This application is the U.S. National Phase application under 35 U.S.C. § 371 of International Patent Application No. PCT/JP2014/081688, International Filing Date Dec. 1, 2014, entitled “EQUIPMENT SAFETY MANAGEMENT DEVICE, EQUIPMENT SAFETY MANAGEMENT METHOD, AND NATURAL GAS LIQUEFACTION DEVICE”, which is hereby expressly incorporated by reference in its entirety for all purposes.
The present invention relates to an equipment safety management device, an equipment safety management method, and a natural gas liquefaction device, and more particularly to an equipment safety management device, an equipment safety management method, and a natural gas liquefaction device that can be used in a natural gas liquefaction plant (LNG plant) or the like.
For liquefaction of natural gas, an LNG (liquefied natural gas: Liquefied Natural Gas) plant generally requires a pretreatment process where a liquid component (condensate) is separated from natural gas sent from a gas field, an acid gas removal process where an acid gas (hydrogen sulfide, carbon dioxide or the like) which is an environmental pollutant is removed, a process where mercury which is detrimental to a liquefaction device is removed, a dehydration process where moisture is removed by an adsorbent or the like, a liquefaction process where natural gas is liquefied in a liquefaction facility, and the like. In addition, in these gas treatment or liquefaction processes or the like, equipment, e.g., a gas compressor, is used (see, for example, Patent Literature 1: JP 2010-25152 A).
Regarding the equipment used, e.g., a compressor, in order to secure safety of the equipment, when the pressure or the like of a hydrocarbon (hydrocarbon)-containing fluid held in the equipment reaches a previously set pressure, a safety means, e.g., a safety valve and a depressurization valve, connected to the equipment is activated and is brought into a released state, so that the fluid within the equipment is released and transferred to a flare pipe which is connected in a fluid communicable manner to the safety means. In addition, the fluid sent from the flare pipe is combusted in a flare and is discharged out of the plant (liquefaction device).
The flare pipe requires a size sufficient enough to send the entire amount of fluid released from the safety means, e.g., a safety valve, to the flare. However, when the amount of fluid released from the safety means for protecting a single piece of equipment or a system is abundant, a single flare pipe sends the fluid and thus has a large size. There has been a problem that an increase in size of the flare pipe results in high cost of associated facilities or the like, e.g., the cost of manufacturing a flare pipe or a flare header (hereinafter sometimes simply referred to as the “flare pipe”), the cost of introducing a large-sized flare pipe or the like into a plant, and the cost of increasing the size of a pipe rack on which the flare pipe is placed. For such a problem, conventionally, an attempt has been made only in a limited extent to reduce the size of a flare pipe or the like on the basis of results obtained by analysis of dynamic simulation or the like.
The present invention has been made to overcome the aforementioned problem, and it is an object of the present invention to provide an equipment safety management device, an equipment safety management method, and a natural gas liquefaction device capable of managing safety of equipment as well as reducing costs by reducing the flow rate of fluid per flare pipe and reducing the size of the flare pipe, for example, in a system typified by an LNG plant using equipment, e.g., a compressor.
To solve the aforementioned problem, according to the present invention, there is provided an equipment safety management device for managing safety of equipment capable of holding fluid, the equipment safety management device including: a safety means configured to be in fluid communication with an outlet of the equipment, the safety means being brought into a released state when pressure of the equipment reaches a previously set pressure, the safety means delivering the fluid to a flare pipe, which is fluidly communicated; and as the flare pipe, at least one first flare pipe allowing a low-temperature fluid to flow therethrough and at least one second flare pipe allowing an aqueous fluid to flow therethrough, wherein the safety means can deliver the fluid to both the first flare pipe and the second flare pipe.
According to the equipment safety management device described above, the safety means includes a plurality of valves, and the plurality of valves are released in stages according to an increase in pressure of the equipment.
According to the equipment safety management device described above, the equipment safety management device further includes a determination portion configured to determine whether the fluid can be delivered to both the first flare pipe and the second flare pipe.
According to the equipment safety management device described above, the equipment is a compressor.
According to the present invention, there is provided an equipment safety management method in which a safety means connected in a fluid communicable manner to an outlet of equipment capable of holding fluid is brought into a released state when pressure of the equipment reaches a previously set pressure so that the fluid is delivered to a flare pipe, which is fluidly communicated, the equipment safety management method including: including, as the flare pipe, at least one first flare pipe allowing a low-temperature fluid to flow therethrough and at least one second flare pipe allowing an aqueous fluid to flow therethrough; and delivering the fluid delivered from the safety means and capable of being flown to both the first flare pipe and the second flare pipe to both the first flare pipe and the second flare pipe.
According to the equipment safety management method described above, the safety means includes a plurality of valves, and the plurality of valves are released in stages according to an increase in pressure of the equipment.
According to the equipment safety management method described above, the equipment safety management method further includes: determining whether the fluid can be delivered to both the first flare pipe and the second flare pipe; and when the fluid can be delivered, delivering the fluid to both the first flare pipe and the second flare pipe.
According to the equipment safety management method described above, the determination determines whether the fluid is neither an aqueous fluid nor a low-temperature fluid.
According to the equipment safety management method described above, the equipment is a compressor.
According to the present invention, there is provided a natural gas liquefaction device including: equipment capable of holding fluid; and the equipment safety management device described above.
According to the natural gas liquefaction device described above, the equipment is at least one of a C3 compressor, an MR compressor and a C3-MR compressor.
According to the present invention, when the pressure of a fluid held in the equipment reaches a predetermined pressure, the fluid can be split and delivered to two types of flare pipes: a first flare pipe and a second flare pipe. Thus, the equipment safety management device and the equipment safety management method can be provided whereby an excessive elevation of the pressure of the equipment can be prevented and the safety of the equipment can be managed securely, and, in addition, the size of a flare pipe or a flare header to be used can be reduced so that the construction cost of a plant or a device to which the equipment is introduced, e.g., the manufacturing cost of the flare pipes, the cost pertaining to introduction into a plant, and the cost of increasing the size of a pipe rack on which the flare pipes are placed, can be reduced.
In addition, the natural gas liquefaction device of the present invention including the aforementioned equipment safety management device enjoys the effect provided by the safety management device and is capable of accurately managing the safety of the equipment constituting the liquefaction device as well as reducing the size of the flare pipes so as to reduce the construction cost of the entire liquefaction device.
An example of an embodiment of the present invention is described below on the basis of the drawings.
An equipment safety management method according to the present invention is described below in conjunction with an equipment safety management device 1 illustrated in
Regarding the equipment safety management device 1 (hereinafter sometimes simply referred to as the “safety management device 1”) according to the present invention,
In the present invention, the safety means 3 connected in a fluid communicable manner to the outlet 22 of the equipment for delivering the introduced fluid to the outside is brought into a released state when the pressure of the equipment 2 exceeds a previously set pressure, and delivers the fluid to the flare pipe 4, which is connected in a fluid communicable manner to outlets 37 (the outlets 37 of the safety valves 3a, 3b, 3c) of the safety means, and the fluid sent is delivered from the flare pipe 4 to a flare, which is not illustrated, and is combusted, and is discharged out of the plant (liquefaction device). In this manner, an excessive elevation of the pressure of the equipment 2 is prevented, and the safety of the equipment 2 is managed.
Hydrocarbon (hydrocarbon)-containing fluid is conceivable as the fluid that is delivered into and held in the equipment 2 through the inlet 21 and delivered to the outside through the outlet 22. The fluid includes those in the form of gas (gas), those in the form of a gas-liquid mixture, and those in the form of liquid (liquid form). Examples of the fluid in cases where the safety management device 1 according to the present invention is applied to a natural gas liquefaction plant or a liquefaction device include a single fluid composed of one of the types including methane, ethane and propane, or a mixed fluid composed of two or more types of the above.
In the present invention, as described above, the equipment 2, which is subjected to safety management, is not particularly limited insofar as the hydrocarbon (hydrocarbon)-containing fluid can be held. However, examples include relatively large-capacity towers and vessels or the like, e.g., a compressor (compression machine) and a distillation tower. Additionally, the equipment 2 does not necessarily include the feature of pressure rising. However, the pressure is assumed to rise due to input of heat from the outside including fire and the inflow of high-pressure fluid from the outside. Therefore, in such a case, the safety means 3 works. In addition, the equipment 2 is not particularly limited insofar as the fluid can be held. The equipment 2 is a concept that covers, for example, a tank.
Examples of the compressor being the equipment 2 include, but not limited to, various compressors such as an off-gas compressor, a refrigerant gas compressor, a boil-off gas (BOG) compressor, and a fuel gas compressor for use in a natural gas liquefaction plant or a liquefaction device. In addition, as the relatively large-capacity towers and vessels, other examples of the equipment 2 include, but not limited to, a distillation tower, a rectification tower, an extraction tower, an absorption tower, a scrubbing tower, a desulfurization tower, a regeneration tower, a reaction tower, a mixing vessel, a fermentation vessel, and a culture vessel.
The safety means 3 is in fluid communication with the outlet 22 of the equipment. As illustrated in
Examples of the safety means 3 include a conventionally publicly known safety valve or depressurization valve the released state of which is adjusted by opening and closing of the valve. The safety valve includes a valve (opening and closing valve) that is automatically brought into a released state when the pressure of the equipment 2 connected reaches a previously set pressure. The depressurization valve includes a valve (opening and closing valve) that is brought into a released state by human operation when the pressure of the equipment connected reaches a previously set pressure. Additionally, as the “pressure of the equipment 2,” the internal pressure of the equipment 2, the pressure of the fluid within the equipment 2, the discharged pressure of the fluid delivered through the outlet 22 of the equipment, or the like may be measured and used as an index. In addition, in the present embodiment, the safety means 3 is described in conjunction with the safety valves 3a, 3b, 3c having a valve function.
Regarding the safety means 3, the inlets 36 are brought into fluid communication with the outlet 22 of the equipment, and the outlets 37 of the safety means 3 are brought into fluid communication with the flare pipe 4. In the present embodiment, the safety means 3 is in a state of being connected in a fluid communicable manner to the flare pipe 4 (the first flare pipe 5 and the second flare pipe 6; the same applies hereinafter) via the pipes B, C, D. When the equipment 2 reaches a previously set pressure and the safety means 3 is brought into a released state, the fluid from the equipment 2 is delivered to the flare pipe 4. In the present invention, the flare pipe 4 to which the fluid from the safety means 3 is delivered includes at least one first flare pipe 5 through which fluid below the freezing point (low-temperature fluid) can flow and at least one second flare pipe 6 through which moisture-containing fluid (aqueous fluid) can flow. In the present embodiment, as illustrated in
The first flare pipe (cold flare (Cold Flare) pipe) 5 is the flare pipe 4 for flowing the fluid below the freezing point (low-temperature fluid), which allows the flow of the low-temperature fluid, but does not allow the flow of the moisture-containing fluid (aqueous fluid). However, regarding the temperature of fluid, the low-temperature fluid as well as a fluid higher in temperature than the low-temperature fluid can flow. Additionally, when an aqueous fluid flows into the first flare pipe (cold flare pipe) 5, in some cases, the aqueous fluid is frozen and blocks the first flare pipe 5.
Similarly, the second flare (wet flare (Wet Flare) pipe 6 is the flare pipe 4 for flowing the moisture-containing fluid (aqueous fluid), which allows the flow of the aqueous fluid, but does not allow the flow of the low-temperature fluid. However, regarding the aqueous state of fluid, the aqueous fluid as well as a fluid not containing moisture can flow. When a low-temperature fluid flows into the second flare (wet flare pipe) 6, in some cases, the moisture within the second flare pipe 6 is frozen and blocks the second flare pipe 6.
Additionally, the word “low-temperature fluid” indicates a fluid below the freezing point. In addition, the word “aqueous fluid” indicates a moisture-containing fluid regardless of the concentration of fluid.
Table 1 indicates a relationship between the fluid that can flow into the aforementioned first flare pipe 5 and second flare pipe 6 and the fluid that cannot flow thereinto (a relationship between the flare pipe 4 and the fluid). In Table 1, symbol “◯” indicates that “the flow is allowed”, and symbol “x” indicates that “the flow is not allowed”.
(Relationship Between the Flare Pipe 4 and the Fluid)
As indicated in Table 1, for example, when the fluid is neither a low-temperature fluid nor an aqueous fluid, the fluid can flow into both the first flare pipe 5 and the second flare pipe 6. Such a fluid may be released to any of the first flare pipe 5 and the second flare pipe 6 from the equipment 2. For example, in the case of Blocked Outlet of a C3 (propane) compressor, Blocked Outlet of a mixed refrigerant (MR) compressor (MR compressor), or Blocked Outlet of a combined C3-MR compressor in a natural gas liquefaction plant (LNG plant), the above fluid is released in large amounts. Thus, the fluid that is neither a low-temperature fluid nor an aqueous fluid is effective. In addition, it is assumed that immediately before and after removal of moisture of Feed Gas when Feed Gas (feed gas) blows through, the fluid (Feed Gas), which is neither a low-temperature fluid nor an aqueous fluid, flows. The fluid can be flown into both of the first flare pipe 5 and the second flare pipe 6.
In the system of the MR compressor, the C3 compressor, or the like, refrigerant is introduced into the equipment (refrigerant compressor) 2 as the fluid. However, when the amount of fluid is relatively small, the fluid is not increased to a high temperature even by being increased in pressure by the equipment 2, and often remains as a low-temperature fluid. The same applies in the case of Back Flow of the MR compressor (backflow to the MR compressor), or the like. In this case, when the pressure of the equipment 2 reaches a previously set pressure and the safety means 3 is brought into a released state, the fluid remains as a low-temperature fluid and is delivered out of the equipment. Therefore, as the flare pipe 4 for fluid delivery, only the first flare pipe 5 is selected. In contrast, when the amount of fluid is relatively large and the fluid is increased in pressure and increased to a high temperature by the equipment 2, it is assumed that a large amount of (a relatively high-temperature) fluid, which is neither a low-temperature fluid nor an aqueous fluid, is released from the equipment 2. In this case, when the pressure of the equipment 2 reaches a previously set pressure, the fluid, which is neither a low-temperature fluid nor an aqueous fluid, is delivered out of the equipment 2 as the safety means 3 is released. Therefore, the fluid can be delivered to the two types of flare pipe 4: the first flare pipe 5 and the second flare pipe 6.
In addition, in such a system, generally, the application of the first flare pipe (cold flare pipe) 5 through which a low-temperature fluid can flow is dominant. Conventionally, on the basis of the assumption that a low-temperature fluid flows, a large amount of fluid flows to the single first flare pipe 5 through which a low-temperature fluid can flow, but not to the second flare pipe 6 through which a low-temperature fluid cannot flow. As a result, it has been needed to increase the size of the first flare pipe 5. In reality, when the amount of fluid is relatively large, as described above, the (relatively high-temperature) fluid, which is neither a low-temperature fluid nor an aqueous fluid, is released, in some cases, the fluid can be delivered to the two types of flare pipes: the first flare pipe 5 and the second flare pipe 6. In view of the above, the present invention provides the two types of flare pipe 4: the first flare pipe 5 and the second flare pipe 6, which are connected in a fluid communicable manner to the outlets 37 of the safety means 3, and divides and delivers the fluid to the two types of flare pipes 5, 6, and thus the size of the flare pipe 4 or a flare header, which is not illustrated, for connection thereof can be reduced.
The flare pipe 4 or a flare header of an LNG plant generally has a large size. However, an increase in size (an increase in diameter) results in higher cost. For safety management of the equipment 2, the present invention includes, as the flare pipe 4, at least one first flare pipe 5 through which a low-temperature fluid can flow and at least one second flare pipe 6 through which an aqueous fluid can flow, and, when the pressure of the equipment 2 reaches a previously set pressure, the safety means 3 is brought into a released state, so that the fluid delivered from the safety means 3 is delivered to both the first flare pipe 5 and the second flare pipe 6. In this manner, the fluid can be separately flown to not only the first flare pipe 5, but also the second flare pipe 6. Therefore, it is economical that, in a system where the application of the first flare pipe (cold flare pipe) 5 is dominant, the size of the first flare pipe 5 can be reduced.
In addition, the safety means 3 may be regarded as a single system including the multiple valves 3a, 3b, 3c. When the safety means 3 includes multiple valves as described above, the multiple valves may be set to be brought into a released state in stages according to an increase in pressure of the equipment. When the safety means 3 includes a single valve, a small amount of fluid can be handled, but when the amount of fluid is large, regarding the safety means 3, e.g., a safety valve and a depressurization valve, the valve is repeatedly opened and closed so as to be or not to be brought into a released state, resulting in a reduction in operation efficiency, which is not beneficial in terms of the safeness of the equipment 2. Thus, when a large amount of fluid is expected to flow, the safety means 3 may include multiple valves to increase the operation efficiency and the safeness.
With the safety management device 1 and the safety management method according to the present embodiment described above, when the pressure of a fluid held in the equipment 2 reaches a previously set pressure, the fluid can be split and delivered to the two types of flare pipe: the first flare pipe 5 and the second flare pipe 6. Therefore, an excessive elevation of the pressure of the equipment 2 can be prevented, and the safety of the equipment 2 can be managed securely. In addition, the size of the flare pipe 4 (first flare pipe 5) or a flare header can be reduced, and the construction cost of a plant, e.g., the manufacturing cost of the flare pipe 4, the cost pertaining to introduction into a plant, and the cost of increasing the size of a pipe rack on which the flare pipe 4 is placed, can be reduced.
Generally, there are multiple cases where the safety means 3 connected in a fluid communicable manner to the equipment 2 is activated. In each of the multiple cases, a designer of the safety means 3 checks the properties (temperature of the fluid and the presence or absence of water content) of the fluid present in the equipment 2. Among the multiple cases, the present invention can be effectively applied in cases where the fluid (which is, for example, neither the low-temperature fluid nor the aqueous fluid) that have to be flown to the limited flare pipe 4 (e.g., the first flare pipe 5) in small amounts, but can be flown to both the first flare pipe 5 and the second flare pipe 6 in large amounts is delivered out of the equipment 2. In this case, in this case, it may be configured and carried out in the following manner: some of the safety valves of the safety means 3 are connected to an appropriate flare pipe 4 on the basis of the assumption that the amount of fluid delivered out of the equipment 2 is small, and the remaining safety valves are connected to a flare pipe 4 (e.g., the second flare pipe 6) which is different from those to which the aforementioned small amount is delivered (for example, in
The safety management device 1 according to the present invention may be applied, for example, to a natural gas liquefaction device (or a natural gas liquefaction plant). When the safety management device 1 is applied to a natural gas liquefaction device, for example, one conceivable configuration or the like would be as follows: the safety means 3 is disposed in fluid communication with the outlet 22 of the equipment, and at least one first flare pipe 5 through which a low-temperature fluid can flow and at least one second flare pipe 6 through which an aqueous fluid can flow are disposed in fluid communication with the outlets 37 of the safety means with regard to the pieces of equipment 2 including a compressor in the natural gas liquefaction plant (LNG plant), for example, a C3 compressor, an MR compressor, or a combined C3-MR compressor, another compressor (e.g., a fuel gas compressor) in the liquefaction plant (LNG plant) for liquefied natural gas of natural gas, and relatively large-capacity towers and vessels or the like, e.g., a distillation tower, as described above.
Similarly, in the liquefaction device configured in the above manner, when the pressure of the fluid held in the equipment 2 reaches a predetermined pressure, the safety means 3 is brought into a released state, and the fluid can be split and delivered to the two types of flare pipe 4: the first flare pipe 5 and the second flare pipe 6. The natural gas liquefaction device of the present invention including the safety management device 1 with the aforementioned configuration or the like is capable of accurately managing the safety of the equipment 2 as well as reducing the size or the like of the flare pipe 4 and reducing the construction cost of the device.
Additionally, the aspect described above indicates one aspect of the present invention. The present invention is not limited to the aforementioned embodiment, however, needless to mention, variations and improvements including the configuration of the present invention within the scope where the object and the effect can be achieved are covered by the content of the present invention. In addition, there is no problem even if a specific structure, shape, or the like in carrying out the present invention may be a different structure, shape, or the like within the scope where the object and the effect of the present invention can be achieved. The present invention is not limited to each embodiment described above, and variations and improvements within the scope where the object of the present invention can be achieved are covered by the present invention.
For example, in the aforementioned embodiment, the equipment safety management device 1 installed with respect to an event, e.g., Blocked Outlet of the C3 compressor, Blocked Outlet of the MR compressor, or Blocked Outlet of the combined C3-MR compressor in a natural gas liquefaction plant is described by assuming the system where, as the fluid, the fluid that can be flown to both the first flare pipe 5 and the second flare pipe 6 is introduced to the equipment 2. In the present invention, the fluid (introduced into the equipment 2, including the fluid within the equipment 2; the same applies hereinafter) delivered through the outlet 22 of the equipment is determined as to whether it can be delivered to both the first flare pipe 5 and the second flare pipe 6, and when it can be delivered, the fluid may be delivered to both the first flare pipe 5 and the second flare pipe 6. Such a configuration is capable of corresponding to a system where a type of fluid cannot be predicted in advance, thereby enjoying the aforementioned effect and enabling efficient safety management.
For such determination, it is preferable to provide a determination portion, which is not illustrated, for determining whether the fluid delivered through the outlet 22 of the equipment can be delivered to both the first flare pipe 5 and the second flare pipe 6 is provided, such that the determination portion determines whether the fluid can be flown to both the first flare pipe 5 and the second flare pipe 6.
The determination portion checks the type of fluid and determines whether the fluid can be flown to both the first flare pipe 5 and the second flare pipe 6. For example, it may be configured such that a sensor (not illustrated) for checking the type of fluid is provided, for example, within the equipment 2 or the pipe A connected to the inlets 36 of the safety means, information of the fluid from the sensor is communicated to a determination device (not illustrated), the determination device determines whether the fluid can be flown to both the first flare pipe 5 and the second flare pipe 6 according to the type of fluid and communicates the information of determination results to the safety means 3.
Furthermore, when the safety means 3 receives information indicating that the fluid can be flown to both the first flare pipe 5 and the second flare pipe 6 as, for example, the fluid is neither a low-temperature fluid nor an aqueous fluid, it is sufficient that, when the pressure of the equipment 2 reaches a previously set pressure, the safety means 3 is brought into a released state so that the fluid is delivered to the first flare pipe 5 and the second flare pipe 6.
In the aforementioned embodiment, as illustrated in
Additionally, in the description below, structures similar to those of the aforementioned embodiment and members which are the same as those of the aforementioned embodiment are designated with the same reference numerals, and the detailed description thereof is omitted or simplified.
As illustrated in
Additionally, the safety means 3 illustrated in
In addition, in the present invention, as illustrated in
In the aforementioned embodiment, an example of the system where the application of the first flare pipe (cold flare pipe) 5 is dominant is given. However, the present invention is not limited thereto, but may be used in another system where the application of the first flare pipe 5 is not dominant.
Moreover, a specific structure, shape or the like in carrying out the present invention may be another structure or the like within the scope where the object of the present invention can be achieved.
The present invention is highly industrially applicable since it can be advantageously used as a means of enabling safety management of equipment, e.g., a compressor, and reducing the construction cost of various plants and devices, e.g., an LNG plant.
Filing Document | Filing Date | Country | Kind |
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PCT/JP2014/081688 | 12/1/2014 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2016/088159 | 6/9/2016 | WO | A |
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