Tank control support system and tank control support method

Abstract

To provide a tank control assisting system and a tank control assisting method that enable proper control of a tank.SOLUTION: A tank control assisting system S comprises a storage unit 1 and a state prediction unit 3. To the storage unit 1, information including information related to input / output of liquefied fuel to / from a plurality of tanks storing liquefied fuel with respect to a total and information related to states of the plurality of tanks are regularly or irregularly input, and the storage unit 1 stores the input information. The state prediction unit 3 predicts the state of at least one tank at and after a second time point on the basis of an operation, which is a plan of output / input of liquefied fuel for that tank which is derived on the basis of the input information that is stored in the storage unit 1 at a first time point and the input information stored in the storage unit 1 at the second time point later than the first time point.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a tank control support system and a tank control support method that support the control of a tank that stores liquefied fuel (a fuel that is gaseous at normal temperature and pressure but is stored in a liquid state, such as liquefied natural gas; the same applies hereinafter). [Background technology]

[0002] Tanks that store liquefied fuels are subject to restrictions on the height of the liquid fuel level and the pressure applied to the tank (the pressure inside the tank minus the pressure outside the tank (atmospheric pressure)—hereafter referred to as "tank pressure"—to ensure safety. For example, in a tank, heat from the outside can cause the liquefied fuel to evaporate, generating boil-off gas (BOG). If a large amount of BOG is generated, the tank pressure increases, opening the tank's safety valve and releasing flammable gas into the atmosphere, potentially resulting in tank damage. Conversely, if too much BOG is vented, the tank pressure can become negative, opening the tank's vacuum safety valve and potentially resulting in tank damage. Therefore, in such tanks, compressors are operated appropriately to compress and vent the BOG in the tank so that the tank pressure remains within the upper and lower control values.

[0003] Tank pressure fluctuates due to changes in atmospheric pressure as well as BOG generated by heat input from liquefied fuel supplied from outside, but if the above control value is set to a value with a certain margin compared to the limit value at which the tank becomes dangerous, even if the tank pressure does exceed the control value, it can be ensured that it does not exceed the limit value. However, the greater the margin of the control value from the limit value, the easier it is to ensure tank safety, but lower tank pressure or a larger fluctuation in tank pressure will increase the amount of BOG generated, resulting in greater energy consumption by the compressor.

[0004] Therefore, Patent Document 1 proposes a tank control support system that ensures tank safety and reduces energy consumption due to compressor operation by formulating a compressor operation plan based on the predicted results of events that cause fluctuations in tank pressure, such as atmospheric pressure. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-175488 Summary of the Invention [Problem to be solved by the invention]

[0006] However, while the system proposed in Patent Document 1 can formulate an appropriate compressor operation plan for a given time, if the assumed conditions change after the plan is formulated, the operation plan may become inappropriate. For example, if an operation plan is formulated to operate the compressor from 11:00 two days later, assuming that liquefied fuel will begin to be received from a tanker at 11:00 two days later, but the start time of the reception is advanced after the operation plan is formulated, the tank pressure may increase earlier than expected due to the reception, potentially exceeding the control value or even the limit value. In anticipation of such a situation, even the tank control support system proposed in Patent Document 1 is forced to ensure a certain margin of the control value relative to the limit value, making it difficult to sufficiently reduce the energy consumption caused by compressor operation. Furthermore, this problem is not limited to tank pressure, but can also occur in various conditions, such as the liquid level and composition of the liquefied fuel stored in the tank.

[0007] The present invention has been made to solve the above-mentioned problems, and provides a tank control support system and a tank control support method that enable appropriate control of a tank. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the tank control support system disclosed below comprises a memory unit that receives input information, either periodically or irregularly, including information regarding the inflow and outflow of liquefied fuel to all of a plurality of tanks that store the liquefied fuel and information regarding the status of each of the plurality of tanks, and stores the input information; and a state prediction unit that predicts the status of the tank from a second point in time onwards based on an operation plan, which is a plan for the inflow and outflow of the liquefied fuel to at least one of the tanks, derived based on the input information stored in the memory unit at a first point in time, and the input information stored in the memory unit at a second point in time that is later than the first point in time. [Effects of the Invention]

[0009] According to the tank control support system, the state prediction unit predicts the future state of the tank based on the input information stored in the storage unit at a point in time after the operation plan is derived. Therefore, even if the input information is changed after the operation plan is derived, a prediction result of the future state of the tank that reflects the impact of the change can be obtained, making it possible to appropriately control the tank based on the prediction result. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a simplified schematic diagram showing an example of the configuration of a storage facility including a tank. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an example of the general configuration of the tank. [Figure 3] FIG. 3 is a block diagram showing the schematic configuration of this system. [Figure 4] FIG. 4 is a graph showing changes in tank pressure. [Figure 5] FIG. 5 is a graph showing changes in tank pressure. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiment, and appropriate design modifications can be made within the scope of the configuration of the present invention. In the following description, the same reference numerals are used in different drawings for identical parts or parts having similar functions, and repeated description thereof will be omitted. The configurations described in the embodiment and modified examples may be combined or modified as appropriate. To facilitate understanding of the description, the drawings referred to below show simplified or schematic configurations, or some of the configurations may be omitted.

[0012] First, we will explain the configuration of tanks, etc. that are the target of a tank control support system (hereinafter also referred to as "this system") according to an embodiment of the present invention, as well as the contents of various operations performed on these tanks, etc. Note that, although the following explanation will be given using a tank that stores liquefied natural gas (LNG) as an example, this system can also be applied to tanks that store liquefied fuels other than LNG.

[0013] FIG. 1 is a simplified schematic diagram showing an example of the configuration of a storage facility including tanks. As shown in FIG. 1, a plurality of tanks 10 are installed in the storage facility, and LNG transported from a production site, another storage facility, or the like by a transport means 11 such as an LNG tanker is supplied to any of the tanks 10. This operation is called "receiving." Also, as shown in FIG. 1, a portion of the LNG stored in any of the tanks 10 is supplied to another tank 10 via a transfer line 12. This operation is called "transfer." Also, as shown in FIG. 1, the LNG stored in any of the tanks 10 is supplied to meet demand for city gas, power generation, and the like via a delivery line 14 associated with that tank 10. This operation is called "delivery."

[0014] As shown in FIG. 1 , the tank 10 is equipped with a transfer pump 13 for transfer and a discharge pump 15 for discharge. A plurality of these pumps (e.g., two pumps each) may be provided for each tank 10 so that transfer or discharge can still be performed even if one pump breaks down or becomes unusable. Furthermore, in order to maintain an extremely low temperature inside the piping through which the LNG flows, a "cooling" process may be performed in which LNG is sent to a transfer line 12 or a discharge line 14 and collected in the tank 10. Note that FIG. 1 illustrates a simplified configuration of the storage facility, and an actual storage facility may be more complex than that shown in FIG. 1 . For example, although FIG. 1 illustrates one tank 10 and a discharge pump 15 capable of discharging to only one discharge line 14, they may also be capable of discharging to multiple discharge lines. For example, FIG. 1 does not illustrate lines and equipment for cooling, or lines and equipment for evacuating and compressing BOG generated by vaporization of LNG in the tank 10.

[0015] Fig. 2 is a schematic cross-sectional view showing an example of the general configuration of a tank. As shown in Fig. 2, tank 10 stores LNG 20 inside. Inside this tank 10, above the liquid surface of the LNG 20, BOG 21 consisting of methane and the like generated by evaporation of LNG 20 fills.

[0016] The tank 10 is provided with a lower supply pipe 101, an upper supply pipe 102, a delivery pipe 103, a pump 104, and an exhaust pipe 105. LNG 20 supplied into the tank 10 from the bottom side of the tank 10 passes through the lower supply pipe 101. LNG 20 supplied into the tank 10 from the ceiling side of the tank 10 passes through the upper supply pipe 102. LNG 20 delivered from inside the tank 10 to the outside passes through the delivery pipe 103. The pump 104 is provided inside the tank 10 and at the tip of the delivery pipe 103, and delivers LNG 20 to the delivery pipe 103. Gas (mainly BOG 21) delivered from inside the tank 10 to the outside passes through the exhaust pipe 105.

[0017] The compressor 30 is provided outside the tank 10 at the tip of the exhaust pipe 105, and forcibly exhausts the gas inside the tank 10 through the exhaust pipe 105. This operation is called "exhaust." The gas exhausted by the compressor 30 may be used as fuel within the storage facility, or may be mixed with LNG sent outside the storage facility.

[0018] Next, the present system will be described with reference to the drawings. Fig. 3 is a block diagram showing an example of the configuration of a tank control support system according to an embodiment of the present invention. As shown in Fig. 3, the present system S includes a storage unit 1, an operation plan derivation unit 2, and a state prediction unit 3.

[0019] The storage unit 1 is configured by a non-volatile storage device such as a hard disk drive (HDD) or a solid state drive (SSD), a volatile storage device such as a random access memory (RAM), or a combination thereof. The operation plan derivation unit 2 and the state prediction unit 3 are configured by a processing device such as a central processing unit (CPU). Note that a part or all of the storage unit 1 may be configured as part of a server or the like located at a location remote from the operation plan derivation unit 2 and the state prediction unit 3, and information may be exchanged between the operation plan derivation unit 2 and the state prediction unit 3 via a network such as the Internet. Similarly, the operation plan derivation unit 2 and the state prediction unit 3 may be configured by separate processing devices or by the same processing device. Furthermore, all or part of the storage unit 1, the operation plan derivation unit 2, and the state prediction unit 3 may be configured as part of an integrated electronic computer.

[0020] The memory unit 1 stores input information and constraint information, as well as data on the intermediate calculations and calculation results of the operation plan derivation unit 2 and the state prediction unit 3. The input information includes information on the inflow and outflow of LNG to and from all of the multiple tanks 10, and information on the status of each of the multiple tanks 10. For example, the input information includes the date and time when the transport means 11 is scheduled to visit the storage facility, the calorific value and supply amount of LNG that the transport means 11 is scheduled to supply, the calorific value of the LNG currently stored in each tank 10, the storage amount or liquid level, tank pressure, expected demand for each discharge line 14, and weather forecasts such as atmospheric pressure.

[0021] The input information is information that changes over time and is input to the storage unit 1 periodically or irregularly, and the storage unit 1 stores the new input information that is input. For example, every time there is a change, such as a change in the visit schedule of the transportation means 11, new input information including the change is input to the storage unit 1, or detected values ​​detected at predetermined cycles by various sensors (such as a sensor that measures the tank pressure or a sensor that measures the height of the LNG liquid surface) provided in the tank 10 are input as new input information at predetermined time intervals. When there is a change in the input information, the storage unit 1 overwrites the input information that was previously stored with the newly input input information, but the previously stored input information may also be stored separately for history recording, backup, etc.

[0022] The memory unit 1 also stores constraint information, which is constraints related to the tanks 10. The constraint information includes information related to constraints on the inflow / outflow and storage of LNG in each of the multiple tanks 10. For example, the constraint information includes the cross-sectional area of ​​the tank 10, the upper and lower limits of the liquid level that the tank 10 can store, the upper and lower limits of the tank pressure, the upper and lower limits of the composition or density of the LNG stored in the tank 10, the discharge line 14 through which the tank 10 can discharge, and the capabilities of various equipment such as the pump and compressor 30. In principle, the constraint information does not change over time, but is updated when the configuration of the tank 10, the LNG storage policy in the tank 10, etc. are changed. When the constraint information is changed, the memory unit 1 overwrites the previously stored constraint information with the newly input constraint information. However, the previously stored constraint information may also be stored separately for backup purposes, etc.

[0023] The operation plan derivation unit 2 derives an operation plan, which is a plan for the inflow and outflow of LNG to and from each of the multiple tanks 10, for a predetermined future planning period (e.g., 30 days), based on the input information and constraint information stored in the storage unit 1. The operation plan derivation unit 2 formulates an appropriate operation plan (various operations such as receiving, discharging, transferring, cooling, and exhausting) for the tanks 10 based on the input information, within the scope of not violating the predetermined constraint conditions given by the constraint information. The operation plan formulated by the operation plan derivation unit 2 is output externally as operation plan information to be provided to the operator of the tank 10, and is also stored in the storage unit 1. Note that any method may be used as a method for deriving an operation plan by the operation plan derivation unit 2. For example, the derivation method proposed in Japanese Patent Application Laid-Open No. 2013-092162 or the derivation method proposed in Japanese Patent Application Laid-Open No. 2015-175488 may be used.

[0024] The operation plan derivation unit 2 derives an operation plan by, for example, solving a problem using mathematical programming. Specifically, for example, the operation plan derivation unit 2 formulates an operation plan by determining variables that represent the contents of various operations related to the tank 10 (such as whether or not an operation is performed, the amount of displacement caused by the operation, etc.) and that satisfy a predetermined condition, such as a minimum or maximum, of an objective function given by the variables, within a range that does not violate the constraint conditions for the variables given by the constraint information. Thus, the derivation of an operation plan by the operation plan derivation unit 2 requires advanced arithmetic processing to solve countless variables, and this arithmetic processing takes a long time even when using a high-performance arithmetic processing device. Therefore, the operation plan derivation unit 2 does not derive an operation plan every time new input information is input to the storage unit 1. Instead, after deriving an operation plan a predetermined period (e.g., several days) before the start of the planning period, it does not derive an operation plan for the same planning period. In addition, the operation plan derivation unit 2 may derive an operation plan for a planning period that partially overlaps with the planning period derived previously (in this example, 29 days overlap), for example, by deriving an operation plan every day with a planning period of 30 days from 3 days ahead to 33 days ahead.

[0025] The state prediction unit 3 predicts the future state of the tank 10 based on the operation plan and input information stored in the memory unit 1, and outputs the prediction result or information based on the prediction result as output information. Specifically, the state prediction unit 3 predicts the future state of the tank 10 when operations on the tank 10 are performed according to the operation plan stored in the memory unit 1, assuming the state of the tank 10 indicated by the input information stored in the memory unit 1 and the surrounding conditions. Note that any method may be used as a method for the state prediction unit 3 to predict the future state of the tank 10. For example, the prediction may be performed using commercially available software (process simulators), such as Aspen HYSYS provided by AspenTech, UniSim Design provided by Honeywell, PRO / II or DYNSIM provided by AVEVA, or Omegaland provided by Omega Simulation Corporation.

[0026] The state prediction unit 3 predicts the state of the tank 10 by applying input information to variables in a given conditional equation, such as a predetermined property estimation equation (PR equation) or a predetermined process model. As will be described later, the purpose and effect of the state prediction unit 3 predicting the state inside the tank 10 is simply to confirm whether the state inside the tank 10 violates predetermined constraints. Therefore, the prediction period may be as short as one to several days. Therefore, the state prediction unit 3 can complete calculations in a significantly shorter time than the operation plan derivation unit 2, and predicts the future state of the tank 10 and generates output information at shorter time intervals than the operation plan derivation unit 2 (for example, every time new input information is input to the storage unit 1).

[0027] Incidentally, it is difficult to determine the operation schedule of the transportation means 11, the density or calorific value of the LNG to be received, the amount of BOG generated by various operations, etc. at the time of deriving the operation plan, and it is impossible to completely avoid differences between the plan and the actual situation. On the other hand, it is conceivable to accept that these plans may differ from the actual situation and repeatedly derive the operation plan in a short period of time, but this would require a considerable simplification of the calculation method of the operation plan deriving unit 2, which would result in a loss of reliability in the derived operation plan, and is therefore not realistic.

[0028] Therefore, in this system S, the state prediction unit 3, which has a relatively small computational load, predicts the future state of the tank 10 based on the input information after the operation plan is derived, thereby realizing a realistic and practical method of accurately understanding the impact that changes in the input information will have on the future state of the tank 10.

[0029] Next, the effects of the state prediction unit 3 predicting the future state of the tank 10 and outputting the output information as described above will be described using an example of controlling the tank pressure.

[0030] 4 and 5 are graphs showing changes in tank pressure, with the horizontal axis representing time and the vertical axis representing tank 1 pressure. In both Figures 4 and 5, (A) represents the tank pressure predicted by the state prediction unit 3, (B) represents the tank pressure predicted by the state prediction unit 3 at a later time than (A), and (C) represents the tank pressure when the operator corrects the operation start time of the compressor 30 based on the prediction result of (B). In the following, an example will be given in which the state prediction unit 3 outputs the prediction result as output information as is.

[0031] 4 shows an example in which an event such as receiving that increases the amount of BOG generated starts at time T10, which is earlier than the originally scheduled time T1. In this case, the operation plan derivation unit 2 formulates an operation plan for operating the compressor 30 so that the tank pressure falls within the range between an upper limit control value P1 and a lower limit control value P2, and the state prediction unit 3 outputs the prediction result shown in FIG. 4(A) as output information.

[0032] After the prediction result of FIG. 4(A) is obtained, the start time of the event that increases the amount of BOG generation is changed to time T10, and input information to that effect is stored in the storage unit 1. However, the operation plan derivation unit 2 does not formulate an operation plan based on the new input information stored in the storage unit 1, and the timing at which the compressor 30 operates remains at T2. Meanwhile, in order to predict the tank pressure based on the new input information stored in the storage unit 1, the state prediction unit 3 predicts the tank pressure on the assumption that the start time of the event that increases the amount of BOG generation has been changed to time T10, and outputs as output information a prediction result that the tank pressure will exceed the upper limit control value P1 at time T2, as shown in FIG. 4(B).

[0033] 4(B), the operator can recognize that the tank pressure will exceed the upper limit control value P1 at time T2, and therefore changes the operation start time of compressor 30 to time T20, which is earlier than time T2. This prevents the tank pressure from exceeding the upper limit control value P1, as shown in FIG. 4(C).

[0034] The example shown in Fig. 5 shows a case where an event that increases the amount of BOG generated, such as receiving, begins at time T11, which is later than the originally scheduled time T1, as opposed to the example shown in Fig. 4. In this case as well, first, the operation plan derivation unit 2 formulates an operation plan for operating the compressor 30 so that the tank pressure falls within the range between the upper limit control value P1 and the lower limit control value P2, and the state prediction unit 3 outputs the prediction result shown in Fig. 5(A) as output information.

[0035] After the prediction result of FIG. 5(A) is obtained, the start time of the event that increases the amount of BOG generation is changed to time T11, and input information indicating this is stored in the storage unit 1. However, the operation plan derivation unit 2 does not formulate an operation plan based on the new input information stored in the storage unit 1, and the timing at which the compressor 30 operates remains at T2. Meanwhile, in order to predict the tank pressure based on the new input information stored in the storage unit 1, the state prediction unit 3 predicts the tank pressure on the assumption that the start time of the event that increases the amount of BOG generation has been changed to time T11, and outputs as output information a prediction result that the tank pressure will be smaller than the lower-limit control value P2 at time T12, which is after time T2, as shown in FIG. 5(B).

[0036] 5(B), the operator recognizes that the tank pressure will become smaller than the lower limit control value P2 at time T12, and changes the operation start time of the compressor 30 to time T21, which is later than time T2. This prevents the tank pressure from becoming smaller than the lower limit control value P2, as shown in FIG. 5(C).

[0037] As described above, in the present system S, the state prediction unit 3 predicts the future state of the tank 10 based on the input information stored in the memory unit 1 at a point in time after the operation plan is derived. Therefore, even if the input information is changed after the operation plan is derived, a prediction result of the future state of the tank 10 that reflects the influence of the change can be obtained, and it becomes possible to appropriately control the tank 10 based on the prediction result.

[0038] Furthermore, according to the present system S, the state prediction unit 3 can accurately predict the future state of the tank 10 based on the changed input information, and can detect possible abnormalities in the tank 10 in advance. Therefore, even if the control values ​​P1 and P2 are set to values ​​close to the limit values ​​of the tank 10 (with a small margin), it is possible to appropriately control the tank 10. Therefore, it is possible to sufficiently suppress the amount of energy consumed by the operation of the compressor 30.

[0039] In the above embodiment, even if the operator performs an operation that differs from the operation plan, by including the operation details in the input information, the state prediction unit 3 can predict the state of the tank 10 taking such changes into account.

[0040] 4 and 5 illustrate an example in which the state prediction unit 3 predicts the tank pressure when the start time of an event that increases the amount of BOG generated (the start time of a specific operation on the tank 10) is changed from the plan. However, even in cases in which it becomes clear that a specific operation will differ from the plan after it has started, such as when it is discovered that the amount of BOG generated differs from the plan after an operation such as receiving has actually started, the state prediction unit 3 can predict the future state of the tank 10 in a short time, and can output the prediction result to the operator so that they can take action.

[0041] 4 and 5 illustrate an example in which the state prediction unit 3 predicts the tank pressure. However, in addition to (or instead of) this, the state prediction unit 3 may output, as output information, information useful for operating the tank 10, such as the liquid level of the LNG stored in the tank 10 and a predicted result of the amount of energy consumed by equipment such as the compressor 30. The liquid level of the LNG stored in the tank 10, like the tank pressure, is useful in determining whether the storage state of the LNG in the tank 10 is safe. Furthermore, the amount of energy consumed by equipment such as the compressor 30 is useful in preventing the operation of the equipment from becoming unstable due to the amount of energy consumed by the equipment exceeding the upper limit that can be supplied, given that the total amount available at the storage facility is fixed (for example, when the compressor 30 operates on electricity, there is an upper limit to the amount of electricity, whether it is self-generated or supplied by a power company).

[0042] Furthermore, in the above-described embodiment, the case where the prediction result by the state prediction unit 3 is output as output information as is has been exemplified, but the output information is not limited to this example. For example, the state prediction unit 3 may output, in addition to (or instead of) the prediction result, information on whether or not the prediction result violates predetermined constraints (the upper limit control value P1 and the lower limit control value P2 in the above example). In this case, if the prediction result violates the predetermined constraints, the state prediction unit 3 warns the operator of the tank 10 via the output information. This allows the operator to reliably recognize that the state of the tank 10 will violate the predetermined constraints in the future, thereby supporting the operator in appropriate operation of the tank 10.

[0043] Furthermore, the state prediction unit 3 may output, as output information, information for controlling equipment that controls the tank 10, such as the compressor 30, in addition to (or instead of) the prediction result and the determination result of the prediction result relative to a predetermined constraint. For example, the memory unit 1 may store the type and degree of an expected violation state and a countermeasure for avoiding the violation state (e.g., if the timing of the tank pressure increase is earlier than expected, then the compressor 30 may be started earlier by the same amount). The state prediction unit 3 may read the countermeasure corresponding to the predicted violation state from the memory unit 1, and include the countermeasure in the output information. In this case, if the prediction result violates the predetermined constraint, the state prediction unit 3 controls the operation of the equipment that controls the state of the tank 10, such as the compressor 30, based on the output information so that the predetermined constraint is not violated, thereby automatically preventing the state of the tank 10 from violating the predetermined constraint.

[0044] The above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiments, and the above-described embodiments can be appropriately modified and carried out without departing from the spirit of the present invention.

[0045] The tank control assistance system and tank control assistance method described above can be explained as follows.

[0046] The tank control support system includes a storage unit that periodically or irregularly receives input information, the input information including information regarding the inflow and outflow of liquefied fuel to and from all of a plurality of tanks that store the liquefied fuel and information regarding the status of each of the plurality of tanks, and stores the input information, and a state prediction unit that predicts the status of the tank at a second time point and thereafter, based on an operation plan that is a plan for the inflow and outflow of the liquefied fuel to and from at least one of the tanks, derived based on the input information stored in the storage unit at a first time point, and the input information stored in the storage unit at a second time point that is later than the first time point (first configuration). With this configuration, even if the input information is changed after the operation plan is derived, a prediction result of the tank status that reflects the effect of the change can be obtained, making it possible to appropriately control the tank based on the prediction result.

[0047] In the first configuration, the calculation processing unit may be configured such that the state prediction unit predicts the state of the tank from the second time point onward in a calculation time shorter than the calculation time required to derive the operation plan (second configuration). This configuration makes it possible to realize a realistic and practical method for accurately understanding the impact of changes in input information on the future state of the tank without affecting the accuracy of the derived operation plan.

[0048] Furthermore, in the second configuration, the state prediction unit may predict the state of the tank at the second time point and thereafter by applying the input information to variables of a given conditional expression (third configuration). With this configuration, the state prediction unit can complete calculations in a short time, for example, by predicting the future state of the tank every time new input information is input to the storage unit.

[0049] In any one of the first to third configurations, the state prediction unit may predict the tank pressure by subtracting the air pressure outside the tank from the air pressure inside the tank (fourth configuration). With this configuration, it is possible to accurately determine whether the tank pressure will become dangerous in the future, and therefore it is possible to set a control value close to the tank's limit value (with a small margin) and sufficiently suppress the amount of energy consumed by operating the compressor.

[0050] In any one of the first to fourth configurations, the state prediction unit may output first output information representing the predicted state of the tank (fifth configuration). This configuration makes it possible to make the operator aware that the state of the tank will violate a predetermined constraint in the future, thereby supporting the operator in appropriate operation of the tank.

[0051] In any one of the first to fifth configurations, the state prediction unit may output second output information for warning an operator of the tank if the predicted state of the liquefied fuel stored in the tank violates a predetermined constraint (sixth configuration). This configuration makes it possible to reliably make the operator aware that the tank state will violate the predetermined constraint in the future.

[0052] In any one of the first to sixth configurations, when the predicted state of the liquefied fuel stored in the tank violates a predetermined constraint, the state prediction unit may output third output information to a device that controls the state of the liquefied fuel stored in the tank, for controlling the device so as not to violate the constraint (seventh configuration). According to this configuration, it is possible to automatically prevent the state of the tank from violating the predetermined constraint.

[0053] Another embodiment of the present invention is a tank control assistance method (eighth configuration) comprising: a first step of acquiring input information including information regarding the inflow and outflow of liquefied fuel to all of a plurality of tanks storing the liquefied fuel and information regarding the state of each of the plurality of tanks; a second step of deriving an operation plan that is a plan for the inflow and outflow of the liquefied fuel to at least one of the tanks based on the input information acquired in the first step; and a third step of predicting the future state of the tank based on the operation plan derived in the second step and the input information obtained later in time than the first step. [Explanation of symbols]

[0054] S...tank operation plan derivation system, 1...storage unit, 2...operation plan derivation unit, 3...state prediction unit, 10...tank, 101...lower supply piping, 102...upper supply piping, 103...delivery piping, 104...pump, 105...BOG exhaust piping, 11...transport means, 12...transfer line, 13...transfer pump, 14...delivery line, 15...delivery pump, 20...LNG, 21...BOG, 30...compressor, 100...tank group

Claims

1. a storage unit that periodically or irregularly receives input information including information regarding the inflow and outflow of liquefied fuel to and from all of a plurality of tanks that store the liquefied fuel and information regarding the status of each of the plurality of tanks, and stores the input information; a state prediction unit that predicts the state of the tank from a second time point onward, based on an operation plan that is a plan for the inflow and outflow of the liquefied fuel to at least one of the tanks, derived based on the input information stored in the storage unit at a first time point, and the input information stored in the storage unit at a second time point that is after the first time point and before the start of operations on the tank in the operation plan; A tank control support system comprising:

2. The tank control support system according to claim 1 , wherein the state prediction unit predicts the state of the tank at the second time point and thereafter in a calculation time shorter than a calculation time required to derive the operation plan.

3. The tank control assistance system according to claim 2, wherein the state prediction unit predicts the state of the tank at the second time point or later by applying the input information to variables of a given conditional expression.

4. 4. The tank control assistance system according to claim 1, wherein the state prediction unit predicts the tank pressure by subtracting the air pressure outside the tank from the air pressure inside the tank.

5. The tank control assistance system according to any one of claims 1 to 4, wherein the state prediction unit outputs first output information representing the predicted state of the tank.

6. A tank control support system as described in any one of claims 1 to 5, wherein the state prediction unit outputs second output information to warn an operator of the tank if the predicted state of the liquefied fuel stored in the tank violates a specified constraint.

7. The tank control support system described in any one of claims 1 to 6, wherein, if the predicted state of the liquefied fuel stored in the tank violates a predetermined constraint, the state prediction unit outputs third output information to an equipment that controls the state of the liquefied fuel stored in the tank, for controlling the equipment so as not to violate the constraint.

8. a first step of acquiring input information including information regarding the inflow and outflow of liquefied fuel to and from a plurality of tanks storing the liquefied fuel and information regarding the status of each of the plurality of tanks; a second step of deriving an operation plan that is a plan for the inflow and outflow of the liquefied fuel to at least one of the tanks based on the input information acquired in the first step; a third step of predicting a future state of the tank prior to the start of an operation on the tank in the operation plan based on the operation plan derived in the second step and the input information obtained later in time than the first step; A tank control assistance method comprising:

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