MODULE FOR PLANT CONFIGURATION, MODULE CONNECTION BODY, AND PLANT

Description

TECHNICAL FIELD

The present invention relates to a technique for constructing a plant.

BACKGROUND ART

When a plant is constructed, a method called a module method is sometimes used to reduce operation on a construction site. To describe an outline of this method, a plurality of blocks that configures the plant is individually assembled as modules at a place called a module yard away from the construction site of the plant. Then, in the module method, each module is transported and installed in the construction site of the plant by a transport ship or the like, and the modules are connected to each other to complete the plant. The connection operation between the modules at the construction site includes connection operation of pipes between the modules, laying operation of cables for instrumentation across a plurality of modules, and the like. Patent Literature 1 discloses a natural gas (NG) plant constructed by the module method.

CITATION LIST

Patent Literature

• • Patent Literature 1: WO 2019/008725

SUMMARY OF INVENTION

Technical Problem

The present invention provides a technique for reducing labor for providing a temporary scaffold at a construction site of a plant.

Solution to Problem

A module for plant configuration of the present invention (first invention) includes:

• • a frame;
  • a cable rack, extending in a lateral direction and provided on the frame to support a cable extending in the lateral direction; and
  • a workbench that is provided on the frame along an extending direction of the cable rack and along which a worker moves to lay the cable on the cable rack.

A second invention is the module for plant configuration according to the first invention, in which,

• • the cable rack is provided on each of left and right sides of the workbench when viewed in the lateral direction, and
  • the workbench is provided along each of the cable racks.

The third invention is the module for plant configuration according to the first invention or the second invention, in which,

• • the frame includes an equipment and a pipe;
  • a first area into which a worker is capable of entering to access the equipment or the pipe during operation of a plant and a second area into which the worker is prohibited from entering during operation of the plant are formed in the frame; and
  • the workbench is provided in the second area.

A fourth invention is a module connection body including a plurality of the modules for plant configuration according to any one of the first to third inventions, in which,

• • the plurality of modules for plant configuration is arranged in the lateral direction, cable racks being connected to each other to form a connection body of the cable racks, and
  • the workbenches are provided side by side in the lateral direction.

A fifth invention is the module connection body according to the fourth invention, in which, left and right positions and heights of the workbenches arranged in the lateral direction are aligned when viewed in the lateral direction.

A sixth invention is the module connection body according to the fifth invention, in which, the workbenches arranged in the lateral direction form a walkway extending from one end to the other end in a length direction of the connection body of the cable racks.

A seventh invention is the module connection body according to any one of the fourth to sixth inventions, in which, the module connection body is a pipe rack that supports a pipe by the frame.

An eighth invention is a plant including: the module for plant configuration according to the first invention.

A ninth invention is the plant according to the eighth invention further including:

• • a pipe rack, extending in the lateral direction, and
  • a plurality of equipment modules, provided along an extending direction of the pipe rack, each of the equipment modules including a tower tank, in which,
  • the module for plant configuration configures the pipe rack, and a pipe is supported by the frame.

Advantageous Effects of Invention

According to the present invention, it is possible to reduce labor for providing a temporary scaffold at a construction site of a plant.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic plan view of an NG plant according to an embodiment of the present invention.

FIG. 2 is a schematic longitudinal sectional front view of a pipe rack that configures the NG plant.

FIG. 3 is a schematic cross-sectional plan view of the pipe rack.

FIG. 4 is a schematic longitudinal sectional side view of a pipe rack forming module forming the pipe rack.

FIG. 5 is a schematic plan view of an NG plant which is a comparative example.

FIG. 6 is a perspective view of a workbench and a cable tray provided in the pipe rack.

FIG. 7 is a side view of a workbench of an adjacent module.

FIG. 8 is a side view of a workbench of an adjacent module.

FIG. 9 is a side view of a workbench of an adjacent module.

DESCRIPTION OF EMBODIMENTS

An NG plant 1 according to an embodiment of the present invention will be described with reference to a schematic plan view of FIG. 1. The NG plant 1 is a plant constructed by the module method, and cools and liquefies a natural gas (NG) produced from a gas well and stores the NG as a liquefied natural gas (LNG). Each module in the present embodiment includes a frame, equipment (dynamic equipment and/or static equipment), pipes, and a cable rack that supports cables. The frame is formed by, for example, joining steel frames, and pipes and cable racks are accommodated and provided in the frame. Except for some equipment provided above the frame like an ACHE 51 described later, each piece of equipment is also accommodated and provided in the frame.

In the present specification, a horizontal direction is indicated as an X direction and a Y direction, and a vertical direction is indicated as a Z direction. Therefore, the X direction and the Y direction are lateral directions. The X, Y, and Z directions are orthogonal to one another. In addition, description will be given assuming that one end side and the other end side in the X direction are +X side and −X side, respectively, and one end side and the other end side in the Y direction are +Y side and −Y side, respectively. Note that the directions given in the description for each module that configures the NG plant 1 are directions in a state where the module is installed in a construction site of the NG plant 1. That is, even in a case where a module being assembled in a module yard is described, the directions given in the description are directions in the state where the module is installed in the construction site to form the NG plant 1. Note that, to prevent complication of the description, the configuration of the plant is more simplified than the actual configuration in the following description. Specifically, the number of modules and the number of cables that configure the plant are reduced, and a structure of a frame included in the module is simplified.

The NG plant 1 includes a plurality of pipe rack forming modules 11 to 13 and a plurality of equipment modules 21, and is illustrated as including three pipe rack forming modules 11 to 13 and six equipment modules 21 in the illustrated example. The pipe rack forming modules 11 to 13 are arranged in the X direction, and the pipe rack forming modules 11, 12, and 13 are arranged in this order from the +X side to the −X side. Then, adjacent modules of the pipe rack forming modules 11 to 13 are connected to each other to form a pipe rack 14 extending in the X direction. As described above, the pipe rack 14 is the pipe rack forming modules 11 to 13, that is, a module connection body formed by connecting a plurality of modules to each other. Specifically, the connection between the modules is connection between pipes and connection between cable racks as described later.

Then, a plurality of equipment modules 21 is provided on each of the +Y side and the −Y side of the pipe rack 14. Then, the plurality of equipment modules 21 on the +Y side and the plurality of equipment modules 21 on the −Y side are arranged so as to be aligned at intervals along the X direction (that is, along an extending direction of the pipe rack 14). These equipment modules 21 are provided with static equipment and dynamic equipment accommodated in the frame. Examples of the static equipment include a tower tank that causes various reactions such as distillation, desulfurization, and dehydration and stores reaction products, and a heat exchanger that exchanges heat between fluids. Examples of the dynamic equipment include a pump and a compressor that allow a fluid (gas or liquid) to flow between the modules to perform necessary processing in the plant.

In the NG plant 1, NG is transferred through the tower tank of each equipment module 21 and undergoes processing, and is stored as LNG in the tower tank (storage tank) of the equipment module 21 to which the NG has been transferred last. The pipes provided in the equipment modules 21 are connected to each other via pipes 55 (not illustrated in FIG. 1) provided in the pipe rack 14 so that the fluid necessary for the processing in the NG plant 1 flows between the equipment modules 21.

An instrument room 31 is provided on the +X side of the pipe rack 14. The instrument room 31 is provided with an instrumentation panel and a control panel in which various types of equipment for performing various types of measurement, monitoring, and control for static equipment and dynamic equipment are stored. In addition, a control room for an operator to operate the equipment of the NG plant 1 is provided, for example, at a place away from the instrument room 31, but is not illustrated.

The above-described equipment module 21 is provided with a junction box (JB) 22 and an instrumentation device 23. Many instrumentation devices 23 are provided in each equipment module 21, but only two are displayed for convenience. Each of the instrumentation devices 23 is a thermometer, a flow meter, a pressure gauge, a liquid level gauge, a vibratory meter, or the like. In each equipment module 21, the JB 22 and each instrumentation device 23 are connected to each other by a single-core cable 24. The instrument room 31 and the JB 22 of each equipment module 21 are connected by a cable 32 that is a multi-core cable. Therefore, the cables 24 and 32 are instrumentation cables.

In the NG plant 1, a laying region 33 in which the cable 32 is laid extends from the instrument room 31 toward the −X side of the pipe rack 14. The laying region 33 branches in the middle of extending to the −X side as described above, and is directed in each of the +Y direction and the −Y direction in the pipe rack 14. The laying region 33 is formed by the cable rack that supports the cable 32. Hereinafter, of the laying region 33, a portion extending in the X direction will be referred to as a trunk, and a portion branching from the trunk will be referred to as a branch. In FIG. 1, the laying region 33 is indicated by many dots. In FIG. 1, a walkway 4 (described later) provided in the pipe rack 14 is indicated by hatching.

Many cables 32 collectively extend from the instrument room 31 toward the −X side of the pipe rack 14 along the trunk of the laying region 33. Each cable 32 is bent at a position corresponding to a position of the equipment module 21 to be connected, drawn out to the branch of the laying region 33, and connected to the JB 22 of the equipment module 21 described above. The many instrumentation cables 32 extending from the instrument room 31 as described above include a power supply cable (that is, an AC cable) that supplies power to the instrumentation device 23 and a signal cable (that is, a DC cable) that transmits a signal from the instrumentation device 23 to the instrument room 31.

The cable rack forming the laying region 33 only needs to be able to support the cable 32, and the shape thereof is arbitrary. On the other hand, in the present embodiment, the portion of the trunk of the laying region 33 provided in the pipe rack 14 is configured by a cable tray 34 which is a tray type cable rack. In the cable tray 34, both ends in the width direction of a long plate are bent in the same direction to form a recess. The cable 32 is laid in the recess along the length direction of the cable tray 34. The cable tray 34 is provided from the +X side end to the −X side end of the pipe rack 14, and horizontally extends in the X direction. Therefore, the trunk of the laying region 33 includes the cable rack provided between the pipe rack 14 and the instrument room 31 and the cable tray 34.

The cable tray 34 is formed by connecting together the cable trays provided in the pipe rack forming modules 11 to 13, and is a connection body of the cable trays. For convenience of description, the cable tray provided in each of the pipe rack forming modules 11 to 13 before being connected together in such a manner will be described as a module cable tray 35. The module cable tray 35 has the same configuration as the cable tray 34 except for the length in the X direction.

Note that in the pipe rack 14, a fan that configures the ACHE 51 (described later) is provided as dynamic equipment. Therefore, the pipe rack 14 is provided with the instrumentation device 23 and the JB 22 attached to the ACHE 51 and the cable 24 connecting the instrumentation device 23 and the JB 22, and the branch of the laying region 33 includes a branch directed toward the JB 22 of the pipe rack 14 in addition to the branch directed toward the JB 22 of the device module 21. However, illustration of such a JB 22, instrumentation device 23, and cable 24 in the pipe rack 14 and branch of the laying region 33 directed toward the JB 22 of the pipe rack 14 is omitted in order to prevent complication of the drawing.

The pipe rack 14 will be described in detail with reference to FIGS. 2 and 3. FIGS. 2 and 3 are a schematic longitudinal sectional front view as viewed in the X direction and a schematic cross-sectional plan view, respectively, of the pipe rack 14. The pipe rack 14 includes a frame 50, and supports and beams forming the frame 50 are denoted as 50A and 50B, respectively. Four levels are formed by the framework of the frame 50, and the levels are referred to as F1, F2, F3, and F4 in this order from the bottom. A ceiling wall 52 is provided on the upper side of level F4, and many air cooled heat exchangers (ACHEs) 51 are provided on the ceiling wall 52 in two rows along the X direction. The ACHE 51 includes a fan and a tube through which a fluid (liquid or gas) flows, and these ACHEs 51 cool the fluid supplied from various parts of the NG plant 1.

In level F4, the instrumentation devices attached to the ACHE 51 described above are provided. A floor board 54 is provided so that a worker can enter level F4 and perform maintenance on the fan and the instrumentation devices of the ACHE 51. Note that by using stairs (not illustrated), the worker can ascend from ground 10 on which the NG plant 1 is built to the floor boards 54. The floor boards 54 partitions level F4 and levels F1 to F3. The pipe 55 is provided in each of levels F1 to F3, and is supported by the frame 50.

The plan view of FIG. 3 illustrates level F2. On level F2, cable trays 34 that form the trunk of the laying region 33 are provided, and are indicated by dots. In addition, the walkway 4, which is a permanent scaffold described in detail later, is provided in level F2. Therefore, the walkway 4 is provided in a region separated from the ACHE 51 which is dynamic equipment and the instrumentation devices attached thereto. In the pipe rack 14, the region thus separated from the installation region of the instrumentation devices is a region that does not originally require a permanent scaffold except for a scaffold for operating a valve 56 of the pipe 55 as described in detail later. Note that the walkway 4 is located at the same height as the cable tray 34.

Incidentally, in order to prevent complication of the description, it has been described that all the cables 32 are laid on the cable tray 34 without being distinguished from each other. However, in practice, at least the DC cable and the AC cable are installed in different cable trays 34 in order to prevent noise from occurring in the signal from the instrumentation device 23. Therefore, a plurality of laying regions 33 described with reference to FIG. 1 is provided, and a plurality of cable trays 34 forming the trunk of the laying region 33 is also provided.

FIGS. 2 and 3 illustrate the cable trays 34 that configure the three laying regions 33. The three cable trays 34 are located at the same height. Two of the three cable trays 34 are adjacent to each other in the Y direction, and the other one is positioned away to the +Y side from the cable trays 34 adjacent to each other. In FIG. 2, two cables 32 are laid on the cable tray 34 in order to avoid complication of illustration, but the number of cables 32 to be laid is arbitrary. In FIG. 3, the cable tray 34 is indicated by dots, and the cable 32 to be laid is omitted. Note that although the branch of the laying region 33 is not illustrated in FIGS. 2 and 3, it is formed to extend from the trunk toward an arbitrary level.

In level F2, the pipe 55 is arranged away from the cable tray 34, and the valve 56 is provided in the pipe 55. A permanent scaffold 57 is provided around the portion where the valve 56 is provided. A worker standing on the scaffold 57 can adjust the opening degree of the valve 56. By using stairs (not illustrated), the worker can ascend from the ground 10 on which the NG plant 1 is built to the scaffold 57. Since no equipment requiring operation and maintenance is provided in level F2 other than the valve 56, and only the scaffold 57 and the walkway 4 are provided as permanent scaffold. Since it is sufficient that the scaffold 57 has a size with which the worker can operate the valve 56, the scaffold is formed only around the valve 56 and is provided away from the walkway 4.

The pipe rack forming modules 11 to 13 forming the above pipe rack 14 will be described. The pipe rack forming modules 11 to 13 have substantially the same configuration except for the layout of the pipes 55. FIG. 4 illustrates a schematic longitudinal sectional side surface of the pipe rack forming module 11 as viewed in the Y direction as a representative of the pipe rack forming modules 11 to 13.

The pipe rack forming modules 11 to 13 are obtained by dividing the pipe rack 14 in the X direction. Therefore, each of the pipe rack forming modules 11 to 13 includes a part of the frame 50 of the pipe rack 14. The partial frame is referred to as a frame 59. Each frame 59 of the pipe rack forming modules 11 to 13 is provided with the module cable tray 35, the ACHE 51, the pipe 55, a part of the ceiling wall 52, and a part of the floor board 54. Each frame 59 of the pipe rack forming modules 11 to 13 is provided with a workbench 41 for forming the walkway 4.

The workbench 41 forming the above-described walkway 4 is provided for a worker who performs laying operation of the cable 32 on the cable tray 34 to walk on and move. In order to explain the reason why the walkway 4 is provided in the NG plant 1, a construction process of an NG plant 101 which is a comparative example will be described below. FIG. 4 is a schematic plan view of the NG plant 101. The NG plant 101 has a configuration similar to that of the NG plant 1 except that the walkway 4 is not provided.

Pipe rack forming modules 11 to 13 and equipment modules 21 are assembled in a module yard. Assembly operation of the modules includes formation of frames 59 that configure the modules, installation of various pipes, dynamic equipment, static equipment, JBs 22, instrumentation devices 23, and the like on the frames 59, connection of the JBs 22 and the instrumentation devices 23 by cables 24, and installation of a cable rack for forming a laying region 33. During this assembly, a temporary scaffold is assembled around each module, and the scaffold is used. However, for the reasons described later, after the assembly is completed, each module is transported to the construction site of the plant in a state where the temporary scaffold is dismantled and removed.

In the construction site, in order to prevent mutual interference, the pipe rack forming modules 11 to 13 and the equipment modules 21 are installed at a slight interval. For the module cable trays 35 of the pipe rack forming modules 11 to 13, the position in the Y direction and the position in the Z direction are aligned with each other. Then, a temporary scaffold is assembled between adjacent modules and in the vicinity thereof. By using the scaffold, pipe connection operation between adjacent modules and cable tray connection operation are performed. Specifically, between the pipe rack forming modules 11 to 13, another cable tray is interposed between the module cable trays 35 and connected to each other as the cable tray connection operation, whereby the cable tray 34 extending between the modules as described above is formed.

The installation of the instrument room 31 and the installation of the cable rack between the instrument room 31 and the pipe rack 14 are performed, whereby the laying region 33 described above is formed. The laying operation of the cable 32 is performed after the formation of the laying region 33, and this operation requires a scaffold along the laying region 33. Specifically, this laying operation is performed by the worker holding the tip end of the cable 32, moving along the scaffold formed along the trunk of the laying region 33 from the +X end side (that is, the instrument room 31 side) of the laying region 33 toward the −X side, and laying the cable 32 in the laying region 33. Then, when the worker reaches the position of the branch where the cable 32 is to be arranged, the worker moves using the scaffold formed along the branch to connect the tip end of the cable 32 and the JB 22 of the equipment module 21. The cable 32 is laid by repeating the movement of the worker holding the cable 32.

Therefore, before this laying operation is performed, a temporary scaffold is assembled along the laying region 33. As described above, the pipe rack 14 is long in the X direction. Therefore, the temporary scaffold may be long in the X direction. In that case, in the construction of the NG plant 101, since it takes a lot of time to start the laying operation of the cable 32 after conveying each module to the construction site, the construction period of the plant may be lengthened, and the construction cost may be increased.

Here, it is conceivable to transport the temporary scaffold assembled in the module yard to the construction site of the plant together with the module without dismantling the temporary scaffold, perform the laying operation of the cable 32 by using the scaffold, and dismantle the scaffold after finishing the laying operation. However, there is a possibility that a trouble such as loosening of a screw used for the scaffold occurs due to a shake or an impact applied to the module during transportation. Therefore, in order to ensure the safety of the worker, it is necessary to perform a total inspection on the scaffold after the module arrives at the construction site. This increases operation at the construction site. This undermines the advantage of the module method of reducing operation at the construction site.

In addition, regulations and standards relating to a scaffold may be different between the construction site of the NG plant 101 and the module yard. Therefore, there is a case where the scaffold assembled in the module yard does not conform to the regulations and standards of the scaffold defined in the construction site and cannot be used. In addition, since the scaffold cannot be used as it is, it may be necessary for a worker with a predetermined license who assembles the scaffold in the module yard to perform operation depending on the regulations of the construction site. If such restrictions are imposed on the worker, there is a possibility that the construction operation of the NG plant 101 will be delayed. From the above various circumstances, it is not realistic to use a temporary scaffold assembled in a module yard in a plant construction site.

Under such circumstances, the NG plant 1 is provided with the walkway 4 which is a permanent scaffold. As illustrated in FIG. 3, the walkway 4 is adjacent to the trunk of the laying region 33 of the cable 32 in the pipe rack 14 and extends along the trunk (that is, along the X direction). The worker holding the cable 32 in his/her hand can lay the cable 32 along the X direction of the laying region 33 by moving along the walkway 4 in the X direction instead of along the temporary scaffold in the NG plant 101.

Here, a permanent scaffold in a plant will be described. As in the illustrated scaffold 57, a permanent scaffold in a plant is provided only around equipment that configures the plant in order to allow a worker to access the equipment when operating or performing maintenance on the equipment. As described above, the installation of the permanent scaffold is limited to a place where access is required after the start of operation of the plant, thereby preventing an increase in size of the plant and avoiding unnecessary construction costs.

However, the cable 32 for instrumentation in the plant is not subjected to any operation after installation, and is not subjected to maintenance because a permanent facility having a sufficient service life is used. That is, after the cable 32 is laid, there is no need to access the cable 32. Therefore, in view of the necessity of access after the start of operation of the plant, the vicinity of the laying region 33 is not a target for forming a permanent scaffold.

However, when a plant is constructed in a construction site without using the module method, the cable 32 can be laid using a temporary scaffold assembled for performing various operations (assembly of frame, piping, installation of various devices, and the like) in the construction site. However, when the module method is used, the temporary scaffold used for performing various operations cannot be used for the cable 32 laying operation as described above. Focusing on the matter caused by carrying out such a module method, the NG plant 1 has a configuration in which the walkway 4, which is a permanent scaffold, is provided at a location that is not necessary for the original application of the permanent scaffold.

Hereinafter, the walkway 4 will be described in detail. In the description, the above-described three cable trays 34 may be described as cable trays 34A, 34B, and 34C in order from the +Y side to the −Y side (see FIG. 3). Two walkways 4 for performing operation on the three cable trays 34A to 34C are provided. One walkway 4 (hereinafter sometimes described as 4A) is provided between and adjacent to the cable trays 34A and 34B. Another walkway 4 (hereinafter sometimes denoted as 4B) is provided adjacent to the cable tray 34C on the −Y side and forms a-Y-side edge portion of the pipe rack 14.

The walkways 4A and 4B are similarly configured except for the width in the Y direction, extend along the extending direction (X direction) of the cable trays 34A to 34C, and are continuously formed from the −X side end to the +X side end of the pipe rack 14. Therefore, the walkways 4A and 4B are continuously formed from one end to the other end in the length direction of the cable trays 34A to 34C. Further, the walkways 4A and 4B are supported by the supports 50A and 50B forming the frame 50, and thus, are positioned at the same height as the adjacent cable tray 34.

As described above, each walkway 4 is formed by the workbench 41 provided in each of the pipe rack forming modules 11 to 13. FIG. 6 is a perspective view of the workbench 41 and the module cable tray 35. The workbench 41 is a member elongated in the X direction and having a rectangular shape in plan view, and is provided to extend from the +X side end to the −X side end in each of the pipe rack forming modules 11 to 13 by being supported by each of the frames 59 of the pipe rack forming modules 11 to 13. The workbench 41 is adjacent to the module cable tray 35 and is provided away from the ground 10 on which the pipe rack 14 is provided. The positions of the workbenches 41 in the Y direction and the Z direction are aligned among the pipe rack forming modules 11 to 13 installed in the construction site. That is, the left and right positions and heights of the workbenches 41 are aligned when viewed in the direction in which the workbenches 41 are arranged.

A connection plate 43 that configures a part of a hinge is provided at an X-side end of each workbench 41, and the direction of the connection plate 43 can be changed with a shaft 44 extending along the Y axis as a rotation shaft. The connection plate 43 is a member for connecting the workbenches 41 between adjacent modules in the pipe rack forming modules 11 to 13 to form the walkway 4. Therefore, the connection plate 43 is provided on both the +X side and the −X side of the workbench 41 of the pipe rack forming module 12, and the connection plate 43 is not provided on the +X side of the workbench 41 of the pipe rack forming module 11 and the −X side of the workbench 41 of the pipe rack forming module 13.

FIGS. 7 and 8 illustrate side surfaces of the workbench 41 of the pipe rack forming modules 11 and 12. FIG. 7 illustrates a state immediately after the pipe rack forming modules 11 and 12 are installed in a construction site. In order to prevent interference between the modules at the time of installation, the tip end of the connection plate 43 is directed to the side opposite to the side where the adjacent module 3 is located so as not to protrude from the workbench 41. In FIG. 7, a gap formed between the workbench 41 of the pipe rack forming module 11 and the workbench 41 of the pipe rack forming module 12 is illustrated as a gap 40.

FIG. 8 illustrates a state when the above-described laying operation is performed. From the state illustrated in FIG. 7, when the worker turns each of the connection plates 43 and directs the tip end thereof toward the gap 40, the tip ends of the connection plates 43 are connected to each other, and are fixed to each other by using, for example, a fixing tool (not illustrated). Similarly to between the pipe rack forming modules 12 and 13, the connection plates 43 are connected and fixed between the pipe rack forming modules 11 and 12. By connecting the workbenches 41 via the connection plates 43 in this manner, the walkway 4 is formed.

As illustrated in FIG. 4, a staircase 45 is connected to the workbench 41 included in the pipe rack forming modules 11 and 13. As illustrated in FIG. 4, the staircase 45 allows the worker to ascend and descend between the ground 10 on which the NG plant 1 is constructed and both ends in the X direction of each walkway 4. Before the operation of the NG plant 1 is started as will be described later, the staircase 45 will be closed and the worker will no longer be able to go up to the walkway 4.

Note that the staircases for going up to the scaffolds 57 of levels F4 and F2 are provided separately from the staircase 45, and even if the staircase 45 is closed, the worker can perform the above-described operation during the operation of the NG plant 1 on level F4 and the scaffold 57. That is, in the frame 50 of the pipe rack 14, areas on the scaffold 57 in level F4 and level F2 are formed as first areas into which the worker can enter even after the start of the operation of the NG plant 1. An area other than the scaffolds 57 of levels F1 to F3 in the frame 50 is formed as a second area where the entry of the worker is prohibited during the operation of the NG plant 1, and the walkway 4 is provided in the second area.

Next, as a construction process in the NG plant 1 including the above-described walkway 4, differences from the construction process of the NG plant 101 described above will be mainly described. In the assembling operation of each of the pipe rack forming modules 11 to 13 in the module yard, the workbench 41 is installed on each of the frames 59 of the pipe rack forming modules 11 to 13. Further, the staircase 45 is connected to each workbench 41 of the pipe rack forming modules 11 and 13.

Then, after the pipe rack forming modules 11 to 13 are transported to the construction site of the NG plant 1 and installed in the construction site, the connection plates 43 are connected to each other as described with reference to FIGS. 7 and 8, and the workbenches 41 are connected via the connection plates 43, so that the walkway 4 (4A, 4B) is formed. Since the walkway 4B forms an end portion on the −Y side of the pipe rack 14, the worker installs supports at an edge portion on the −Y side on the walkway 4B at intervals along the X direction, and stretches a rope between the supports to form a handrail. This prevents falling during the laying operation. Meanwhile, a necessary temporary scaffold is formed in order to install the cable 32 on the branch of the laying region 33.

Thereafter, the worker carrying the cable 32 moves, not along the temporary scaffold described above, but along the walkway 4 in the X direction to perform the operation of laying the cable 32 on the cable trays 34A to 34C forming the laying region 33. The cable trays 34A and 34B are laid by the worker moving along the walkway 4A, and the cable tray 34C is laid by the worker moving along the walkway 4B. The tip end side of each cable 32 is laid on a branch of the laying region 33 using the temporary scaffold, and the tip end of each cable 32 is connected to the JB 22 of each equipment module 21.

After completion of the laying operation of the cable 32, the handrail is removed from the walkway 4B, for example. In addition, the temporary scaffold is dismantled and removed. Then, the staircase 45 is closed to ensure safety so that people cannot enter the walkway 4. In closing the staircase 45, a chain is hung across left and right handrails (not illustrated) provided in the staircase 45, for example, to prevent people from going up to the walkway 4. Thereafter, the operation of the NG plant 1 is started.

As described above, each of the pipe rack forming modules 11 to 13 that configures the NG plant 1 is provided with the workbench 41 serving as a scaffold when performing the laying operation along the X direction which is the extending direction of the cable 32 laid in the module cable tray 35. Therefore, as compared with the construction process of the NG plant 101 of the comparative example, it is possible to suppress the region where the temporary scaffold needs to be assembled for the laying operation of the cable 32 after the pipe rack forming modules 11 to 13 are installed in the construction site of the NG plant 1, so that the labor of assembling the scaffold is reduced. Therefore, since the laying operation can be promptly started after the modules are installed in the construction site of the NG plant 1, the construction period of the NG plant 1 can be prevented from becoming long, and the construction cost of the NG plant 1 can be prevented from increasing.

When the workbench 41 forming the walkway 4A is viewed in the X direction which is the extending direction thereof, it has a layout such that the module cable tray 35 forming the cable tray 34A is provided on one of the left and right sides of the workbench 41, and the module cable tray 35 forming the cable tray 34B is provided on the other of the left and right sides, and the workbench 41 is provided along the module cable trays 35. Therefore, the worker can perform the laying operation of the cable 32 on both the cable trays 34A and 34B using the workbench 41. Therefore, it is possible to prevent an increase in the size of the NG plant 1 and to prevent an increase in the construction cost of the NG plant 1 as compared with the case where the walkway 4 is individually provided for the cable trays 34A and 34B. In addition, the configuration in which the laying operation can be performed on the plurality of cable trays 34 by one walkway 4 as described above can reduce the number of times of ascent/descent of the staircase 45 of the worker necessary for the laying operation, and thus, the efficiency of the laying operation can be enhanced.

Furthermore, in the NG plant 1, the pipe rack forming modules 11 to 13 including the module cable tray 35 are arranged in the X direction, so that the cable tray 34 extending across the pipe rack forming modules 11 to 13 is formed, and the workbench 41 extending in the X direction along the cable tray 34 is arranged in the X direction. According to this configuration, it is possible to reduce a region where a temporary scaffold is required in the vicinity of the cable tray 34 of each module while making it possible to lay the cable 32 straddling the modules. Therefore, it is possible to more reliably prevent an increase in the construction period of the NG plant 1 and an increase in the construction cost.

The positions in the Y direction and the Z direction of the workbenches 41 thus arranged in the X direction are aligned. Therefore, as illustrated in FIGS. 7 and 8, the workbenches 41 can be easily connected. In addition, if the position in the Y direction is shifted, the width in the Y direction is narrow at the connection portion between the workbenches 41, and if the position in the Z direction is shifted, a step is formed at the connection portion. Since these problems are prevented, the worker can easily walk on the walkway 4 along the X direction. That is, the laying operation of the cable 32 is facilitated.

In addition, the workbenches 41 are connected to each other via the connection plate 43, so that the walkway 4 forms a scaffold continuously formed from one end to the other end of the cable tray 34 in the X direction. That is, the walkway 4 is formed so as to extend from the position of the +X-side end to the position of the −X-side end of the cable tray 34 in the X direction. Therefore, it is not necessary to form a temporary scaffold in the gap 40 between the pipe rack forming modules 11 to 13, and the laying operation of the cable 32 straddling the pipe rack forming modules 11 to 13 can be started more quickly. Therefore, it is possible to more reliably prevent an increase in the construction period and the construction cost of the NG plant 1.

However, the present invention is not limited to using the connection plate 43. FIG. 9 is a side view of the workbench 41 without the connection plate 43. Since the connection plate 43 is not provided, a temporary scaffold 49 is assembled in the gap 40 between the workbenches 41. The workbench 41 and the temporary scaffold 49 form a walkway 48 that is continuous from one end to the other end in the length direction of the cable tray 34, similarly to the walkway 4. The scaffold 49 between the workbenches 41 is removed together with other temporary scaffolds after completion of the laying operation of the cable 32. Therefore, when the walkway 48 is viewed after the removal operation, the cable tray 34 extends from one end to the other end in a state where the gap 40 is formed between the workbenches 41. Note that the walkway 4 extends from one end to the other end of the cable tray 34 without forming the gap 40.

In the construction site, the temporary handrail by the rope is formed in the walkway 4B for the laying operation, but the present invention is not limited thereto. For example, a metal handrail is formed on the workbench 41 forming the walkway 4B in the module yard. The laying operation may be performed using the handrail. Note that the handrail is a permanent handrail that is not removed after completion of the laying operation.

Furthermore, the means for enabling the worker to go up to the walkway 4 is not limited to the staircase 45, and for example, a ladder erected on the ground 10 may be hung on the walkway 4. After completion of the laying operation, the ladder may be removed to set the area where the walkway 4 is provided as an area where people are prohibited from entering.

While FIGS. 1 and 3 illustrate an example in which the walkway 4 and the cable tray 34 extend to the −X side end of the pipe rack 14, it is sufficient that the walkway 4 and the cable tray 34 extend to a position necessary for laying the cable 32. That is, although the example in which the pipe rack 14 extends to the −X side end is illustrated, the pipe rack 14 may extend partway. In addition, for the safety of the worker, in both the case of including the temporary scaffold 49 and the case of not including the temporary scaffold, it is preferable that the walkway is continuously formed from one end to the other end in the length direction of the cable tray 34 in the X direction. That is, it is preferable that there is no break in the middle of the extending direction. However, the break may be formed with a size that does not interfere with safety. Therefore, the walkways 4 and 48 may be configured as scaffolds intermittently provided in the X direction. Note that the cable tray 34, too, is not limited to be continuous from the +X side end to the −X side end of the pipe rack 14, and may have a break.

Note that as the cable rack other than the tray type, for example, a ladder type cable rack can be used. Therefore, instead of the cable tray 34, a ladder type cable rack may extend in the X direction to form the trunk of the laying region 33 in the pipe rack 14.

In the example described above, the walkway 4 is formed along the cable tray 34 and is adjacent to the cable tray 34. However, the walkway 4 and the cable tray 34 do not need to be adjacent to each other, and the heights of the walkway 4 and the cable tray 34 may be shifted within a range in which the laying operation can be performed. However, by providing the walkway 4 and the cable tray 34 adjacent to each other, the laying operation is facilitated, which is preferable. Incidentally, the layout in which the cable tray 34 is provided on both left and right sides of the walkway 4 and the layout in which the cable tray 34 is provided on one of the left and right sides when the cable tray and the walkway 4 are viewed in the extending direction have been described above. When the cable tray 34 is provided on one of the left and right sides of the walkway 4 as described above, the cable tray may be provided on either the left side or the right side.

Although the pipe rack 14 is described as being configured of the pipe rack forming modules 11 to 13, the number of pipe rack forming modules that configure the pipe rack 14 is arbitrary. In addition, the layout of the instrument room 31 and the device module 21 is not limited to the above-described example, and is arbitrary. For example, the instrument room 31 may be provided not only on the +X side but also on the −X side of the pipe rack 14. Similarly to the +X-side instrument room 31, the cable 32 may extend in the laying region 33 from the −X-side instrument room 31 to be connected to each device module 21.

In the NG plant 1, only the instrumentation cables 32 are provided in the laying region 33, and power supply cables for supplying power to various types of dynamic equipment such as pumps are laid in a region different from the laying region 33. However, the power supply cables of the dynamic equipment may be provided in the laying region 33. Therefore, the walkway 4 is not limited to be used for laying the cable 32 for instrumentation.

The module provided with the workbench 41 forming the walkway 4 may have a configuration in which at least a cable rack is provided on the frame 59 in addition to the workbench 41, and may have a configuration not including pipes or equipment. Therefore, the module provided with the workbench 41 and the cable rack is not limited to the pipe rack forming module. Although the configuration in which the workbench 41 is provided in all the pipe rack forming modules 11 to 13 has been described, it is possible to provide the workbench 41 only in some of the pipe rack forming modules 11 to 13. Even in such a case, it is possible to reduce the region where the temporary scaffold for laying the cable 32 is assembled as compared with the case where the temporary scaffold is assembled from one end to the other end of the cable tray 34.

Although the example in which one equipment module 21 is connected to each of the +Y side and the −Y side of one pipe rack forming module has been described, the number of equipment modules 21 connected to the +Y side and the −Y side is arbitrary. In addition, the present technique is not limited to being applied to an NG plant that generates LNG. For example, the present invention can be applied to various plants such as an oil refining plant that performs distillation, desulfurization, and the like for crude oil and various intermediate products, a chemical plant that performs production of petrochemical products, intermediate chemicals, polymers, and the like, and a plant that manufactures pharmaceuticals and foods. Therefore, the tower tank included in the equipment module 21 may be, for example, a distillation tower, a rectification tower, an extraction tower, an absorption tower, a washing tower, a desulfurization tower, a regeneration tower, a reaction tower, a stirring tank, a fermentation tank, or a culture tank, which performs various reactions.

It should be construed that embodiments disclosed herein are given by way of illustration in all respects, not by way of limitation. The above-described embodiments may be omitted, substituted, modified, or combined in various forms without departing from the scope and spirit of the appended claims.

REFERENCE SIGNS LIST

• • 11 to 13 Pipe rack forming module
  • 59 Frame
  • 32 Cable
  • 35 Module cable tray
  • 41 Workbench