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JP-2026514383-A - Determination of operating energy losses in liquefied gas carriers

JP2026514383AJP 2026514383 AJP2026514383 AJP 2026514383AJP-2026514383-A

Abstract

The present invention relates to a method (10) for determining the operational energy loss (Df, Ds) over time intervals for a liquefied gas carrier equipped with a liquefaction system, the method comprising: (12) calculating the amount of energy consumed by the ship's energy consumption devices; (14) calculating the energy fluctuation (D2) as a function of temperature fluctuations of the liquefied gas; (16) adding the energy fluctuation (D2) to the amount of energy consumed (D1) to generate the actual operational energy loss (Df); and, if the liquefaction system is operating over time intervals, the method comprising: (18) calculating the amount of energy saved by the liquefaction system (D3); and (20) adding the energy saved (D3) to the actual operational energy loss (Df) to generate the estimated operational energy loss (Ds) that would have been observed if the liquefaction system had not been operating.

Inventors

  • アントワーヌ、ワランゲム
  • ピエール－エマニュエル、ド、セーズ

Assignees

  • ギャズトランスポルト エ テクニギャズ

Dates

Publication Date
20260511
Application Date
20240319
Priority Date
20230328

Claims (17)

  1. A method (10) for determining data representing the operating energy loss (Df, Ds) of a liquefied gas carrier (40) over a certain time interval, This energy is initially stored in the form of liquefied gas and evaporated gas in at least one tank (42) of the vessel (40), and the vessel (40) is equipped with a liquefaction system for the evaporated gas. The aforementioned determination method (10) is, Step (12) of calculating a first data (D1) representing the amount of energy consumed over the time interval as a function of at least one measurement related to the activity of at least one energy consumption device (44) of the vessel (40), Step (14) of calculating a second data (D2) that represents the energy fluctuation of the liquefied gas present in the tank as a function of the temperature fluctuation of the liquefied gas in the tank (42) over the aforementioned time interval, The step (16) includes adding the second data (D2) to the first data (D1), and generating data representing the actual operating energy loss (Df) of the vessel (40), The determination method (10) is determined when the liquefaction system operates over the time interval, Step (18) of calculating a third data (D3) representing the amount of energy saved by the liquefaction system over the aforementioned time interval, A determination method (10) further comprising the step (20) of adding the third data (D3) to the data representing the actual operating energy loss (Df), wherein the step (20) generates data representing the estimated operating energy loss (Ds) that would have been observed if the liquefaction system had not been operating.
  2. The aforementioned vessel (40) is equipped with a vaporizer for the liquefied gas, The aforementioned method, A step of calculating a fifth data (D5) representing the amount of energy of the liquefied gas that is pumped from the tank and planned to pass through the vaporizer over the time interval, A method for determining data representing operational energy loss according to claim 1 (10), further comprising the step of subtracting the fifth data (D5) from the data representing the actual operational energy loss (Df).
  3. The steps include calculating a sixth data (D6) that represents the energy fluctuation of the gas phase of the liquefied gas present in the tank, as a function of the pressure fluctuation and temperature fluctuation in the tank over the aforementioned time interval, A method for determining data representing operational energy loss according to claim 1 or 2 (10), further comprising the step (XX) of adding the sixth data (D6) to the data representing the actual operational energy loss (Df).
  4. The first, second, third, fifth, and sixth data (D1, D2, D3, D5, D6) and the data representing the actual operating energy loss (Df) and the data representing the estimated operating energy loss (Ds) are, on the one hand, the amount of energy lost over the aforementioned time interval and, On the other hand, The ratio of the amount of energy calculated at the start of the usage period of the determination method (10) to a reference energy amount selected from either the amount of energy loaded onto the vessel (40), corresponds to the following: A method for determining data representing operational energy loss according to any one of claims 1 to 3 (10).
  5. A method (11) for monitoring operational data relating to at least one tank (42) of a liquefied gas carrier (40), A monitoring method (11) characterized by performing a method (10) for determining data representing operational energy loss according to any one of claims 1 to 4, and calculating a fourth data (D4) representing the volume fluctuation of the liquefied gas in the tank (42) over the time interval (22).
  6. A data determination device (55) representing operational energy loss, comprising means for implementing the determination method (10) described in any one of claims 1 to 4 or the monitoring method (11) described in claim 5.
  7. A data determination system (50) for a liquefied gas carrier (40) that represents the operational energy loss over a certain time interval, This energy is initially stored in the form of liquefied gas and evaporated gas in at least one tank (42) of the vessel (40), and the vessel (40) is equipped with a liquefaction system for the evaporated gas. The aforementioned decision system (50) A first means for calculating first data (D1) representing the amount of energy consumed over the time interval as a function of at least one measurement value relating to the activity of at least one energy consumption device (44) of the vessel (40), A second means for calculating a second data (D2) representing the energy fluctuation of the liquefied gas present in the tank (42) as a function of the temperature fluctuation of the liquefied gas in the tank (42) over the aforementioned time interval, Adding means for adding the second data (D2) to the first data (D1), comprising adding means for generating data representing the actual operating energy loss (Df) in the vessel (40), The aforementioned decision system (50) A third means for calculating a third data (D3) representing the amount of energy saved by the liquefaction system over the time interval when the liquefaction system operates over the time interval, A determination system (50) further comprising: an adding means for adding the third data (D3) to the data representing the actual operating energy loss (Df), wherein the adding means generates data representing the estimated operating energy loss (Ds) that would have been observed if the liquefaction system had not been operating, when the liquefaction system has been operating over the time interval.
  8. The aforementioned vessel (40) is equipped with a vaporizer for the liquefied gas, A fifth means for calculating a fifth data (D5) representing the amount of energy of the liquefied gas that is pumped from the tank and planned to pass through the vaporizer over the time interval, The determination system (50) according to claim 7 further comprises an additional subtraction means for subtracting the fifth data (D5) from the data representing the actual operational energy loss (Df).
  9. A sixth means for calculating a sixth data (D6) representing the energy fluctuation of the gas phase of the liquefied gas present in the tank, as a function of the pressure fluctuation and temperature fluctuation in the tank over the aforementioned time interval, The determination system (50) according to claim 7 or 8, further comprising additional adding means for adding the sixth data (D6) to the data representing the actual operating energy loss (Df).
  10. The system includes a human-machine interface comprising a display means (58) adapted to provide a representation of the first, second, third, fifth, and sixth data (D1, D2, D3, D5, D6), as well as data representing the actual operating energy loss (Df) and estimated operating energy loss (Ds), The data representing the actual operating energy loss (Df) is visualized as the sum of at least two of the first, second, fifth, and sixth data (D1, D2), As the liquefaction system operates over the time interval, the data representing the estimated operational energy loss (Ds) is visualized in the form of a third data (D3) representing the actual operational energy loss (Df) and an accumulation of the data, according to any one of claims 7 to 9 (50).
  11. The aforementioned representation is a waterfall chart (4), the decision system (50) according to claim 10.
  12. The display means (58) is adapted to display the data representing the actual operating energy loss (Df) at a first position on the waterfall chart (4) when the liquefaction system is operating over the time interval, or at a second position on the waterfall chart (4) that is different from the first position when the liquefaction system is stopped over the time interval. The determination system (50) according to claim 11, wherein the data representing the estimated operating energy loss (Ds) is shown by the display means (58) at the second position if the liquefaction system is operating over the time interval.
  13. The human-machine interface of the decision system (50) further comprises means (1) for selecting at least a portion of the voyage performed by the vessel (40), and means (B1) for selecting a first time interval in which the liquefaction system was operating throughout the partial voyage. The display means (58) is activated when the first time interval is selected by the user of the decision system (50). The average value of each of the first, second, fifth, and sixth data (D1, D2, D5, D6) provided by the means for calculating the data at each of the first time intervals, The average value of the data representing the actual operational energy loss (Df) provided by the adding means for each of the first time intervals, The average value of the third data (D3) provided by the third calculation means at each of the first time intervals, A determination system (50) according to any one of claims 10 to 12, adapted to represent the average value of data representing the estimated energy loss of operation (Ds) provided by the adding means for each of the first time intervals.
  14. The human-machine interface of the decision system (50) further comprises means (B2) for selecting a second time interval during which the liquefaction system was stopped throughout the partial voyage. The display means (58) is used when the second time interval is selected by the user of the decision system (50). The average value of each of the first, second, fifth, and sixth data (D1, D2, D5, D6) provided by the means for calculating the data at each of the second time intervals, The determination system (50) according to claim 13, which is adapted to display the average value of the data representing the actual operational energy loss (Df) provided by the adding means for each of the second time intervals.
  15. The human-machine interface further comprises means for selecting at least one tab relating to operational data concerning the liquefied gas, evaporated gas, reliquefied gas, or consumed gas in the tank (42), The display means (58) is adapted to display a graph (3) of the values corresponding to the selected tab. The determination system (50) according to any one of claims 10 to 14, wherein the value is a value of the operation data over one or more time intervals and is recorded in the memory of the determination system (50).
  16. A monitoring system for operational data relating to at least one tank (42) of a liquefied gas transport vessel, A data determination system (50) for determining operational energy loss according to any one of claims 7 to 15, A monitoring system characterized by comprising means for calculating a fourth data (D4) representing the volume fluctuation of the liquefied gas in the tank (42) over the aforementioned time interval.
  17. A computer program, which, when executed on one or more processors, includes program code instructions for performing the steps of the determination method (10) described in any one of claims 1 to 4.

Description

This invention relates to the field of liquefied gas carriers, particularly methane tankers, and to equipment for monitoring energy consumption in such vessels. More specifically, this invention relates to a method for determining data representing operational energy losses in such vessels. Such vessels have cargo holds designed to accommodate one or more tanks for transporting gas in liquid form, with capacities ranging from several thousand cubic meters to tens of thousands of cubic meters. In the case of natural gas, the latter is held in the tanks at atmospheric pressure and approximately -163°C. Therefore, the tanks are sealed and insulated by a double layer of insulation. However, liquefied natural gas (LNG) tends to evaporate despite the double insulation due to factors such as a drop in gas pressure within the tank and heat flow through the tank walls, so the upper part of each tank, the so-called upper tank space, is filled with gas in vapor form. The latter is generally used as fuel for one or more engines of the vessel. Gas in vapor form that is not used and cannot be held in the tanks is either burned via a flare and then released into the atmosphere, or rarely released as is, or reliquefied by the vessel's (re)liquefaction system, the so-called liquefaction system in this application, and returned to the tanks in liquid form at -163°C. Therefore, this liquefaction system consumes energy itself to operate, while simultaneously saving gas and thus energy that would be lost without it. Estimating the energy balance of the operational losses of liquefied gases during a ship's voyage, the so-called ship's operational BOR ("Boil-Off Rate"), is difficult. It particularly depends on the consumption of the ship's engines that reduce the pressure in at least one tank, weather conditions (temperature, swell), the heat resistance of the tanks, and the efficiency of the liquefaction system. Severe weather conditions can cause significant movement of the ship and, consequently, the liquefied gases in the tanks, leading to greater evaporation of the liquefied gases than when the ship is sailing in calm waters. However, shipowners of such vessels want to know the precise performance of their ships, particularly in terms of energy losses during operation, for reasons related to contractual guarantees. Currently, shipowners evaluate operational performance using the decrease in the volume of liquefied gas in the tanks. However, this method is inaccurate due to fluctuations in the movement of the liquid in the tanks caused by the movement of the ship itself. Furthermore, this decrease does not distinguish energy losses resulting from gas consumption by the ship's engines from other losses. Furthermore, the operational performance that shipowners are interested in should take into account the optimal operating conditions of the vessel, particularly the ship's liquefaction system. However, this liquefaction system, which consumes energy itself, does not always operate during a ship's voyage; therefore, operational performance measured by methods based on volume fluctuations does not necessarily represent the operational performance that the ship will achieve. Prediction methods can provide operational performance that considers the optimal operating conditions for a vessel by using the estimated energy consumption of a vessel during voyage as a function of various usage scenarios. However, these prediction methods are complex and ultimately not very accurate, resulting in an insufficient evaluation of the operational performance that a vessel will achieve, and a loss of interest and confidence in the data provided by these methods. Therefore, in order to understand the differences in operational performance as a function of the vessel's operating conditions, it is necessary to provide accurate operational performance data for liquefied gas carriers equipped with liquefaction systems. This invention aims to at least partially overcome the shortcomings of the prior art by providing a method for determining data representing operational energy loss over a certain time interval in a liquefied gas carrier, a corresponding determination apparatus and system, and a computer program. This makes it possible to accurately compare the active operational performance corresponding to the operating mode of a vessel with the liquefaction system in operation with the passive operational performance corresponding to the operating mode of a vessel with the liquefaction system shut down. For this purpose, the present invention provides a method for determining data representing the operational energy loss of a liquefied gas carrier over a certain time interval, wherein this energy is initially stored in the form of liquefied gas and evaporated gas in at least one tank of the vessel, and the vessel is equipped with a system for liquefying evaporated gas, and the determination method is as follows: - A step of calculating first data re