CN111637358B - Control method of compressor unit, compressor unit and plurality of compression sections - Google Patents

Control method of compressor unit, compressor unit and plurality of compression sections Download PDF

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Publication number
CN111637358B
CN111637358B CN202010570773.9A CN202010570773A CN111637358B CN 111637358 B CN111637358 B CN 111637358B CN 202010570773 A CN202010570773 A CN 202010570773A CN 111637358 B CN111637358 B CN 111637358B
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Prior art keywords
pressure
target gas
flow path
storage tank
bypass valve
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CN202010570773.9A
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CN111637358A (en
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手塚智志
濑山胜广
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Kobe Steel Ltd
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Kobe Steel Ltd
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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
    • 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
    • B63H21/12—Use of propulsion power plant or units on vessels the vessels being motor-driven
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/22—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00 by means of valves
    • F04B49/24—Bypassing
    • 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
    • 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
    • B63H21/12—Use of propulsion power plant or units on vessels the vessels being motor-driven
    • B63H21/14—Use of propulsion power plant or units on vessels the vessels being motor-driven relating to internal-combustion engines
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B63/00—Adaptations of engines for driving pumps, hand-held tools or electric generators; Portable combinations of engines with engine-driven devices
    • F02B63/04—Adaptations of engines for driving pumps, hand-held tools or electric generators; Portable combinations of engines with engine-driven devices for electric generators
    • 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
    • F17C13/00—Details of vessels or of the filling or discharging of vessels
    • F17C13/02—Special adaptations of indicating, measuring, or monitoring equipment
    • F17C13/025—Special adaptations of indicating, measuring, or monitoring equipment having the pressure as the parameter
    • 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
    • F17C13/00—Details of vessels or of the filling or discharging of vessels
    • F17C13/04—Arrangement or mounting of valves
    • 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
    • F17C2201/00—Vessel construction, in particular geometry, arrangement or size
    • F17C2201/01—Shape
    • F17C2201/0104—Shape cylindrical
    • 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
    • F17C2205/00—Vessel construction, in particular mounting arrangements, attachments or identifications means
    • F17C2205/03—Fluid connections, filters, valves, closure means or other attachments
    • F17C2205/0302—Fittings, valves, filters, or components in connection with the gas storage device
    • F17C2205/0352—Pipes
    • 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
    • F17C2205/00—Vessel construction, in particular mounting arrangements, attachments or identifications means
    • F17C2205/03—Fluid connections, filters, valves, closure means or other attachments
    • F17C2205/0388—Arrangement of valves, regulators, filters
    • 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
    • F17C2221/00—Handled fluid, in particular type of fluid
    • F17C2221/03—Mixtures
    • F17C2221/032—Hydrocarbons
    • F17C2221/033—Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
    • 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
    • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
    • F17C2223/01—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the phase
    • F17C2223/0146—Two-phase
    • F17C2223/0153—Liquefied gas, e.g. LPG, GPL
    • F17C2223/0161—Liquefied gas, e.g. LPG, GPL cryogenic, e.g. LNG, GNL, PLNG
    • 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
    • F17C2225/00—Handled fluid after transfer, i.e. state of fluid after transfer from the vessel
    • F17C2225/01—Handled fluid after transfer, i.e. state of fluid after transfer from the vessel characterised by the phase
    • F17C2225/0146—Two-phase
    • F17C2225/0153—Liquefied gas, e.g. LPG, GPL
    • F17C2225/0161—Liquefied gas, e.g. LPG, GPL cryogenic, e.g. LNG, GNL, PLNG
    • 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
    • F17C2225/00—Handled fluid after transfer, i.e. state of fluid after transfer from the vessel
    • F17C2225/03—Handled fluid after transfer, i.e. state of fluid after transfer from the vessel characterised by the pressure level
    • F17C2225/036—Very high pressure, i.e. above 80 bars
    • 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
    • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
    • F17C2227/01—Propulsion of the fluid
    • F17C2227/0128—Propulsion of the fluid with pumps or compressors
    • F17C2227/0157—Compressors
    • F17C2227/0164—Compressors with specified compressor type, e.g. piston or impulsive type
    • 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
    • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
    • F17C2227/01—Propulsion of the fluid
    • F17C2227/0128—Propulsion of the fluid with pumps or compressors
    • F17C2227/0171—Arrangement
    • F17C2227/0185—Arrangement comprising several pumps or compressors
    • 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
    • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
    • F17C2227/03—Heat exchange with the fluid
    • F17C2227/0337—Heat exchange with the fluid by cooling
    • 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
    • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
    • F17C2250/04—Indicating or measuring of parameters as input values
    • F17C2250/0404—Parameters indicated or measured
    • F17C2250/043—Pressure
    • 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
    • F17C2250/00—Accessories; Control means; Indicating, measuring or monitoring of parameters
    • F17C2250/06—Controlling or regulating of parameters as output values
    • F17C2250/0689—Methods for controlling or regulating
    • 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
    • F17C2260/00—Purposes of gas storage and gas handling
    • F17C2260/02—Improving properties related to fluid or fluid transfer
    • 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
    • F17C2265/032—Treating the boil-off by recovery
    • F17C2265/037—Treating the boil-off by recovery with pressurising
    • 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
    • F17C2265/05—Regasification
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/30—Use of alternative fuels, e.g. biofuels
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T70/00—Maritime or waterways transport
    • Y02T70/50—Measures to reduce greenhouse gas emissions related to the propulsion system
    • Y02T70/5218—Less carbon-intensive fuels, e.g. natural gas, biofuels

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • General Engineering & Computer Science (AREA)
  • Ocean & Marine Engineering (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Control Of Multiple Motors (AREA)

Abstract

The invention provides a control method of a compressor unit, the compressor unit and a plurality of compression sections. The control method is a method for controlling a compressor unit that is provided in a ship and compresses a target gas, which is a boil-off gas sucked from a liquefied natural gas storage tank of the ship. In the control method, when it is determined that the target gas in the storage tank connection passage connected to the liquefied natural gas storage tank is in a predetermined low-pressure state while the compressor unit is being driven, the bypass valve is opened, and the target gas is returned to the storage tank connection passage through the bypass line. Accordingly, even when the amount of the target gas generated is small, the target gas can be supplied to the customer without excessively increasing the load on the compression stage of the compressor unit.

Description

Control method of compressor unit, compressor unit and plurality of compression sections
Technical Field
The present invention relates to a method of controlling a compressor unit for supplying a target gas, which is a boil-off gas, from an LNG storage tank of a ship to a demand side, a compressor unit, and a plurality of compression stages for the compressor unit.
Background
Conventionally, a compressor unit has been developed which boosts a pressure of a boil-off Gas (hereinafter referred to as "target Gas") generated from LNG (liquefied Natural Gas) and supplies the boosted pressure to a demand side such as an engine or a generator (see japanese patent publication No. 6371930, japanese patent application laid-open publication No. 2011-. In order to prevent the pressure on the discharge side of the compression stage of the compressor unit from becoming excessively high, the compressor unit has a bypass line for returning the target gas to the upstream (see japanese patent No. 6371930 and japanese patent publication No. 2011 and 517749). Generally, when the pressure on the discharge side of the compression stage exceeds a predetermined threshold value, a bypass valve provided in a bypass line is opened, and the high-pressure target gas is returned upstream. As a result, the pressure on the discharge side of the compression stage is reduced, and the load on the compression stage is suppressed.
The amount of target gas generated in an LNG storage tank storing LNG may be reduced due to various factors. If the pressure of the target gas in the storage tank connection flow path connected to the LNG storage tank is excessively reduced, the load on the first compression stage in the compressor unit may be excessively increased. In this way, in the case of the above-described conventional technique, even if the control is performed so that the pressure on the discharge side of the compression stage is not excessively increased, the increase in the load in the compression stage may not be suppressed.
Disclosure of Invention
The purpose of the present invention is to provide a method for controlling a compressor unit, and a plurality of compression stages for the compressor unit, which are capable of supplying target gas to a demand side without excessively increasing the load on the compression stages of the compressor unit even when the amount of target gas generated is small.
One aspect of the present invention relates to a method for controlling a compressor unit that is provided in a ship and compresses a target gas, which is boil-off gas generated in a liquefied natural gas storage tank of the ship. The compressor unit includes: a plurality of compression stages for sequentially pressurizing the target gas; a bypass line extending from one end connected to a storage tank connection flow path that connects the initial compression stage to the liquefied natural gas storage tank, and extending across a part of the plurality of compression stages; and a bypass valve disposed in the bypass line. The other end of the bypass line is connected to a flow path section between the compression stages adjacent to each other. The compressor unit further includes: another bypass line having one end connected to the flow path section and the other end located on the downstream side of the flow path section so as to straddle one or more compression stages; and a further bypass valve arranged in the further bypass line. The control method performs control as follows: when it is determined that the target gas in the storage tank connection passage is in a predetermined low-pressure state when the compressor unit is driven, the bypass valve is opened, and the target gas is returned to the storage tank connection passage via the bypass line, so that the pressure of the target gas in the passage section is reduced and the pressure of the target gas in the storage tank connection passage is increased. When it is determined that the target gas in the flow path section is in a predetermined low-pressure state, the other bypass valve is opened, and the target gas is returned to the flow path section via the other bypass line, so that the pressure of the target gas in the flow path in which the other end portion of the other bypass line is located is decreased, and the pressure of the target gas in the flow path section is increased. The low-pressure-side threshold value when it is determined that the target gas in the flow path section is in the predetermined low-pressure state is larger than the low-pressure-side threshold value when it is determined that the target gas in the storage tank connection flow path is in the predetermined low-pressure state.
Another aspect of the present invention relates to another method for controlling a compressor unit that is provided in a ship and compresses a target gas, which is boil-off gas generated in a liquefied natural gas storage tank of the ship. The compressor unit includes: a plurality of compression stages for sequentially pressurizing the target gas; a bypass line extending from one end connected to a storage tank connection flow path that connects the initial compression stage to the liquefied natural gas storage tank, and extending across a part of the plurality of compression stages; and a bypass valve disposed in the bypass line. The other end of the bypass line is connected to a flow path section between the compression stages adjacent to each other. The control method performs control as follows: when it is determined that the target gas in the storage tank connection passage is in a predetermined low-pressure state when the compressor unit is driven, opening the bypass valve and returning the target gas to the storage tank connection passage via the bypass line; closing the bypass valve when it is determined that the low pressure state is disengaged; and a bypass valve that opens when the target gas in the passage section is in a predetermined high-pressure state due to a decrease in the temperature of the target gas in the storage tank connection passage.
A further aspect of the invention relates to a compressor unit for use in the control method. The compressor unit includes: the plurality of compression sections; a driving part driving the plurality of compression stages; the bypass line; the bypass valve; the other bypass line; the other bypass valve; a pressure sensor that detects a pressure of the target gas in the storage tank connection flow path; another pressure sensor for detecting a pressure of the target gas in the flow path section; and a control unit that controls: comparing the pressure value obtained by the pressure sensor with the low-pressure-side threshold value of the target gas in the storage tank connection flow path, and opening the bypass valve when it is determined that the target gas in the storage tank connection flow path is in the predetermined low-pressure state; and a pressure sensor for detecting a pressure of the target gas in the flow path section, the pressure sensor being configured to detect a pressure value of the target gas in the flow path section, the pressure value being acquired by the other pressure sensor, and the other bypass valve being opened when it is determined that the target gas in the flow path section is in the predetermined low-pressure state.
A further aspect of the invention relates to another compressor unit for use in the control method. The compressor unit includes: the plurality of compression sections; a driving part driving the plurality of compression stages; the bypass line; the bypass valve; a pressure sensor that detects a pressure of the target gas in the storage tank connection flow path; a separate pressure sensor that detects a pressure of the target gas in the flow path section; and a control unit that controls: opening the bypass valve when it is determined that the target gas in the storage tank connection passage is in the predetermined low pressure state based on the pressure acquired by the pressure sensor; closing the bypass valve when it is determined that the low pressure state is disengaged; and opening the bypass valve when it is determined that the target gas in the flow path section of the bypass line is in the predetermined high-pressure state due to a decrease in the temperature of the target gas in the storage tank connection flow path based on the pressure acquired by the other pressure sensor.
A further aspect of the invention relates to a plurality of compression stages for use in said compressor train.
According to the present invention, even when the amount of the target gas generated is small, the target gas can be supplied to the customer without excessively increasing the load on the compression stage of the compressor unit.
The objects, features and advantages of the present invention will be further apparent from the following detailed description and the accompanying drawings.
Drawings
Fig. 1 is a schematic flow diagram of a compressor unit.
Fig. 2 is a schematic flowchart showing a control method for a bypass valve of a compressor unit.
Fig. 3 is a schematic flowchart showing a control method for a bypass valve of a compressor unit.
Fig. 4 is a schematic flow diagram of the compressor unit.
Detailed Description
Fig. 1 is a schematic flow diagram of a compressor unit 100. A compressor package 100 is described with reference to fig. 1.
The compressor train 100 is installed in a ship (not shown) having an LNG storage tank 101 for storing LNG (liquefied Natural Gas). The compressor unit 100 sucks a target gas (boil off gas) generated in the LNG storage tank 101 and compresses the sucked target gas. Specifically, the compressor unit 100 boosts the target gas to about 300barG (30MPaG), and supplies the boosted target gas to a specified demand side. In the following description, terms "upstream" and "downstream" are used with reference to the flow direction of the target gas.
The compressor unit 100 is a reciprocating compression mechanism, and includes: a flow path 110 through which the target gas flows toward the demand side; a plurality of compression stages 201 to 205 for sequentially pressurizing a target gas; a plurality of coolers 281-284; and a driving unit (not shown). The driving unit includes a driving source (a motor, an engine, and the like) and a crank mechanism that transmits power of the driving source to the first compression stage 201 to the fifth compression stage 205. In fig. 1, a compressor unit 100 is shown as a device including components within a two-dot chain line shown in fig. 1.
The upstream end of the flow path 110 is connected to the upper portion of the LNG storage tank 101 so that the boil-off gas generated in the LNG storage tank 101 flows therein. The downstream end of the flow path 110 is connected to the demand side. The flow path 110 includes a storage tank connection flow path 111, a stage connection flow path 113, and a demand side connection flow path 114.
The storage tank connection line 111 is connected to the LNG storage tank 101 and guides the boil-off gas to the first compression stage 201 of the compressor train 100. Since the compressor unit 100 has 2 first compression stages 201, the storage tank connection passage 111 includes a main pipe 111C extending from the LNG storage tank 101 and branch portions 111A and 111B branching from the main pipe 111C. These branch portions 111A and 111B are connected to the first compression stage 201, respectively. That is, 2 first compression stages 201 are connected to branch portions 111A and 111B in parallel with each other. In addition, the compressor train 100 may also have 1 first compression stage 201.
The stage connecting passage 113 is composed of a plurality of passages connecting the first to fifth compression stages 201 to 205 so that the target gas flows from one compression stage to the next compression stage. On the upstream side of the stage connecting passage 113, the connecting portion with the first compression stage 201 is branched into two branched portions 113A and 113B. The second to fifth compression stages 202 to 205 are provided in other portions of the stage connection channel 113. The second to fifth compression stages 202 to 205 are arranged in series so as to sequentially increase the pressure of the target gas compressed in the first compression stage 201.
The demand side connection flow path 114 is a flow path for connecting the fifth compression stage 205 to the demand side.
The crank mechanism has a crosshead connected to the respective piston rods of the first compression stage 201 to the fifth compression stage 205. The crankshaft mechanism converts rotation of the crankshaft into reciprocating motion of the crosshead, thereby reciprocating the piston rod and the piston connected to the distal end of the piston rod.
The coolers 281 to 284 are provided in the stage connection flow path 113 and the demand side connection flow path 114 to cool the target gas compressed in the second to fifth compression stages 202 to 205, respectively. The coolers 281 to 284 can exchange heat between the target gas and cooling water having a temperature lower than that of the target gas.
The cooler 281 is installed in a flow path section between the second compression stage 202 and the third compression stage 203 in the stage connection flow path 113. The cooler 282 is installed in a flow path section between the third compression stage 203 and the fourth compression stage 204 in the stage connection flow path 113. The cooler 283 is installed in a flow path section between the fourth compression stage 204 and the fifth compression stage 205 in the stage connection flow path 113. The cooler 284 is installed in the demand side connection flow path 114.
The compressor unit 100 performs control for adjusting the pressure of the target gas in the storage tank connection passage 111, the stage connection passage 113, and the demand side connection passage 114. The control-related portions for pressure control are explained below.
The compressor unit 100 includes bypass pipes 411 to 413, bypass valves 421 to 423, pressure sensors 431 to 434, and a control unit 414.
The bypass line 411 is connected to the storage tank connection passage 111 and the stage connection passage 113 so as to straddle the first compression stage 201 and the second compression stage 202. One end of the bypass line 411 is connected to the main pipe 111C of the reserve tank connection passage 111. The other end of the bypass line 411 is connected to the stage connection flow path 113 between the cooler 281 and the third compression stage 203.
A bypass line 412 spans the third compression stage 203. One end of the bypass line 412 is connected to a flow path section between the cooler 281 and the third compression stage 203 (i.e., a flow path section to which the other end of the bypass line 411 is connected) in the stage connection flow path 113. The other end of the bypass line 412 is connected to a flow path section between the cooler 282 and the fourth compression stage 204 in the stage connection flow path 113.
Bypass line 413 spans fourth compression stage 204 and fifth compression stage 205. One end of the bypass line 413 is connected to a flow path section between the cooler 282 and the fourth compression stage 204 in the stage connection flow path 113. The other end of the bypass line 413 is connected to the demand side connection flow path 114 on the downstream side of the cooler 284.
Bypass valves 421 to 423 are installed in bypass pipes 411 to 413, respectively. The bypass valves 421 to 423 are electrically connected to the control section 414. The bypass valves 421 to 423 can be adjusted in opening degree under the control of the control section 414.
The pressure sensor 431 is attached to the main pipe 111C of the storage tank connection passage 111. The pressure sensor 431 detects the pressure of the target gas in the storage tank connection passage 111 (that is, the pressure of the target gas generated in the LNG storage tank 101), and generates a detection signal indicating the detected pressure (hereinafter, referred to as "detection pressure").
The pressure sensor 432 is installed in the stage connecting flow path 113 in the flow path section between the cooler 281 and the third compression stage 203. The pressure sensor 432 detects the pressure of the target gas in the flow path section between the cooler 281 and the third compression stage 203, and generates a detection signal indicating the detected pressure. The detection pressure acquired by the pressure sensor 432 indicates the pressure of the target gas sucked into the third compression stage 203.
The pressure sensor 433 is installed in a flow path section between the cooler 282 and the fourth compression stage 204 in the stage connection flow path 113. The pressure sensor 433 detects the pressure of the target gas in the flow path section between the cooler 282 and the fourth compression stage 204, and generates a detection signal indicating the detected pressure. The detection pressure acquired by the pressure sensor 433 indicates the pressure of the target gas sucked into the fourth compression stage 204.
The pressure sensor 434 is installed in the demand side connection flow path 114. The pressure sensor 434 detects the pressure of the target gas in the demand connection passage 114, and generates a detection signal indicating the detected pressure.
The control section 414 is electrically connected to the bypass valves 421 to 423 and the pressure sensors 431 to 434. The control unit 414 receives detection signals from the pressure sensors 431 to 434, and determines the opening degrees of the bypass valves 421 to 423 based on the received detection signals. The control unit 414 may be configured as software or may be configured with a dedicated circuit.
The operation of the compressor unit 100 and the flow of the target gas will be described below with reference to fig. 1 to 3. Fig. 2 and 3 are schematic flowcharts showing a method of controlling the bypass valve 421. Fig. 2 shows a control method for eliminating a predetermined low pressure state in the reserve tank connection passage 111. Fig. 3 shows a control method for eliminating a specified high-pressure state of the stage connection flow path 113 between the second compression stage 202 and the third compression stage 203.
When the compressor unit 100 is driven, the suction and discharge of the target gas are repeated in the first to fifth compression stages 201 to 205. The target gas ejected from the second to fifth compression stages 202 to 205 is cooled by the coolers 281 to 284. After the compression process by the first to fifth compression stages 201 to 205 and the cooling process by the coolers 281 to 284, the target gas is supplied to the demand side. Meanwhile, the pressure of the target gas in the flow path 110 is acquired by the pressure sensors 431 to 434. Normally, when the suction pressure and the discharge pressure of each of the first compression stage 201 to the fifth compression stage 205 are within the normal range, the bypass valves 421 to 423 are closed. However, when the suction pressure and the discharge pressure are out of the normal ranges, the controller 414 controls the bypass valves 421 to 423 based on the detected pressures of the pressure sensors 431 to 434 to adjust the pressure of the target gas in the flow path 110.
First, the opening degree control of the bypass valve 421 will be described. While the compressor unit 100 is driven, the amount of target gas generated in the LNG storage tank 101 may decrease due to various factors. This reduces the pressure of the target gas in the storage tank connection passage 111. In contrast, as shown in fig. 2, the bypass valve 421 is controlled to eliminate the low pressure state in the reserve tank connection passage 111.
While the compressor unit 100 is driven, the pressure sensor 431 detects the pressure of the target gas in the storage tank connection passage 111. The control unit 414 compares the pressure acquired by the pressure sensor 431 with a predetermined low-pressure threshold value (step S110). If it is determined that the pressure of the target gas in the storage tank connection passage 111 is lower than the low-pressure-side threshold value, that is, the target gas is in a low-pressure state, the control unit 414 opens the bypass valve 421 (step S120). In addition, if the detected pressure of the pressure sensor 431 is not lower than the low-pressure side threshold value, the state in which the bypass valve 421 is closed is maintained. The low-pressure side threshold is set to, for example, about ObarG (0 MPaG). In addition, when the load of the first compression stage 201 is allowable even when the target gas at a low pressure is sucked, the low pressure side threshold value may be set to a value smaller than ObarG.
When the bypass valve 421 is opened, the high-pressure target gas compressed in the first compression stage 201 and the second compression stage 202 flows into the storage tank connection passage 111 through the bypass line 411. As a result, the pressure of the target gas in the flow path section between the second compression stage 202 and the third compression stage 203 decreases, and the pressure of the target gas in the storage tank connection flow path 111 increases.
After the bypass valve 421 is opened, the control unit 414 continuously or intermittently compares the detection pressure of the pressure sensor 431 with the low-pressure threshold value (step S130). If the detected pressure of the pressure sensor 431 is lower than the low-pressure side threshold value, the state in which the bypass valve 421 is opened is maintained (step S120). The loop processing constituted by step S120 and step S130 is continued until the detected pressure of the pressure sensor 431 becomes equal to or higher than the low-pressure side threshold value, and if the detected pressure of the pressure sensor 431 becomes equal to or higher than the low-pressure side threshold value, the bypass valve 421 is closed (step S140).
Here, while the bypass valve 421 is opened (step S120), the opening degree of the bypass valve 421 is sequentially adjusted based on a comparison between the low-pressure side threshold value and the pressure detected by the pressure sensor 431. Specifically, the control unit 414 increases the opening degree of the bypass valve 421 according to the magnitude of the difference between the detected pressure and the low-pressure-side threshold value. Accordingly, when the pressure in the reserve tank connection passage 111 is excessively low, the amount of the target gas returned to the reserve tank connection passage 111 through the bypass line 411 increases, and the pressure in the reserve tank connection passage 111 can be quickly restored. Further, if the pressure of the storage tank connection passage 111 approaches the low-pressure side threshold value, the opening degree decreases, and the target gas is prevented from being unnecessarily returned to the storage tank connection passage 111.
Next, control in a case where the target gas in the stage connecting passage 113 between the second compression stage 202 and the third compression stage 203 is in a high-pressure state will be described with reference to fig. 3. In the compressor unit 100, for example, when the temperature of the target gas in the storage tank connection passage 111 decreases, the throughput of the compressor unit 100 may become excessive.
While the compressor unit 100 is being driven, the compression sensor 432 detects the pressure of the target gas in the flow path section between the second compression stage 202 and the third compression stage 203. The control unit 414 compares the pressure acquired by the pressure sensor 432 with a predetermined high-pressure threshold value (step S210). If it is determined that the pressure of the target gas is greater than the high-pressure-side threshold value, that is, the target gas is in a high-pressure state, the control unit 414 opens the bypass valve 421 (step S220). Further, if the detected pressure of the pressure sensor 432 is equal to or lower than the high-pressure side threshold value, the state in which the bypass valve 421 is closed is maintained. The high pressure side threshold is set to, for example, 11 barG.
When the bypass valve 421 is opened, the high-pressure target gas compressed in the first compression stage 201 and the second compression stage 202 flows into the storage tank connection passage 111 through the bypass line 411. As a result, the pressure of the target gas in the flow path section between the second compression stage 202 and the third compression stage 203 decreases, and the pressure of the target gas in the storage tank connection flow path 111 increases.
After the bypass valve 421 is opened, the control unit 414 continuously or intermittently compares the detected pressure of the pressure sensor 432 with the high-pressure threshold value (step S230). If the detected pressure of the pressure sensor 432 is greater than the high-pressure side threshold value, the state in which the bypass valve 421 is opened is maintained (step S220). The loop process constituted by step S220 and step S230 is continued until the detected pressure of the pressure sensor 432 becomes equal to or lower than the high-pressure side threshold value, and if the detected pressure of the pressure sensor 432 becomes equal to or lower than the high-pressure side threshold value, the bypass valve 421 is closed (step S240).
Here, while the bypass valve 421 is opened (step S220), the opening degree of the bypass valve 421 is sequentially adjusted based on the comparison between the high-pressure side threshold value and the pressure detected by the pressure sensor 432. Specifically, the control unit 414 increases the opening degree of the bypass valve 421 according to the magnitude of the difference between the detected pressure and the high-pressure-side threshold value. Accordingly, when the pressure of the target gas in the flow path section between the second compression stage 202 and the third compression stage 203 is excessively high, the amount of the target gas returned to the reserve tank connection flow path 111 through the bypass line 411 increases, and the pressure in the flow path section can be rapidly reduced. Further, if the pressure in the flow path section approaches the high-pressure-side threshold value, the opening degree decreases, and the target gas is prevented from being unnecessarily returned to the storage tank connection flow path 111.
As described above, in the compressor unit 100, the pressure sensors 431 and 432 acquire the pressures of the target gas at the end portions on both sides of the bypass passage 411. The opening degree of the bypass valve 421 is controlled when the target gas at the end of the bypass line 411 of the flow path (the reserve tank connection flow path 111) located on the low pressure side is in a low pressure state and when the target gas at the end of the flow path (the flow path section between the second compression stage 202 and the third compression stage 203) located on the high pressure side is in a high pressure state.
Next, the opening degree control of the bypass valves 422 and 423 will be described. The opening degree control of the bypass valves 422 and 423 is performed in the same manner as the bypass valve 421. For the opening degree control of the bypass valve 422, the control unit 414 acquires the pressures (detected pressures of the pressure sensors 432 and 433) on the suction side and the discharge side of the third compression stage 203 across the bypass passage 412. The control unit 414 opens the bypass valve 422 when the detected pressure of the pressure sensor 432 is lower than a predetermined low-pressure-side threshold value, that is, when the target gas is in a low-pressure state, or when the detected pressure of the pressure sensor 433 is higher than a predetermined high-pressure-side threshold value, that is, when the target gas is in a high-pressure state. The low-pressure side threshold value and the high-pressure side threshold value set for the bypass valve 422 are higher than the low-pressure side threshold value and the high-pressure side threshold value set for the bypass valve 421, respectively.
In the opening degree control of the bypass valve 423, the control unit 414 acquires the pressure on the suction side of the fourth compression stage 204 and the pressure on the discharge side of the fifth compression stage 205 (the detection pressures of the pressure sensors 433 and 434) across which the bypass passage 413 extends. When the detected pressure of the pressure sensor 433 is lower than a predetermined low-pressure side threshold value or when the detected pressure of the pressure sensor 434 is higher than a predetermined high-pressure side threshold value, the control unit 414 opens the bypass valve 423. The low-pressure side threshold value and the high-pressure side threshold value set for the bypass valve 423 are higher than the low-pressure side threshold value and the high-pressure side threshold value set for the bypass valve 422, respectively.
As described above, according to the embodiment of the present invention, even when the target gas in the storage tank connection passage 111 is in a low pressure state, the bypass valve 421 is opened to prevent an excessive load from being applied to the first compression stage 201 and the second compression stage 202. Further, even if the target gas in the flow path section between the second compression stage 202 and the third compression stage 203 is in a low pressure state, the bypass valve 422 is opened to prevent an excessive load from being applied to the third compression stage 203. Similarly, even when the target gas in the flow path section between the third compression stage 203 and the fourth compression stage 204 is in a low-pressure state, the bypass valve 423 is opened to prevent an excessive load from being applied to the fourth compression stage 204 and the fifth compression stage 205.
Further, if the flow path section target gas between the second compression stage 202 and the third compression stage 203 is in a high pressure state, the bypass valve 421 is opened. Accordingly, the first compression stage 201 and the second compression stage 202 are inhibited from being excessively loaded. Similarly, even when the target gas is in a high-pressure state in the flow path section between the third compression stage 203 and the fourth compression stage 204, the bypass valve 422 is opened to suppress an excessive load from being applied to the third compression stage 203. Even when the target gas is in a high-pressure state in the demand side connection passage 114, the bypass valve 423 is opened to suppress an excessive load from being applied to the fourth compression stage 204 and the fifth compression stage 205.
The embodiments disclosed herein are illustrative in all respects and should not be construed as being limiting. The scope of the present invention is defined by the claims rather than the description above, and includes meanings equivalent to the claims and all modifications within the scope.
In the above embodiment, if the amount of the target gas generated in the LNG storage tank 101 decreases, the detection pressure of the pressure sensor 431 decreases, and therefore, the difference between the detection pressures of the pressure sensors 431 and 432 increases. Instead of this, in step S110 in fig. 2, a difference between the pressure detected by the pressure sensor 431 and the pressure detected by the pressure sensor 432 may be calculated, and the low-pressure state may be determined based on whether or not the magnitude of the calculated difference is larger than a predetermined pressure difference upper limit value. If it is determined that the target gas in the storage tank connection passage 111 is in the low pressure state, step S120 in fig. 2 is executed and the bypass valve 421 is opened.
In the embodiment, when it is determined whether or not the target gas is out of the low pressure state (step S120), a value larger than the low pressure side threshold value may be used as the determination value. Further, when it is determined whether or not the target gas is out of the high-pressure state (step S220), a value smaller than the high-pressure side threshold value may be used as the determination value.
In the above embodiment, the opening degree of the bypass valve 421 may be adjusted based on the ratio of the detected pressure of the pressure sensor 431 (or the pressure sensor 432) to the low pressure side threshold value (or the high pressure side threshold value). The same is true for the bypass valves 422, 423. Further, when precise opening degree control is not required, the bypass valves 421 to 423 may be controlled to be fully closed and fully opened in two values. The same is true for the bypass valves 422, 423.
In the present embodiment, as shown in fig. 4, the bypass line 411 may be connected to the flow path 110 (i.e., the reserve tank connection flow path 111 and the demand side connection flow path 114) so as to extend over the first compression stage 201 to the fifth compression stage 205. In addition, a bypass line may be provided in each of the compression stages 201 to 205. Thus, the bypass line can be appropriately changed.
In the described embodiment, less than 5 (e.g., 3) compression stages are possible, and more than 5 compression stages (e.g., 6) may be used.
The control method of the bypass valve according to the above embodiment may be applied to other screw-type and turbine-type compressors. In this case, the compressor unit may use a gear mechanism instead of the crankshaft mechanism to transmit power to the compression stage. It is also possible to transmit power directly from the drive source to the compression section.
The above embodiment mainly includes the following inventions.
In one aspect of the embodiment, the present invention relates to a method for controlling a compressor unit that is installed in a ship and compresses a target gas, which is a boil-off gas generated in a liquefied natural gas storage tank of the ship. The compressor unit includes: a plurality of compression stages for sequentially pressurizing the target gas; a bypass line extending from one end connected to a storage tank connection flow path that connects the initial compression stage to the liquefied natural gas storage tank, and extending across a part of the plurality of compression stages; and a bypass valve disposed in the bypass line. The other end of the bypass line is connected to a flow path section between the compression stages adjacent to each other. The compressor unit further includes: another bypass line having one end connected to the flow path section and the other end located on the downstream side of the flow path section so as to straddle one or more compression stages; and a further bypass valve arranged in the further bypass line. The control method performs control as follows: when it is determined that the target gas in the storage tank connection passage is in a predetermined low-pressure state when the compressor unit is driven, the bypass valve is opened, and the target gas is returned to the storage tank connection passage via the bypass line, so that the pressure of the target gas in the passage section is reduced and the pressure of the target gas in the storage tank connection passage is increased. When it is determined that the target gas in the flow path section is in a predetermined low-pressure state, the other bypass valve is opened, and the target gas is returned to the flow path section via the other bypass line, so that the pressure of the target gas in the flow path in which the other end portion of the other bypass line is located is decreased, and the pressure of the target gas in the flow path section is increased. The low-pressure-side threshold value when it is determined that the target gas in the flow path section is in the predetermined low-pressure state is larger than the low-pressure-side threshold value when it is determined that the target gas in the storage tank connection flow path is in the predetermined low-pressure state.
According to the above method, if the bypass valve is opened, a part of the target gas is returned to the reserve tank connection passage through the bypass line, and the pressure in the reserve tank connection passage rises. As a result, the pressure in the reserve tank connection passage is prevented from excessively decreasing, and an excessive load is suppressed from being applied to the compression stage across which the bypass line extends.
In the control method, the opening degree of the bypass valve is adjusted based on a result of comparison between a preset value and the pressure of the target gas in the storage tank connection passage. The opening degree of the other bypass valve is adjusted based on a result of comparison between a preset value and the pressure of the target gas in the flow path section.
According to the above method, the opening degree of the bypass valve is adjusted based on the result of comparison between the preset set value and the pressure of the target gas in the reserve tank connection passage, and therefore the amount of the target gas returned to the reserve tank connection passage can be adjusted by the bypass line.
Another aspect of the embodiment relates to a method for controlling a compressor unit that is installed in a ship and compresses target gas, which is boil-off gas generated in a liquefied natural gas storage tank of the ship. The compressor unit includes: a plurality of compression stages for sequentially pressurizing the target gas; a bypass line extending from one end connected to a storage tank connection flow path that connects the initial compression stage to the liquefied natural gas storage tank, and extending across a part of the plurality of compression stages; and a bypass valve disposed in the bypass line. The other end of the bypass line is connected to a flow path section between the compression stages adjacent to each other. The control method performs control as follows: when it is determined that the target gas in the storage tank connection passage is in a predetermined low-pressure state when the compressor unit is driven, opening the bypass valve and returning the target gas to the storage tank connection passage via the bypass line; closing the bypass valve when it is determined that the specified low pressure state is disengaged; and a bypass valve that opens when the target gas in the passage section is in a predetermined high-pressure state due to a decrease in the temperature of the target gas in the storage tank connection passage.
According to the above method, the pressure of the target gas in the flow path on the downstream side of the storage tank connection flow path is prevented from becoming excessively high, and an excessive load is suppressed from being applied to the compression stage across which the bypass line extends.
In the control method, the opening degree of the bypass valve when it is determined that the predetermined low pressure state is achieved is adjusted based on a result of comparison between a preset value and the pressure of the target gas in the storage tank connection passage. The opening degree of the bypass valve when it is determined that the predetermined high-pressure state is achieved is adjusted based on a result of comparison between a preset value and the pressure of the target gas in the flow path section.
A compressor unit according to still another aspect of the embodiment is used in the control method. The compressor unit includes: the plurality of compression sections; a driving part driving the plurality of compression stages; the bypass line; the bypass valve; the other bypass line; the other bypass valve; a pressure sensor that detects a pressure of the target gas in the storage tank connection flow path; another pressure sensor for detecting a pressure of the target gas in the flow path section; and a control unit that controls: comparing the pressure value obtained by the pressure sensor with the low-pressure-side threshold value of the target gas in the storage tank connection flow path, and opening the bypass valve when it is determined that the target gas in the storage tank connection flow path is in the predetermined low-pressure state; and a pressure sensor for detecting a pressure of the target gas in the flow path section, the pressure sensor being configured to detect a pressure value of the target gas in the flow path section, the pressure value being acquired by the other pressure sensor, and the other bypass valve being opened when it is determined that the target gas in the flow path section is in the predetermined low-pressure state.
A compressor unit according to still another aspect of the embodiment is used in the control method. The compressor unit includes: the plurality of compression sections; a driving part driving the plurality of compression stages; the bypass line; the bypass valve; a pressure sensor that detects a pressure of the target gas in the storage tank connection flow path; a separate pressure sensor that detects a pressure of the target gas in the flow path section; and a control unit that controls: opening the bypass valve when it is determined that the target gas in the storage tank connection passage is in the predetermined low pressure state based on the pressure acquired by the pressure sensor; closing the bypass valve when it is determined that the specified low pressure state is disengaged; and opening the bypass valve when it is determined that the target gas in the flow path section of the bypass line is in the predetermined high-pressure state due to a decrease in the temperature of the target gas in the storage tank connection flow path based on the pressure acquired by the other pressure sensor.
In yet another aspect, the embodiments described herein relate to a plurality of compression stages for use in the compressor rack.
Industrial applicability
The technique according to the above embodiment can be used for a compressor unit mounted on a ship.

Claims (7)

1. A method for controlling a compressor unit that is installed in a ship and compresses target gas, which is boil-off gas generated in a liquefied natural gas storage tank of the ship,
the compressor unit includes:
a plurality of compression stages for sequentially pressurizing the target gas;
a bypass line extending from one end connected to a storage tank connection flow path that connects the initial compression stage to the liquefied natural gas storage tank, and extending across a part of the plurality of compression stages; and
a bypass valve disposed in the bypass line, wherein,
the other end of the bypass pipeline is connected with a flow path section between the adjacent compression sections,
the compressor unit further includes:
another bypass line having one end connected to the flow path section and the other end located on the downstream side of the flow path section so as to straddle one or more compression stages; and
a further bypass valve being provided in the further bypass line, wherein,
the control method performs control as follows:
when it is determined that the target gas in the storage tank connection passage is in a predetermined low-pressure state when the compressor unit is driven, opening the bypass valve and returning the target gas to the storage tank connection passage via the bypass line, thereby reducing the pressure of the target gas in the passage section and increasing the pressure of the target gas in the storage tank connection passage;
when it is determined that the target gas in the flow path section is in a predetermined low-pressure state, the other bypass valve is opened, and the target gas is returned to the flow path section via the other bypass line, so that the pressure of the target gas in the flow path in which the other end portion of the other bypass line is located is decreased, and the pressure of the target gas in the flow path section is increased,
the low-pressure-side threshold value when it is determined that the target gas in the flow path section is in the predetermined low-pressure state is larger than the low-pressure-side threshold value when it is determined that the target gas in the storage tank connection flow path is in the predetermined low-pressure state.
2. The control method of a compressor unit according to claim 1,
the opening degree of the bypass valve is adjusted based on a result of comparison between a preset value and the pressure of the target gas in the storage tank connection passage,
the opening degree of the other bypass valve is adjusted based on a result of comparison between a preset value and the pressure of the target gas in the flow path section.
3. A method for controlling a compressor unit that is installed in a ship and compresses target gas, which is boil-off gas generated in a liquefied natural gas storage tank of the ship,
the compressor unit includes:
a plurality of compression stages for sequentially pressurizing the target gas;
a bypass line extending from one end connected to a storage tank connection flow path that connects the initial compression stage to the liquefied natural gas storage tank, and extending across a part of the plurality of compression stages; and
a bypass valve disposed in the bypass line, wherein,
the other end of the bypass pipeline is connected with a flow path section between the adjacent compression sections,
the control method performs control as follows:
when it is determined that the target gas in the storage tank connection passage is in a predetermined low-pressure state when the compressor unit is driven, opening the bypass valve and returning the target gas to the storage tank connection passage via the bypass line;
closing the bypass valve when it is determined that the specified low pressure state is disengaged;
and a bypass valve that opens when the target gas in the passage section is in a predetermined high-pressure state due to a decrease in the temperature of the target gas in the storage tank connection passage.
4. The control method of a compressor unit according to claim 3,
the opening degree of the bypass valve when it is determined that the predetermined low pressure state is achieved is adjusted based on a result of comparison between a preset value and the pressure of the target gas in the storage tank connection passage,
the opening degree of the bypass valve when it is determined that the predetermined high-pressure state is achieved is adjusted based on a result of comparison between a preset value and the pressure of the target gas in the flow path section.
5. A compressor unit for use in a method of controlling a compressor unit according to claim 1 or 2, the compressor unit comprising:
the plurality of compression sections;
a driving part driving the plurality of compression stages;
the bypass line;
the bypass valve;
the other bypass line;
the other bypass valve;
a pressure sensor that detects a pressure of the target gas in the storage tank connection flow path;
another pressure sensor for detecting a pressure of the target gas in the flow path section; and
a control unit for controlling:
comparing the pressure value obtained by the pressure sensor with the low-pressure-side threshold value of the target gas in the storage tank connection flow path, and opening the bypass valve when it is determined that the target gas in the storage tank connection flow path is in the predetermined low-pressure state;
and a pressure sensor for detecting a pressure of the target gas in the flow path section, the pressure sensor being configured to detect a pressure value of the target gas in the flow path section, the pressure value being acquired by the other pressure sensor, and the other bypass valve being opened when it is determined that the target gas in the flow path section is in the predetermined low-pressure state.
6. A compressor unit for use in a method of controlling a compressor unit according to claim 3 or 4, the compressor unit comprising:
the plurality of compression sections;
a driving part driving the plurality of compression stages;
the bypass line;
the bypass valve;
a pressure sensor that detects a pressure of the target gas in the storage tank connection flow path;
a separate pressure sensor that detects a pressure of the target gas in the flow path section; and
a control unit for controlling:
opening the bypass valve when it is determined that the target gas in the storage tank connection passage is in the predetermined low pressure state based on the pressure acquired by the pressure sensor;
closing the bypass valve when it is determined that the specified low pressure state is disengaged;
and opening the bypass valve when it is determined that the target gas in the flow path section of the bypass line is in the predetermined high-pressure state due to a decrease in the temperature of the target gas in the storage tank connection flow path based on the pressure acquired by the other pressure sensor.
7. A plurality of compression stages for use in a compressor train according to claim 5 or 6.
CN202010570773.9A 2019-07-22 2020-06-19 Control method of compressor unit, compressor unit and plurality of compression sections Active CN111637358B (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2019-134677 2019-07-22
JP2019134677A JP6716183B1 (en) 2019-07-22 2019-07-22 Control method of compressor unit, compressor unit and compression stage

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