CN117751267A

CN117751267A - Natural gas treatment equipment

Info

Publication number: CN117751267A
Application number: CN202180101243.2A
Authority: CN
Inventors: 中山彻
Original assignee: Nikkei Global Co ltd
Current assignee: Nikkei Global Co ltd
Priority date: 2021-10-26
Filing date: 2021-10-26
Publication date: 2024-03-22
Also published as: WO2023073811A1

Abstract

The present invention provides a technique for simplifying the structure of a flare piping system provided in a natural gas processing facility. The natural gas treatment device of the present invention comprises: high pressure running machines; a low pressure running machine (222, 312); a flare piping (110) connected to the flare stack unit (112) for circulation of a first excess fluid discharged from the high pressure operating machine; and an external discharge pipe (160) for directly discharging the second excess fluid containing the combustible gas to the outside without passing through the flare stack unit (112). The extraction pipes (221 a, 311 a) are provided with regulating valves (223, 313) for regulating the discharge amount of the second excess fluid, one end of each of which is connected to the low-pressure operation machine (222, 312), and the other end of each of which is connected to the external discharge pipe (160). The pressure relief pipes (221 b, 311 b) are provided with relief valves (224, 314), one end of which is connected to the low-pressure operation devices (222, 312), and the other end of which is connected to the flare pipe (110).

Description

Natural gas treatment equipment

Technical Field

The present invention relates to a natural gas treatment facility for liquefying natural gas or separating and recovering components in natural gas.

Background

For natural gas produced from a well, the following treatments are performed: pretreatment that removes various impurities from natural gas using a natural gas processing facility; and a liquefaction process that liquefies the pretreated natural gas to obtain LNG (Liquidized Natural Gas). Further, a natural gas treatment facility is known which separates and recovers heavy components in natural gas and leaves a factory in a light hydrocarbon gas state.

The natural gas processing facility is provided with a plurality of equipment such as various processing towers, heat exchangers, and the like for pretreatment, liquefaction, and heavy component separation. During the processing of natural gas, an excess stream consisting mainly of combustible gases (light hydrocarbons or hydrogen sulphide, etc.) may be produced in these machines. When a large amount of excess fluid is generated, in order to avoid a pressure rise in the machine, the excess fluid is discharged from a flare stack unit that burns a combustible gas and discharges to the outside. The excess fluid discharged from the flare stack unit is also referred to as flare gas or the like.

In the natural gas processing plant, a flare piping is provided for the excess fluid discharged from the machine to flow to a flare stack unit. Depending on the pressure and properties of the device discharging the excess fluid, a plurality of systems of flare piping are provided.

On the other hand, the flare piping is piping equipment having a large caliber and a long arrangement distance among a plurality of piping systems provided in the natural gas processing equipment. Therefore, from the viewpoint of suppressing construction costs and maintenance costs, it is required to further simplify the equipment structure related to the flare piping.

In contrast, patent document 1 describes a technique for reducing the size of flare piping or the like by dispersing and delivering a fluid discharged from a device provided in a natural gas liquefaction device to two types of flare piping. However, patent document 1 does not describe a technique for simplifying a system configuration in which a plurality of system flare piping are provided.

Prior art literature

Patent literature

Patent document 1: international publication No. 2016/088159

Disclosure of Invention

Technical problem to be solved by the invention

The present invention has been made in view of such a background, and provides a technique for simplifying a structure of a flare piping system provided in a natural gas processing apparatus.

Technical scheme for solving technical problems

The natural gas treatment device of the invention is a natural gas treatment device for carrying out natural gas liquefaction or component separation and recovery in natural gas, wherein,

the device is provided with:

a high-pressure operation machine which operates at a pressure higher than normal pressure,

a low pressure operation machine operating at a pressure lower than that of the high pressure operation machine,

a flare stack unit provided with a burner for burning a combustible gas and discharging to the atmosphere,

a flare piping connected to the flare stack unit for circulating a humidified first excess fluid containing the combustible gas discharged from the high-pressure operating machine,

an external discharge pipe through which a wet second excess fluid containing the combustible gas discharged from the low-pressure operation device flows, the second excess fluid being directly discharged to the outside without passing through the flare stack unit,

a pump-out piping having one end connected to the low-pressure operation machine, provided with a regulating valve for regulating the discharge amount of the second surplus fluid, and

a pressure relief pipe having one end connected to the low pressure operation device and provided with a safety valve that opens when the pressure in the low pressure operation device reaches a predetermined operating pressure or higher;

the other end of the extraction pipe is connected to the external discharge pipe,

the other end of the pressure release pipe is connected to the flare pipe.

In addition, the natural gas processing facility may also be provided with the following features.

(a) The design pressure of the low-pressure operation machine is set to be higher than the design pressure of the external discharge pipe.

(b) The design pressure of the low-pressure operation machine is set to a pressure corresponding to the flare piping.

(c) The low-pressure operation device includes a device for discharging an acid gas as the combustible gas, and an incineration pipe for discharging the second surplus fluid to an incinerator for burning the combustible gas is connected to the device for discharging the acid gas.

(d) The external discharge pipe is configured to discharge the second surplus fluid containing the management target component having the allowable concentration to the outside, i.e., the atmosphere, at a position higher than the installation surface where the natural gas processing facility is installed; the discharge position of the second surplus fluid is set at a height position as follows: the concentration of the management target component is lower than the allowable concentration at a position spaced from the discharge position by a predetermined distance.

(e) The plurality of machines constituting the natural gas processing plant are disposed on an aquatic plant disposed on water.

Effects of the invention

Regarding the discharge destination of the surplus fluid (second surplus fluid) discharged from the common low-pressure operation machine, the suction pipe provided with the regulating valve for regulating the discharge amount of the surplus fluid and the relief pipe provided with the relief valve are connected to different discharge destinations in the present invention. As a result, the installation of the low-pressure operation machine flare piping conventionally provided as the common discharge destination of the extraction piping and the pressure relief piping can be omitted, and the system structure of the flare piping can be simplified.

Drawings

Fig. 1 is a schematic configuration diagram of a natural gas processing facility according to a conventional configuration.

Fig. 2 is a schematic configuration diagram of a natural gas processing facility according to an embodiment.

Fig. 3 is a diagram of a discharge system for discharging excess fluid from a low-pressure operating machine according to the conventional structure.

Fig. 4 is a diagram of a discharge system for discharging excess fluid from the low-pressure operation machine according to the embodiment.

Fig. 5 is a schematic diagram of FLNG equipped with a natural gas processing facility according to a conventional structure.

Fig. 6 is a schematic FLNG diagram including a natural gas processing facility according to an embodiment.

Detailed Description

The natural gas processing facility according to the embodiment of the present invention will be described below with reference to the natural gas processing facility having the conventional structure shown in fig. 1, 3, and 5 (fig. 2, 4, and 6).

Fig. 1 and 2 are schematic configuration diagrams of a natural gas processing facility according to the conventional configuration and embodiment, respectively. In these figures, examples are shown of a Natural Gas processing facility constituted by an LNG facility that produces LNG from Natural Gas (NG) in a gaseous state.

First, the same structure of the LNG facility according to the conventional structure and embodiment will be described. For NG supplied to the LNG facility, pretreatment for removing impurities is performed in each of the gas-liquid separation unit 21, the acid gas removal unit 22, the water removal unit 23, and the mercury removal unit 24. The NG passes through a heavy component separation unit 25 for heavy component separation, is liquefied and supercooled in each of the liquefaction unit 26 and the end flash unit 27, and is stored in a LNG tank 28 for shipment. In addition, the heavy component separated in the heavy component separation unit 25 is distilled in the distillation unit 33. Of the hydrocarbons separated from each other by distillation, light components (C1, C2) are sent to the liquefaction unit 26, C3, C4 are stored in the LPG tank 34, and condensate is stored in the condensate tank 32. The liquid component gas-liquid separated from the natural gas in the gas-liquid separation unit 21 is subjected to steam pressure adjustment in the steam pressure adjustment unit 31 to remove light hydrocarbons, and then stored in the condensate storage tank 32.

In each of the devices constituting the LNG facility, when the operation varies, an excessive fluid containing a flammable gas (light hydrocarbon or acid gas) may be discharged. This excess fluid is discharged to a flare stack unit provided with a burner for burning the combustible gas and discharging to the atmosphere. The excess fluid flows to the flare stack unit via the flare piping.

In LNG facilities, flare piping for a plurality of systems is provided according to the properties of the excess fluid, the operating pressure of the equipment as a discharge source of the excess fluid, and the like. The LNG facility of the conventional structure shown in fig. 1 is provided with 4 systems of flare piping (HP-WET flare piping 110, HP-DRY flare piping 120, LP-WET flare piping 130, LP-DRY flare piping 140) according to the amount of moisture content in the excess fluid and the operating pressure of the equipment.

The HP-WET flare piping 110 and the HP-DRY flare piping 120 are connected to high-pressure operation equipment that operates at a pressure higher than normal pressure, for example, high-pressure operation equipment that operates at a pressure of about 3.1 to 6.1MPag (30 to 60 Barg). Examples of the high-pressure operation equipment connected to the HP-WET flare piping 110 include equipment provided in the gas-liquid separation unit 21 or the water removal unit 23. Examples of the high-pressure operation equipment connected to the HP-DRY flare piping 120 include equipment provided in the mercury removal unit 24, the heavy component separation unit 25, and the like.

The HP-WET flare piping 110 is configured to circulate an excess fluid containing moisture, and a gas-liquid separation tank (knockout column) 111 is provided at a distal end portion. The gas-liquid separation tank 111 has a function of separating liquid such as water and oil from the surplus fluid by gravity. After the liquid component is separated in the gas-liquid separation tank 111, the surplus fluid is burned in the burner of the flare stack unit 112. The WET excess fluid discharged from the high-pressure operating machine to the HP-WET flare piping 110 corresponds to "first excess fluid".

On the other hand, the HP-DRY flare piping 120 is configured to allow an excessive fluid substantially free of moisture to flow therethrough, and the excessive fluid flowing through the HP-DRY flare piping 120 is directly combusted in the combustor of the flare stack unit 121.

The LP-WET flare piping 130 and the LP-DRY flare piping 140 are connected to low-pressure operation equipment that operates at a lower pressure than the high-pressure operation equipment, for example, low-pressure operation equipment that operates at a pressure of about 0.01 to 0.1MPag (0.1 to 1.0 barg). Examples of the low-pressure operation equipment connected to the LP-WET flare piping 130 include equipment provided in the acid gas removal unit 22 or the steam pressure adjustment unit 31. The low-pressure operation equipment connected to the LP-DRY flare piping 140 may be exemplified by the LNG tank 28, the LPG tank 34, and the like.

The LP-WET flare pipe 130 is configured to pass through a humid excess fluid containing moisture, and a gas-liquid separation tank 131 is provided at a distal end portion, which is the same as the HP-WET flare pipe 110. The wet excess fluid discharged from the low pressure operating machine corresponds to "second excess fluid".

On the other hand, the LP-DRY flare piping 140 is configured to allow an excessive fluid substantially free of moisture to flow therethrough, and the excessive fluid is directly burned in the burner of the flare stack unit 141 without passing through the gas-liquid separation tank, which is the same as the HP-DRY flare piping 120.

Here, the flare piping 110, 120, 130, 140 is one of the piping with the largest diameter among the piping disposed in the LNG facility, and the disposition distance is also long. For example, the diameters of the HP-WET flare piping 110 and the HP-DRY flare piping 120 are, for example, about 1.5m (60 inch), and the arrangement distances are several tens of meters to hundreds of meters or more. The diameters of the LP-WET flare piping 130 and the LP-DRY flare piping 140 are, for example, about 0.5m (20 inch), and the arrangement distance is several tens of meters to hundreds of meters or more.

Therefore, the system structure of the flare piping is a component having a great influence on the construction cost and maintenance cost of the entire LNG facility.

In contrast, as shown in fig. 2, the LNG facility according to the embodiment omits the LP-WET flare piping 130 and the gas-liquid separation tank 131 and the flare stack unit 132 attached thereto provided in the LNG facility of the conventional structure by improving the discharge destination of the second surplus fluid discharged from the acid gas removal unit 22 and the steam pressure adjustment unit 31, which are low-pressure operation devices.

Hereinafter, piping connections related to discharging excess fluid from the low-pressure operation equipment (the acid gas removal unit 22 and the steam pressure adjustment unit 31) in the conventional configuration and the embodiment will be described with reference to fig. 3 and 4.

Fig. 3 shows an example of piping connection involved in discharging excess fluid from a low-pressure operating machine in the conventional structure.

The acid gas removal unit 22 of this example is configured to: the acid gas (for example, carbon dioxide or hydrogen sulfide) is absorbed in the absorption tower by the absorption liquid such as amine, and the absorption liquid after the acid gas has been absorbed is heated in the regeneration tower 222, whereby the acid gas is discharged. The steam pressure adjusting means 31 further includes a stabilizer 312, and the stabilizer 312 distills and separates light hydrocarbons contained in the condensate gas-liquid separated from NG, thereby adjusting the steam pressure.

Acid gas removal unit 22 is first described. The acid gas discharged in association with the heating regeneration of the absorption liquid is discharged from the top of the regeneration tower 222. The acid gas is supplied to the incinerator 151 through the incineration piping 225, and the incinerator 151 burns a combustible acid gas such as hydrogen sulfide and discharges the combustible acid gas to the atmosphere.

A suction pipe 221a is provided at the top of the regeneration tower 222, and the suction pipe 221a includes a regulating valve 223 for regulating the discharge amount of the acid gas. For example, during a period when the operation of the incinerator 151 is stopped for maintenance or the like, the extraction pipe 221a functions to circulate the acid gas, which is an excessive fluid, to the LP-WET flare pipe 130.

A pressure relief pipe 221b is provided at the top of the regeneration tower 222, and the pressure relief pipe 221b includes a relief valve 224 that opens to relieve pressure when the internal pressure of the regeneration tower 222 increases to a pressure equal to or higher than the operating pressure (for example, the design pressure of the regeneration tower 222).

Since the acid gas discharged from the absorption liquid contains moisture, the surplus fluid discharged from the regeneration tower 222 as a low-pressure operation machine becomes a wet state. From this point of view, the excess fluid discharged from the regeneration tower 222 corresponds to the second excess fluid. In fig. 1, the extraction pipe 221a and the pressure relief pipe 221b are collectively referred to as an excess fluid pipe 221.

Next, with respect to the vapor pressure adjusting unit 31, the light hydrocarbons separated by distillation from the condensate are discharged from the stabilizer 312 as an exhaust gas. The off-gas is used as fuel for a heating furnace or the like in an LNG facility.

A suction pipe 311a is provided at the top of the stabilizer 312, and the suction pipe 311a includes a regulating valve 313 for regulating the amount of exhaust gas discharged. When the demand for off-gas in the LNG facility decreases, the extraction pipe 311a functions to circulate off-gas, which is an excess fluid, to the LP-WET flare pipe 130.

Further, a pressure relief pipe 311b is provided at the top of the stabilizer 312, and the pressure relief pipe 311b includes a relief valve 314 that opens to relieve pressure when the internal pressure of the stabilizer 312 increases to a pressure equal to or higher than the operating pressure (for example, the design pressure of the stabilizer 312).

Since the condensate gas-liquid separated by the gas-liquid separation unit 21 contains moisture, the surplus fluid discharged from the stabilizer 312 as a low-pressure operation machine becomes a wet state. From this point of view, the excess fluid discharged from the stabilizer 312 corresponds to the second excess fluid. In fig. 1, the extraction pipe 311a and the pressure relief pipe 311b are collectively referred to as an excess fluid pipe 311.

As described above, the LNG facility having the conventional structure is provided with the LP-WET flare piping 130, and the LP-WET flare piping 130 circulates the humid excess fluid (second excess fluid) discharged from the regeneration tower 222 of the acid gas removal unit 22 or the stabilizer 312 of the steam pressure adjustment unit 31, which is a low-pressure operation device, to the flare stack unit 132 provided with the burner.

In contrast, the LNG facility according to the embodiment omits the LP-WET flare piping 130, the gas-liquid separation tank 131, and the flare stack unit 132 by changing the discharge destination of the second excess fluid.

That is, as shown in fig. 4, one end of the extraction pipe 221a provided with the regulator valve 223 is connected to the top of the regeneration tower 222, and the other end is connected to the external discharge pipe 160. Further, one end of the extraction pipe 311a provided with the adjustment valve 313 is connected to the top of the stabilizer 312, and the other end is connected to the external discharge pipe 160.

Conventionally, in LNG facilities, in order to discharge non-combustible gas or the like discharged from an operating machine, an external discharge pipe 160 is provided that directly discharges the gas to the outside without passing through flare stack units 112, 121, 141. The external discharge pipe 160 may be configured to directly discharge the fluid flowing inside to the atmosphere. The external discharge pipe 160 may be configured to: the terminal part is connected to a packed tower packed with an adsorbent, and the adsorbent adsorbs and removes predetermined components and then discharges the remaining gas to the atmosphere.

When the second surplus fluid is discharged to the atmosphere from the distal end portion of the external discharge piping 160, the second surplus fluid may contain components that may affect the human body or the environment. In this case, in order to avoid affecting personnel working in the LNG facility, the distal end portion of the external discharge pipe 160 is preferably configured to: at a higher level than the installation surface where the LNG facility is installed, the second surplus fluid is discharged toward the outside, i.e., the atmosphere.

Here, as the installation surface of the LNG facility, a case where the installation height (installation level) of the equipment constituting the LNG facility is used can be exemplified. The installation height of the machine is a height dimension from a predetermined reference height (for example, an altitude of 0 m) to a position where each machine is installed. For example, when a mounting table is provided at the uppermost layer of the multi-layer frame and a machine is mounted on the mounting table, the height dimension from the reference height to the lower end of the machine mounted on the mounting table corresponds to the mounting height. Since a plurality of devices are provided in the LNG facility, a case where the distal end portion of the external discharge pipe 160 is disposed at a position higher than the device having the largest installation height among the devices can be exemplified.

In addition, the second surplus fluid may contain a management target component that sets the allowable concentration in the atmosphere sampled at a position spaced from the discharge position of the external discharge piping 160 by a predetermined distance. In this case, the distal end portion of the external discharge piping 160 is provided at a height position where the concentration of the management target component in the sample is lower than the allowable concentration. The height position can be grasped in advance by performing atmospheric diffusion simulation or the like using fluid analysis software.

If a legal standard is provided for the allowable concentration of the component to be managed, the standard should be complied with at the time of setting. In addition to legal standards, if there are standard values obtained by combining the influence of the management target components published by ILO (international labor organization) on the human body, standard values derived from the funding standard published by world banks or the like, standard values specific to the construction site of each LNG facility, standard values independently formulated by enterprises having or operating the LNG facilities, and the like, the allowable concentration of the management target components should be set in consideration of these standard values.

As described above, if a structure is employed in which the second surplus fluid is directly discharged to the atmosphere from the distal end portion of the external discharge piping 160, the distal end portion of the external discharge piping 160 is often disposed at a high position. In this case, as in the example using FLNG4 described later with reference to fig. 6, the distal end portion of the external discharge pipe 160 may be disposed on a tower shared with the other flare stack units 112, 121, 141.

In this way, when the external discharge pipe 160 and the flare stack units 112, 121, 141 are disposed adjacent to each other, it is necessary to avoid the flame of the burner from contacting the external discharge pipe 160. Therefore, the height position of the distal end portion of the external discharge pipe 160 is disposed at the same height position as the flame base end portion of the flare stack unit 112, 121, 141, or disposed below the same.

On the other hand, when the distal end portion of the external discharge pipe 160 and the flare stack units 112, 121, 141 are disposed at different positions in the LNG facility floor, there is no restriction in consideration of the burner flame at the height position where the distal end portion of the external discharge pipe 160 is disposed.

The external discharge piping 160 is a piping having a diameter of, for example, about 1.2m (48 inch), and has a lower pressure resistance than the LP-WET flare piping 130 provided in the LNG facility having the conventional structure (the piping has a smaller wall thickness than the LP-WET flare piping 130). In this case, the construction cost and maintenance cost can be significantly reduced by omitting the LP-WET flare piping 130 and the installation of the gas-liquid separation tank 131 and the flare stack unit 132, which are the auxiliary equipment.

On the other hand, as described above, the second surplus fluid flowing through the extraction pipes 221a and 311a is discharged as exhaust gas in the normal operation. In the case where the incinerator 151 is provided, the second surplus fluid is incinerated in the incinerator 151, and thus there is less chance that the second surplus fluid is directly discharged to the atmosphere. Further, even when the installation of the incinerator 151 is omitted, it is assumed that the extraction pipe 221a of the acid gas removal unit 22 is connected to the external discharge pipe 160, the hydrogen sulfide contained in NG is trace as compared with the content in crude oil. As described above, components such as hydrogen sulfide may be removed in the packed column packed with the adsorbent and then discharged to the atmosphere.

As described above, the extraction pipes 221a and 311a, which adjust the discharge amount by using the adjustment valves 223 and 313, are connected to the external discharge pipe 160, and thus the second surplus fluid can be discharged to the external discharge pipe 160.

On the other hand, the design pressure of the regeneration tower 222 or the stabilizer 312, which is a low-pressure operation device, is set to be higher than the design pressure of the external discharge pipe 160. That is, since the design pressure of the external discharge pipe 160 is low, the external discharge pipe cannot be a connection target of the pressure release pipes 221b and 311b provided with the relief valves 224 and 314.

Accordingly, as shown in fig. 4, in the LNG facility according to the embodiment, one end of the pressure release pipe 221b provided with the relief valve 224 is connected to the top of the regeneration tower 222, and the other end is connected to the HP-WET flare pipe 110. Further, one end of a pressure release pipe 311b provided with a relief valve 314 is connected to the top of the stabilizer 312, and the other end is connected to the HP-WET flare pipe 110. That is, the first surplus fluid, which is the WET surplus fluid discharged from the high-pressure operation equipment such as the gas-liquid separation unit 21 and the water removal unit 23, flows through the HP-WET flare piping 110, and the second surplus fluid discharged from the pressure release piping 221b and 311b of the low-pressure operation equipment (the acid gas removal unit 22 and the steam pressure adjustment unit 31) also flows through the first surplus fluid.

Here, the design pressure of the HP-WET flare piping 110 is higher than that of the LP-WET flare piping 130 described in the conventional structure. Therefore, the operating pressure of the relief valves 224 and 314 provided in the pressure relief pipes 221b and 311b is higher when the relief valves are connected to the HP-WET flare pipe 110 (the operating pressure is, for example, 0.8 to 1.1MPa (7 to 10 Barg)) than when the relief valves are connected to the LP-WET flare pipe 130 (the operating pressure is, for example, about 0.5MPa (3.5 Barg)).

In contrast, the design pressures of the regeneration tower 222 and the stabilizer 312, which are low-pressure operation machines, are required to have pressure-resistant performances corresponding to the relief valves 224 and 314 that can be connected to the HP-WET flare piping 110. Therefore, in order to make the design pressure of the regeneration tower 222 and the stabilizer 312 equal to the design pressure of the HP-WET flare piping 110, the wall thickness of the components is required to be thicker than in the conventional structure in which the relief valves 224 and 314 are connected to the LP-WET flare piping 130. However, since the LP-WET flare piping 130, the gas-liquid separation tank 131, and the flare stack unit 132 can be omitted, the influence of the change in the design pressure is relatively small compared with the effect of reducing the construction cost and the maintenance cost.

According to the LNG facility according to the embodiment, the following effects are obtained. Regarding the discharge destination of the surplus fluid (second surplus fluid) discharged from the low-pressure operation device (regeneration column 222, stabilizer 312), the extraction pipes 221a, 311a provided with the regulator valves 223, 313 and the pressure release pipes 221b, 311b provided with the relief valves 224, 314 are connected to different discharge destinations. As a result, the LP-WET flare pipe 130 for the low-pressure operation machine, which is conventionally provided as a common discharge destination for the extraction pipes 221a and 311a and the pressure relief pipes 221b and 311b, can be omitted, and the system structure of the flare pipe can be simplified.

As a specific example of the LNG facility according to the conventional configuration and embodiment described above, FLNG4a and FLNG4 each including a plurality of devices constituting the LNG facility are provided in a water facility provided on water with reference to fig. 5 and 6.

First, the same structure as in the conventional structure and embodiment will be described. FLNG4a, 4 are water facilities disposed on water, and the LNG facilities are provided on the upper surface of a Hull (Hull) 40 in which the LNG tank 28, the LPG tank 34, and the like are formed. A turret 45 as a mooring device is provided on the bow side of the hull 40. The turret 45 is connected to the mooring lines, thereby tethering the hull 40, and also to risers (the mooring lines and risers not shown) for transporting the produced NG in the water. Next, a description will be given of a direction in which the turret 45 is provided as a front of the hull 40.

A flare stack 44 for burning excess gas generated by LNG facilities, LNG tanks, and the like is provided in the body of the hull 40, for example, near the bow-side port. As shown in fig. 5 (b) and 6 (b), the hull 40 has a planar shape with a longer ship length direction than a ship width direction. In the center region of the hull 40 in the width direction, a pipe frame 41 is provided so as to extend in the longitudinal direction of the hull 40. The pipe rack 41 is a frame that supports a plurality of facility pipes through which various fluids handled in FLNG4a, 4 flow.

The areas adjacent to the left and right sides of the pipe frame 41 are facility arrangement areas 42 for arranging the equipment constituting the LNG facility. In these facility arrangement areas 42, a plurality of LNG facility devices 421 for configuring LNG facilities are provided in parallel in the front-rear direction, respectively. These LNG facility facilities 421 include the above-described low-pressure operation devices and high-pressure operation devices.

Fig. 5 and 6 show an example of LNG facilities constructed by a so-called building-by-building (stick-building) system in which facility arrangement areas 42 are respectively arranged on the deck of a hull 40.

Instead of this example, a plurality of LNG facility devices 421 of the LNG facility may be assembled into a plurality of frames to form a module, and the modules may be provided after the hull 40 is completed, thereby forming the LNG facility. In this case, the hull 40 and the modules are built at different sites.

As shown in fig. 5 (a) and 5 (b), in FLNG4a provided with an LNG facility of a conventional structure, an HP-WET flare pipe 110, an HP-DRY flare pipe 120, an LP-WET flare pipe 130, and an LP-DRY flare pipe 140 are supported on a pipe rack 41. In the LNG facility of the conventional structure, a plurality of pipes including the external discharge pipe 160 are supported by the pipe frame 41, but for convenience of illustration, description of these pipes is omitted.

The distal end portions of these flare piping 110, 120, 130, and 140 are connected to flare stacks 44 (flare stack units 112, 121, 132, 141) provided on a common tower.

On the other hand, as shown in fig. 6 (a) and 6 (b), in FLNG4 provided with the LNG facility of the embodiment, only the HP-WET flare pipe 110, the HP-DRY flare pipe 120, and the LP-DRY flare pipe 140 are supported on the pipe frame 41. The distal end portions of these flare piping 110, 120, and 140 are connected to flare stacks 44 (flare stack units 112, 121, 141) provided on a common tower.

In contrast, the LP-WET flare piping 130, the gas-liquid separation tank 131, and the flare stack unit 132 are not provided in FLNG4 according to the embodiment. Here, when an LNG facility is installed in a water facility, as in FLNG4, there is a limit to the area of an installation surface on which a plurality of devices constituting the LNG facility can be arranged. In this case, the space advantage can be obtained by omitting the installation of the LP-WET flare piping 130 and the like, and the area available for installing other equipment becomes large. In addition, the advantage of weight reduction can be obtained by omitting the installation of the LP-WET flare piping 130 or the like.

Fig. 6 b also schematically illustrates a case where the external discharge pipe 160 through which the second surplus fluid discharged from the low-pressure operation device (the regeneration tower 222 and the stabilizer 312) flows is supported by the pipe frame 41. In the example shown in fig. 6 (a), the external discharge pipe 160 is provided so as to extend to a position midway along the tower supporting the flare stack 44, and the distal end portion thereof is configured to discharge the second surplus fluid or the like to the atmosphere at a position below the burner of the flare stack 44. With this configuration, as described above, the flame of the burner can be prevented from contacting the external discharge pipe 160. In addition, the direction of the discharge from the external discharge piping 160 to the atmosphere is preferably set to be opposite to the direction in which the living unit 43 is provided, as viewed from the flare stack 44.

Although the example in which the LNG facility is provided to the hull 40, which is a kind of water plant, has been described above, the water plant in which the LNG facility according to the embodiment is provided is not limited to this example. For example, the LNG facility according to the embodiment may be installed on a Gravity-based structure (GBS) or a platform fixed to the water bottom. The term "water" herein is not limited to the sea, but may be water such as lake water.

On the other hand, LNG facilities may also be provided on the ground.

The natural gas processing facility to which the present invention is applied is not limited to the LNG facility. For example, the present invention can be applied to a NGL (Natural Gas Liquids) facility which is a natural gas processing facility from which light hydrocarbons are produced in a gaseous state, for separating and recovering heavy components in NG.

Symbol description

110: HP-WET torch piping; 112: a flare stack unit; 160: an external discharge pipe; 221a, 311a: drawing out the piping; 221b, 311b: piping for pressure relief; 222: a regeneration tower; 223. 313: a regulating valve; 224. 314: a safety valve; 312: a stabilizer.

Claims

1. A natural gas treatment device for liquefying natural gas or separating and recovering components in natural gas, wherein,

the device is provided with:

the other end of the pressure release pipe is connected to the flare pipe.

2. The natural gas processing facility according to claim 1, wherein a design pressure of the low-pressure operation machine is set to be higher than a design pressure of the external discharge piping.

3. The natural gas processing facility of claim 1, wherein a design pressure of the low pressure operating machine is set to a pressure corresponding to the flare piping.

4. The natural gas processing facility according to claim 1, wherein the low-pressure operation machine includes a machine that discharges acid gas as the combustible gas, and an incineration piping for discharging the second surplus fluid to an incinerator that burns the combustible gas is connected to the machine that discharges the acid gas.

5. The natural gas processing facility of claim 1, wherein the external discharge piping is configured to: discharging the second surplus fluid containing the management target component, in which the allowable concentration is set, to the outside, i.e., the atmosphere, at a position higher than the installation surface where the natural gas processing facility is installed;

the discharge position of the second surplus fluid is set at a height position as follows: the concentration of the management target component is lower than the allowable concentration at a position spaced from the discharge position by a predetermined distance.

6. A natural gas processing plant as defined in claim 1, wherein a plurality of machines constituting the natural gas processing plant are provided on an on-water plant provided on water.