KR20170117441A - Fluid management in sealing and insulation tanks - Google Patents

Abstract

The present invention relates to a method for managing the fluid in a sealing and adiabatic tank (1) for storing liquefied gas (8) at low temperatures. The walls of the tank having a multi-layered structure include an outer load bearing wall 2, a first sealing membrane 9 in contact with the liquefied gas stored in the tank, an intermediate space 3 disposed between the first sealing membrane and the outer bearing wall Wherein the method comprises the steps of aspirating the gas phase out of the walls of the tank in the intermediate space to lower the pressure in the intermediate space below the working pressure of the intermediate space and detecting the stabilization of the measured pressure of the intermediate space during the aspiration step, And heating the walls of the tank.

Description

Fluid management in sealing and insulation tanks

The invention relates to sealing and insulation tanks for the storage and / or transport of liquefied gas at low temperatures and in particular to the field of membrane tanks.

The density of the gas can be reduced at a very high rate by liquefaction of the gas. Therefore, it is advantageous to store or transport the gas in a liquefied state at a low temperature. For example, in the case of liquefied natural gas (LNG), the density decreases in the gaseous state at room temperature and atmospheric pressure, and in the liquid state at approximately -163 ° C and atmospheric pressure by 600.

It is known that the sealing and adiabatic tanks have a multi-layered structure. The multilayer structure includes an outer bearing wall, a first sealing membrane in contact with the liquefied gas stored in the tank, a second sealing membrane disposed between the outer bearing wall and the first sealing membrane, a second sealing membrane and an outer bearing wall A first space located between the second sealing membrane and the first sealing membrane, and a second insulating barrier formed of a solid insulation material disposed in the second space.

In some tank constructions, the first adiabatic barrier is also disposed in the first space. When the wall of the tank is in a normal operating state, the reservoir of the tank is insulated from the outside by overlapping the first and second insulating barriers. When the liquefied gas stored in the tank is introduced into the first space after the first membrane ruptures or fails, in order to prevent the proof wall from reaching an excessive cooling temperature, which is liable to be destroyed, especially in the case of a vessel hull , The second insulating barrier is maintained to insulate the load bearing structure from the cooled fluid.

The other tank structure has a very thin first space relative to the second space, so that the first insulating barriers are omitted or greatly reduced. For example, the tanks are disclosed in FR-A-2709725, FR-A-2781036 and EP-A-1898143.

The advantage of this choice is that the insulation of the proof wall is substantially the same when in normal operating condition and the liquefied gas enters the first space. For this reason, the material of the load bearing structure, in particular the grade of the steel of the hull of the ship, can be optimized. Moreover, since the thermal equilibrium hardly changes, there is no component that is likely to suffer a thermal shock when the sealing of the first membrane is lost. It is therefore necessary to dimension the second sealing membrane for two very different operating points which simplify the optimization and design of such membranes to withstand fatigue stresses, for example stresses due to extension of the ship's beam due to expansion. no need.

WO-A-2010139914 describes a method for testing the sealing of membrane tanks. The test is initially carried out in a tank whose temperature is close to ambient temperature. Therefore, this method is not related to the sealing and insulation tank in which the first sealing membrane is the low temperature of the liquefied gas load.

The underlying idea of the present invention is to prevent the occurrence of abrupt overpressure in the first space of the membrane tank, especially in the case of a tank in which the first space is very thin.

Some aspects of the present invention start from observing the leakage of fluid or vapor through the first sealing membrane caused by the presence of a liquid phase in a very thin first space, at a considerably load temperature. The liquid phase may actually enter the liquid form and remain on the equilibrium curve, or may enter the vapor form and be condensed under the first sealing membrane or may be based on a substance present in the first space, Can be absorbed by the solid material showing the phenomenon. For this purpose, plywood is a material commonly used in insulating barriers. For example, tests conducted in the laboratory indicate that the material can absorb LNG. Under conditions of temperature and pressure corresponding to the two-phase equilibrium curve of methane in the first space and liquid leaking, the plywood can be filled with 18 to 20% of the weight of the LNG.

During heating of the membrane tank, the gas in the condensed form in the first space or in the form of adsorbed by the wood will vaporize. In a system with a reduced first space where head loss is very important, there is a risk of overpressure forming in the region of the first space away from the discharge point. The pressure can severely damage the first barrier and thus cause severe damage to the tank. In some arrangements, the load on the anchorage connecting the two barriers can damage the second barrier, which itself creates the outflow channel, thus threatening the integrity of the vessel with the tank.

Therefore, one object of the present invention is to propose a heating process without the risk of increasing the pressure of the first space. The heating process can be applied to other situations such as, for example, regulatory inspection of tanks, technical intervention of the user into tanks such as maintenance or repair of tank components. It can also be applied to temporarily or permanently stop the operation of the tank.

To this end, according to one embodiment, the present invention provides a method for managing fluid in a sealing and adiabatic tank for storing liquefied gas at low temperatures,

The wall of the tank has a multi-layer structure, and has an outer proof wall, a first sealing membrane in contact with the liquefied gas stored in the tank, an intermediate space (3) disposed between the first sealing membrane and the outside proof wall, silver,

Sucking the gaseous phase out of the walls of the tank in the middle space to lower the pressure in the middle space below the working pressure in the middle space,

Detecting the stability of the pressure in the intermediate space during the inhalation phase,

Heating the wall of the tank.

The step of heating the walls of the tank may include emptying the liquefied gas load from the tank at low temperatures.

Thanks to this technical feature, when heating the wall of the tank, it is possible to forcibly vaporize the liquid phase which may accumulate in the intermediate space, especially in the first space. Even if it is a solid phase, the pressure acting on the intermediate space below the parallel point at that temperature, which is the temperature of the load in contact with the first membrane, can be shifted to force the vaporization.

The emptying and heating of these sealing and adiabatic tanks can be followed by the following sequence of steps when the liquefied gas load is initially filled at low temperatures:

- Offloading: The load is offloaded to the offloading tank using one or more main pumps located in the tank. At the end of the off-loading, the heel of the liquefied gas that can not be pumped by the main pump remains.

Drying: Offloading can be completed using a dry pump that discharges to a manifold with a smaller diameter than the main pump, prior to stopping the tank. At the end of this step, the heel of the liquefied gas decreases in a so-called non-pumpable amount.

- Heating: Heating is an operation aimed at evaporating non-pumpable loads while bringing the temperature of the tank wall including the insulation close to the ambient temperature.

Heating does not necessarily follow off loading immediately. In fact, during and after the off-loading step, all or almost all of the first membrane can be maintained at a low temperature of the liquefied gas for a short time or a long time. For this purpose, it is possible to spray the liquefied gas onto the inner surface of the first sealing membrane. The jetting process is particularly applicable to liquefied gas-transporting vessels that load on the floor with an almost empty tank. In this case, the liquefied gas to be sprayed may come from the tank itself.

In order to reduce the steam load stored in the tank and the associated transfer system and to avoid the risk of ignition, the heating can be done after the inert gas injection process: the operator then approaches the inside of the tank and performs an internal inspection, A ventilation operation is carried out in order to perform the periodic inspection.

According to a preferred embodiment, the method of managing the fluid may have one or more of the following characteristics.

In the indicated sequence, the fluid management method may be triggered at another step at a moment when the sealing membrane is at a low temperature of the load. The method can be triggered particularly at the beginning, during or at the end of the off-loading phase, or at the beginning, during, or at the end of the drying step as required.

According to one embodiment, the method is triggered while the sealing and adiabatic tanks are still filled with liquefied gas at low temperatures.

According to one embodiment, the method is triggered while the sealing and adiabatic tanks initially store the heels of the liquefied gas at low temperatures, and the heating step of the walls of the tanks is carried out at a low temperature with a heel of liquefied gas And emptying the tank.

According to one embodiment, the method may include, for example, injecting a liquefied gas onto the inner surface of the first sealing membrane, so that during the duration of the pressure stabilization test and at least at the beginning of the heating step, Further comprising the step of retaining the membrane.

According to one embodiment, the heel of the liquefied gas at low temperature is triggered while the pump installed in the sealing and adiabatic tank at low temperature has an amount of liquefied gas that is not pumped. In order to maintain the first sealing membrane at the low temperature of the liquefied gas at least up to the beginning of the heating step, liquefied gas may be injected into it from a different source than the tank itself.

In one embodiment, the aspiration of the gaseous phase is effected by a vacuum pump adjusted to reach a set pressure. Preferably, the difference between the predetermined set pressure and the working pressure of the intermediate space is greater than 10 kPa.

In one embodiment, the stabilization of the pressure in the intermediate space is detected after the pressure stops changing for at least one hour, preferably for at least two hours. Qualitatively, the stability time should be increased in direct proportion to the magnitude of the free volume of the intermediate space.

The stability of the pressure can be verified using various quantitative criteria. One criterion that can be used to determine that the physical quantity has stabilized during the settling time T is to verify that the relative change in the quantity is maintained below a predetermined threshold X. [ That is, when the pressure change at t0 is DP (t), the pressure P (t) is defined as:

The criteria for stability during the settling time (T) are:

,

,

During the methods described herein, the level of accuracy required depends on the particular application-specific considerations and, in particular, on the safety requirements associated with the nature of the stored fixture and the nature of the content stored therein. X may be, for example, 5% or less, preferably 2% or less, or even 1% or less. The criterion also applies to other physical quantities such as temperature.

In one embodiment, the method further comprises selecting a heating process based on the stabilized pressure in the intermediate space during the inhalation step. By virtue of this feature, it is possible to select a heating process suitable for the conditions actually acquired in the intermediate space.

In one embodiment, a fast heating process is selected when the stabilized pressure of the intermediate space during the aspiration step is less than or equal to a predetermined threshold pressure lower than the working pressure. The rapid heating process may further include the step of injecting the hot gas into the tank from which the liquefied gas is removed at a low temperature. The hot gas is, for example, an exhaust gas from a heat engine, a gas heated through a heat exchanger, or another gas higher than the atmospheric temperature.

In one embodiment, a slow heating process is selected when the stabilized pressure of the intermediate space during the aspiration step is higher than a predetermined threshold pressure value lower than the working pressure. The slow heating process may include evacuating the tank slowly and / or exiting the walls of the tank to naturally balance the ambient temperature as the tank is emptied. The slow heating process may include the step of injecting cooling gas into the tank, or injecting a flow of LNG or liquid nitrogen into the tank, especially the top of the tank, in a tank where the tank removes the liquefied gas load at low temperatures. The cooling gas may be nitrogen or other inert gases below ambient temperature. Spraying the flow of liquefied gas can naturally slow the temperature rise more effectively by consuming latent heat due to vaporization of the flow. If necessary, a liquid nitrogen tank connected to a spray boom may be used as follows.

In one embodiment, the method further comprises:

Detecting the presence of a liquid phase in the intermediate space,

Maintaining the aspiration of meteorology in the intermediate space to significantly evaporate and / or adsorb all liquid phase prior to heating the tank wall.

Detection of the liquid phase can be carried out in various ways. In one embodiment, the presence of the liquid phase is detected corresponding to the stabilization of the pressure in the intermediate space at the intermediate level between the predetermined target pressure and the working pressure. Evaporation and / or adsorption of the entire liquid phase is detected corresponding to a subsequent drop in pressure in the intermediate space below the mid-level.

In one embodiment, the detection of the liquid phase comprises:

Measuring the temperature in the middle space of the intermediate space from the drop of the absolute pressure in the intermediate space for a certain period of time,

Vapor phase equilibrium point of the liquefied gas with respect to a predetermined target pressure and detects the liquid phase corresponding to the stability of the temperature in the intermediate space near the temperature of the liquefied gas stored in the tank, / RTI > and / or < RTI ID = 0.0 > adsorption,

Thanks to these technical features, the determining step determines whether the fluid in the intermediate space behaves like a two-phase equilibrium with the pressure under consideration, or whether it is in thermal equilibrium with the environment of the fluid, independent of the pressure applied. do.

In one embodiment, lowering the pressure in the intermediate space includes:

Lowering the pressure in the intermediate space to a first pressure threshold lower than the working pressure,

Reducing the pressure to a first pressure threshold, then measuring a first pressure in the middle space,

Lowering the pressure in the neutral space to a second pressure threshold lower than the first pressure threshold,

Measuring the second temperature of the intermediate space at successive moments after lowering the pressure to a second pressure threshold,

Determining a difference between the second temperature and the first temperature,

Retarding the heating of the tank and maintaining suction if the difference between the second temperature and the first temperature is not less than a predetermined threshold temperature value,

And selecting the heating step after the difference between the first temperature and the second temperature is lower than a predetermined threshold temperature value. The slow or fast process can be selected based on the stabilized pressure.

In one embodiment, if the second temperature and the first temperature difference are not lower than a predetermined temperature threshold after a predetermined maximum inhalation time, a slow heating process is selected. Such a condition means that there is a risk of a very large entry of the liquid phase present through the first membrane, so heating of the tank must involve safety measures.

In one embodiment, the intermediate space comprises a second sealing membrane disposed between the outer proof wall and the first sealing membrane, a second space positioned between the second sealing membrane and the outer proof wall, a second sealing membrane and a first sealing membrane And a second solid insulating barrier disposed in the second space,

The thickness of the first space is much smaller than the thickness of the second space,

The pressure in the second space and the first space is lowered so that the pressure difference between the second space and the first space is kept below the safety threshold,

Stability of the pressure in at least the first space is detected to select the heating process based on the stable pressure of the first space.

In one embodiment, the pressure of the second space is lowered below the pressure of the first space.

The present invention also provides a device for fluid management for sealing and thermal insulation tanks for storing liquefied gases at low temperatures. The wall of the tank has a multi-layer structure, the multi-layer structure includes an outer proof wall, a first sealing membrane in contact with the liquid gas stored in the tank, an intermediate space located between the first sealing membrane and the outer proof wall,

The fluid management device comprises:

A pressure sensor for measuring the pressure in the intermediate space,

A vacuum pump connected to the intermediate space for drawing the gas phase out of the wall of the tank at an intermediate space and capable of lowering the pressure in the intermediate space below the working pressure of the intermediate space,

And a control module capable of detecting the stabilization of the pressure in the intermediate space during the suction step and selecting the heating process based on the stabilized pressure in the intermediate space during the suction step.

The apparatus can be applied to carry out the method described above. According to a preferred embodiment, the device may have one or more of the following features.

In one embodiment, the apparatus further comprises a temperature sensor for measuring the temperature in the neutral space, and the control module drives the vacuum pump and the temperature sensor as follows.

Lowering the pressure in the intermediate space to a first critical pressure value lower than the working pressure,

Measuring the first temperature of the intermediate space after lowering the pressure to a first critical pressure value,

Lowering the pressure in the intermediate space to a second critical pressure value lower than the first critical pressure value,

Measuring the second temperature of the intermediate space at a successive instant after lowering the pressure to a second critical pressure value,

Determining a difference between the second temperature and the first temperature,

If the difference between the second temperature and the first temperature is not lower than a predetermined threshold temperature value, delay heating of the tank and maintain suction,

Selecting the heating step after the difference between the first temperature and the second temperature is lower than a predetermined threshold temperature value.

In one embodiment, the neutral space comprises a second sealing membrane disposed between the outer proof wall and the first sealing membrane, a second space between the second sealing membrane and the outer proof wall, a second sealing membrane between the second sealing membrane and the first sealing membrane, And a second solid insulating barrier disposed in the second space,

The thickness of the first space is much smaller than the thickness of the second space, and

A vacuum pump connected to at least the first space,

And a control module capable of detecting the stability of the pressure in at least the first space in order to select the heating process based on the stabilized pressure of the first space.

In one embodiment, the apparatus further comprises a fluid link connecting the second space and the first space, wherein the fluid link is basically closed and has a pressure difference greater than a predetermined opening threshold between the first and second spaces, And a valve that can be opened corresponding to the valve.

In one embodiment, the first vacuum pump is connected to the first space and the second vacuum pump is connected to the second space. In another embodiment, the vacuum pump is connected in parallel to the first space by a first suction pipe and to the second space by a second suction pipe, each suction pipe having a head loss member.

A tank with a fluid management device may be a part of a land storage installation for storing LNG, for example, or may be a coastal or deep sea structure, in particular a methane tanker, an ethane tanker, a floating storage and regasification unit (FSRU) It can be a crude oil production storage and unloading facility (FPSO).

According to one embodiment, the liquefied gas carrier comprises a double hull and the aforementioned tank disposed in the double hull.

According to one embodiment, the present invention also relates to a method of loading or offloading a ship, wherein the fluid is transported from the floating structure or the land structure to the tank of the ship via the insulated pipeline, from the tank of the ship to the floating structure or land structure .

According to one embodiment, the present invention also provides a transport system for a fluid. The transport system may include an insulating pipe arranged to connect a tank installed on the hull of the ship to a floating storage facility or a land storage facility, a floating storage or land storage facility, a tank of the ship, A facility or land storage facility has a pump to drive the fluid through the insulation pipeline.

Therefore, one object of the present invention is to propose a heating process without the risk of increasing the pressure of the first space. The heating process can be applied to other situations such as, for example, regulatory inspection of tanks, technical intervention of the user into tanks such as maintenance or repair of tank components. It can also be applied to temporarily or permanently stop the operation of the tank.

Other objects, features and advantages of the invention will become more apparent from the following detailed description of several specific embodiments thereof, It will become clear.
1 is a cross-sectional view of a seal and adiabatic tank with a fluid management device according to one embodiment.
2 is a diagram showing steps of a management method that can be applied to a tank according to the first embodiment of Fig. 1; Fig.
3 is a diagram showing steps of a management method that can be applied to a tank according to the second embodiment of Fig. 1; Fig.
Figure 4 is a diagram illustrating complementary steps of the management of Figure 3;
5 is a diagram showing the pressures measured in the tank of FIG. 1 under normal operating conditions; FIG.
6 is a view showing the pressure measured in the tank of FIG. 1 in the leakage state of the proof wall; FIG.
7 is a diagram showing the pressure measured in the tank of FIG. 1 in a leak state of the second membrane; FIG.
8 is a view showing the pressure measured in the tank of FIG. 1 in the leaked state and the non-leaked state of the first membrane; FIG.
9 is a diagram showing steps of a management method that can be applied to the tank of Fig. 1 according to the third embodiment. Fig.
10 is a diagram showing complementary steps of the management of FIG. 9; FIG.
11 is a view showing the pressures measured in the tank of FIG. 1 during the management method of FIG. 9. FIG.
12 is a diagram showing the temperatures measured in the tank of FIG. 1 during the management method of FIG. 9. FIG.
13 is a partial view of the fluid management apparatus of Fig. 1 according to a modification. Fig.
14 is a partial view of the fluid management device of Fig. 1 according to another variant. Fig.
15 is a bottom view of a first insulating barrier member that may be applied in the tank of FIG. 1;
16 is a partial cross-sectional view of the tank wall to which the first insulating barrier member of Fig. 15 is applied.
17 is an exploded view of a methane tanker equipped with a terminal for loading / offloading the tank and the tank.

In the description and claims, the term "gas" refers to a gas having a general characteristic and consisting of a pure single substance or a mixture of plural components. Thus, the liquefied gas represents a chemical or a mixture of chemicals that are placed in a liquid state at low temperatures and are present in a vapor state at normal temperature and pressure conditions.

1, there is shown a sealing and adiabatic tank 1 for storage and transportation of liquefied gas. The tank 1 may be installed on a land or floating structure. In the case of a floating structure, the tank may be installed on the hull of a liquefied gas carrier such as a methane tanker. It can also be applied to any vessel that consumes gas-powered means such as powertrain, generator sets, steam generators, or other means of energy utilization. For example, it may be a cargo carrier, a passenger ship, a fishing vessel, a floating electricity production unit, or the like.

The tank 1 is a membrane tank having a multi-layered wall, and the wall of the multi-side structure is formed by a wall 1 having an internal wall from the outside to the inside of the tank 1, , A second sealing membrane (5) in contact with the second insulating member (4), a second sealing member (5) in contact with the second sealing member (5) A first space 6 which may have a member 7 and a first sealing membrane 9 in contact with the liquefied gas 8 stored in the tank.

The tank may in particular have a parallelepiped, prismatic or polyhedral shape.

The tank 1 shown in Fig. 1 has a first space 6 of small thickness, and thus has a small volume. Is filled with a solid modular element 7 of small thickness, which can perform the thermal insulation function, the load transfer function and / or the mechanical protection function against the perforation of the second sealing membrane 5. The solid modular element 7, such as the secondary insulating member 4, may be made of different materials, such as plywood, polymeric form, glass wool or rock wool, expanded perlite, aerosol, balsa and other insulating materials.

In a variant, the first space 6 may also be a void space between the two sealing membranes, without a solid material. An example of such a first space is described in published document EP-A-1898143.

The liquefied gas 8 is a cooling substance that can be evaporated when heated to room temperature. Particularly, the liquefied gas 8 can be liquefied natural gas (LNG), which is mainly composed of methane and one or more hydrocarbons such as ethane, propane, n-butane, i-butane, Neopentane and nitrogen in a small proportion.

The liquefied gas 8 can also be ethane or liquefied petroleum gas (LPG), which is a hydrocarbon mixture extracted from refined oil, which essentially contains propane and butane. The liquefied gas 8 may also be nitrogen, helium, ethylene or liquefied hydrogen.

The liquefied gas 8 is stored in the internal space of the tank in a two-phase liquid-vapor equilibrium state. Therefore, there is a gas in the vapor state 10 at the top of the tank. The equilibrium temperature of the liquefied natural gas corresponding to the two-phase liquid-vapor equilibrium state is approximately -162 ° C when stored at atmospheric pressure.

At the time of driving, the tank 1 inevitably receives a high temperature fluctuation. Particularly, since there is no load that is stored or transported in the tank 1 and used immediately, or the intermediate repair or maintenance requires the tank 1 to enter the tank 1 by a person and / or tool, 1 is operated to transport or store the liquefied gas 8, the tank must be completely emptied and the tank 1 should be heated to ambient temperature.

The tank 1 of Figure 1 comprises at least one pressure sensor 41 for measuring the pressure of the first space 6, at least one pressure sensor 42 for measuring the pressure of the second space 3, One or more temperature sensors 45 for measuring the temperature of the first space 6 and one or more temperature sensors 46 for measuring the temperature of the second space 3. The purpose of the sensors will be described in the following detailed description of the methods.

A detailed description of the processes by which the tank 1 can be safely heated as a whole while preventing the occurrence of unacceptable overpressure in the first space 6 is as follows. It is important to note that the pressure change produced by the flow of gas entering the proposed enclosure is faster as the volume of the space is smaller. Thus, the risk of overpressure, which is suddenly generated in the first space by a certain amount of vaporization in the form of gas in the liquid phase, is higher in the first space of small volume. Nevertheless, the process described below can be applied to any membrane tank regardless of the volume of the first space.

Referring to Fig. 2, the heating method according to the first embodiment will be described. For illustrative purposes, it is assumed that tank 1 initially stores a stored LNG load at tank pressure close to atmospheric pressure. The liquid-vapor equilibrium point is close to -162 ° C. The tank pressure here represents the absolute pressure prevailing in the vapor state at the top of the tank 1 and thus determines the two-phase equilibrium temperature in the tank 1. Within the strength limits of the sealing membranes, this is approximately +/- 10 kPa difference at atmospheric pressure.

The actual storage of the first space 6 and the second space 3 is not specifically known at the beginning of the heating process and the presence of a liquid state which can be vaporized during the heating process is not certain or excluded. However, except for the presence of sealing defects in the first membrane 9 and the load bearing wall 2, the first space 6 and the second space 3 are initially stored in the gaseous state at a pressure close to the tank temperature .

In step 11, the heating process is started to empty the tank, complete the emptying of the tank and heat the wall of the tank. In step 12, the second space 3 is depressurized using a vacuum pump 22. The vacuum pump is installed to pump the gas phase into the second space 3 and to discharge the gas pumped to the outside of the tank wall, for example the atmosphere, through the vapor manifold of the vessel or tank 1. In step 13, the first space 6 is depressurized by using a vacuum pump 21. The vacuum pump is installed to pump the gas phase into the first space 6 and to discharge the gas pumped to the outside of the tank wall, for example the atmosphere, through the steam manifold of the vessel or tank 1.

The vacuum pumps 21 and 22 are each configured to perform the adjustment of the absolute pressure of the first space 6 and the second space 3, respectively. To this end, the target pressure is set: the first target pressure for the first space (6) (P ₀ -dp1) and a second target pressure for a space _{(3) (P 0 -dp2)} , where P ₀ Represents the pressure of the tank, and dp1 and dp2 represent positive values. The purpose of the decompression (-dp1) is to move the liquid-vapor equilibrium which can be set in the first space 6. For example, if leakage of the liquefied gas 8 occurs within, or if other gases are condensed or absorbed, liquid forced evaporation may be induced. Decompression (-dp1) must be high so that the vaporization exhibits sufficient kinetic energy. Preferably, dp1 is approximately 10 to 50 kPa, for example approximately 20 kPa. While the vacuum pump 21 regulates the pressure in the first space 6 in order to set and maintain the first target pressure P ₀ -dp 1, the vacuum pump 22 sets the second set pressure P ₀ -dp 2 The pressure of the second space 3 is adjusted. The purpose of the decompression (-dp2) is to maintain a relative pressure balance on both sides of the second membrane 5, if the second membrane 5 can not withstand typically high pressure differentials. The set pressure should satisfy the following relation.

| dp1-dp2 | ≪ DP,

DP represents a predetermined safety threshold to ensure the integrity of the second membrane (5). Preferably, the DP is set between 0.5 kPa and 4 kPa, and is, for example, 2 kPa. Preferably, the set pressure also satisfies the following relationship.

dp2> dp1

The pressure difference on both sides of the second membrane 5 tends to press the latter against the second insulation barrier and prevent it from tearing in the second insulation barrier.

Vacuum pumps 21 and 22 are cryogenic pumps capable of withstanding cryogenic temperatures below -150 ° C. They are also designed to comply with ATEX regulations and to prevent the risk of explosion. The vacuum pump can be provided in various ways, for example, as a Roots type (so-called rotary lobes), a vane, a liquid ring, a screw, and a venturi type effector. Vacuum pump suppliers are, for example, MPR Industries or Bosch Group.

Adjustment of the absolute pressure using the vacuum pumps 21, 22 in the first space 6 and the second space 3 may be started simultaneously or sequentially and may be started for a sufficient time to stabilize the pressure at the level of the target pressure And can be stably maintained for a predetermined settling time as shown in step 14.

According to one embodiment, especially if there is no other means for detecting the presence of a liquid phase in the first space 6, the settling time may be relatively long to permit evaporation of any liquid state that may be present with sufficient safety margin Is selected. Thus, the stabilization time can be several hours, for example between 2 hours and 10 hours. Conversely, if detection of liquid phase is also implemented, a shorter settling time can be selected, which is described below.

At the end of the settling time, step 15 comprises advancing the evacuation and heating of the tank 1. Depending on the initial state of the tank, the blanks can only be associated here with all liquids or liquid heels at the bottom of the tank. Heating can be realized by simply connecting the empty tank to the ambient atmosphere or by injecting a hot gas, for example a combustion gas from a heating device, to increase the heating rate. The pressure regulation by the vacuum pumps 21, 22 preferably lasts for the step 15. This pre-heating makes it possible for the flow of liquid to the first space 6 to continue to be vaporized by the sealing defect of the first membrane 9.

Fig. 5 shows an exemplary embodiment of the method when the reduced pressure (dp1, dp2) is 20 kPa. 5 is a graph showing the absolute pressure in k-axis on the y-axis and the time in seconds on the x-axis. Curve 16 represents the pressure in the first space and curve 17 represents the pressure in the second space. In this embodiment, the pressures 16 and 17 effectively reach the target desired pressure, which means that there are no sealing defects. Indeed, the detection of the fact that the targeted pressure has been effectively reached includes detecting the downward crossing of the detection threshold, which is indicative of the difference between the set pressure and the positive tolerance of the vacuum pump. The difference in tolerance is lower than dp1 and dp2, and is generally between 0.1 and 1kPa. Can be more specifically fixed depending on the function of the structural characteristics of the tank, in particular on the function of the head loss between the inlet of the vacuum pump and the pressure sensor, on the other hand as a function of the settling time.

The above-described process can be implemented under the control of an electronic control device 50, such as, for example, a programmed computer. To this end, the control device 50 is connected to the pressure sensors 41, 42 by means of links 43, 44 to obtain pressure measurements over time. The control device 50 is connected to the vacuum pumps 21 and 22 by links 23 and 24 to drive the vacuum pumps 21 and 22 after a lapse of time. Step 11 may be triggered manually, for example by actuation of a control member of an unrepresented human-machine interface, or may be triggered automatically, for example by receipt of an instruction at the central computer system, which is not indicated.

In this embodiment, it is assumed that the first space 6 is initially the tank pressure P ₀ of the tank 1. The first space 6 is initially depressurized such that the working pressure Ps of the first space 6 is _{equal to} the tank pressure P0 of the tank 1 when the tank is full of the load, . In this case, if a liquid phase is incidentally present in the first space 6, the pressure Ps is in equilibrium thereafter. The evaporation of the liquid phase may thus also occur by lowering the pressure below the operating pressure Ps. Therefore, the method can be used in the above case by setting the set pressure Ps-dp1 in the first space 6 and setting the set pressure Ps-dp2 in the second space 3.

The above-described method can also be applied to a tank having a single sealed membrane. For example, the second membrane 5 can be removed or replaced with an automatically sealed cover that can withstand pressure differentials. In this case, step 12 may be omitted.

The process of FIG. 2 is a purge process based on reduced pressure, which does not identify an abnormality such as a sealing defect of the first membrane 9 or the second membrane 5. In addition, the presence of a significant safety margin in the settling time does not optimize the duration of the process. Thus, the process of detecting the sealing defects of the first membrane 9, the second membrane 5 or the proof wall 2 can be preferred. Also, a process capable of detecting the presence of liquefied gas or gas absorbed by the material in the first space 6 may be preferred.

Figs. 3 and 4 show the heating process according to the second embodiment satisfying these conditions.

The first two steps of 11 and 12 are not changed in comparison with Fig. In step 25, the trend of the pressure of the second space 3 is monitored using a pressure sensor to determine whether the pressure converges toward the expected target pressure (P ₀ -dp 2). If the test is satisfied, that is, true in the example of FIG. 5, the method proceeds to step 13, which is unchanged compared to FIG. Otherwise, the process proceeds to Figure 4, which is described below.

The test of step 25 is useful for preventing the second membrane 5 from being damaged in the presence of a sealing defect of the proof wall 2. This case will be described with reference to Fig. Figure 6 shows an illustrative embodiment of the method as a figure similar to Figure 5; At this time, the decompression (dp1, dp2) is equal to 20 kPa and has considerable sealing defects in the wall 2. Curve 117 is a reference curve showing the trend of pressure expected in the second space 3 under normal operating conditions. The curve 117 rapidly converges toward the target pressure P ₀ -dp2. Curve 17 represents the pressure actually measured in the second space 3. In this case, it is considerably more stable than the target pressure due to the permanent leakage flow through the load bearing wall 2. Due to the leakage, there is a risk of the second space 3 storing a considerable amount of gas absorbed by the secondary insulation element 4. The risk is that it evaporates suddenly during heating and damages the sealed membrane. For this reason, if the test of step 25 is not satisfied after a specific monitoring time, the process of FIG. 4 is performed.

Referring to Fig. 4, step 31 includes modifying the first target pressure to be compatible with the actually measured pressure (P ₀ -2) in the second space 3. That is, the value of dp1 is | dp1-2 | ≪ DP.

Step 32 is equivalent to step 13 described above, but has a new set pressure (P ₀ -dp 1). Thus, the curve 16 of FIG. 6 represents the pressure measured in the first space 6 during the course. If a low decompression is applied, step 32 can not guarantee the release of the liquid phase with the same degree of stability as in step 13.

Step 33 finally consists of performing the evacuation and heating of the tank 1, but has a slow kinetic energy if the risk of sudden evaporation of the contents in the second space and / or the first space occurs. Depending on the initial state of the tank, the blanks can only relate here to all loads or liquid heels at the bottom of the tank. The slow heating process includes, for example, injecting LNG from the load into the tank 1 during all or part of the emptying time or heating time.

Returning to Figure 3, when the step 13 is carried out, step 26 comprises a first space (6), using the pressure sensor 41 to determine if the pressure is converged toward the estimated target pressure (P ₀ -dp1) Lt; RTI ID = 0.0 > a < / RTI > pressure trend. If the test is satisfied, for example, in the example of FIG. 5, the method proceeds to step 15, which is unchanged as compared to FIG. Otherwise, the method proceeds to step 27.

The test of step 26 is useful for determining if there is a leak in the first membrane 9. This case will be described with reference to Fig. Figure 8 is a view similar to Figure 5 showing an exemplary embodiment of the method. The decompression dp1, dp2 is equal to 20 kPa and there is a significant sealing defect of the first membrane 9. Curve 116 is a reference curve representing the pressure trend expected in the first space 6 under normal operating conditions. The curve 116 converges sharply toward the set pressure P ₀ -dp1. Curve 16 represents the pressure actually measured in the first space 6. In this case, because of the permanent leakage flow through the first membrane 9, it is considerably more stable than the target pressure. Due to the leakage, there is a risk of the first space 6 containing a significant amount of liquid and / or a significant amount of gas absorbed by the first insulation member 7. The risk is that it evaporates suddenly during heating and damages the sealed membrane. For this reason, if the test of step 26 is not satisfied after a specific monitoring time, step 27 is performed.

Step 27 includes analyzing the trend curve of the pressure measured in the first space 6 to detect whether an intermediate stabilization plateau has crossed. Curve 16 of FIG. 8 shows this trend. The curve 16 forms a stabilizer at a midpoint Pi where the pressure of the first space 6 is between the initial pressure and the final stable pressure, before finally stabilizing to a value close to 90 kPa over 27000 s for a moment It stabilizes temporarily between 15,000 s and 20,000 s and approaches 97 kPa. The presence of the stabilizer means that the accumulated liquid state is evaporated or that a regular flow of gas is generated during the period under the effect of depressurization in the first space 6 by desorption in the absorbed state. Therefore, the intersection of the ballast and the stabilization of the pressure at low level means that the liquid state or the absorbed state has completely evaporated and that current heating can be performed slowly or rapidly depending on whether there is a current leakage. To this end, the method returns to step 26, indicated by arrow 28. In the example of curve 16 of Fig. 8, shown in dashed lines, the final stable pressure is clearly higher than the set pressure, which means that there is a permanent leakage flow rate. Stable pressure occurs in the balance between the pumping flow rate and the leak flow rate. In this case, the slow heating process has to be continued, i. E. The pressure has stabilized, and the method returns to step 27.

   In FIG. 8, the curve 216, shown in dashed lines, illustrates another embodiment in which the amount of liquid state that is condensed or absorbed is stored in the first space without a permanent leakage flow rate. After passing through the vaporizer, the pressure is finally stabilized to the target pressure level. The method is unchanged with respect to FIG. 2 and proceeds to step 15. The presence of gas condensed or absorbed in the first space without leakage flow at the membrane can have a variety of causes. For example, the residual gas may be due to a defective or misconfigured sweep gas generator. This is because instead of creating a flow of pure nitrogen, a significant amount of other gases, such as for example carbon dioxide, nitrogen dioxide or other impurities, are introduced into the first space. Another possible cause of impurities is in solid materials entering the first space for insulation and structural reinforcement. For example, it may be in the form of a polymer filled with an expansion material that is released by diffusion during the operating period of the tank. At the end of the driving period of several months or years, this phenomenon can produce a substantial accumulation of gas that condenses or adsorbs into the interior of the first space.

Depending on the embodiment, there may be several successive stabilizing stabilizers prior to the final stabilizer of pressure. For example, there is an example of a specific pair of adsorbent-adsorbent materials. On the contrary, if it is immediately lowered to the final stable value without the stabilizer, it means that there is no significant amount of content in the liquid to be evaporated or the absorbed state.

In all examples, it is the level of final stabilization pressure that allows for a choice of either a fast heating process or a slow process. However, a relatively long settling time must be observed to ensure that the final pressure is actually reached. Therefore, a faster and more robust process for detecting the presence of a liquid phase may also be to monitor the trend of temperature as described below.

As described above, no defect occurs in the second membrane 5. In fact, the defects can only modify the kinetic energy trend of the pressure in the first and second spaces under the operation of the vacuum pump, and in itself do not prevent lowering of the target pressure, especially the pressure to the lowest target pressure. This embodiment is shown in Fig. Fig. 7 is a view similar to Fig. 5 showing an illustrative embodiment of the method, in which the reduced pressure dp1, dp2 is equal to 20 kPa and there is a considerable sealing defect of the second membrane 5. Curve 117 is a reference curve representing the pressure trend expected in the second space 3 under normal operating conditions. Curve 117 rapidly converges toward set pressure P ₀ -dp2. Curve 17 represents the pressure actually measured in the second space 3. Curve 16 represents the pressure actually measured in the first space 6. Due to the connection between the two spaces, the vacuum pump 22 lowers the pressure in the second space 3 less rapidly than expected. In a variant, step 25 is also modified to detect the presence of defects in the second sealing membrane 5. To this end, a comparison of the variation over time between the measured pressure 17 and the reference curve 117 is performed. In the rest, the process is not changed.

The reference curves 116 and 117 are displayed when the operation status of the tank 1 is immediately checked, for example, when the vessel is in a "bedded-in" state.

9 to 12, a detailed description of the heating process according to the third embodiment using the temperature measuring device in which the temperature measurement is used to detect the presence of the liquid state in the first space 6 is as follows . The purpose of the temperature measuring device is to evaluate the local behavior of the fluid in the first space 6. In order to obtain information about the characteristics of the fluid at a given point, the process comprises reducing the pressure and following the trend of the temperature. Lowering the pressure is believed to cool the vapor phase by expansion. However, if a large exchange surface of the first membrane 6 is provided with the liquid load 8, the vapor cooled in the first space is immediately heated to the temperature of the load 8 by contact with the first membrane 8 do. Thus, when the pressure is lowered, the temperature returns to the initial temperature within a few minutes, after which the fluid in the first space 6 becomes a vapor phase. However, if the temperature tends to be towards the equilibrium temperature of the liquid considered to be at a low temperature, the first space will contain a non-zero liquid at least close to the temperature measurement point. Therefore, a network of temperature and pressure sensors distributed on the walls of the tank 1 is necessary in order to be able to make local measurements in other areas of the wall of the tank 1. [

Figure 9 shows a method for managing pressure and obtaining a measured value. 11 is a graph showing the absolute pressure indicated by kPa on the y-axis and the time expressed in seconds on the x-axis, and curves 16 and 17 are plotted in the first space 6 and the second space 3). 12 shows the temperature in degrees centigrade on the y-axis and the time in seconds on the x-axis. The curves 37 and 40 show the temperature in the first space (Fig. 6).

In step 51, the pressure of the second space is lowered by a small difference Rs, for example, 1 kPa, in order to lower the pressure similarly to the first space without generating an excessive load on the second membrane 5. In step 52, the pressure of the first space is lowered by a small difference Rp, where Rp < = Rs. In step 53, a predetermined time delay is advanced so that the temperature of the steam state in the first space 6 is stabilized. In step 54, the reference temperature measurement value Tr is acquired in the first space 6, which generally reflects a slight cooling compared to the initial temperature, and both return to equilibrium more quickly when the liquid mass is low do.

In step 55, the pressure of the second space is lowered by a large difference Qs, e.g., 20 kPa, in order to lower the pressure similarly to the first space without causing an excessive load on the second membrane 5. In step 56, the pressure of the first space is lowered by a large difference Qp, where Qp < = Qs. In step 57, a predetermined time delay is set so that the temperature of the steam state in the first space 6 is stabilized. In step 58, a second temperature measurement Tm is obtained in the first space 6.

Figure 10 shows a method of processing temperature measurements. In step 61, the two-phase equilibrium temperature of the liquefied gas at the set pressure P ₀ -Rp is expressed by Te. At step 62, | Te-Tr | A positive threshold value is determined, which is denoted by?. In step 63, the following inequality is tested:

| Tm-Tr |??

If the inequality is satisfied, it means that the temperature is considerably balanced at the same level due to the small pressure difference and the large pressure difference. The method leads to detecting the dry vapor phase at the level of the measurement point in step 65. This case corresponds to the curve 39 in Fig. Then, the heating can be performed immediately without risk.

If the inequality is not satisfied, it means that the temperature is balanced at a significantly different level due to the small pressure difference and the large pressure difference. The method proceeds to step 64, where the two-phase equilibrium temperature of the liquefied gas at the set pressure (P ₀ -Qp) is denoted Tf. In step 66 the following inequality is tested:

| Tf-Tm |??

If the above inequality is proved, the temperature at the equilibrium point at low pressure means that it is fairly balanced. The method leads to detecting the liquid phase that vaporizes at the level of the measurement point in step 68. This case corresponds to the curve 40 in Fig.

If the above inequality is not satisfied, the stabilization ratio? Is calculated in step 67 according to the following equation:

τ = (Tm-Tf) / (Tr-Tf)

Decompression should be maintained in the first space prior to heating of the tank, and the time should be kept longer if the stabilization rate is low. 12, heating can be performed at an instant when the curve 40 is sufficiently close to the temperature Te, for example, from 20,000 seconds.

The above-described method can be performed simultaneously or sequentially in all measurement areas covered by the sensor network. The process of the third embodiment can easily make a map of the area including the liquid portion. Through continuous measurement, it is possible to track the trend of the liquid content of the first space.

Therefore, the heating process according to the second embodiment and the third embodiment can check the integrity of the storage system. They can be performed jointly to obtain information about the macroscopic information of the state of the tank and the trend of the purging process or condensate of the first space at different points of the first space. Further, the above processes can be performed under the control of the electronic control device 50. [

Advantageously, if the second membrane 5 is made of a thermally conductive material, for example a metallic material, the temperature sensors for measurement in the first space 6 can be used to limit the subsequent passage of the second membrane 5, As shown in FIG. However, it is necessary to limit the contact resistance between the temperature sensor and the second membrane (5).

Referring to another embodiment according to Figs. 13 and 14, a single vacuum pump is applied to depressurize the first and second spaces.

13 shows a partial view of the wall of the tank with the connecting device 35 establishing a fluid connection between the second space 6 and the first space 3. [ The connecting device 35 includes a regulating valve 36. The adjustment valve is basically in a closed state and opens when the pressure of the second space 6 exceeds the pressure of the first space 3 by a value greater than a given threshold value. The open threshold value is preferably 1 to 5 kPa, for example 3 kPa. In this case, if the pressure of only the first space 3 is adjusted by using the vacuum pump 21, the vacuum pump 22 can be omitted, and the above-described method can be simplified. The pressure of the second space 6 is manually adjusted by the connecting device 35 based on the trend of the first space 3 so that the integrity of the second membrane 5 is not compromised. The connecting device 35 may be permanently fixed to the wall of the tank.

Figure 14 shows a partial view of the walls of the tank with a vacuum pump 21 and a T-shaped connection circuit 37 establishing a fluid connection between each first space 3 and the second space 6 . The loss head measuring or regulating device 38 is adapted to generate a pressure difference between the two sides of the second membrane 5 without any difference exceeding the pre-established safety threshold, for example 3 kPa, . At least one sectional valve is provided to prevent any connection between the first space 3 and the second space 6 outside the heating process. The head loss device 38 may be a compartment valve.

In order to obtain the accurate effectiveness of the depressurization of the first space, it is preferable that the head loss between the other areas of the first space 3 is not too high. Particularly, when the first space 6 is filled with the solid modular member 7, it is advantageous that such a solid modular member 7 inserted between the membranes combines the flow channels to facilitate the flow of gas. Thus, the pressure of the first space 3 can be easily adjusted. The flow channels are manufactured in such a way that they do not impair the supporting function of the solid modular member 7. 15 and 16 illustrate an example of a solid modular member in the form of a parallelepipedal separator 47 comprising flow channels 48 and 49 made in the shape of a right angle groove disposed on the side of the second membrane 5 FIG. 15 is a bottom view of the parallelepipedic separator 47. Fig. Fig. 16 is a partial sectional view of the tank wall having the piece 47. Fig. In this embodiment, the membranes 5, 9 are wavy.

The techniques described above for heating the tank can be applied to various types, such as, for example, land-based LNG tanks or floating structures such as methane tankers or similar structures.

As described above, the heating of the tank can be performed more safely thanks to the test prior to heating. If the preliminary test described above is satisfied, heating can be started immediately after the test is completed. Various selections can be made at the moment the preliminary test is started. However, the first sealing membrane and the space below it should primarily maintain the temperature of the liquefied gas until the end of the test.

17 is an exploded view of a methane oil tanker 70 showing a generally rectangular prismatic seal and a thermal insulation tank 71 mounted on the ship's double hull 72. As shown in FIG. The wall of the tank 71 includes a first sealing barrier in contact with the LNG contained in the tank, a second sealing barrier disposed between the first sealing barrier 71 and the ship's double hull 72, And one or two insulating barriers which are disposed between the first sealing barriers and the second sealing barriers, respectively.

The loading / offloading pipeline 73 disposed on the deck of the vessel, as is well known in the art, is a suitable connector for receiving loads in the form of LNG from the tank 71 or delivering it to the tank 71, Lt; / RTI >

17 shows an example of a maritime terminal including a loading and offloading station 75, an underwater pipe 76 and a land installation 77. [ The loading and unloading station 75 is a fixed coastal installation having a movable arm 74 and a riser 78 supporting the movable arm 74. The movable arm 74 carries a bundle of adiabatic flexible pipes 79 that can be connected to the loading / offloading pipeline 73. The directional movable arm 74 is applied to the template of all methane tankers. A link duct, not shown, extends into the riser 78. The loading and offloading station 75 may load and offload the methane tanker 70 from the landfill 77 or landfill 77. Followed by a liquefied gas storage tank 80 connected to the loading or offloading station 75 by an underwater pipe 76 and a link duct 81. The underwater pipe 76 may deliver the liquefied gas to a long distance between the loading or offloading station 75 and the landfill 77, for example over a length of 5 km. This allows the methane tanker 70 to remain a long distance from the coast during loading and offloading operations.

A pump incorporated in the vessel 70 and / or a pump mounted on land equipment, and / or a pump mounted on the loading and offloading station 75 are executed to generate the pressure necessary to deliver the liquefied gas.

Although the present invention has been described in connection with a number of specific embodiments, it is to be understood that the invention is not to be construed as limited to the particular embodiments set forth herein, nor is it limited to the technical equivalents of the means described, And the like.

The word "comprises" or "comprising" and its conjugations do not exclude the presence of other elements or processes other than those specified in a claim. Unless otherwise specified, the indefinite expression "a" or "an" in an element or step does not exclude the presence of a plurality of such elements or processes.

Reference numerals between parentheses in the claims are not construed as limitations on the above claims.

1: Sealing and insulation tank
2: outer load bearing wall
3: Intermediate space
5: Second sealing membrane
6: First space
8: Liquefied gas
9: First sealing membrane

Claims (27)

A method of managing fluid in a sealing and adiabatic tank (1) for storing liquefied gas (8) at low temperatures,
The wall of the tank is composed of an outer load bearing wall 2 having a multilayer structure, a first sealing membrane 9 in contact with the liquefied gas stored in the tank, an intermediate space 3 disposed between the first sealing membrane and the outer bearing wall Wherein the first sealing membrane (9) is from the low temperature sealing of the liquefied gas (8) and from the state of the thermal insulation tank (1):
A suction step in which the gaseous phase is sucked (13, 56) from the intermediate space to the outside of the wall of the tank to lower the pressure in the intermediate space below the working pressure of the intermediate space,
A measuring step of measuring a pressure in the intermediate space using a pressure sensor during the suction step,
A detection step of detecting (14, 57) the stabilization of the measured pressure of the intermediate space during the inhalation phase,
A method of managing a fluid in a sealing and adiabatic tank (1), comprising heating a wall of the tank (15, 33). The method according to claim 1,
The sealing and adiabatic tank is initially filled with a liquefied gas load at low temperature and the step of heating the wall of the tank comprises the step of emptying the tank, which is a liquefied gas, at a low temperature from the tank, ). The method according to claim 1,
The sealing and adiabatic tank initially includes a heel of liquefied gas at a low temperature and the step of heating the wall of the tank comprises removing the heel of the liquefied gas from the tank at a low temperature, 1). The method of claim 3,
Comprising the step of spraying a liquefied gas on the inner surface of the first sealing membrane (9) to maintain the first sealing membrane (9) at said low temperature of the liquefied gas (8), at least until the start of the heating step A method for managing fluid in a tank (1). 5. The method according to any one of claims 1 to 4,
Wherein the suction of the gas phase is driven by a vacuum pump (21) adjusted to reach a target pressure. 6. The method of claim 5,
Wherein the difference between the predetermined target pressure and the working pressure of the intermediate space is greater than 10 kPa. 7. The method according to any one of claims 1 to 6,
Wherein the stabilization of the pressure in the intermediate space is detected after the pressure has ceased to fluctuate for more than 1 hour, preferably more than 2 hours, more than the stabilization time, in the sealing and adiabatic tank (1). 8. The method according to any one of claims 1 to 7,
Further comprising selecting (26) a heating process during a fast heating process and a slow heating process (26) based on the stabilized pressure in the intermediate space during the suction phase. 9. The method of claim 8,
Wherein the rapid heating process (15) is selected when the stabilized pressure in the intermediate space during the suction phase is less than or equal to a predetermined threshold pressure value lower than the working pressure. 10. The method of claim 9,
The rapid heating process (15) further comprises the step of injecting hot gas into the tank from which the liquefied gas is removed at low temperature. 11. The method according to any one of claims 8 to 10,
Wherein the slow heating process (33) is selected when the stabilized pressure in the intermediate space during the suction phase is higher than a predetermined threshold pressure value lower than the working pressure. 12. The method of claim 11,
The slow heating process 33 includes the step of injecting the flow of liquefied gas into the tank 1 at low temperature while the load of liquefied gas is removed from the tank at low temperature, Way. 13. The method according to any one of claims 1 to 12,
Detecting (27, 63) the presence of a liquid phase inside the intermediate space,
Further comprising the step (13, 56) of maintaining the suction of the gaseous phase to an intermediate space so as to substantially evaporate and / or desorb the entire liquid phase prior to heating the wall of the tank. How to manage. 14. The method of claim 13,
(The intermediate level Pi between the predetermined target pressure and the working pressure), the presence of the liquid phase corresponding to the pressure stabilization in the intermediate space is detected 27, and at an intermediate level, corresponding to the subsequent pressure drop in the intermediate space A method for managing fluid in a sealing and adiabatic tank (1), wherein evaporation and / or desorption of the entire liquid is detected. 14. The method of claim 13,
Measuring (54, 58) the temperature of the intermediate space for a period of time from the absolute pressure drop (52, 56) in the intermediate space,
A step (68) of detecting a liquid phase corresponding to a stabilization of the temperature in the intermediate space near the liquid-vapor equilibrium point of the liquefied gas to a predetermined target pressure, and a step Further comprising the step of detecting (65) the evaporation and / or desorption of the entire liquid phase in response to the stabilization of the temperature. 13. The method according to any one of claims 1 to 12,
The step of lowering the pressure of the intermediate space comprises:
(52) lowering the pressure in the intermediate space to a first critical pressure value lower than the working pressure,
(54) measuring the first temperature (Tr) of the intermediate space after lowering the pressure to the first critical pressure value,
Lowering (56) the pressure in the intermediate space to a second critical pressure value that is lower than the first critical pressure value,
(58) measuring the second temperature (Tm) of the intermediate space at successive moments after lowering the pressure to a second threshold pressure value,
Determining (63) a difference between the second temperature and the first temperature,
Delaying the heating of the tank and maintaining suction if the difference between the second temperature and the first temperature is not less than a predetermined threshold temperature value,
And selecting a heating process after the difference between the first temperature and the second temperature is lower than a predetermined threshold temperature value. 17. The method according to any one of claims 1 to 16,
In the intermediate space,
A second sealing membrane 5 disposed between the outer proof wall 2 and the first sealing membrane 9, a second space 3 disposed between the second sealing membrane and the outside proof wall, a second sealing membrane 5, A first space (6) disposed between the first sealing membrane and a second solid insulating barrier (4) disposed within the second space,
The thickness of the first space is much smaller than the thickness of the second space,
The pressure is low in the second space and the first space, and the pressure difference between the second space and the first space is kept below the safety threshold,
A method of managing a fluid in a sealing and adiabatic tank (1) in which, based on a stabilization pressure in a first space, stability of pressure in at least a first space is detected to select a heating process. 18. The method of claim 17,
Wherein the pressure in the second space is lower than the pressure in the first space. 1. A fluid management device for a sealing and thermal insulation tank (1) for storing liquefied gas at low temperatures,
The apparatus is a device for carrying out the method according to claim 8, wherein the wall of the tank comprises an outer load bearing wall (2), a first sealing membrane (9) in contact with the liquefied gas stored in the tank, a first sealing membrane And an intermediate space (3) disposed in the intermediate layer
The fluid management device comprising:
A pressure sensor 41 for measuring the pressure in the intermediate space,
A vacuum pump 21 connected to the intermediate space for sucking the gaseous phase from the intermediate space to the outside of the wall of the tank and capable of lowering the pressure in the intermediate space below the working pressure of the intermediate space,
And a control module (50) that is capable of detecting pressure stabilization in the intermediate space during the aspiration step and selecting a heating process during the fast heating process and the slow heating process based on the stabilized pressure in the intermediate space during the inhalation phase, Management device. 20. The method of claim 19,
Further comprising a temperature sensor (45) for measuring the temperature in the intermediate space, the control module driving a vacuum pump and a temperature pump,
(54) measuring the first temperature in the intermediate space after lowering the pressure to a first critical pressure value,
(56) lowering the pressure in the intermediate space to a second threshold pressure value that is lower than the first threshold pressure value,
(58) measuring the second temperature of the intermediate space at successive moments after lowering the pressure to a second threshold pressure value,
Determining (63) a difference between the second temperature and the first temperature,
Delaying the heating of the tank and maintaining suction if the difference between the second temperature and the first temperature is not less than a predetermined threshold temperature value,
And selecting the heating step after the difference between the first temperature and the second temperature is lower than a predetermined threshold temperature value. 21. The method according to claim 19 or 20,
The intermediate space may include a second sealing membrane disposed between the outer proof wall and the first sealing membrane, a second space disposed between the second sealing membrane and the outer proof wall, a second sealing membrane disposed between the second sealing membrane and the first sealing membrane, One space, and a second solid insulating barrier (4) disposed within the second space,
The thickness of the first space is much smaller than the thickness of the second space,
The pump 21 is connected to at least the first space 3,
Wherein the control module (50) is capable of detecting at least a stabilization of pressure in the first space to select a heating process based on the stabilized pressure of the first space. 22. The method of claim 21,
Further comprising a fluid link (35) connecting the second space and the first space, wherein the fluid link is essentially closed, and the openings corresponding to a pressure difference greater than a predetermined opening threshold between the second space and the first space And a valve (35) that can be in fluid communication with the fluid. 23. The method of claim 21 or 22,
A first vacuum pump (21) connected in parallel with the first space, and a second vacuum pump (22) connected with the second space. 23. The method of claim 21 or 22,
And a vacuum pump (21) connected in parallel with a first space by a first suction pipe and a second space by a second suction pipe, each suction pipe comprising a fluid head Management device. Double hull,
A sealing and adiabatic tank (1) for storing the liquefied gas at low temperature and disposed in said double hull, and
A vessel (70) comprising a fluid management device according to any one of claims 19 to 24 in which a tank is installed. A method for loading or offloading a ship (90) of claim 25,
The fluid flows from the tank of the ship 71 to the floating or land storage structure 77 through the adiabatic pipeline 73, 79, 76, 81 towards the tank of the ship 71 from the floating or land storage structure 77 The loading or offloading of the vessel. 26. A fluid movement system comprising the vessel (70) of claim 25,
An insulating pipeline 73, 79, 76, 81 arranged to connect the tank 71 installed in the hull of the ship to the floating or land storage structure, and
And a pump for driving the fluid through the insulated pipeline from the tank of the ship to the floating or land storage structure or from the tank of the ship to the floating or land storage structure.

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