NO20191267A1 - Compressor, method of operating compressor and boil-off gas recovery system - Google Patents

Compressor, method of operating compressor and boil-off gas recovery system

Info

Publication number
NO20191267A1
NO20191267A1 NO20191267A NO20191267A NO20191267A1 NO 20191267 A1 NO20191267 A1 NO 20191267A1 NO 20191267 A NO20191267 A NO 20191267A NO 20191267 A NO20191267 A NO 20191267A NO 20191267 A1 NO20191267 A1 NO 20191267A1
Authority
NO
Norway
Prior art keywords
gas
path
bypass
bypass path
compression part
Prior art date
Application number
NO20191267A
Inventor
Katsuhiro Seyama
Satoshi Tezuka
Kenji Nagura
Original Assignee
Kobe Steel Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kobe Steel Ltd filed Critical Kobe Steel Ltd
Publication of NO20191267A1 publication Critical patent/NO20191267A1/en

Links

Classifications

    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • F04B41/00—Pumping installations or systems specially adapted for elastic fluids
    • F04B41/06—Combinations of two or more pumps
    • 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
    • F04B49/007—Installations or systems with two or more pumps or pump cylinders, wherein the flow-path through the stages can be changed, e.g. from series to parallel
    • 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
    • F04B49/02—Stopping, starting, unloading or idling control
    • F04B49/03—Stopping, starting, unloading or idling control by means of valves
    • F04B49/035—Bypassing
    • 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
    • F04B49/08—Regulating by delivery pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C14/00—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
    • F04C14/24—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valves
    • F04C14/26—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valves using bypass channels
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C28/00—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids
    • F04C28/24—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valves
    • F04C28/26—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids characterised by using valves controlling pressure or flow rate, e.g. discharge valves or unloading valves using bypass channels
    • 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
    • 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
    • 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
    • F17C9/00—Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure
    • F17C9/02—Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure with change of state, e.g. vaporisation
    • 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
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0201—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using only internal refrigeration means, i.e. without external refrigeration
    • F25J1/0202—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using only internal refrigeration means, i.e. without external refrigeration in a quasi-closed internal refrigeration loop
    • 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
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0228—Coupling of the liquefaction unit to other units or processes, so-called integrated processes
    • F25J1/0229—Integration with a unit for using hydrocarbons, e.g. consuming hydrocarbons as feed stock
    • F25J1/023—Integration with a unit for using hydrocarbons, e.g. consuming hydrocarbons as feed stock for the combustion as fuels, i.e. integration with the fuel gas system
    • 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
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0257—Construction and layout of liquefaction equipments, e.g. valves, machines
    • F25J1/0275—Construction and layout of liquefaction equipments, e.g. valves, machines adapted for special use of the liquefaction unit, e.g. portable or transportable devices
    • F25J1/0277—Offshore use, e.g. during shipping
    • 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
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0279—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc.
    • F25J1/0298—Safety aspects and control of the refrigerant compression system, e.g. anti-surge control
    • 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
    • F04B2205/00—Fluid parameters
    • F04B2205/15—By-passing over the pump
    • 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
    • F17C2205/0323—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
    • 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
    • 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
    • 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
    • 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
    • F17C2265/033—Treating the boil-off by recovery with cooling
    • 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
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/004—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by flash gas recovery
    • 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
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/30—Compression of the feed stream

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Ocean & Marine Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Fluid Mechanics (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)
  • Separation By Low-Temperature Treatments (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
  • Control Of Positive-Displacement Pumps (AREA)

Description

COMPRESSOR, METHOD OF OPERATING COMPRESSOR AND BOIL-OFF GAS
RECOVERY SYSTEM
Technical Field
The present invention relates to a compressor, a method of operating a compressor and a boil-off gas recovery system.
Background Art
Conventionally, as disclosed in JP 2016-173184 A (Patent Literature 1), there is known a multi-stage compressor having a plurality of compression cylinders. The compressor disclosed in Patent Literature 1 is used in a liquefied gas treatment system mounted on a ship, and adopts a configuration in which a plurality of compression cylinders are arranged in series. With the use of the compressor, a pressure of a boil-off gas generated in a storage tank of a liquefied gas is elevated to a predetermined pressure, a pressure elevated gas is supplied to a demander such as an engine, or the pressure elevated gas is re-liquefied and, thereafter, the re-liquefied gas can be returned to the storage tank.
Recently, there has been a demand for a compressor which can realize different discharge pressures for each kind of gas. In the compressor disclosed in Patent Literature 1, compression is performed by allowing gas to sequentially pass through the compression cylinders arranged in series and hence, a pressure of gas discharged from the compressor becomes a fixed value regardless of a kind of gas.
Summary of Invention
It is an object of the present invention to provide a compressor and a method of operating the same capable of suitably changing a discharge pressure of gas, and a boil-off gas recovery system including the compressor.
According to an aspect of the present invention, there is provided a compressor including a main path through which gas to be compressed flows, a first bypass path having an upstream end and a downstream end which are connected to the main path, a second bypass path having an upstream end and a downstream end, the upstream end of the second bypass path being connected to a portion of the main path located upstream of the downstream end of the first bypass path and downstream of the upstream end of the first bypass path, and the downstream end of the second bypass path being connected to a portion of the main path located downstream of the downstream end of the first bypass path, a first bypass valve that switches flowing and interruption of gas in the first bypass path, a second bypass valve that switches flowing and interruption of gas in the second bypass path, a first compression part positioned between the upstream end of the first bypass path and the upstream end of the second bypass path, a second compression part positioned between the downstream end of the first bypass path and the downstream end of the second bypass path and a first main path valve that switches flowing and interruption of gas in the main path, the first main path valve being disposed between the downstream end of the first bypass path and the upstream end of the second bypass path.
According to another aspect of the present invention, there is provided a method of operating a compressor which includes a main path through which gas to be compressed flows, and a first compression part and a second compression part disposed in series in the main path, the second compression part being disposed downstream of the first compression part. In this operation method, an operation state of the compressor is switched between a first operation state and a second operation state, the first operation state being a state where a gas route which allows the gas to sequentially pass through the first compression part and the second compression part is formed, and the second operation state being a state where a gas route which allows the gas to bypass the first compression part and to pass through the second compression part and a gas route which allows the gas to pass through the first compression part and to bypass the second compression part are respectively formed.
According to still another aspect of the present invention, there is provided a boil-off gas recovery system including a plurality of tanks for storing different kinds of liquefied gases, the compressor for increasing a pressure of a boil-off gas generated due to evaporation of the liquefied gas in the tank, an introducing path for introducing the boil-off gas generated in the tank into the compressor and a re-liquefying unit for liquefying the boil-off gas discharged from the compressor and for returning the liquefied boil-off gas into the tank.
According to the present invention, it is possible to provide a compressor and a method of operating the same capable of suitably changing a discharge pressure of gas, and a boil-off gas recovery system including the compressor.
Brief Description of Drawings
FIG. 1 is a view schematically showing a configuration of a boil-off gas recovery system according to a first embodiment of the present invention.
FIG. 2 is a view schematically showing a configuration of a compressor according to the first embodiment of the present invention.
FIG. 3 is a schematic view showing a four-stage compression state brought about by the compressor according to the first embodiment of the present invention.
FIG. 4 is a schematic view showing a three-stage compression state brought about by the compressor according to the first embodiment of the present invention.
FIG. 5 is a schematic view showing a two-stage compression state brought about by the compressor according to the first embodiment of the present invention.
FIG. 6 is a view schematically showing a configuration of a compressor according to a second embodiment of the present invention.
FIG. 7 is a schematic view showing a three-stage compression state brought about by the compressor according to the second embodiment of the present invention.
FIG. 8 is a schematic view showing a two-stage compression state brought about by the compressor according to the second embodiment of the present invention.
FIG. 9 is a schematic view showing a compressor according to another embodiment of the present invention.
Description of Embodiments
Hereinafter, a compressor, a method of operating a compressor and a boil-off gas recovery system according to embodiments of the present invention are described in detail with reference to drawings.
(First embodiment)
<Boil-off gas recovery system>
First, a configuration of a boil-off gas recovery system 2 according to the first embodiment of the present invention is described with reference to FIG.1. The boil-off gas recovery system 2 is installed in a ship which carries a low-temperature liquefied gas such as a liquefied natural gas, for example. As shown in FIG.1, the boil-off gas recovery system 2 includes a plurality of tanks 3 (a first tank 3A, a second tank 3B and a third tank 3C), a compressor 1 and a re-liquefying unit 60.
The plurality of tanks 3 respectively store different kinds of liquefied gases L (a first liquefied gas L1, a second liquefied gas L2 and a third liquefied gas L3). In this embodiment, the first liquefied gas L1 is liquefied ethylene, the second liquefied gas L2 is liquefied propane, and the third liquefied gas L3 is liquefied butane. However, kinds of the first to third liquefied gases L1 to L3 are not limited to the above-mentioned kinds. Further, the number of tanks 3 is not particularly limited, and two tanks 3 may be provided or four or more tanks 3 may be provided.
The first to third liquefied gases L1 to L3 are respectively stored in the tanks 3 in a cryogenic temperature state. In the tank 3, due to intrusion of heat from the outside, a portion of the liquefied gas L evaporates so that boil-off gases G (a first boil-off gas G1, a second boil-off gas G2 and a third boil-off gas G3) are generated.
The boil-off gas recovery system 2 includes an introducing path 4 for introducing a boil-off gas G generated in the tank 3 to the compressor 1. As shown in FIG.1, a portion of the introducing path 4 on an upstream side is branched to a plurality of (three in this embodiment) branched paths corresponding to the number of the tanks 3, and the respective paths are respectively connected to upper portions of the tanks 3. Switching valves 4A to 4C which switch flowing and interruption of the boil-off gas G are respectively provided to the respective branched paths. A kind of gas introduced into the compressor 1 can be switched by switching opening and closing of the switching valves 4A to 4C. The switching valves 4A to 4C may be formed of a manual valve or an automatic control valve.
On the other hand, a downstream end of the introducing path 4 is connected to a gas inlet 1’
of the compressor 1. With such a configuration, it is possible to introduce a boil-off gas G generated in the tank 3 into the compressor 1 through the introducing path 4.
The compressor 1 is a compressor of a reciprocating type (a reciprocating compressor), and elevates a pressure of a boil-off gas G to a predetermined pressure. The configuration of the compressor 1 is described in detail later.
The boil-off gas recovery system 2 includes a discharge path 5 through which a high pressure gas discharged from the compressor 1 flows. As shown in FIG.1, an upstream end of the
discharge path 5 is connected to a gas outlet 1’’ of the compressor 1. On the other hand, a portion of the discharge path 5 on a downstream side is branched to a plurality of (three in this embodiment) branched paths. The respective branched paths are respectively connected to the engine 6, a gas combustion device 7 and a power generator 8. With such a configuration, after a pressure of the boil-off gas G is elevated, the boil-off gas G can be supplied to the engine 6, the gas combustion device 7 and the power generator 8 respectively. Although not illustrated, a switching valve may be provided to the respective branched paths respectively so that the supply of gas to the respective demanders (the engine 6, the gas combustion device 7 and the power generator 8) may be controlled by opening and closing the switching valves.
The re-liquefying unit 60 is provided for liquefying a boil-off gas G discharged from the compressor 1 and for returning the liquefied boil-off gas G to the tank 3. As shown in FIG.1, the re-liquefying unit 60 includes a first path 65, a heat exchanger 61, an expansion valve 62, a gas liquid separator 63 and a second path 64.
An upstream end of the first path 65 is connected to a portion 5A located upstream of a branched portion of the discharge path 5, and a downstream end of the first path 65 is connected to a gas liquid separator 63. As shown in FIG.1, the heat exchanger 61 and the expansion valve 62 are disposed sequentially on the first path 65 in a flow direction of gas.
The heat exchanger 61 includes a low temperature side flow path 61A connected to the introducing path 4 and a high temperature side flow path 61B connected to the first path 65. The heat exchanger 61 is configured to perform heat exchange between a fluid which flows through the low temperature side flow path 61A and a fluid which flows through the high temperature side flow path 61B. With such a configuration, the heat exchanger 61 can perform heat exchange between a high-temperature boil-off gas G (a fluid flowing through the high temperature side flow path 61B) flown from a portion 5A into the first path 65 after being discharged from the compressor 1 and a low-temperature boil-off gas G (a fluid flowing through the low temperature side flow path 61A) flown from the tank 3 to the compressor 1. In such an operation, a portion of the boil-off gas G which flows through the high temperature side flow path 61B may be liquefied.
The expansion valve 62 is provided for lowering a pressure of the boil-off gas G by expanding the boil-off gas G cooled by the heat exchanger 61. A portion of the boil-off gas G which flows through the first path 65 can be liquefied by the expansion valve 62.
The gas liquid separator 63 is provided for separating the boil-off gas G having a portion liquefied by the heat exchanger 61 and the expansion valve 62 into a liquid component and a gas component. As shown in FIG.1, an upstream end of the second path 64 is connected to a bottom portion of the gas liquid separator 63, and portions of the second path 64 on a downstream side are branched to a plurality of (three in this embodiment) branched paths. The respective branched paths are respectively connected to the tanks 3. Switching valves 64A, 64B, 64C are respectively mounted on respective branched portions of the second path 64. With such a configuration, a liquefied boil-off gas G can be recovered to the tank 3. A third path 71 is connected to an upper portion of the gas liquid separator 63, and a gas component separated at the gas liquid separator 63 can be introduced into the introducing path 4 through the third path 71.
As described above, according to the boil-off gas recovery system 2, the elevation of a tank internal pressure can be prevented by re-liquefying a boil-off gas G generated in the tanks 3 and returning the re-liquefied boil-off gas G to the tanks 3. On the other hand, the first to third boil-off gases G1 to G3 are different from each other with respect to a pressure necessary for re-liquefying. Specifically, a pressure necessary for re-liquefying a first boil-off gas G1(ethylene gas) is approximately 84 bar, a pressure necessary for re-liquefying a second boil-off gas G2 (propane gas) is approximately 10.5 to 14 bar, and a pressure necessary for re-liquefying a third boil-off gas G3 (butane gas) is approximately 2.8 to 5.6 bar. That is, a pressure necessary for re-liquefying is decreased along with the increase of a molecular weight.
In view of the above, the compressor 1 is configured to switch the number of compression parts 15 which are arranged in series corresponding to a kind of a boil-off gas G to be compressed so that a discharge pressure of the gas can be suitably changed to be a pressure necessary for re-liquefying. Hereinafter, the configuration of the compressor 1 is described in detail.
<Compressor>
As shown in FIG.2, the compressor 1 includes a main path 10 through which gas (boil-off gas G) to be compressed flows and a plurality of (four) compression parts 15 disposed in series in the main path 10. The plurality of compression parts 15 include a first compression part 11, a second compression part 12 disposed downstream of the first compression part 11, a third compression part 13 disposed upstream of the first compression part 11 and a fourth compression part 14 disposed upstream of the third compression part 13. Each compression part 15 is formed of a cylinder (not illustrated) and a piston (not illustrated) which is movable in the cylinder in a reciprocating manner. In each compression part 15, gas is sucked into a compression chamber in the cylinder, and the piston compresses the gas. Each compression part 15 is driven by one drive part. Although not illustrated, a cooler may be disposed between the respective compression parts 15.
In this embodiment, the respective compression parts 15 are referred to as a fourth compression part 14, a third compression part 13, a first compression part 11 and a second compression part 12 in order in the flow direction of gas (from a left side to a right side in FIG.2). In the main path 10, a portion through which gas to be sucked into the first compression part 11 flows is referred to as “a first gas suction part 10C”, a portion where gas is discharged from the first compression part 11 is referred to as “a first gas discharge part 10D”, a portion where gas is discharged from the second compression part 12 is referred to as “a second gas discharge part 10E”, and a portion through which gas to be sucked into the third compression part 13 flows is referred to as “a third gas suction part 10F”.
The compressor 1 includes a switching mechanism 20 which switches the number of the compression parts 15 arranged in series by changing a flow route of gas in the compressor 1. The switching mechanism 20 includes a first bypass path 21, a first bypass valve 22, a second bypass path 23, a second bypass valve 24, a third bypass path 31, a third bypass valve 32, a fourth bypass path 33, a fourth bypass valve 34, a first main path valve 51 and a second main path valve 41.
The first bypass path 21 is a path which bypasses the first compression part 11, and an upstream end and a downstream end of the first bypass path 21 are connected to the main path 10.
Specifically, the first bypass path 21 is a path which starts from a point P1 and reaches a point P2 by bypassing the first compression part 11 in FIG.2. The first bypass path 21 has an upstream end connected to the first gas suction part 10C and a downstream end connected to the first gas discharge part 10D. The first bypass valve 22 is provided for switching flowing and interruption of gas in the first bypass path 21. The first bypass valve 22 is formed of a manually operated valve or an automatically controlled valve, for example. In the first bypass path 21, in a state where the first bypass valve 22 is released, gas flows only in one direction from a suction side to a discharge side of the compressor 1 (from a left side to a right side in FIG.2). Gas flows in the same manner also in the second to fourth bypass paths 23, 31, 33.
The second bypass path 23 is a path which bypasses the second compression part 12. The second bypass path 23 has an upstream end and a downstream end. The upstream end of the second bypass path 23 is connected to a portion of the main path 10 located upstream of a downstream end (point P2) of the first bypass path 21 and downstream of an upstream end (point P1) of the first bypass path 21. The downstream end of the second bypass path 23 is connected to a portion of the main path 10 located downstream of the downstream end (point P2) of the first bypass path 21. Specifically, the second bypass path 23 is a path which starts from a point P3, bypasses the second compression part 12, and reaches the point P4 as shown in FIG.2. As shown in FIG.2, the second bypass path 23 has an upstream end connected to a portion of the first gas discharge part 10D located upstream of the downstream end (point P2) of the first bypass path 21 and a downstream end connected to the second gas discharge part 10E. The second bypass valve 24 is provided for switching flowing and interruption of gas in the second bypass path 23. The second bypass valve 24 is formed of a manually operated valve or an automatically controlled valve, for example.
In the compressor 1, the first compression part 11 can be defined as a compression part positioned between the upstream end of the first bypass path 21 (the position of the point P1 in FIG.
2) and the upstream end of the second bypass path 23 (the position of the point P3 in FIG.2). The second compression part 12 can be defined as a compression part positioned between the downstream end of the first bypass path 21 (the position of the point P2 in FIG.2) and the downstream end of the second bypass path 23 (the position of the point P4 in FIG.2). These definitions are also applicable to an embodiment shown in FIG.6 described later.
The third bypass path 31 is a path which bypasses the third compression part 13.
Specifically, the third bypass path 31 is a path which starts from a point P6 in FIG.2, bypasses the third compression part 13 and reaches a point P7. The third bypass path 31 has an upstream end (point P6) connected to a third gas suction part 10F and a downstream end (point P7) connected to the first bypass path 21. As shown in FIG.2, in this embodiment, gas which flows in the third bypass path 31 from the upstream end (point P6) returns to the main path 10 through the first bypass path 21. The third bypass valve 32 is provided for switching flowing and interruption of gas in the third bypass path 31. The third bypass valve 32 is formed of a manually operated valve or an automatically controlled valve, for example.
The fourth bypass path 33 is a path which bypasses the first compression part 11.
Specifically, the fourth bypass path 33 is a path which starts from a point P5 in FIG.2, bypasses the first compression part 11 and reaches a point P8. The fourth bypass path 33 has an upstream end (point P5) connected to a portion of the first gas suction part 10C located upstream of the upstream end (point P1) of the first bypass path 21, and a downstream end (point P8) connected to the second bypass path 23. As shown in FIG.2, in this embodiment, gas which flows into the fourth bypass path 33 from the upstream end P5 returns to the main path 10 through the second bypass path 23. The fourth bypass valve 34 is provided for switching flowing and interruption of gas in the fourth bypass path 33. The fourth bypass valve 34 is formed of a manually operated valve or an automatically controlled valve, for example.
In the compressor 1, the third compression part 13 can be defined as a compression part positioned between the upstream end of the third bypass path 31 (the position of the point P6 in FIG.
2) and the upstream end of the fourth bypass path 33 (the position of the point P5 in FIG.2). The fourth compression part 14 can be defined as a compression part positioned upstream of all of first to fourth bypass paths 21,23,31,33 (the same applies to the embodiment shown in FIG.6).
The first main path valve 51 is a switching valve (a manually operated valve or an automatically controlled valve) that switches flowing and interruption of gas in the main path 10. As shown in FIG.2, the first main path valve 51 is disposed on a portion of the first gas discharge part 10D between the downstream end (point P2) of the first bypass path 21 and the upstream end (point P3) of the second bypass path 23.
The second main path valve 41 is a switching valve (a manually operated valve or an automatically controlled valve) that switches flowing and interruption of gas in the main path 10. As shown in FIG.2, the second main path valve 41 is disposed on a portion of the first gas suction part 10C between the upstream end (point P1) of the first bypass path 21 and the upstream end (point P5) of the fourth bypass path 33.
According to the switching mechanism 20 having the above-mentioned configuration, in accordance with a kind of gas to be compressed, an operation state can be switched between a first operation state where gas is compressed by the four-stage compression part 15, a second operation state where gas is compressed by the three-stage compression part 15 and a third operation state where gas is compressed by the two-stage compression part 15. Hereinafter, the switching of the number of the compression parts 15 arranged in series is described based on a method of operating a compressor according to this embodiment.
<Method of operating compressor>
The method of operating a compressor according to the present embodiment is a method of compressing a boil-off gas G using the compressor 1 described above. In this method, an operation state is switched between the first operation state (FIG.3), the second operation state (FIG. 4) and the third operation state (FIG.5) corresponding to a kind of gas (any one of first to third boil-off gases G1 to G3) to be compressed. In FIG.3 to FIG.5, the valve in an open state is indicated by a blanked portion, and the valve in a closed state is indicated by a black matted portion.
First, in a case of compressing a first boil-off gas G1 (ethylene gas), as shown in FIG.3, the first operation state is adopted where a gas route is formed such that the first boil-off gas G1 sequentially passes through the fourth compression part 14, the third compression part 13, the first compression part 11 and the second compression part 12. The first operation state is a state where the first and second main path valves 51, 41 are opened, and first to fourth bypass valves 22, 24, 32, 34 are closed. In this case, as indicated by a broken-line arrow R1 in FIG.3, only a route is formed where the gas flows into none of the bypass paths, and flows through the main path 10 so that the gas is compressed in four stages by the first to fourth compression parts 11 to 14.
Next, in a case of compressing a second boil-off gas G2 (propane gas), the operation state is switched to the second operation state (FIG.4). In the second operation state, as shown in FIG.
4, the second main path valve 41, the first bypass valve 22 and the second bypass valve 24 are opened, and other valves (the first main path valve 51, the third bypass valve 32, the fourth bypass valve 34) are closed. In this case, two gas routes R1, R2 shown in FIG.4 are formed. As shown in FIG.4, in the gas route R1, gas sequentially passes through the fourth compression part 14 and the third compression part 13. Then, the gas flows into the first bypass path 21 from the point P1, passes through the first bypass path 21 so as to bypass the first compression part 11, flows into the main path 10 from the point P2, and then passes through the second compression part 12. On the other hand, in the gas route R2, gas sequentially passes through the fourth compression part 14, the third compression part 13 and the first compression part 11. Then, the gas flows into the second bypass path 23 from the point P3, passes through the second bypass path 23 so as to bypass the second compression part 12, and flows into the main path 10 from the point P4.
With such an operation, it is possible to allow gas to flow in a state where the first and second compression parts 11, 12 are arranged parallel to each other. Accordingly, while allowing all of the first to fourth compression parts 11 to 14 to perform a gas compression operation, the number of the compression parts 15 arranged in series can be reduced from four stages to three stages.
Next, in a case of compressing a third boil-off gas G3 (butane gas), an operation state is switched to a third operation state (FIG.5). In the third operation state, as shown in FIG.5, an operation state is adopted where the first and second main path valves 41, 51 are closed, and all other valves (the first to fourth bypass valves 22, 24, 32, 34) are opened. In this case, three gas routes R1, R2, R3 shown in FIG.5 are respectively formed. In the gas route R1, gas sequentially passes through the fourth compression part 14 and the third compression part 13. Then, the gas flows into the fourth bypass path 33 from the point P5, sequentially passes through the fourth bypass path 33 and the second bypass path 23 so as to bypass the first compression part 11 and the second compression part 12, and flows into the main path 10 from the point P4. In the gas route R2, gas passes through the fourth compression part 14. Then, the gas flows into the third bypass path 31 from the point P6, sequentially passes through the third bypass path 31 and the first bypass path 21 so as to bypass the third compression part 13 and the first compression part 11, flows into the main path 10 from the point P2, and then passes through the second compression part 12. In the gas route R3, gas passes through the fourth compression part 14. Then, the gas flows into the third bypass path 31 from the point P6, passes through the third bypass path 31 so as to bypass the third compression part 13, and flows into the main path 10 from the point P1. Then, the gas passes through the first compression part 11, flows into the second bypass path 23 from the point P3, passes through the second bypass path 23 so as to bypass the second compression part 12, and flows into the main path 10 from the point P4.
With such an operation, it is possible to allow gas to flow in a state where the first to third compression parts 11, 12, 13 are arranged parallel to each other. Accordingly, while allowing all of the first to fourth compression parts 11 to 14 to perform a gas compression operation, the number of the compression parts 15 arranged in series can be reduced from four stages to two stages.
As has been described above, according to the compressor 1 of the present embodiment, the number of the compression parts 15 arranged in series can be switched between two stages to four stages by switching opening and closing of the respective valves. Accordingly, a discharge pressure can be suitably changed corresponding to a kind of gas to be compressed. Accordingly, it is unnecessary to install the compressor 1 for each kind of the liquefied gas L and hence, a cost can be reduced. Further, in the compressor 1, even in the case where the number of the compression parts 15 arranged in series is reduced from four stages to two or three stages, a state where a gas compression operation is performed in all compression parts 15 is maintained. Accordingly, a gas processing amount by the compression parts 15 arranged parallel to each other is increased.
Accordingly, it is possible to avoid occurrence of a drawback generated due to an idling operation of the compression part 15. Specifically, when the compression part 15 is brought into an idling operation, there is a concern that behaviors of a suction valve and a discharge valve become unstable resulting in rupture of the valve. However, no such drawback occurs in the compressor 1 according to the present embodiment.
(Second embodiment)
Next, a compressor 1A according to the second embodiment of the present invention is described with reference to FIG.6 to FIG.8. The compressor 1A according to the second embodiment basically has the same configuration as the compressor 1 according to the first embodiment, and can acquire the same advantageous effects as the compressor 1 according to the first embodiment. However, the compressor 1A according to the second embodiment differs from the compressor 1 according to the first embodiment with respect to a point that, while the compressor 1 according to the first embodiment is switchable between the first to third operation states, the compressor 1A according to the second embodiment is switchable only between the first operation state and the second operation state. Hereinafter, only the points which make the second embodiment different from the first embodiment are described.
As shown in FIG.6, the compressor 1A according to the second embodiment is configured such that the third compression part 13, the third bypass path 31, the third bypass valve 32, the fourth bypass path 33, the fourth bypass valve 34 and the second main path valve 41 are omitted from the compressor 1 according to the first embodiment. The compressor 1A according to the second embodiment is the same as the compressor 1 of the first embodiment with respect to other configurations. Accordingly, in the compressor 1A, by switching opening and closing of the first and second bypass valves 22, 24 and the first main path valve 51, the number of compression parts 15 arranged in series can be reduced from three stages to two stages.
FIG. 7 shows a first operation state (three-stage compression state) of the compressor 1A, and FIG.8 shows a second operation state (two-stage compression state) of the compressor 1A. Gas routes in the respective operation states are the same as the corresponding gas routes in the first embodiment and hence, the description of the gas routes is omitted.
(Other embodiments)
Other embodiments of the present invention are described below. In the first and second embodiments, one, or two or more other compression parts may be disposed on downstream side of the downstream end P4 of the second bypass path 23.
In the first embodiment, the case is described where the compressor 1 is used for increasing a pressure of a boil-off gas G to a pressure suitable for re-liquefying. However, the use of the compressor of the present invention is not limited to such a case. That is, the compressor of the present invention is applicable to various scenes where a change of a discharge pressure of gas is required.
The respective compression parts 15 (respective first to fourth compression parts) are not always limited to a compression part which includes only one compression chamber. For example, in the case where two compression chambers are formed in one cylinder with a piston sandwiched between two compression chambers (so-called double acting structure), one compression part 15 is formed of these two compression chambers. Also, in the case where a plurality of compression chambers are formed in one cylinder by a plurality of pistons (so-called tandem structure), one compression part 15 may be formed of the plurality of compression chambers. Each compression part 15 may be formed of a plurality of cylinders and a plurality of pistons. A plurality of compression chambers formed in the plurality of cylinders may be arranged in series, may be arranged parallel to each other, or may be arranged in combination of series arrangement and parallel arrangement.
As shown in FIG.9, a downstream end (point P7) of a third bypass path 31 and a downstream end (point P8) of a fourth bypass path 33 may be respectively connected to the main path 10. That is, in the embodiment shown in FIG.9, the third bypass path 31 has the downstream end (point P7) connected to a portion of the main path 10 located upstream of an upstream end (point P1) of a first bypass path 21 and an upstream end (point P6) connected to a portion of the main path 10 located upstream of the downstream end (point P7). The fourth bypass path 33 has a downstream end (point P8) connected to a portion of the main path 10 located upstream of an upstream end (point P3) of the second bypass path 23 and downstream of a first compression part 11 and an upstream end (point P5) connected to a portion of the main path 10 located upstream of the downstream end (point P7) of the third bypass path 31 and downstream of the upstream end (point P6) of the third bypass path 31. In this case, a second main path valve 41 is disposed between the downstream end (point P7) of the third bypass path 31 and the upstream end (point P5) of the fourth bypass path 33.
It should be construed that the embodiments disclosed in this specification are illustrative in all aspects, and are not limitative. The scope of the present invention is not limited by the above-mentioned description but is shown by the claims, and it is intended that the scope of the present invention includes all modifications within the meaning and the scope equivalent to the claims.
For example, it is not always necessary that all compression parts 15 are driven by one drive part, and some compression parts 15 may be driven by another drive part. Some compression parts 15 may be a turbo-type or a screw-type compression part. Two or more types of compression methods among a reciprocation-type, a turbo-type and a screw-type may be used in combination.
In the compressor 1, in addition to the first to fourth bypass paths 21, 23, 31, 33, a return flow path which returns a portion of gas discharged from discharge sides of the respective compression parts 15 to suction sides of the respective compression parts 15 may be provided. By mounting a control valve on the return flow path, and controlling an amount of gas which forms a reverse flow by the control valve, a discharge pressure of the gas can be adjusted.
The above-mentioned embodiments can be briefly described as follows.
The compressor according to the above-mentioned embodiment includes a main path through which gas to be compressed flows, a first bypass path having an upstream end and a downstream end which are connected to the main path, a second bypass path having an upstream end and a downstream end, the upstream end of the second bypass path being connected to a portion of the main path located upstream of the downstream end of the first bypass path and downstream of the upstream end of the first bypass path, and the downstream end of the second bypass path being connected to a portion of the main path located downstream of the downstream end of the first bypass path, a first bypass valve that switches flowing and interruption of gas in the first bypass path, a second bypass valve that switches flowing and interruption of gas in the second bypass path, a first compression part positioned between the upstream end of the first bypass path and the upstream end of the second bypass path, a second compression part positioned between the downstream end of the first bypass path and the downstream end of the second bypass path and a first main path valve that switches flowing and interruption of gas in the main path, the first main path valve being disposed between the downstream end of the first bypass path and the upstream end of the second bypass path.
In this compressor, by closing the first bypass valve and the second bypass valve and opening the first main path valve, only a gas route is formed where gas does not flow in the first bypass path and the second bypass path, but sequentially passes through the first compression part and the second compression part. On the other hand, by opening the first bypass valve and the second bypass valve and closing the first main path valve, a gas route where gas bypasses the first compression part and passes through the second compression part, and a gas route where the gas passes through the first compression part and bypasses the second compression part can be respectively formed. With such a configuration, the number of the compression parts arranged in series can be reduced by one stage and hence, a discharge pressure of gas can be changed. Further, in reducing the number of compression parts arranged in series, it is possible to allow gas to pass in a state where the first compression part and the second compression part are arranged parallel to each other and hence, a processing amount of the gas can be increased. Accordingly, even in the case where the number of the compression parts arranged in series is reduced, a gas compression operation can be performed by both the first compression part and the second compression part and hence, a drawback which occurs due to an idling operation of the compression part can be avoided.
The above-mentioned compressor may further include a third bypass path having a downstream end and an upstream end, the downstream end of the third bypass path being connected to the first bypass path, and the upstream end of the third bypass path being connected to a portion of the main path located upstream of the upstream end of the first bypass path, a fourth bypass path having a downstream end and an upstream end, the downstream end of the fourth bypass path being connected to the second bypass path, and the upstream end of the fourth bypass path being connected to a portion of the main path located upstream of the upstream end of the first bypass path and downstream of the upstream end of the third bypass path, a third bypass valve that switches flowing and interruption of gas in the third bypass path, a fourth bypass valve that switches flowing and interruption of gas in the fourth bypass path, a third compression part positioned between the upstream end of the third bypass path and the upstream end of the fourth bypass path and a second main path valve that switches flowing and interruption of gas in the main path, the second main path valve being disposed between the upstream end of the first bypass path and the upstream end of the fourth bypass path.
With such a configuration, by closing the first main path valve and the second main path valve and opening the first to fourth bypass valves, the following three gas routes can be formed. That is, it is possible to form a gas route where gas passes through the third compression part and bypasses the first compression part and the second compression part, a gas route where gas bypasses the first compression part and the third compression part and passes through the second compression part and a gas route where gas bypasses the second compression part and the third compression part and passes through the first compression part. With such a configuration, while performing a compression operation in all of the first to third compression parts, it is possible to reduce the number of compression parts arranged in series by two stages.
The above-mentioned compressor may further include a third bypass path having a downstream end and an upstream end, the downstream end of the third bypass path being connected to a portion of the main path located upstream of the upstream end of the first bypass path, and the upstream end of the third bypass path being connected to a portion of the main path located upstream of the downstream end of the third bypass path, a fourth bypass path having a downstream end and an upstream end, the downstream end of the fourth bypass path being connected to a portion of the main path located upstream of the upstream end of the second bypass path and downstream of the first compression part, and the upstream end of the fourth bypass path being connected to a portion of the main path located upstream of the downstream end of the third bypass path and downstream of the upstream end of the third bypass path, a third bypass valve that switches flowing and interruption of gas in the third bypass path, a fourth bypass valve that switches flowing and interruption of gas in the fourth bypass path, a third compression part positioned between the upstream end of the third bypass path and the upstream end of the fourth bypass path and a second main path valve that switches flowing and interruption of gas in the main path, the second main path valve being disposed between the downstream end of the third bypass path and the upstream end of the fourth bypass path.
With such a configuration, by closing the first main path valve and the second main path valve and opening the first to fourth bypass valves, the following three gas routes can be formed. That is, it is possible to form a gas route where gas passes through the third compression part and bypasses the first compression part and the second compression part, a gas route where gas bypasses the first compression part and the third compression part and passes through the second compression part and a gas route where gas bypasses the second compression part and the third compression part and passes through the first compression part. With such a configuration, while performing a compression operation in all of the first to third compression parts, it is possible to reduce the number of compression parts arranged in series by two stages.
The method of operating a compressor according to the above-mentioned embodiment is a method of operating a compressor which includes a main path through which gas to be compressed flows, and a first compression part and a second compression part disposed in series in the main path, the second compression part being disposed downstream of the first compression part. In this operation method, an operation state of the compressor is switched between a first operation state and a second operation state, the first operation state being a state where a gas route which allows the gas to sequentially pass through the first compression part and the second compression part is formed, and the second operation state being a state where a gas route which allows the gas to bypass the first compression part and to pass through the second compression part and a gas route which allows the gas to pass through the first compression part and to bypass the second compression part are respectively formed.
According to such a method, by switching an operation state from the first operation state to the second operation state, the number of the compression parts arranged in series can be reduced by one stage and hence, a discharge pressure of the gas can be changed. Further, in the second operation state, gas is allowed to pass both the first compression part and the second compression part. Accordingly, even in the case where the number of compression parts arranged in series is reduced by one stage, a gas compression operation can be performed in both the first compression part and the second compression part and hence, a drawback which occurs due to an idling operation of the compression part can be avoided.
In the above-mentioned method of operating a compressor, the compressor may further include the third compression part disposed upstream of the first compression part. In this operation method, the operation state of the compressor may be further switched to a third operation state where a gas route which allows the gas to pass through the third compression part and to bypass the first compression part and the second compression part, a gas route which allows the gas to bypass the first compression part and the third compression part and to pass through the second compression part, and a gas route which allows the gas to bypass the second compression part and the third compression part and to pass through the first compression part are respectively formed.
According to this method, by switching an operation state between the first to third operation states, the number of the compression parts arranged in series can be reduced by two stages at maximum. In the third operation state, it is possible to allow gas to pass through all of the first to third compression parts. Accordingly, even when the number of the compression parts arranged in series is reduced by two stages, a drawback which occurs due to an idling operation of the compressor can be prevented.
A boil-off gas recovery system according to the above-mentioned embodiment includes a plurality of tanks for storing different kinds of liquefied gases, the compressor for increasing a pressure of a boil-off gas generated due to evaporation of the liquefied gas in the tank, an introducing path for introducing the boil-off gas generated in the tank into the compressor and a re-liquefying unit for liquefying the boil-off gas discharged from the compressor and for returning the liquefied boil-off gas into the tank.
According to this boil-off gas recovery system, by changing the number of the compression parts arranged in series in the compressor corresponding to a kind of liquefied gas, a discharge pressure of the gas can be changed. Accordingly, it is possible to acquire a pressure suitable for re-liquefying the respective liquefied gases. Accordingly, it is unnecessary to install the compressor for each kind of the liquefied gas and hence, a cost can be reduced.
This application is based on Japanese Patent application No.2018-204028 filed in Japan Patent Office on October 30, 2018, the contents of which are hereby incorporated by reference.
Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be understood that various changes and modifications will be apparent to those skilled in the art. Therefore, unless otherwise such changes and modifications depart from the scope of the present invention hereinafter defined, they should be construed as being included therein.

Claims (6)

Claims
1. A compressor comprising:
a main path through which gas to be compressed flows;
a first bypass path having an upstream end and a downstream end which are connected to the main path;
a second bypass path having an upstream end and a downstream end, the upstream end of the second bypass path being connected to a portion of the main path located upstream of the downstream end of the first bypass path and downstream of the upstream end of the first bypass path, and the downstream end of the second bypass path being connected to a portion of the main path located downstream of the downstream end of the first bypass path;
a first bypass valve that switches flowing and interruption of gas in the first bypass path; a second bypass valve that switches flowing and interruption of gas in the second bypass path;
a first compression part positioned between the upstream end of the first bypass path and the upstream end of the second bypass path;
a second compression part positioned between the downstream end of the first bypass path and the downstream end of the second bypass path; and
a first main path valve that switches flowing and interruption of gas in the main path, the first main path valve being disposed between the downstream end of the first bypass path and the upstream end of the second bypass path.
2. The compressor according to claim 1, further comprising:
a third bypass path having a downstream end and an upstream end, the downstream end of the third bypass path being connected to the first bypass path, and the upstream end of the third bypass path being connected to a portion of the main path located upstream of the upstream end of the first bypass path;
a fourth bypass path having a downstream end and an upstream end, the downstream end of the fourth bypass path being connected to the second bypass path, and the upstream end of the fourth bypass path being connected to a portion of the main path located upstream of the upstream end of the first bypass path and downstream of the upstream end of the third bypass path;
a third bypass valve that switches flowing and interruption of gas in the third bypass path; a fourth bypass valve that switches flowing and interruption of gas in the fourth bypass path;
a third compression part positioned between the upstream end of the third bypass path and the upstream end of the fourth bypass path; and
a second main path valve that switches flowing and interruption of gas in the main path, the second main path valve being disposed between the upstream end of the first bypass path and the upstream end of the fourth bypass path.
3. The compressor according to claim 1, further comprising:
a third bypass path having a downstream end and an upstream end, the downstream end of the third bypass path being connected to a portion of the main path located upstream of the upstream end of the first bypass path, and the upstream end of the third bypass path being connected to a portion of the main path located upstream of the downstream end;
a fourth bypass path having a downstream end and an upstream end, the downstream end of the fourth bypass path being connected to a portion of the main path located upstream of the upstream end of the second bypass path and downstream of the first compression part, and the upstream end of the fourth bypass path being connected to a portion of the main path located upstream of the downstream end of the third bypass path and downstream of the upstream end of the third bypass path;
a third bypass valve that switches flowing and interruption of gas in the third bypass path; a fourth bypass valve that switches flowing and interruption of gas in the fourth bypass path;
a third compression part positioned between the upstream end of the third bypass path and the upstream end of the fourth bypass path; and
a second main path valve that switches flowing and interruption of gas in the main path, the second main path valve being disposed between the downstream end of the third bypass path and the upstream end of the fourth bypass path.
4. A method of operating a compressor which includes a main path through which gas to be compressed flows, and a first compression part and a second compression part disposed in series in the main path, the second compression part being disposed downstream of the first compression part,
the method comprising: switching an operation state of the compressor between a first operation state and a second operation state,
the first operation state being a state where a gas route which allows the gas to sequentially pass through the first compression part and the second compression part is formed, and
the second operation state being a state where a gas route which allows the gas to bypass the first compression part and to pass through the second compression part and a gas route which allows the gas to pass through the first compression part and to bypass the second compression part are respectively formed.
5. The method of operating a compressor according to claim 4, wherein
the compressor further includes a third compression part disposed upstream of the first compression part, and
the method includes: further switching the operation state of the compressor to a third operation state where a gas route which allows the gas to pass through the third compression part and to bypass the first compression part and the second compression part, a gas route which allows the gas to bypass the first compression part and the third compression part and to pass through the second compression part, and a gas route which allows the gas to bypass the second compression part and the third compression part and to pass through the first compression part are respectively formed.
6. A boil-off gas recovery system comprising:
a plurality of tanks for storing different kinds of liquefied gases;
the compressor described in any one of claims 1 to 3 for increasing a pressure of a boil-off gas generated due to evaporation of the liquefied gas in the tank;
an introducing path for introducing the boil-off gas generated in the tank into the compressor; and
a re-liquefying unit for liquefying the boil-off gas discharged from the compressor and for returning the liquefied boil-off gas into the tank.
NO20191267A 2018-10-30 2019-10-23 Compressor, method of operating compressor and boil-off gas recovery system NO20191267A1 (en)

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