LNG cooling unit.
The LNG cooling unit includes an
Since other configurations are similar to those of the above-described embodiments, duplicate descriptions are omitted
5B schematically shows the system of the second modification described above and a control system for controlling the same.
As shown in FIG. 5B, the present system is a control system for controlling BOG processing in the system of the second modification.
The present control system controls the liquefaction amount of the re-liquefying processing unit capable of re-liquefying the BOG and the amount of fuel supplied to the fuel consuming stations E1 and E2, including the
The control of the liquefaction system for the evaporative gas treatment basically aims at securing the safety of the LNG storage tank and increasing the LNG transport rate by treating the BOG generated in the LNG storage tank. That is, the control of the evaporative gas treatment system is connected to the pressure control of the LNG storage tank. To this end, the system of the present embodiment further comprises a tank pressure control unit (TPC) for controlling the pressure of the LNG storage tank such that the LNG temperature range of the LNG storage tank is in a saturated state, And the control unit controls the amount of re-liquefaction processing in the re-liquefaction processing unit.
The fuel consuming destination includes a first fuel consuming destination E1 such as a DFDE that is supplied with fuel as a BOG compressed through a part of the HD compressor unit as described in the above embodiments and a second fuel consuming destination E1 such as the HD compressor unit and the boost com- pressor, And a second fuel consumption point E2 such as a propulsion engine that is supplied with a compressed BOG through the second fuel consumption point E2.
In order to control the supply of BOG fuel to these fuel consumption points, the present control system includes a first fuel control section F1C for sensing and controlling the amount of BOG supplied to the first fuel consumption point, The GPC control unit GPC receives a signal from the tank pressure control unit and determines the amount of BOG generated in the LNG storage tank based on the amount of BOG generated by the first and second fuel control units 1 and the remaining BOG excluding the fuel supply amount to the second fuel consuming destination is re-liquefied.
The BOG thermally expanded from the
The system includes a first HD pressure indication control unit H1C for sensing the pressure of the BOG compressed by the first HD compressor from the rear end of the first HD compressor cooler, And a second HD pressure indicating control unit H2C for sensing the pressure of the BOG from the first and second HD compressing units A and B through the HD control unit ALC1 interlocked with the first and second HD pressure indicating adjusting units. 210b ', 210bB'. The BOG discharge pressure in the first HD compressor through the HD control unit ALC1 is preferably operated at the fuel supply pressure of the first fuel consumption point. For example, when the first fuel consumption point is DFDE, the BOG discharge of the first HD compressor The pressure can be maintained at about 6 bara. This enables smooth fuel supply from the downstream of the first HD compressor to the first fuel consumer and maintains the gas density of the second HD compressor inlet at a constant level. The BOG discharge pressure in the second HD compressor through the HD control unit ALC1 is appropriately operated to achieve preheating of the BOG refrigerant and subsequent cryogenic temperature at the downstream of the expander. For example, the discharge pressure of the second HD compressor can be maintained at 28 to 30 bara.
When the spray cooler for spraying the LNG supplied from the LNG storage tank to the BOG to be introduced into the precooler and cooling the BOG is provided upstream of the precooler as described in the second modification, A cooler control unit for controlling the spray cooler by sensing the temperature of the BOG may be provided in the control system.
And a load control unit LC1 that detects the pressure of the BOG from the rear end of the boost compressor unit and controls the boost compressor unit. The boost compressor maintains the set pressure higher than the critical pressure, for example, 80 bar or more, so as to increase the BOG heat exchange efficiency in the
The high-
The evaporation gas processing system is similar to the above-described embodiments, so that duplicate descriptions are omitted.
6 schematically shows the evaporative gas treatment system of the third embodiment of the present invention extended from the basic embodiment.
The system according to the third embodiment is provided for the case where the cold energy due to BOG in the
To this end, a
The BOG compressed through the HD compressor unit is cooled by the heat exchange between the BOG to be introduced into the BOG compressor and the refrigerant circulating in the refrigerant circulating unit in the precooler to a temperature of 0 to -70 DEG C, preferably 50 DEG C or less, Can be introduced.
Since the present embodiment can lower the temperature of the compressed BOG introduced into the
Other configurations are similar to those of the above-described basic embodiment, so duplicate descriptions are omitted.
7 schematically shows a vaporized gas processing system according to a fourth embodiment of the present invention, which is extended from the basic embodiment.
In the embodiments of the present invention, as described above, BOG is directly used as a refrigerant in the precooler. However, as in the initial operation of the system, the temperature of the BOG generated in the LNG storage tank is relatively high, When the temperature is relatively high, the BOG supplied to the precooler may not be sufficiently cooled. In this case, the time is delayed until the system can be stably operated from the initial driving, and the energy efficiency of the BOG is lowered, resulting in waste of energy.
In order to solve this problem, in this embodiment, an
The
Since some of the supplied LNG may be vaporized in contact with the injected LNG and the BOG, the vaporized gas and the cooled BOG are supplied to the
Other configurations are similar to those of the above-described embodiments, so duplicate descriptions are omitted.
8 schematically shows a vaporized gas processing system of a fifth embodiment of the present invention extended from the basic embodiment.
The system of the fifth embodiment shown in Fig. 8 is particularly applicable to the second embodiment described above in which the configuration of the fifth embodiment is added and the LNG can be supplied as fuel for smooth fuel supply to the first and second fuel consuming stations This is a system that adds a system for fuel supply.
As in the second embodiment described above, the first fuel consumption point E1 supplied with the low-pressure gas is a marine engine that is supplied with BOG compressed to 3 to 15 bar through only a part of the
A first fuel supply line FL1E for supplying fuel to the first fuel consumption destination E1 for supplying BOG fuel to these consuming destinations is connected to the first HD compressor 210aE of the
If the second fuel consuming place is the ME-GI engine, a high-pressure compressor (BOG) is added to the second fuel supply line FL2E to supply BOG in accordance with the fuel supply conditions of about 150 to 400 bar, more preferably 300
Additionally, in this embodiment, a
The
The
Thus, the LNG pumped from the LNG storage tank into the LNG storage tank may be branched and supplied to the spray cooler, re-condenser, low pressure vaporizer or high pressure pump.
In the system of this embodiment, as in the above-described embodiments, the devices for compressing the BOG are configured in multiple stages such as a multi-stage HD compressor unit and a boost compressor unit, so that the BOG can be liquefied with a small energy, The compressed BOG can be branched and supplied as fuel through all or a part of the multistage configuration in accordance with the pressure conditions.
Further, in the ballast voyage state of the ship in which the BOG generation amount is not much, the LNG can be vaporized through the
The present embodiment is characterized in that a re-condenser is provided in the fuel supply section so that the BOG can be used as the refrigerant to be discharged from the re-condenser without operating the HD-compressor section, the boost compressor section, the precooler, the main heat exchanger, BOG can be processed to a certain extent by using LNG, and BOG can be processed with less energy than when the whole liquid-repellent loop is operated.
Even when the temperature of the BOG is not high during the initial operation of the system, it is possible to cool the BOG through the LNG cooling unit and supply it as refrigerant to the precooler, so that the temperature of the BOG refrigerant can be kept constant, have.
As described above, the present embodiment can be effectively driven in response to various operating conditions, and the BOG can be efficiently processed.
Other configurations are similar to those of the above-described embodiments, so duplicate descriptions are omitted.
Fig. 9 schematically shows a vaporized gas processing system of a sixth embodiment of the present invention extended from the basic embodiment.
The system of the present embodiment is configured so that the compressed BOG from a ship or an offshore structure can be supplied to off-shore off-shore or offshore consumption sites. The ship or marine structure of this embodiment may be, for example, a Floating Storage and Regulation Unit (FSRU) or a Regasification Vessel (RV).
The system of this embodiment is provided with a vaporizing and supplying
The vaporizing and supplying
On the other hand, if the amount of generated BOG is large, it may be liquefied and stored, or may be compressed directly through the
The
Through this configuration and operation, the system can be operated effectively and the BOG can be processed according to the amount of generated BOG and the gas demand in the off-shore region.
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. It is.
T: LNG storage tank
100: Compander
200: HD compressor section
300: pre-cooler
400: Boost compressor
500: main heat exchanger
600: Expansion means
700: flash drum
Claims (9)
An HD (High Duty) compressor unit for further compressing the BOG compressed by the BOG compressor of the compander;
A precooler in which a part of the BOG compressed by the HD compressor unit is cooled by heat exchange with a BOG to be introduced from the LNG storage tank to the BOG compressor;
A main heat exchanger in which the remaining BOG not transmitted to the precooler among the BOG compressed through the HD compressor unit is cooled by heat exchange with the BOG thermally expanded from the expander of the compander; And
And a fuel consuming unit which is provided in the ship or the sea structure and receives BOG compressed by at least a part of the HD compressor unit as fuel,
Wherein the BOG cooled by the precooler after being compressed by the HD compressor unit is introduced into the expander to be thermally expanded.
At least one HD compressor for further compressing the BOG compressed in the BOG compressor of the compander; And
And at least one HD compressor cooler provided at a rear end of the HD compressor to cool the compressed BOG,
Wherein the HD compressor and the HD compressor cooler are alternately provided.
Wherein the fuel consuming unit is a marine engine that is supplied with BOG compressed at 3 to 15 bar through at least a part of the HD compressor unit.
A boost compressor for receiving the BOG compressed by the HD compressor and further compressing the BOG to a pressure exceeding a critical pressure; And a boost compressor provided at a rear end of the boost compressor to cool the compressed BOG,
And the BOG compressed through the boost compressor unit is cooled by heat exchange with the BOG cooled by the expansion in the main heat exchanger from the expander.
Expansion means for thermally expanding the fluid cooled by the main heat exchanger after being compressed by the boost compressor portion; And
A flash drum for gas-liquid separating the fluid expanded by the expansion means;
Further comprising: an evaporative gas treatment system.
The liquid LNG separated from the flash drum is restored to the LNG storage tank,
Wherein the gaseous flash gas separated from the flash drum is joined to the flow of the BOG through the precooler and into the BOG compressor of the compander.
And a GCU (Gas Combustion Unit) provided in the ship or the marine structure for supplying and burning the BOG to be introduced into the HD compressor from the BOG compressor of the compander.
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Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2001132899A (en) * | 1999-11-08 | 2001-05-18 | Osaka Gas Co Ltd | Boil-off gas reliquefying method |
KR200403633Y1 (en) * | 2005-09-08 | 2005-12-12 | 주식회사 동화엔텍 | Pre-cooling system of boil-off gas from LNG |
JP2009030675A (en) * | 2007-07-25 | 2009-02-12 | Mitsubishi Heavy Ind Ltd | Device and method for re-liquefying gas |
KR20130080204A (en) * | 2012-01-04 | 2013-07-12 | 에스티엑스조선해양 주식회사 | Fuel gas supply and re-liquefaction system of lng/lpg combined carrier |
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2015
- 2015-07-03 KR KR1020150095397A patent/KR101681726B1/en active IP Right Grant
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2001132899A (en) * | 1999-11-08 | 2001-05-18 | Osaka Gas Co Ltd | Boil-off gas reliquefying method |
KR200403633Y1 (en) * | 2005-09-08 | 2005-12-12 | 주식회사 동화엔텍 | Pre-cooling system of boil-off gas from LNG |
JP2009030675A (en) * | 2007-07-25 | 2009-02-12 | Mitsubishi Heavy Ind Ltd | Device and method for re-liquefying gas |
KR20130080204A (en) * | 2012-01-04 | 2013-07-12 | 에스티엑스조선해양 주식회사 | Fuel gas supply and re-liquefaction system of lng/lpg combined carrier |
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