AU2017419936A1

AU2017419936A1 - Natural gas liquefaction device

Info

Publication number: AU2017419936A1
Application number: AU2017419936A
Authority: AU
Inventors: Hayato ASANO; Eisuke NAKANISHI; Yasuo Tsuzuki
Original assignee: JGC Corp
Current assignee: JGC Corp
Priority date: 2017-06-23
Filing date: 2017-06-23
Publication date: 2019-09-12
Anticipated expiration: 2037-06-23
Also published as: AU2017419936B2; WO2018235267A1

Abstract

[Problem] To provide a natural gas liquefaction device that can be easily maintained and that has a compact configuration. [Solution] A natural gas liquefaction device to liquefy natural gas comprises: equipment installation areas A1 to A5 in which an equipment group comprising a plurality of devices is installed; and an access path 4 for maintenance that is provided along the equipment installation areas A1 to A5 and into which only a maintenance crane, which is a mobile crane of a size that is not greater than a preset maximum lifting load, can enter and operate. When a maintenance crane 40 has been disposed along the boundary of the equipment installation area A1 to A5 including the edges of the access path 4 for maintenance, a device, from the plurality of devices contained in the equipment group, on which maintenance is to be performed using a crane is disposed in an area within the work radius of the maintenance crane 40 decided upon according to the load to be lifted.

Description

NATURAL GAS LIQUEFACTION DEVICE

TECHNICAL FIELD [0001] The present invention relates to a technology for determining an installation position of a device to be arranged in a natural gas liquefaction apparatus.

BACKGROUND ART [0002] A natural gas liquefaction apparatus (NG liquefaction apparatus) is a facility, which is configured to perform pretreatment of removing impurities contained in natural gas (NG) produced in a gas well or the like, and cool and liquefy the NG to produce liquefied natural gas (LNG).

[0003] In the NG liquefaction apparatus, various fluids and chemical substances, such as an absorbing liquid and an adsorbent used for removing the impurities, refrigerant for cooling the NG, and a heating medium used for various heating operations, are handled in addition to the NG to be processed, fuel gas obtained by extracting a part of the NG, a condensate that is a liquid component contained in the NG, and the like.

Therefore, in the NG liquefaction apparatus, a large number of devices, such as devices configured to perform various processings related to those substances and devices configured to transfer and temporarily store various fluids are arranged.

[0004] Here, in Patent Literature 1, there is described an NG liquefaction facility in which a plurality of modules are combined with a heat exchanger bank so as to form a process train of LNG. The plurality of modules each include a device group forming the NG liquefaction facility (liquefied natural gas production facility) on a base having a rectangular shape in plan view. The heat exchanger bank includes a large number of air-cooled heat exchangers provided in a main pipe rack upper portion (first level).

[0005] In the above-mentioned NG liquefaction facility, a major axis is set in the process train, and a large number of heat exchangers are arranged side by side along a major axis direction of the process train in the heat exchanger bank. Meanwhile, a major axis forming a long side of each base of the plurality of modules is formed so as to be orthogonal to the major axis of the process train (arranged to lie perpendicular to the major axis of the train), and the other modules are provided so as to be spaced apart from each other (a plurality of space-apart modules).

A part of the heat exchanger bank (a subset of the plurality of heat exchangers) is arranged so as to obtain a state in which the modules are partially covered (partially covered module). With this, compact device arrangement is achieved.

[0006] In addition, in Patent Literature 2, there is described a liquefied gas production facility, which is configured to perform compression of precooling refrigerant after being used for precooling NG and cooling main refrigerant and compression of the main refrigerant after being used for liquefying the precooled NG through use of a plurality of various compressors (first and fourth compressors are used for compression of the precooling refrigerant, and second and third compressors are used for compression of the main refrigerant).

[0007] In the above-mentioned liquefied gas production facility, the first compressor, a precooling heat exchanger configured to precool the NG, an auxiliary heat exchanger configured to cool the main refrigerant, and the fourth compressor are arranged in the stated order along one long side of a pipe rack, and the second compressor, a main heat exchanger configured to liquefy the NG, and the third compressor are arranged in the stated order along another long side of the pipe rack. With this, device arrangement in which complication of pipe routing and an increase in installation space are suppressed is achieved.

Citation List

Patent Literature [0008] [Patent Literature 1] WO 2014/028961 Al [Patent Literature 2] JP 2016/038193 A

SUMMARY

Technical Problem [0009] In the technologies described in Patent Literature 1 and Patent Literature 2, device arrangement is performed based on each concept. With this, space saving of the NG liquefaction apparatus (NG liquefaction facility and liquefied gas production facility) is achieved.

However, in Patent Literature 1 and Patent Literature 2, there is no disclosure of a technology involving arranging a large number of devices in a limited device installation area also in consideration of ease of maintenance of the devices in a constructed NG liquefaction apparatus.

[0010] The present invention has been made in view of the above-mentioned circumstances and has an object to provide a natural gas liquefaction apparatus, which is easily subjected to maintenance and has a compact configuration.

Solution to Problem [0011] According to one embodiment of the present invention, there is provided a natural gas liquefaction apparatus for liquefying a natural gas, including: a device installation area in which a device group including a plurality of devices forming a part of the natural gas liquefaction apparatus is installed; and an maintenance access, which is arranged along the device installation area, and allows only a maintenance crane to enter the maintenance access and to be operated therein through arrangement of an obstacle on another edge portion side opposite to one edge portion extending along the device installation area, the maintenance crane being a mobile crane having a size equal to or smaller than a maximum lifting load set in advance, wherein, of the plurality of devices included in the device group, each of the devices to be subjected to maintenance through use of the maintenance crane is installed within a range of a working radius of the maintenance crane determined in accordance with a lifting load required at a time of maintenance of the device when the maintenance crane is arranged along a boundary of the device installation area including the one edge portion of the maintenance access.

[0012] The gas liquefaction apparatus may have the following features.

(a) When the device installation area is defined as one device installation area, the obstacle comprises a structure in another device installation area in which a device group that forms a part of the natural gas liquefaction apparatus and is different from the devices included in the device group installed in the one device installation area is installed.

(b) The device installation area is provided along a main pipe rack having a frame structure configured to hold a pipe through which a fluid to be handled in the natural gas liquefaction apparatus flows, and each of the devices to be subjected to maintenance through use of the maintenance crane is installed under a setting condition of a device installation position in which maintenance with the maintenance crane being arranged is prevented from being performed from a boundary side of the device installation area along the main pipe rack.

(c) In (b), an air-cooled heat exchanger configured to cool the fluid to be handled in the device group is provided in the device installation area. Moreover, when the natural gas liquefaction apparatus is viewed in plan view, the maintenance access is provided so as to extend in a direction crossing the boundary along the main pipe rack.

(d) In (b), a sub pipe rack having a frame structure configured to hold the pipe through which the fluid to be handled in the device group flows is provided in the device installation area. When the natural gas liquefaction apparatus is viewed in plan view, the sub pipe rack is provided so as to extend in a direction crossing the boundary along the main pipe rack. The devices to be subjected to maintenance through use of the maintenance crane arranged in the maintenance access are installed on both sides of the sub pipe rack.

[0013] (e) At least one of a substation room configured to supply an electric power to a power consumption device provided in the natural gas liquefaction apparatus and a refrigerant compressor configured to compress a refrigerant for cooling the natural gas is provided at a position away from the maintenance access, which is outside the device installation area and is prevented from being constrained by the maximum lifting load set in advance of the maintenance crane.

(f) A sub pipe rack having a frame structure configured to hold a pipe through which a fluid to be handled in the device group flows is provided in the device installation area. When the natural gas liquefaction apparatus is viewed in plan view, the sub pipe rack is provided so as to extend in a direction crossing the boundary along the main pipe rack. The sub pipe rack extends so as to protrude from the device installation area, and has a substation room in a distal end portion of an extending pipe rack, the substation room being configured to supply an electric power to a power consumption device provided in the natural gas liquefaction apparatus.

(g) The maximum lifting load set in advance of the maintenance crane that is allowed to enter the maintenance access is 50 tons or less.

Advantageous Effects of Invention [0014] In the present invention, when the maintenance crane is arranged along the boundary of the device installation area in which the device group of the natural gas liquefaction apparatus is installed, not only at a position in contact with the maintenance access, in which an upper limit is set to the size of the maintenance crane that can enter the maintenance access, but also at another position, the device to be subjected to maintenance is arranged exclusively within the range of the working radius of the maintenance crane having a size equal to or smaller than the upper limit.

As a result, as long as a maintenance crane having a size equal to or smaller than the upper limit set in advance is prepared, maintenance of the device in the device installation area can be performed. With this, device arrangement in which maintenance is easily performed is achieved. In addition, it is not required to enlarge a width of the maintenance access in accordance with a maintenance crane having a size larger the upper limit, and hence a natural gas liquefaction apparatus having a compact configuration can be obtained.

BRIEF DESCRIPTION OF DRAWINGS [0015] FIG. 1 is an explanatory diagram for illustrating a configuration example of an NG liquefaction apparatus according to an embodiment of the present invention.

FIG. 2 are each a schematic view for illustrating a procedure for determining installation positions of devices in a device installation area of the NG liquefaction apparatus.

FIG 3 is a plan view for illustrating one example of installation layout of the devices in the NG liquefaction apparatus.

FIG 4 are each a plan view for illustrating exemplary installation positions of devices in a device installation area of a liquefaction process unit.

FIG 5 are each a first plan view for illustrating exemplary installation positions of devices in a device installation area of a pretreatment unit.

FIG 6 are each a plan view for illustrating exemplary installation positions of devices in a device installation area of a rectifying unit.

FIG 7 are each a second plan view for illustrating the exemplary installation positions of the devices in the device installation area of the pretreatment unit.

FIG 8 is a plan view for illustrating one example of installation layout of devices in a related-art NG liquefaction apparatus.

DESCRIPTION OF EMBODIMENTS [0016] FIG. 1 is an illustration of a schematic configuration example of a natural gas (NG) liquefaction apparatus that is configured through use of a module for a natural gas liquefaction apparatus according to an embodiment of the present invention.

In FIG. 1 to FIG. 7, there is illustrated an embodiment in which the present invention is applied to an NG liquefaction apparatus. This NG liquefaction apparatus has an annual LNG production amount of from about 200,000 tons to about 1,000,000 tons, and is configured not to precool NG or cool main refrigerant through use of precooling refrigerant (C3 refrigerant) containing propane as a main component.

[0017] The NG liquefaction apparatus includes a gas-liquid separation unit 11, a mercury removal unit 12, an acid gas removal unit 13, a dehdration unit 14, a liquefaction process unit 15, and a storage tank 17. The gas-liquid separation unit 11 is configured to separate a liquid from NG The mercury removal unit 12 is configured to remove mercury from the NG The acid gas removal unit 13 is configured to remove acid gas, such as carbon dioxide and hydrogen sulfide, from the NG The dehydration unit 14 is configured to remove a trace amount of moisture contained in the NG. The liquefaction process unit 15 is configured to cool and liquefy the NG having those impurities removed therefrom to obtain LNG The storage tank 17 is configured to store the liquefied LNG [0018] The gas-liquid separation unit 11 is configured to separate a condensate, which is a liquid at normal temperature, contained in the NG transported through a pipeline or the like. For example, the gas-liquid separation unit 11 includes an elongated pipe and a drum The elongated pipe and the drum are arranged so as to be inclined, and are configured to separate a liquid from the NG through use of a difference in specific gravity. The gas-liquid separation unit 11 may include a device group including a regeneration column and a reboiler of an antifreeze liquid configured to regenerate and heat an antifreeze liquid to be added as necessary in order to prevent clogging in the pipeline in the process of transportation and supplementary facilities thereof.

[0019] The mercury removal unit 12 is configured to remove a trace amount of mercury contained in the NG having the liquid separated therefrom. For example, the mercury removal unit 12 includes a device group including, for example, a mercury adsorption column in which a mercury removal agent is filled in an adsorption column and supplementary facilities thereof.

[0020] The acid gas removal unit 13 is configured to remove acid gas, such as carbon dioxide and hydrogen sulfide, which are liable to be solidified in LNG at a time of liquefaction. As a method of removing the acid gas, there are given a procedure using a gas absorbing liquid containing an amine compound or the like and a procedure using a gas separation membrane that allows acid gas in the NG to pass therethrough.

[0021] When the gas absorbing liquid is adopted, the acid gas removal unit 13 includes a device group including, for example, an absorption column 131, a regeneration column 132, a reboiler, and supplementary facilities thereof. The absorption column 131 is configured to bring the natural gas and the gas absorbing liquid into countercurrent contact with each other. The regeneration column 132 is configured to regenerate the gas absorbing liquid having absorbed the acid gas. The reboiler is configured to heat the gas absorbing liquid in the regeneration column 132.

In addition, when the gas separation membrane is adopted, the acid gas removal unit 13 includes a device group including, for example, a gas separation unit configured to accommodate a large number of hollow fiber membranes in a main body and supplementary facilities thereof.

[0022] The dehydration unit 14 is configured to remove a trace amount of moisture contained in the NG. For example, the dehydration unit 14 includes a device group including, for example, a plurality of adsorption columns 141a and 141b, a heater, and supplementary facilities thereof. In the plurality of adsorption columns 141a and 141b, an adsorbent, such as a molecular sieve or silica gel, is filled, and a moisture removing operation of the NG and a regeneration operation of the adsorbent having adsorbed moisture are alternately switched to be performed. The heater is configured to heat regeneration gas (for example, the NG having the moisture removed therefrom) for the adsorbent supplied to the adsorption columns 141a and 141b in which the regeneration operation is performed.

[0023] The NG having the impurities removed therefrom by various processing units (pretreatment units) described above is supplied to the liquefaction process unit 15 to be liquefied. The liquefaction process unit 15 includes a device group including a scrub column 152, a main cryogenic heat exchanger (MCHE) 151, and supplementary facilities thereof. The scrub column 152 is configured to remove a heavy component from the NG. The main cryogenic heat exchanger (MCHE) 151 is configured to cool, liquefy, and subcool the NG with main refrigerant being mixed refrigerant containing a plurality of kinds of refrigerant raw materials, such as nitrogen, methane, ethane, and propane.

[0024] In addition, as a large supplementary facility of the liquefaction process unit 15, there is also a device group including a refrigerant compressor 21, a gas turbine 22, a suction drum, and the like. The refrigerant compressor 21 is configured to compress gas of the main refrigerant vaporized by heat exchange with the NG. The gas turbine 22 is configured to drive the refrigerant compressor 21. The suction drum is configured to perform gas-liquid separation of gas (vaporized main refrigerant) supplied to the refrigerant compressor 21.

A plurality of refrigerant compressors 21 are provided in series in accordance with a pressure boosting level, and in addition, a plurality of gas turbines 22 are also provided in some cases in conformity with the installation number of the refrigerant compressors 21. In FIG 1, the refrigerant compressors 21 and the gas turbines 22 are illustrated as one unit, respectively. [0025] In addition, in FIG 1, there is illustrated an example using the gas turbine 22 as a power source configured to drive the refrigerant compressor 21, but a motor or the like may also be used in accordance with the scale of the refrigerant compressor 21 and the like.

As described later, in the NG liquefaction apparatus according to this embodiment, the device group including the refrigerant compressor 21 and the gas turbine 22 is installed at a position away from the MCHE 151 and the scrub column 152. Therefore, in the description of the installation layout of the devices, the above-mentioned device group is dealt with independently from the liquefaction process unit 15.

[0026] Further, a rectifying unit 16 is juxtaposed to the liquefaction process unit 15. The rectifying unit 16 includes a deethanizer 162 configured to separate ethane from a liquid (liquid heavy component) separated from the cooled NG, a depropanizer 163 configured to separate propane from the liquid having ethane separated therefrom, a debutanizer 164 configured to separate butane from the liquid having propane separated therefrom to obtain a condensate that is a liquid at normal temperature, and the stabilizer 161 configured to adjust a vapor pressure of the condensate. The deethanizer 162, the depropanizer 163, the debutanizer 164, and the stabilizer 161 each include a device group including, for example, a rectifying column configured to rectify each component, a reboiler configured to heat the liquid in each rectifying column, and supplementary facilities thereof. When it is not required to adjust a vapor pressure of the condensate, the stabilizer 161 may not be provided.

[0027] Liquefied natural gas (LNG), which has been liquefied and subcooled in the liquefaction process unit 15, is fed to and stored in the storage tank 17. The LNG stored in the storage tank 17 is fed with an LNG pump (not shown) and shipped to an LNG tanker, a truck, or a pipeline.

[0028] In addition, in the NG liquefaction apparatus, there are also provided device groups including, for example, an oil heater, a boiler, and the like configured to perform various heating operations performed in the above-mentioned various processing units 11 to 16 and perform heating of a heating medium (for example, hot oil, vapor, or the like) supplied to a heater configured to prevent freezing of the ground surface or the like, which is provided on a bottom surface of the storage tank 17, and a supplementary facility thereof, and a gas turbine generator and a gas engine generator configured to supply electric power to be consumed in the NG liquefaction apparatus, and a supplementary facility.

[0029] In addition, as described above, in this embodiment, description is given of the example of the NG liquefaction apparatus that is not configured to precool the NG or cool the main refrigerant through use of the precooling medium. However, when those processings are performed, a precooling heat exchanger configured to precool the NG with the precooling medium, a refrigerant compressor configured to compress the vaporized precooling medium, and a gas turbine or a motor serving as a power source may be provided.

[0030] As described above, when the NG liquefaction apparatus including a large number of devices is constructed in a predetermined site, it is required not only to satisfy the constraints on an area and a shape of the site but also to determine installation layout of the devices also in consideration of maintenance of each device after construction and the like.

[0031] For example, FIG. 8 is a view for illustrating one example of installation layout of an NG liquefaction apparatus which has hitherto been known. The NG liquefaction facility described in Patent Literature 1 exemplified as a related-art also has a configuration based on the installation layout of the NG liquefaction apparatus illustrated in FIG. 8.

[0032] The NG liquefaction apparatus illustrated in FIG 8 includes a main pipe rack 31 having an elongated band shape arranged in a straight line shape when viewed from an upper surface side. The main pipe rack 31 has a frame structure, and is configured to hold pipes (not shown) through which various fluids handled in the NG liquefaction apparatus flow. A plurality of device installation areas Al to A6 are arranged at intervals at positions on both sides along a long side direction of the main pipe rack 31. In each of the device installation areas Al to A6, there is installed a device group including a plurality of devices forming a part (for example, the above-mentioned various processing units 11 to 16, refrigerant compressor 21, and gas turbine 22) of the NG liquefaction apparatus.

[0033] In FIG 8 in which the related-art installation layout is illustrated, and FIG 3 to FIG 7 in which the installation layout of the NG liquefaction apparatus according to this embodiment is illustrated, the broken lines represent partition lines that are set so as to define outer edges of each of the device installation areas Al to A6 from the viewpoint of facility management and the like.

[0034] In addition, for convenience of illustration, in the device installation areas Al to A6 illustrated in FIG 3 to FIG 8 described below, of the large number of devices arranged in the device installation areas A1 to A6, only a part of the devices required to be subjected to maintenance through use of a crane are selected to be displayed.

Further, in the description of FIG. 3 to FIG. 8, an origin side of the X-axis arrow illustrated in FIG. 3 to FIG. 8 is sometimes referred to as left side, and a distal end side thereof is sometimes referred to as right side. An origin side of the Y-axis arrow is sometimes referred to as front side, and a distal end side thereof is referred to as back side.

[0035] In the example illustrated in FIG. 8, the device installation areas A6 each including the refrigerant compressor 21 and the gas turbine 22, the device installation area A2 including the mercury removal unit 12 and the dehydration unit 14, and the like are arranged side by side in a row along a long side on the back side of the main pipe rack 31. In addition, the device installation area A4 including the rectifying unit 16, the device installation area A1 including the liquefaction process unit 15, the device installation area A5 including the gas-liquid separation unit 11 and the acid gas removal unit 13, and the like are arranged side by side in a row along the long side on the front side of the main pipe rack 31.

[0036] Here, in general, in the NG liquefaction apparatus, also after the construction is completed, and the production of LNG is started, the operation of the NG liquefaction apparatus is stopped, for example, every several years, and the devices are released, to thereby perform maintenance involving inspection and repair. Of those devices, there are some devices that are required to be subjected to maintenance through use of a crane when the devices are released and large components are removed.

[0037] Meanwhile, as described above, the large number of devices are installed in each of the device installation areas A1 to A6. Therefore, when the devices are installed at random positions without considering maintenance using a crane, there is a risk in that the device arranged at a certain position may serve as an obstacle to maintenance of the device installed at another position.

[0038] In view of the foregoing, as illustrated in FIG. 8, the related-art NG liquefaction apparatus has a configuration in which relatively large devices are arrayed along the partition line of each of the device installation areas A1 to A6, and smaller devices are arrayed in the remaining area. In addition, a rack having a multiple-stage structure (not shown) is provided in the remaining area, and those small devices are installed in each stage of the rack in some cases.

[0039] Specifically, in the device installation area A2, the devices 141a, 141b, and 121 are provided side by side along the partition line on the left side. In addition, in the device installation area A4, the devices 162, 163, 164, and 161 are provided side by side along the partition line on the left side. Then, in the device installation area Al, the devices 151 and 152 are provided at positions of both ends of the partition line on the back side, and the device 151 and related devices 155 and 156 thereof are provided side by side along the partition line on the left side. In addition, in the device installation area A5, the devices 11, 131, and 132 are provided side by side along the partition line on the back side. Small devices are not illustrated in each of the device installation areas A2, A4, Al, and A5.

[0040] Now, consideration is made of a case in which, of the devices 11, 131, and 132 provided along the partition line on the back side of the device installation area A5, the devices 131 and 132 indicated by the hatched lines in FIG. 8 are subjected to maintenance through use of a crane.

As described above, in the device installation area A5, the large number of devices are arranged in addition to the devices 11, 131, and 132 illustrated in FIG 8. Therefore, it is difficult to allow a mobile crane to enter the device installation area A5 up to a center side thereof and arrange the crane at the center side. In this respect, there is a large space on the front side of the device installation area A5, and hence through arrangement of the crane having a working radius capable of reaching the devices 131 and 132 to be subjected to maintenance along the partition line on the front side of the device installation area A5, the devices 131 and

132 can be subjected to maintenance.

[0041] When maintenance is performed by the above-mentioned method, it is required to prepare a crane having a size in conformity with a distance between the partition lines from the front side to the back side of the device installation area A5. In this respect, when the distance between the partition lines is long, maintenance of the devices 131 and 132 cannot be performed unless a large crane is prepared. However, from the viewpoint of cost, as a crane is larger, it is more difficult to constantly station the crane in the NG liquefaction apparatus. In addition, even when a crane is obtained from an outside source, large cranes that are available in a limited number may be constrained by a usable period of time.

[0042] In view of the foregoing, when the shape of the device installation area A5 in plan view is further elongated in a right-and-left direction, the distance between the partition lines from the front side to the back side is shortened, with the result that maintenance of the devices 131 and

132 can be performed even through use of a relatively small crane. However, in this case, the entire NG liquefaction apparatus is enlarged in the right-and-left direction, and there is a risk in that the NG liquefaction apparatus may not be accommodated in a predetermined site.

[0043] Next, consideration is made of a case in which, of the devices 141a, 141b, and 121 provided along the partition line on the left side of the device installation area A2, the devices 141b and 121 indicated by the hatched lines are subjected to maintenance through use of a crane. [0044] When a crane is arranged, for example, along the partition line on the back side in the device installation area A2, there is a risk in that the device 141a positioned on the backmost side may serve as an obstacle, and it may be difficult to perform maintenance of the other devices 141b and 121 on the front side.

In this case, the crane is allowed to enter an entry path 4' for maintenance formed along the partition line on the left side of the device installation area A2, and maintenance is performed from a side position on the left side of the device installation area A2.

[0045] However, when the large devices 141a, 141b, and 121 are arranged adjacently to each other at positions close to each other as illustrated in the device installation area A2 in FIG. 8, there is also a risk in that another device may serve as an obstacle, and removed components may not be able to be conveyed by rotation movement of the crane.

In this case, a space is formed between the partition line of the device installation area

A2 and the arrangement position of the crane, and the components removed from the devices 141b and 121 are extracted to the crane side. After that, the removed components are conveyed by rotation movement at a position where another device does not serve as an obstacle.

[0046] However, in order to form the space for extracting the components between the partition line of the device installation area A2 and the arrangement position of the crane as in the above-mentioned example, it is required to ensure a wide path width (for example, 10 m or more) of the entry path 4' for maintenance. As a result, in the related-art NG liquefaction apparatus, the arrangement intervals between the device installation areas Al to A6 each arranged with the entry path 4' for maintenance interposed therebetween become larger, and the entire NG liquefaction apparatus tends to become longer in the right-and-left direction.

[0047] Further, in order to avoid the occurrence of the above-mentioned problem, when the devices 141a, 141b, and 121 illustrated in the device installation area A2 and the devices 155 and

156 illustrated in the device installation area Al are arrayed in the right-and-left direction along the partition line on the front side or the back side of each of the device installation areas A2 and Al (along the main pipe rack 31) in the same manner as in the device installation area A5, the shape of each of the device installation areas A2 and Al in plan view becomes longer in the right-and-left direction, and there also arises a problem in that the entire NG liquefaction apparatus is enlarged in the right-and-left direction.

[0048] In view of the problem of the related-art layout described above, the NG liquefaction apparatus according to this embodiment has a configuration in which the devices are arranged so that maintenance can be easily performed through use of a crane in the compact device installation areas Al to A5 while the path width of an entry path 4 for maintenance is suppressed to a requisite minimum as illustrated in FIG. 3 to FIG. 7.

Here, FIG. 3 is a plan view for illustrating the overall layout of the NG liquefaction apparatus, and FIG. 4 to FIG 7 are enlarged plan views of the device installation areas Al, A2,

A4, and A5, respectively.

[0049] Before the installation positions of the devices in the NG liquefaction apparatus according to this embodiment are specifically described, a procedure for determining the installation positions of the devices in the device installation areas Al to A5 is described with reference to FIG 2.

FIG 2(a) and FIG 2(b) are each a view for illustrating the device installation area A illustrated as a model for description of the procedure for determining the installation positions of the devices in this embodiment. The solid line on each outer edge side of the device installation area A represents a boundary, on an inner side of which a 25-ton crane 41 cannot be arranged.

[0050] The boundary is set to a position, which is separated, by a distance to be ensured from the viewpoint of safety, from a structure arranged on an outermost peripheral side of the device installation area A in operation using the maintenance crane 40 when the devices and structures such as a rack are arranged in the device installation area A. In other words, the boundary corresponds to an outer edge of the device installation area A, on an inner side of which the maintenance crane 40 cannot be arranged.

Meanwhile, the partition lines represented by the broken lines in FIG 3 to FIG 8 each represent an outer edge for facility management of each of the device installation areas Al to A6 after the installation position of each device is determined, and the boundary and the partition line are not strictly matched with each other in some cases.

[0051] In the example illustrated in FIG 2(a) and FIG 2(b), a shape of the boundaries of the device installation area A in plan view is set to a rectangular shape, and the boundary on the front side is formed along the long side of the main pipe rack 31 represented by the alternate long and short dash line.

On the side of the boundary on the left side of the device installation area A, an obstacle

101 is arranged, and an area between the obstacle 101 and the boundary on the left side of the device installation area A serves as the entry path 4 for maintenance which allows the mobile maintenance crane 40 to enter. In other words, it can be said that, in this embodiment, the boundary on the left side of the device installation area A forms one edge portion extending along the device installation area A, and the obstacle 101 is arranged on another edge portion side opposite to the one edge portion, with the entry path 4 for maintenance being formed so as to be sandwiched between the two edge portions.

[0052] As the obstacle 101, there may be given, for example, structures such as a branch pipe rack 32 described later and a device and a rack in another device installation area. In this case, when the device installation area A is defined as one device installation area, a device group, which forms a part of the NG liquefaction apparatus and is different from the devices included in the device group installed in the one device installation area, is installed in the another device installation area.

[0053] Further, the path width of the entry path 4 for maintenance has such a dimension that only the maintenance crane 40 having a size equal to or smaller than a maximum lifting load set in advance is allowed to enter the entry path 4 for maintenance. In this embodiment, description is given of a case in which the maximum lifting load of the maintenance crane 40 that is allowed to enter the entry path 4 for maintenance is 25 tons. The path width of the entry path 4 for maintenance in this case is, for example, 6 m.

[0054] Consideration is made of a case in which maintenance is performed through use of two kinds of maintenance cranes 40 (25-ton crane 41 and 10-ton crane 42) having a maximum lifting load of 25 tons and 10 tons, respectively, in the entry path 4 for maintenance having the above-mentioned path width.

In this case, as shown in the following Table 1, the maintenance crane 40 is constrained by a working radius capable of performing lifting operation depending on the length of a boom and a lifting load at a time of operation.

(Table 1)

25-ton crane

Length of boom	Working radius [m]	Lifting load [t]
18m	4	16.00
6	13.70
9	8.80
10	7.20
12	5.00
33 m	14	4.10
16	3.50
22	1.70
24	1.35

10-ton crane

Length of boom	Working radius [m]	Lifting load [t]
18.2 m	6	2.47
8	1.70
9	1.35

[0055] As is understood from (Table 1), when the 25-ton crane 41 is arranged in the entry path 4 for maintenance, the working radius in the case of a lifting load of 16 tons is 4 meters. Therefore, only maintenance of a device having a required lifting load of 16 tons or less is performed within a working radius of 4 meters or less from the arrangement position of the 25-ton crane 41. In addition, the working radius in the case of a lifting load of 13.7 tons is 6 meters. Therefore, only maintenance of a device having a required lifting load of 13.7 tons or less can be performed in an area of from 4 meters to 6 meters from the arrangement position of the 25-ton crane 41.

As described above, there is the following relationship. As the working radius is increased, a lifting load that can be lifted by the 25-ton crane 41 is decreased.

[0056] Meanwhile, the larger maintenance crane 40 can also be arranged on the boundary line on the back side and the boundary on the right side of the device installation area A, which are not in contact with the entry path 4 for maintenance.

However, as in the problems mentioned in the description of the related-art NG liquefaction apparatus of FIG 8, there is a problem in that it is difficult to constantly station the large maintenance crane 40 in the NG liquefaction apparatus and to freely obtain the large maintenance crane 40 from an outside source.

[0057] In view of the foregoing, in the device installation area A in this embodiment, when the maintenance crane 40 is arranged along the boundary, within a range of each of the work radii shown in (Table 1), devices that require lifting loads in accordance with the work radii at a time of maintenance are installed.

The above-mentioned procedure for determining the installation position of each of the devices is not limited to the area along the boundary on the left side of the device installation area A extending along the entry path 4 for maintenance, and can be applied also to an area along another boundary (boundary on the back side and boundary on the right side).

[0058] More specifically, as illustrated in FIG 2(a), when the maintenance crane 40 is arranged along each boundary on the left side, the back side, and the right side of the device installation area A, a device that requires a lifting load of Xi tons at a time of maintenance is installed within an installation range ai identified based on a working radius Ri of the maintenance crane 40 determined depending on the lifting load (Xi tons).

[0059] In addition, as illustrated in FIG 2(b), when the maintenance crane 40 is arranged along each boundary on the left side, the back side, and the right side of the device installation area A, a device that requires a lifting load of X2 tons smaller than Xi tons at a time of maintenance is installed within an installation range a2 identified based on a working radius R2 (>Ri) of the maintenance crane 40 determined depending on the lifting load (X2 tons).

[0060] It is difficult to arrange the maintenance crane 40 along the boundary on the front side extending in contact with the main pipe rack 31. In addition, even when the maintenance crane 40 is arranged on a further front side of the main pipe rack 31, in the case in which operation is performed through a space above the main pipe rack 31 with the small maintenance crane 40, such as the 25-ton crane 41 or the 10-ton crane 42, the working radius is significantly limited. [0061] In view of the foregoing, in this embodiment, the installation positions of the devices are determined under a setting condition of a device installation position in which maintenance with the maintenance crane 40 being arranged is prevented from being performed from the boundary side on the front side.

The above-mentioned precondition is a provisional condition for determining the installation positions of the devices and does not completely exclude the case in which maintenance of a device is actually performed beyond the main pipe rack 31 through use of a large crane.

[0062] Through adoption of the above-mentioned concept of the device installation, it becomes possible to configure the NG liquefaction apparatus in which maintenance can be performed through use of only the small maintenance crane 40 that can be constantly stationed in the NG liquefaction apparatus or relatively easily prepared from an outside source or the like. In this case, as the maintenance crane 40 that is relatively easily prepared, there can be given, for example, the maintenance crane 40 having a maximum lifting load of up to 50 tons.

[0063] In addition, when the installation positions of the devices are determined based on the above-mentioned procedure, a space area in which the installation number of devices is small is formed in an area on a center side of the device installation area A away from the boundaries on three sides along the arrangement position of the maintenance crane 40. For example, when the shape of the device installation area A in plan view is a rectangular shape, the space area is an area having a rectangular shape in plan view, which extends in a direction crossing the long side direction of the main pipe rack 31.

[0064] In view of the foregoing, a sub pipe rack 100 may be provided so as to extend in a direction crossing the main pipe rack 31 (boundary on the front side along the main pipe rack 31) in conformity with the shape of the space area in plan view. In this case, it can also be said that parts of the devices in the device installation area A are installed on both sides of the sub pipe rack 100 when viewed therefrom.

The sub pipe rack 100 is capable of holding pipes configured to connect the pipes held in the main pipe rack 31 to each of the devices in the device installation area A, and is capable of arranging air-cooled heat exchangers (ACHEs) configured to cool a fluid flowing through those pipes in a top portion as necessary.

[0065] FIG. 3 is a view for illustrating one example of layout of the device installation areas Al to A6 in the NG liquefaction apparatus configured based on the above-mentioned concept of the device installation. In the NG liquefaction apparatus according to this embodiment, the plurality of device installation areas Al to A5 are arranged separately in two lines along the long side direction of the main pipe rack 31.

[0066] For example, the devices included in the device groups forming the liquefaction process unit 15, the mercury removal unit 12 and the dehydration unit 14, the rectifying unit 16, and the acid gas removal unit 13 illustrated in FIG 1 are separately installed in the device installation areas Al, A2, A4, and A5. In addition, in the device installation area A3, for example, devices configured to heat and supply hot oil to be used in the NG liquefaction apparatus are installed. [0067] Now, with reference to FIG 4 to FIG 7, description is given of a specific example of the installation positions of the devices in each of the device installation areas Al, A2, A4, and A5.

For convenience of description, devices to be subjected to maintenance through use of the 25-ton crane 41 are referred to as type 1 lifting devices, and devices to be subjected to maintenance through use of the 10-ton crane 42 are referred to as type 2 lifting devices.

In addition, in FIG. 4 to FIG. 7, devices having a circular shape or exhibiting an elongated contour with both ends having a semicircular shape represent static devices such as a column, a tank, and a heat exchanger, and the devices exhibiting a rectangular contour represent rotating devices such as a pump and an ACHE.

[0068] As illustrated in FIG. 3, the device installation area Al is a area having a rectangular shape in plan view arranged along the long side on the back side of the main pipe rack 31 extending in the right-and-left direction. The entry paths 4 for maintenance formed so as to extend in a direction crossing the boundary along the long side of the main pipe rack 31 are formed respectively between the boundary on the left side of the device installation area Al and the branch pipe rack 32 described later and between the boundary on the right side of the device installation area Al and the device installation area A2.

[0069] In the device installation area Al, type 1 lifting devices 15A to 15C to be subjected to maintenance through use of the 25-ton crane 41 are installed within a range of each working radius of the 25-ton crane 41 of which arrangement position is illustrated in FIG. 4(a).

In addition, type 2 lifting devices 15a and 15b to be subjected to maintenance through use of the 10-ton crane 42 are installed within a range of each working radius of the 10-ton crane 42 of which arrangement position is illustrated in FIG. 4(b).

[0070] Further, in the device installation area Al, a sub pipe rack 150 is arranged so as to extend in the direction crossing the main pipe rack 31.

In addition, in an area along the boundary on the back side of the device installation area Al, a main refrigerant cooler 153 formed of an ACHE is arranged. In the device installation area Al, an expansion area B to which devices are added at a time of future enhancement of production ability is ensured.

[0071] Next, as illustrated in FIG. 3, the device installation area A2 is a area having a rectangular shape in plan view arranged along the long side on the back side of the main pipe rack 31 extending in the right-and-left direction. The entry paths 4 for maintenance formed so as to extend in the direction crossing the boundary along the long side of the main pipe rack 31 are formed between the boundary on the left side of the device installation area A2 and the device installation area Al and between the boundary on the right side of the device installation area A2 and the device installation area A3.

[0072] In the device installation area A2, type 1 lifting devices 12A to 12C, 14A and 16A to be subjected to maintenance through use of the 25-ton crane 41 are installed within a range of each working radius of the 25-ton crane 41 of which arrangement position is illustrated in FIG. 5(a).

In addition, type 2 lifting devices 12a, 14a, and 16a to be subjected to maintenance through use of the 10-ton crane 42 are installed within a range of each working radius of the 10-ton crane 42 of which arrangement position is illustrated in FIG. 4(b).

[0073] Further, in the device installation area A2, a sub pipe rack 120 is arranged so as to extend in the direction crossing the main pipe rack 31. A regeneration gas cooler 142 formed of an ACHE is arranged in a top portion of the sub pipe rack 120.

[0074] Next, as illustrated in FIG. 3, the device installation area A4 is a area having a rectangular shape in plan view arranged along the long side on the front side of the main pipe rack 31 extending in the right-and-left direction. The entry paths 4 for maintenance formed so as to extend in the direction crossing the boundary along the long side of the main pipe rack 31 are formed between the boundary on the right side of the device installation area A4 and the device installation area A5.

[0075] In the device installation area A4, type 1 lifting devices 16B and 16C to be subjected to maintenance through use of the 25-ton crane 41 are installed within a range of each working radius of the 25-ton crane 41 of which arrangement position is illustrated in FIG. 6(a).

In addition, type 2 lifting devices 16b to 16e to be subjected to maintenance through use of the 10-ton crane 42 are installed within a range of each working radius of the 10-ton crane 42 of which arrangement position is illustrated in FIG. 6(b).

[0076] Further, in the device installation area A4, a sub pipe rack 160 is arranged so as to extend in the direction crossing the main pipe rack 31. A overhead cooler 165 formed of an ACHE is arranged in a top portion of the sub pipe rack 160.

Further, as illustrated in FIG. 3, the sub pipe rack 160 extends so as to protrude from the device installation area A4 to form the branch pipe rack 32, and a substation room SS configured to supply electric power to a power consumption device provided in the NG liquefaction apparatus is provided in a distal end portion of the extending branch pipe rack 32.

[0077] Finally, as illustrated in FIG. 3, the device installation area A5 is a area having a substantially rectangular shape in plan view arranged along the long side on the front side of the main pipe rack 31 extending in the right-and-left direction. The entry paths 4 for maintenance formed so as to extend in the direction crossing the boundary along the long side of the main pipe rack 31 are formed between the boundary on the left side of the device installation area A5 and the device installation area A4.

[0078] In the device installation area A5, type 1 lifting devices 13A to 13F to be subjected to maintenance through use of the 25-ton crane 41 are installed within a range of each working radius of the 25-ton crane 41 of which arrangement position is illustrated in FIG. 7(a).

In addition, type 2 lifting devices 13a to 13c to be subjected to maintenance through use of the 10-ton crane 42 are installed within a range of each working radius of the 10-ton crane 42 of which arrangement position is illustrated in FIG. 7(b).

In addition, in the device installation area A5, a sub pipe rack 130 is arranged so as to extend in the direction crossing the main pipe rack 31.

[0079] Although description using the detailed figure is omitted, also in the device installation area A3 in which the devices configured to heat and supply hot oil are installed, the type 1 lifting devices to be subjected to maintenance through use of the 25-ton crane 41 and the type 2 lifting devices to be subjected to maintenance through use of the 10-ton crane 42 are arranged so as to be classified into positions in accordance with the working radius of each of the cranes 41 and based on the procedure described with reference to FIG. 2.

[0080] As described with reference to FIG 4 to FIG 7, when the devices are arranged along the boundary of each of the device installation areas Al, A2, A4, and A5, the arrangement intervals of the devices can be enlarged as compared to the related art in which the devices are arranged side by side along one side of the partition line of each of the device installation areas Al, A2, A4, and A5 described with reference to FIG 8. Through determination of the installation positions of the devices also in consideration of the working radius of the maintenance crane 40 (25-ton crane 41 and 10-ton crane 42) under the above-mentioned condition, the installation position of each device can be determined while consideration is made so that the devices installed adjacently to each other do not serve as obstacles at a time of maintenance.

[0081] Returning to the description of the overall layout of the NG liquefaction apparatus of FIG 3, the device installation area A6 in which the above-mentioned refrigerant compressor 21 and gas turbine 22 are installed and the substation room SS are provided at positions, which are away from an area in which the device installation areas Al to A5 are arranged along the main pipe rack 31 (positions away from the entry path 4 for maintenance), and which are not constrained by a maximum lifting load depending on the path width of the entry path 4 for maintenance.

The pipes and electric cables configured to connect the devices in the device installation area A6 and the substation room SS to the devices in the device installation areas Al to A5 are held by the branch pipe rack 32 provided so as to be branched from the main pipe rack 31.

[0082] When the device installation area A6 and the substation room SS, which include the large devices and may require a larger crane, are arranged at the positions away from the other device installation areas Al to A5, the above-mentioned arrangement area of the device installation areas Al to A5 can be defined in a compact manner.

The present invention does not exclude the adoption of layout in which at least one of the device installation area A6 or the substation room SS is arranged side by side with the other device installation areas Al to A5 along the long side of the main pipe rack 31 in accordance with the constraint of a site shape in which the NG liquefaction apparatus is constructed. In this case, it is only required that the device installation area A6 or the substation room SS be arranged at a distal end of the lines of the other device installation areas Al to A5, which is less liable to be constrained by the selection of a crane depending on the path width of the entry path for maintenance.

[0083] The NG liquefaction apparatus according to this embodiment has the following effect. When the maintenance crane 40 is arranged along the boundary of each of the device installation areas Al to A5 in which the device groups of the NG liquefaction apparatus are installed, not only at a position in contact with the entry path 4 for maintenance, in which an upper limit is set to the size of the maintenance crane 40 that can enter the entry path 4 for maintenance, but also at another position, the device to be subjected to maintenance is arranged exclusively within a range of the working radius of the maintenance crane 40 having a size equal to or smaller than the upper limit.

[0084] As a result, as long as the maintenance crane 4 having a size equal to or smaller than the upper limit set in advance is prepared, maintenance of the devices in the device installation areas Al to A5 can be performed. With this, device arrangement in which maintenance is easily performed is achieved. In addition, it is not required to enlarge the width of the entry path 4 for maintenance in accordance with a maintenance crane having a size larger the upper limit, and hence a natural gas liquefaction apparatus having a compact configuration can be obtained.

[0085] In this case, in maintenance of the devices in the device installation areas Al to A6, in which the installation position of each of the devices has been determined based on the above-mentioned concept, there is no prohibition against performing, for example, maintenance from outside of the entry path 4 for maintenance through use of a crane larger than the maintenance crane 40 that can enter the entry path 4 for maintenance. For example, when it is required to perform maintenance different from usual maintenance, such as update of the device, the above-mentioned maintenance using a large crane may be performed.

Also in this case, at a time of usual maintenance, the effect of the present invention, in which maintenance of the devices in the device installation areas Al to A5 can be performed through use of only the relatively small maintenance crane 40, is not lost.

REFERENCE SIGNS FIST [0086] A, Al to A6 device installation area

100 sub pipe rack

101 obstacle

4, 4' maintenance access maintenance crane

25-ton crane

10-ton crane

Claims

1. A natural gas liquefaction apparatus for liquefying a natural gas, comprising:

a device installation area, in which a device group including a plurality of devices forming a part of the natural gas liquefaction apparatus is installed; and an maintenance access, which is arranged along the device installation area, and allows only a maintenance crane to enter the maintenance access and to be operated therein through arrangement of an obstacle on another edge portion side opposite to one edge portion extending along the device installation area, the maintenance crane being a mobile crane having a size equal to or smaller than a maximum lifting load set in advance, wherein, of the plurality of devices included in the device group, each of the devices to be subjected to maintenance through use of the maintenance crane is installed within a range of a working radius of the maintenance crane determined in accordance with a lifting load required at a time of maintenance of the device, when the maintenance crane is arranged along a boundary of the device installation area including the one edge portion of the maintenance access.

2. The natural gas liquefaction apparatus according to claim 1, wherein when the device installation area is defined as one device installation area, the obstacle comprises a structure in another device installation area in which a device group that forms a part of the natural gas liquefaction apparatus and is different from the devices included in the device group installed in the one device installation area is installed.

3. The natural gas liquefaction apparatus according to claim 1, wherein the device installation area is provided along a main pipe rack having a frame structure configured to hold a pipe through which a fluid to be handled in the natural gas liquefaction apparatus flows, and wherein each of the devices to be subjected to maintenance through use of the maintenance crane is installed under a setting condition of a device installation position in which maintenance with the maintenance crane being arranged is prevented from being performed from a boundary side of the device installation area along the main pipe rack.

4. The natural gas liquefaction apparatus according to claim 3, wherein an air-cooled heat exchanger configured to cool the fluid to be handled in the device group is provided in the device installation area.

5. The natural gas liquefaction apparatus according to claim 3, wherein when the natural gas liquefaction apparatus is viewed in plan view, the maintenance access is provided so as to extend in a direction crossing the boundary along the main pipe rack.

6. The natural gas liquefaction apparatus according to claim 3, wherein a sub pipe rack having a frame structure configured to hold a pipe through which the fluid to be handled in the device group flows is provided in the device installation area, when the natural gas liquefaction apparatus is viewed in plan view, the sub pipe rack is provided so as to extend in a direction crossing the boundary along the main pipe rack, and the devices to be subjected to maintenance through use of the maintenance crane arranged in the maintenance access are installed on both sides of the sub pipe rack.

7. The natural gas liquefaction apparatus according to claim 1, wherein at least one of a substation room configured to supply an electric power to a power consumption device provided in the natural gas liquefaction apparatus and a refrigerant compressor configured to compress a refrigerant for cooling the natural gas is provided at a position away from the maintenance access, which is outside the device installation area and is prevented from being constrained by the maximum lifting load set in advance of the maintenance crane.

8. The natural gas liquefaction apparatus according to claim 1, wherein a sub pipe rack having a frame structure configured to hold a pipe through which a fluid to be handled in the device group flows is provided in the device installation area, when the natural gas liquefaction apparatus is viewed in plan view, the sub pipe rack is provided so as to extend in a direction crossing the boundary along the main pipe rack, and the sub pipe rack extends so as to protrude from the device installation area, and has a substation room in a distal end portion of an extending pipe rack, the substation room being configured to supply an electric power to a power consumption device provided in the natural gas liquefaction apparatus.

9. The natural gas liquefaction apparatus according to claim 1, wherein the maximum lifting load set in advance of the maintenance crane that is allowed to enter the maintenance access is 50 tons or less.