• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a method for inerting a wall of a sealed and thermally insulating tank (1) intended to contain a liquefied fuel gas, in which the wall has a multilayer structure comprising two impervious barriers (2, 4) and a thermally insulating barrier (3), said method providing: - implementing a first inerting mode in which the gaseous phase of the thermally insulating barrier (3) is placed under a relative pressure lower than a limiting pressure of flammability Pi of the combustible gas; detecting, during the first mode of inerting, that the pressure of the gaseous phase of the thermally insulating barrier (3) exceeds said threshold pressure Ps; to switch from the first inerting mode to a second inerting mode, the second inerting mode providing for scanning the thermally insulating barrier (3) with an inert gas.
    公开号:FR3017924A1
    申请号:FR1451416
    申请日:2014-02-21
    公开日:2015-08-28
    发明作者:Bruno Deletre；Fabrice Lombard
    申请人:Gaztransport et Technigaz SARL；
    IPC主号:
    专利说明:

    [0001] TECHNICAL FIELD The invention relates to the inerting of a sealed and thermally insulating tank wall intended to contain a liquefied fuel gas. The invention may especially apply to the inerting of membrane cell walls which are used for the storage of liquefied natural gas (LNG). BACKGROUND OF THE INVENTION Sealed and thermally insulating vessels are known for the storage of liquefied natural gas comprising a tank wall having successively, in the direction of the thickness, from the inside to the outside of the tank, a primary sealing membrane intended to be in contact with the liquefied natural gas, a primary thermally insulating barrier, a secondary sealing membrane, a secondary thermally insulating barrier and a bearing structure defining the general shape of the vessel. The sealing membranes of such a tank may leak 15 causing the liquefied natural gas to pass from the interior of the tank to the thermally insulating, primary and secondary barriers. However, when a combustible gas is in the presence of an oxidizing gas and the concentration of combustible gas is in a concentration range between its lower explosive limit (LEL) and its upper explosive limit (LSE) ) and that the oxidant gas is in a suitable concentration range, the fuel gas is likely to ignite and explode. Also, to avoid accidents, it is known to maintain the thermally insulating barriers under an inert atmosphere by circulating nitrogen within these barriers. Thus, the combustible and oxidizing gases, which might be present in the thermally insulating barriers, are diluted so that the explosive conditions are not reached. It is also planned to equip the tank with a gas analyzer for measuring a concentration of combustible gas within the thermally insulating barrier in order to detect a leak of liquefied natural gas through the primary and / or secondary watertight barriers. . It is moreover known to maintain the gaseous phase of one and / or the other of the thermally insulating barriers under an absolute pressure lower than the ambient atmospheric pressure, that is to say at a negative relative pressure, in order to to increase the insulating power of said thermally insulating barriers. Such a method is for example described in the French patent application FR2535831. However, most gas analyzers are not likely to provide reliable low pressure measurements. Therefore, the pressure inside the thermally insulating barriers must be maintained above a minimum pressure, generally of the order of 80 KPa so that the inert nature of the thermally insulating barrier can be reliably monitored. Similarly, the gas flow rates inside the thermally insulating barriers must also be maintained above a minimum flow rate.
    [0002] Thus, it is not possible to reliably monitor the inert nature of a thermally insulating barrier when it is maintained at low pressure. Summary An idea underlying the invention is to provide a method and system for inerting a vessel wall for containing a liquefied combustible gas which is reliable and allow to increase the insulating capacity of the vessel. According to one embodiment, the invention provides a method for inerting a wall of a sealed and thermally insulating tank intended to contain a liquefied fuel gas, in which the wall has a multilayer structure comprising two impervious barriers and a thermally insulating barrier disposed between the two impervious barriers, said thermally insulating barrier comprising insulating solids and a gaseous phase, said method providing for: - implementing a first inerting mode in which the gaseous phase is the thermally insulating barrier under a negative relative pressure P1 lower than a threshold pressure Ps, said threshold pressure Ps being less than a flammable limit pressure Pi of the fuel gas; detecting, during the first mode of inerting, that the pressure of the gaseous phase of the thermally insulating barrier exceeds said threshold pressure Ps; To switch from the first inerting mode to a second inerting mode in response to the detection of a pressure of the gas phase of the thermally insulating barrier exceeding the threshold pressure Ps, the second inerting mode providing for sweeping; the thermally insulating barrier with an inert gas.
    [0003] Thus, the first mode of inerting makes it possible, on the one hand, to ensure the inert nature of the gaseous phase present in the thermally insulating barrier since it is placed at a pressure lower than the flammable limit pressure of the combustible gas. and, on the other hand, to increase the insulating power of the tank by maintaining said thermally insulating barrier in depression. In addition, the inert nature is reliably ensured since, in the event of loss of leaktightness of one of the leaktight membranes preventing the maintenance of a pressure lower than the flammability limit, the method provides as soon as a threshold pressure Ps is reaching, in a second mode of operation, in which the thermally insulating barrier is swept by an inert gas in order to sufficiently dilute the fuel gas and / or oxidant so that the explosive conditions are not reached. Note that within the meaning of the present description, the term inerting process of a thermally insulating barrier, a process for ensuring that the gas phase contained in said thermally insulating barrier is not placed in explosive conditions or flammable fuel gas. According to embodiments, such a method may comprise one or more of the following characteristics: the threshold pressure Ps is less than the partial pressure of said combustible gas, at atmospheric pressure, in a gaseous mixture comprising a concentration of the corresponding fuel gas; at the lower explosive limit of said fuel gas in air at 25 ° C. the threshold pressure Ps is between 20 and 35% of the partial pressure of said combustible gas, at atmospheric pressure, in a gaseous mixture comprising a concentration of the fuel gas corresponding to the lower explosive limit of said fuel gas in the air at 25 ° C. the threshold pressure Ps is 30% of the partial pressure of said combustible gas, at atmospheric pressure, in a gaseous mixture comprising a concentration of the fuel gas corresponding to the lower explosive limit of said combustible gas in the air, 25 ° C. the threshold pressure Ps is less than the partial pressure of the air, at atmospheric pressure, in a gaseous mixture comprising an air concentration corresponding to an oxygen concentration equal to a minimum concentration of oxygen allowing the flammability combustible gas. in the second mode of inerting the thermally insulating barrier is swept with an inert gas at atmospheric pressure. the fuel gas is selected from the group consisting of methane, ethane, n-butane, propane, ethylene and mixtures thereof. the inert gas is selected from the group consisting of diazo e, helium, argon and mixtures thereof. one of the impervious barriers is constituted by a bearing structure, the other impervious barrier consists of a secondary metal membrane and the thermally insulating barrier is a secondary thermal insulating barrier, the multilayer structure further comprising a primary metal membrane intended to to be in contact with the combustible gas stored inside the tank and a primary heat-insulating barrier disposed between the primary metal membrane and the secondary metal membrane, said primary heat-insulating barrier comprising insulating solids and a gaseous phase, the a method further comprising: o implementing a first mode of inerting the primary thermally insulating barrier in which the gaseous phase of the primary thermally insulating barrier is placed under a negative relative pressure P1 'less than a threshold pressure Ps ', said threshold pressure Ps' being in less than the flammable limit pressure Pi of the combustible gas; o during the first mode of inerting of the primary thermally insulating barrier, detecting that the pressure of the gas phase in said primary thermally insulating barrier exceeds said threshold pressure Ps, o switch from the first inerting mode to a second mode inerting the primary thermally insulating barrier in response to detecting a pressure of the gas phase of the primary thermally insulating barrier exceeding the threshold pressure Ps', the second inerting mode providing for sweeping the primary thermally insulating barrier with an inert gas. the threshold pressure Ps is variable and the threshold pressure Ps is assigned a first value as long as the first inerting mode of the primary thermally insulating barrier is implemented and the threshold pressure Ps is assigned a second value in response to the detection of a gas phase pressure of the primary thermally insulating barrier exceeding the threshold pressure Ps'. According to one embodiment, the invention also provides a system for inerting a wall of a sealed and thermally insulating tank intended to contain a liquefied fuel gas, in which the wall has a multilayer structure comprising two impervious barriers and a thermally insulating barrier disposed between the two impervious barriers, said thermally insulating barrier comprising insulating solids and a gaseous phase, the inerting system comprising: - a pumping device arranged to place the gaseous phase of the thermally insulating barrier under a pressure relative negative P1 lower than a threshold pressure Ps, said threshold pressure Ps being less than a flammable limit pressure Pi of the fuel gas; a pressure sensor capable of supplying a signal representative of the pressure of the gas phase inside the thermally insulating barrier; an inert gas injection equipment connected to an inert gas storage tank and / or an inert gas generator, and to a born of inert gas inside the thermally insulating barrier; and a driving unit adapted to: detect that the pressure of the gaseous phase of the thermally insulating barrier exceeds said threshold pressure Ps; and generating a start-up signal of the inert gas injection equipment in response to detecting a pressure of the gas phase of the thermally insulating barrier exceeding the threshold pressure Ps. such an inerting system may comprise one or more of the following characteristics: the inert gas injection equipment is connected to a dinitrogen generator. the inerting system comprises a gas analyzer for measuring a concentration of combustible gas in the gas phase. According to one embodiment, the invention also provides a sealed and thermally insulating vessel intended to contain a liquefied combustible gas having a wall having a multilayer structure comprising two watertight barriers and a thermally insulating barrier disposed between the two watertight barriers, said heat barrier. insulating material comprising insulating solids and a gaseous phase, and an inerting system mentioned above. In one embodiment, one of the impervious barriers consists of a supporting structure and the other impervious barrier consists of a secondary metal membrane, the multilayer structure further comprising a primary metal membrane intended to be in contact with each other. with the combustible gas stored inside the vessel and a thermally insulating barrier disposed between the primary metal membrane and the secondary metal membrane. Such a tank can be part of a land storage facility, for example to store LNG or be installed in a floating structure, coastal or deep water, including a LNG tank, a floating storage and regasification unit (FSRU) , a floating production and remote storage unit (FPSO) and others. According to one embodiment, a vessel for the transport of a fluid 15 comprises a aforementioned tank. According to one embodiment, the invention also provides a method for loading or unloading such a vessel, in which a fluid is conveyed through isolated pipes from or to a floating or land storage facility to or from the tank of the vessel. ship. According to one embodiment, the invention also provides a transfer system for a cold liquid product, the system comprising the abovementioned vessel, insulated pipes arranged to connect the vessel installed in the hull of the vessel to a storage facility. Float or ground pump and a pump for driving fluid through the insulated pipelines from or to the floating or ground storage facility to or from the vessel vessel. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent in the following description of several particular embodiments of the invention, given only in connection with the invention. illustrative and non-limiting, with reference to the accompanying drawings. - Figure 1 is a schematic view of a tank equipped with an inerting system. FIG. 2 is a curve illustrating the influence of pressure and temperature on the flammability limits of methane in the air. FIG. 3 is a schematic view showing a tank of cut-off LNG carrier that can be equipped with an inerting system and a loading / unloading terminal of this tank. DETAILED DESCRIPTION OF EMBODIMENTS Referring to FIG. 1, a tank 1 is schematically represented for storing a combustible gas. Each wall of the vessel 1 comprises a multilayer structure comprising, from the outside towards the inside of the vessel 1, a carrier structure 2 defining the general shape of the vessel 1, a secondary thermally insulating barrier 3 comprising insulating elements against the carrier structure 2, a secondary sealing membrane 4, a primary thermally insulating barrier 5 comprising insulating elements resting against the secondary sealing membrane 4 and a primary sealing membrane 6 intended to be in contact with the liquefied fuel gas contained in the tank 1. The supporting structure 2 may in particular be a self-supporting metal sheet and / or be formed by the hull or the double hull of a ship. Thermally insulating barriers 3, 5 comprise insulating solids and a gas phase. According to one embodiment, the thermally insulating barriers 3, 5 are formed of heat insulating boxes, not shown. The boxes include a bottom panel and a cover panel, for example plywood, and a plurality of spacers interposed between the bottom and top panels. Compartments for housing a heat-insulating lining are provided between the spacers. The heat insulating lining may be made of any material having appropriate thermal insulation properties. By way of example, the heat-insulating lining is chosen from materials such as perlite, glass wool, polyurethane foam, polyethylene foam, polyvinyl chloride foam, aerogels or others. The primary and secondary waterproofing membranes 4, 6 consist, for example, of a continuous sheet of metal strakes with raised edges, said strakes being welded by their raised edges on parallel welding supports, fixed on the lid of the boxes. . The primary and secondary waterproofing membranes 4, 6 are gas and liquid tight. The supporting structure 2 is also waterproof. Therefore, within the meaning of the present description and the claims, the term "sealed barrier" covers both the waterproofing membranes 4, 6 and the supporting structure 2. Thus, the secondary heat-insulating barrier 3 is arranged in a sealed space which is isolated from the ambient pressure, on the one hand, by a first sealed barrier constituted by the secondary sealing membrane 4, on the other hand, by a second sealed barrier constituted by the supporting structure 2. to avoid that, due to leakage of liquefied natural gas through the sealing membranes 4, 6 and / or air through the carrier structure 2, a gas mixture is present in explosive proportions in the walls of the tank 1, these are subjected to an inerting process which will be detailed below. Note that, in the embodiment described and shown, the inerting method = more specifically aims to ensure the inerting = of the secondary thermally insulating barrier 3. The method and the inerting system which will be detailed below 20 have the particular feature of being able to operate according to two distinct inerting modes. According to a first mode of inerting, the gaseous phase contained in the thermally insulating barrier 3 is kept around a set pressure P1 lower than a flammable limit pressure Pi of the fuel gas. There is indeed a flammable pressure limit Pi below which a combustible gas is no longer flammable. The set pressure P1 is an absolute pressure lower than the ambient atmospheric pressure, that is to say a negative relative pressure. Figure 2 illustrates, by way of example, the flammability limits of methane in air as a function of pressure and temperature. It is thus observed that the flammability limit pressure Pi of methane in air is, at 25 ° C., of the order of 130 mm of mercury, namely 17331 Pa. Also, whatever the proportions of combustible gas and oxygen in the gas phase of the thermally insulating barrier 3, it is not likely to ignite and explode when placed at such a set pressure P1, lower than the limit pressure of Pi flammability of the combustible gas. This first mode of inerting also has the advantage of increasing the insulating capacity of the thermally insulating barrier 3. In order to ensure such an inerting mode, the inerting system comprises a pumping device 7 connected by a pipe 8 to the thermally insulating barrier 3. The pumping device 7 comprises one or more vacuum pumps capable of making it possible to maintain the thermally insulating barrier 3 under a low pressure, of the order of a few hundred or thousands of Pascal. The vacuum pumping device is for example a staged or series set of vane pumps and Roots pumps. The system also comprises a pressure sensor 9 for delivering a signal representative of the pressure of the gas phase inside the thermally insulating barrier 3. The pressure sensor 9 is connected to a pressure regulating device for controlling the pumping device 7 as a function of the set pressure P1. The regulating device is capable of operating the pumping device 7 when the pressure measured by the pressure sensor 9 is greater than the set pressure P1 and stopping the pumping device 7 when the measured pressure is less than the set pressure P1. The control device is advantageously equipped with a hysteresis to improve the stability of the regulation. The control device may optionally be integrated with the pumping device 7 or be integrated with a control unit 10 of the inerting system.
    [0004] Furthermore, the inerting system is also adapted to operate in a second mode in which the inerting of the thermally insulating barrier 3 is ensured, at atmospheric pressure, by an inert gas sweep. This second mode of inerting corresponds to a degraded mode of operation which is particularly adapted when there occurs a loss of tightness of one of the sealed barriers 2, 4 bordering the thermally insulating barrier 3. In fact, in such a case , the thermally insulating barrier 3 is no longer isolated from the ambient pressure and it thus becomes impossible to maintain a negative relative pressure lower than a threshold pressure Ps.
    [0005] In order to implement this second mode of inerting, the inerting system comprises an inert gas injection equipment 11 for sweeping the thermally insulating barrier 3 with an inert gas. The injection equipment 11 comprises a tank of pressurized inert gas 12 connected to an inert gas supply pipe 14 opening inside the thermally insulating barrier 3. The pressurized inert gas tank 12 is connected. to the pipe 14 by a valve 16 for regulating the flow and / or the pressure of the injection of inert gas inside the thermally insulating barrier 3. The size of the inert gas reservoir 12 under pressure must be sufficient so that, in case of leakage of one and / or the other of the sealed barriers 2, 4 bordering the secondary heat-insulating barrier 3, the injection equipment 11 is able to ensure sufficient dilution of the gas fuel and / or oxidizing gas in order not to reach the explosive limit concentrations. The reservoir 12 must in particular be able to store a quantity of inert gas substantially equivalent to the quantity of gaseous phase contained at atmospheric pressure in the thermally insulating barrier 3. The inert gas is chosen from the group consisting of dinitrogen, helium, argon and their mixtures. In one embodiment, the inert gas used is dinitrogen.
    [0006] According to an embodiment of the invention not shown, the inerting system comprises an inert gas generator in addition to or in lieu of the inert gas pressure tank 12. The inert gas generator may in particular be a nitrogen generator allowing extract nitrogen from the surrounding air.
    [0007] Where appropriate, the pipe 14 may also be equipped with an additional pump 13, optional, to ensure the injection of inert gas, especially when the injection equipment is equipped with an inert gas generator. The inerting system also comprises a control unit 10 connected to the pressure sensor 9, to the pumping device 7 and to the inert gas injection equipment 11. The function of the control unit 10 is notably to trigger automatically the second mode of inerting when the first mode of inerting can no longer be implemented under satisfactory safety conditions, due to a loss of tightness of one and / or the other of the watertight barriers 2 , 4 bordering the thermally insulating barrier 3. To do this, the control unit 10 is able to receive and process the signal representative of the pressure of the gaseous phase of the thermally insulating barrier 3 generated by the pressure sensor 9 During the first mode of inerting, the control unit 10 compares the pressure P of the gas phase inside the thermally insulating barrier 3 to a threshold pressure Ps, higher than the set pressure P1. As soon as the pressure P of the gaseous phase exceeds the threshold pressure Ps, the control unit 10 automatically switches from the first inerting mode to the second inerting mode. In other words, the control unit 10 generates a start-up signal of the inert gas injection equipment 11 and a stop signal of the pumping device 7. In addition, according to one embodiment , the control unit 10 is also able to generate an alarm signal, upon detection of a threshold pressure overshoot Ps. The threshold pressure Ps, and consequently the set pressure P1 of the pumping device 7 , must be judiciously chosen according to the nature of the fuel gas contained in the tank 1 to ensure the safety of the return of the gaseous phase to atmospheric pressure under the effect of the injection of inert gas. The threshold pressure Ps must be defined in such a way that, when a leakage occurs, the gaseous phase in the thermally insulating barrier 3 is not likely to comprise combustible gas and / or oxidizing gas. in proportions that would be likely to be included in the explosive zone when the gaseous phase returns to atmospheric pressure under the effect of the injection of inert gas. To do this, it is expected that the threshold pressure Ps is less than the partial pressure of the combustible gas, at atmospheric pressure, at a concentration corresponding to the lower explosive limit of said fuel gas in the air, at 25.degree. ° C. By way of example, the lower flammability limit of methane is 5% by volume at atmospheric pressure (101,325 Pa) and at 25 ° C. The methane partial pressure corresponding to a volume concentration of 5% methane at atmospheric pressure is therefore about 5 066 Pa. In other words, if a quantity of methane corresponding to the lower explosive limit of the methane, the atmospheric pressure, was to constitute alone the entire gas phase contained in the thermally insulating barrier 3, its pressure would be 5,066 Pa. Therefore, as long as during the first mode of inerting, the pressure P of the gas phase in the thermally insulating barrier 3, is less than 5,066 Pa, there is no risk that the concentration of methane once returned to atmospheric pressure of 101,325 Pa reaches the lower explosive limit, considering a complete and instantaneous dilution of the fuel gas in nitrogen. Advantageously, the threshold pressure Ps is chosen by taking a safety margin with respect to the pressure mentioned above, in particular in order to take into account the inhomogeneous mixing phenomena of the gas phase in the thermally insulating barrier 3 and the time required to inject a quantity of inert gas sufficient for the gas phase to rise to atmospheric pressure.
    [0008] Therefore, a threshold pressure Ps is chosen between 20 and 35%, and preferably of the order of 30%, of the partial pressure of the fuel gas, at atmospheric pressure, at the concentration of the fuel gas corresponding to its lower explosive limit. Therefore, in the case of a methane storage tank, a threshold pressure Ps between 1013 and 1773 Pa, and preferably of the order of 1520 Pa will be chosen. By way of example, the table below shows the lower flammability limits of different combustible gases and comprises the threshold pressure values Ps corresponding to 30% of the partial pressure of the combustible gases, at atmospheric pressure, at a concentration corresponding to their lower explosive limit. LIE fuel gas (% by volume) in Ps (Pa) air and at 25 ° C Methane 5 1520 Ethane 3 912 n-Butane 1.5 456 Propane 2.2 669 Ethylene 2.7 821 We note that for some In the case of combustible gases, the threshold pressure Ps may not be defined as a function of the lower flammability limit of the fuel gas but as a function of the minimum concentration of oxidizer 5 allowing the inflammability of the combustible gas. This is particularly the case when the minimum air concentration for flammability of the fuel gas is lower than the concentration of fuel gas corresponding to its lower explosive limit. In other words, in order to further enhance safety, it is necessary to provide a threshold pressure Ps which is also lower than the partial pressure of air, at atmospheric pressure, in a gaseous mixture comprising an air concentration. corresponding to an oxygen concentration equal to the minimum concentration of oxygen permitting the flammability of the fuel gas. We also note that in the embodiment shown, the inerting system also includes a gas analyzer 15 for measuring a concentration of fuel gas in the gas phase. The gas analyzer 15 is here placed at the outlet of the pumping device 7. The gas analyzer 15 can in particular comprise a combustible gas detector selected from the group consisting of catalytic wire detectors, infra-red detectors, including those operating by absorbance and / or transmittance measurement, and electrochemical cell detectors. The gas analyzer 15 can be used during the first mode of inerting to detect combustible gas leaks, in addition to the comparison of the pressure P of the gas phase inside the thermally insulating barrier 3 to a However, in order to allow operation of the gas analyzer, the gaseous phase sample extracted from the thermally insulating barrier 3 must first be diluted with an inert gas prior to its analysis. Furthermore, the gas analyzer 15 can also be used to analyze the gas phase of the thermally insulating barrier 3, at regular intervals, during the second inerting mode. In this case, it is conceivable to provide that the control unit 10 regulates the injection rates of inert gas into the thermally insulating barrier 3 as a function of the concentrations of combustible gases measured. Note that if the inerting process described above is more particularly intended to ensure the inerting of the secondary thermally insulating barrier 3, the invention is not limited to such an embodiment. Indeed, according to other embodiments, the inerting process can also be implemented at the level of the primary thermally insulating barrier 5 or be applied to a tank 1 having only one thermally insulating barrier extending between a sealing membrane intended to be in contact with the liquefied fuel gas and a carrier structure. Also, in general, the inerting process can be applied to any thermally insulating barrier disposed between two impervious barriers and isolated from the ambient pressure by said impermeable barriers. Further, in one embodiment, an inerting process as described above is independently applied both within the secondary heat-insulating barrier 3 and within the primary heat-insulating barrier 5 Accordingly, the inerting system further comprises: a pumping system for maintaining the gas phase pressure contained in the primary thermally insulating barrier around a set pressure P1 '; an equipment for injecting inert gas and for sweeping the primary thermally insulating barrier with an inert gas; and a pressure sensor for delivering a signal representative of the pressure of the gas phase inside the primary heat-insulating barrier 5. As previously, the control unit 10 compares the pressure of the gas phase with the inside the thermally insulating barrier 5 at a threshold pressure Ps ', higher than the set pressure P1' and automatically switches from the first inerting mode to the second inerting mode of the primary thermally insulating barrier 5 when the pressure the gas phase contained in the primary thermally insulating barrier 5 exceeds the threshold pressure Ps'. We note that, according to one embodiment, it is possible to predict that the threshold pressure Ps is variable. Indeed, as the pressure in the primary thermally insulating barrier 3 is kept below the threshold pressure Ps', it can be considered that the primary 6 and secondary 4 waterproofing membranes properly seal. Therefore, a rise in pressure in the secondary thermally insulating barrier 3 can, in these cases, be due to a loss of sealing of the carrier structure 2 and the gas entering the secondary thermally insulating barrier 3 can not be only air. Therefore, as long as the first mode of inerting of the primary thermally insulating barrier 5 is implemented, it is possible to assign to the threshold pressure Ps a first value defined solely as a function of the minimum concentration of oxidizer allowing the flammability combustible gas. However, as soon as the control unit 10 detects a pressure of the gas phase of the primary thermally insulating barrier 5 exceeding the threshold pressure Ps', it is then necessary to assign the threshold pressure Ps a second value which must also be defined depending on the lower limit of flammability of the fuel gas as we have seen above. In the same way, it can also be provided that the threshold pressure Ps' whose overshoot is likely to trigger the second mode of inerting of the primary thermally insulating barrier 5 is variable depending on the inerting mode used in the secondary heat-insulating barrier 3. With reference to FIG. 3, a cut-away view of a LNG tanker 70 shows a sealed and insulated tank 71 of generally prismatic shape mounted in the double hull 72 of the ship. In a manner known per se, loading / unloading lines 73 arranged on the upper deck of the ship can be connected, by means of appropriate connectors, to a marine or port terminal for transferring a cargo of LNG from or to the tank 71. FIG. 3 shows an example of a marine terminal comprising a loading and unloading station 75, an underwater pipe 76 and an onshore installation 77. The loading and unloading station 75 is a fixed offshore installation comprising a movable arm 74 and a tower 78 which supports the movable arm 74. The movable arm 74 carries a bundle of insulated flexible pipes 79 which can be connected to the loading / unloading pipes 73. The movable arm 74 can be adapted to all the jigs of LNG. A connecting pipe (not shown) extends inside the tower 78. The loading and unloading station 75 permits the loading and unloading of the LNG tank 70 from or to the shore facility 77. liquefied gas storage tanks 80 and connecting lines 81 connected by the underwater line 76 to the loading or unloading station 75. The underwater line 76 allows the transfer of the liquefied gas between the loading or unloading station. unloading 75 and the onshore installation 77 over a large distance, for example 5 km, which makes it possible to keep the LNG ship 70 at a great distance from the coast during the loading and unloading operations.
    [0009] In order to generate the pressure necessary for the transfer of the liquefied gas, pumps on board the ship 70 and / or pumps fitted to the shore installation 77 and / or pumps fitted to the loading and unloading station 75 are used. Although the invention has been described in connection with several particular embodiments, it is quite obvious that it is in no way limited thereto and that it comprises all the technical equivalents of the means described as well as their combinations if these enter in the context of the invention. The use of the verb "to include", "to understand" or "to include" and its conjugated forms does not exclude the presence of other elements or steps other than those set out in a claim. The use of the undefined article "a" or "an" for an element or a step does not exclude, unless otherwise stated, the presence of a plurality of such elements or steps. In the claims, any reference sign in parentheses can not be interpreted as a limitation of the claim.
    权利要求:
    Claims (18)
    [0001]
    REVENDICATIONS1. Process for inerting a wall of a sealed and thermally insulating tank (1) intended to contain a liquefied combustible gas, in which the wall has a multilayer structure comprising two impervious barriers (2, 4) and a thermally insulating barrier ( 3) disposed between the two impervious barriers (2, 4), said thermally insulating barrier (3) comprising insulating solids and a gaseous phase, said method providing: - to implement a first inerting mode in which the the gaseous phase of the thermally insulating barrier (3) is placed under a negative relative pressure P1 lower than a threshold pressure Ps, said threshold pressure Ps being lower than a flammable limit pressure P1 of the fuel gas; detecting, during the first mode of inerting, that the pressure of the gaseous phase of the thermally insulating barrier (3) exceeds said threshold pressure Ps; to switch from the first inerting mode to a second inerting mode in response to the detection of a pressure of the gas phase of the thermally insulating barrier (3) exceeding the threshold pressure Ps, the second mode of inerting providing for scanning the thermally insulating barrier (3) with an inert gas.
    [0002]
    2. A method of inerting a wall according to claim 1, wherein the threshold pressure Ps is less than the partial pressure of said fuel gas, at atmospheric pressure, in a gaseous mixture comprising a concentration of the fuel gas corresponding to the lower explosive limit of said combustible gas in air at 25 ° C.
    [0003]
    3. A method of inerting a wall according to claim 2, wherein the threshold pressure Ps is between 20 and 35% of the partial pressure of said fuel gas, at atmospheric pressure, in a gas mixture comprising a concentration of fuel gas corresponding to the lower explosive limit of said fuel gas in air at 25 ° C.
    [0004]
    4. A method of inerting a wall according to claim 2, wherein the threshold pressure Ps is 30% of the partial pressure of said fuel gas, at atmospheric pressure, in a gaseous mixture comprising a concentration of the corresponding fuel gas. at the lower explosive limit of said fuel gas in air at 25 ° C.
    [0005]
    5. A method of inerting a wall according to any one of claims 1 to 4, wherein the threshold pressure Ps is less than the partial pressure of air, at atmospheric pressure, in a gaseous mixture comprising a concentration. of air corresponding to an oxygen concentration equal to a minimum concentration of oxygen permitting the flammability of the fuel gas.
    [0006]
    6. A method of inerting a wall according to any one of claims 1 to 5, wherein in the second mode of inerting, the thermally insulating barrier (3) is swept with an inert gas, at atmospheric pressure.
    [0007]
    Inerting process according to any of claims 1 to 6, wherein the fuel gas is selected from the group consisting of methane, ethane, n-butane, propane, ethylene and the like. of their mixtures.
    [0008]
    8. Inerting process according to any one of claims 1 to 7, wherein the inert gas is selected from the group consisting of dinitrogen, helium, argon and mixtures thereof. 15
    [0009]
    9. A method of inerting a wall according to any one of claims 1 to 8, wherein one of the impervious barriers consists of a carrier structure (2), the other sealed barrier consists of a secondary metal membrane (4), and the thermally insulating barrier is a secondary heat-insulating barrier (3), the multilayer structure further comprising a primary metal membrane (6) intended to be in contact with the combustible gas stored therein of the vessel (1) and a primary heat-insulating barrier (5) disposed between the primary metal membrane (4) and the secondary metal membrane (6), said primary heat-insulating barrier (5) comprising insulating solids and a gas phase the method further comprising: - implementing a first mode of inerting the primary thermally insulating barrier (5) in which the gaseous phase of the thimble is placed; hermetically insulating primary (5) under a negative relative pressure P1 'lower than a threshold pressure Ps', said threshold pressure Ps' being lower than the flammability limit pressure Pi of the fuel gas; detecting, during the first inerting mode of the primary thermally insulating barrier (5), that the pressure of the gas phase in said primary thermally insulating barrier (5) exceeds said threshold pressure Ps'; - to switch from the first mode inerting to a second mode of inerting the primary thermally insulating barrier (5) in response to detecting a pressure of the gas phase of the primary thermally insulating barrier (5) exceeding the threshold pressure Ps', the second mode of inerting provided to sweep the primary thermally insulating barrier (5) with an inert gas.
    [0010]
    Inerting process according to claim 9, in which the threshold pressure Ps is variable and in which the threshold pressure Ps is assigned a first value as long as the first mode of inerting of the thermally insulating barrier (5). primary is used and the threshold pressure Ps is assigned a second value in response to the detection of a pressure of the gaseous phase of the primary thermally insulating barrier (5) exceeding the threshold pressure Ps'.
    [0011]
    11. System for inerting a wall of a tank (1) sealed and thermally insulating for containing a liquefied fuel gas, wherein the wall has a multilayer structure comprising two watertight barriers (2, 4) and a heat barrier insulation (3) disposed between the two watertight barriers (2, 4), said thermally insulating barrier (3) comprising insulating solids and a gaseous phase, the inerting system comprising: - a pumping device (7) arranged to placing the gaseous phase of the thermally insulating barrier (3) under a negative relative pressure P1 less than a threshold pressure Ps, said threshold pressure Ps being less than a flammable limit pressure P1 of the fuel gas; a pressure sensor (9) capable of supplying a signal representative of the pressure of the gas phase inside the thermally insulating barrier (3); an inert gas injection equipment (11) connected, on the one hand, to an inert gas storage tank (12) and / or to an inert gas generator, and, on the other hand, to a pipe supplying inert gas (14) into the thermally insulating barrier (3); and a control unit (10) capable of: detecting that the pressure of the gaseous phase of the thermally insulating barrier (3) exceeds said threshold pressure Ps; and generating a start-up signal for the inert gas injection equipment (11) in response to detecting a pressure of the gaseous phase of the thermally insulating barrier (3) exceeding the threshold pressure Ps.
    [0012]
    12. Inerting system according to claim 11, wherein the inert gas injection equipment (11) is connected to a dinitrogen generator.
    [0013]
    13. Inerting system according to claim 11 or 12, comprising a gas analyzer (15) for measuring a concentration of combustible gas in the gas phase.
    [0014]
    14. A tank (1) sealed and thermally insulating for containing a liquefied fuel gas having a wall having a multilayer structure comprising two watertight barriers (2, 4) and a thermally insulating barrier (3) disposed between the two watertight barriers (2, 4), said thermally insulating barrier (3) having insulating solids and a gaseous phase, and a wall-inerting system according to any one of claims 11 to 13.
    [0015]
    15.. A sealed and thermally insulating vessel (1) according to claim 14, wherein one of the impervious barriers comprises a carrier structure (2) and the other impervious barrier comprises a secondary metal diaphragm (4) , the multilayer structure further comprising a primary metal membrane (6) intended to be in contact with the combustible gas stored inside the tank - (- 1-) and a thermally insulating barrier (5) arranged between the primary metal membrane (4) and the secondary metal membrane (6).
    [0016]
    16. A vessel having a tank (1) for liquefied gas storage according to claim 14 or 15.
    [0017]
    A method of loading or unloading a ship (70) according to claim 16, wherein a fluid is conveyed through isolated ducts (73, 79, 76, 81) from or to a floating or land storage facility ( 77) to or from the vessel vessel (71). 25
    [0018]
    18. Transfer system for a fluid, the system comprising a ship (70) according to claim 16, insulated pipes (73, 79, 76, 81) arranged to connect the tank (71) installed in the hull of the ship at a floating or land storage facility (77) and a pump for driving fluid through the insulated pipelines from or to the floating or land storage facility to or from the vessel vessel.
    类似技术:
    公开号 | 公开日 | 专利标题
    FR3017924A1|2015-08-28|METHOD AND SYSTEM FOR INERTING A WALL OF A STORAGE TANK OF A LIQUEFIED FUEL GAS
    EP3129700B1|2018-12-19|Sealed, heat-insulated vessel housed in a buoyant structure
    EP3074744B1|2019-10-23|Monitoring of a sealed and thermally insulated vat
    EP3472509B1|2020-07-22|Gas dome structure for a sealed, thermally insulated vessel
    EP2758302B1|2015-09-09|Sea platform having external containers
    WO2015132307A1|2015-09-11|Forced diffusion treatment for an insulating part made from expanded synthetic foam
    WO2016128696A1|2016-08-18|Management of fluids in a sealed and thermally insulated tank
    FR3073601B1|2019-11-22|DEVICE FOR INERTING A LIQUEFIED GAS STORAGE TANK FOR A TRANSPORT VESSEL OF THIS GAS
    FR3073602B1|2019-11-22|METHOD FOR DETERMINING AN OPTIMUM VALUE OF AT LEAST ONE PARAMETER FOR IMPLEMENTING A METHOD FOR COLDING A WATERPROOF AND THEMALLY INSULATING TANK
    WO2020128273A1|2020-06-25|Method for detecting a leak in a sealed and thermally insulating tank
    EP3899472A1|2021-10-27|Method for checking the leakproofness of a leakproof and thermally insulating tank for storing a fluid
    WO2015144897A1|2015-10-01|Apparatus for storing and dispensing a material, method for manufacturing said apparatus, and use of such an apparatus
    同族专利:
    公开号 | 公开日
    RU2016131896A3|2018-06-09|
    JP6537518B2|2019-07-03|
    WO2015124536A2|2015-08-27|
    CN106068418B|2018-08-03|
    SG11201606636VA|2016-09-29|
    AU2015220997B2|2017-11-30|
    FR3017924B1|2016-08-26|
    RU2673837C2|2018-11-30|
    CN106068418A|2016-11-02|
    AU2015220997A1|2016-09-08|
    KR20160123323A|2016-10-25|
    JP2017511866A|2017-04-27|
    PH12016501564A1|2016-09-14|
    WO2015124536A3|2015-11-05|
    RU2016131896A|2018-03-26|
    KR102302435B1|2021-09-15|
    PH12016501564B1|2016-09-14|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    FR2509839A1|1981-07-20|1983-01-21|Marathon Oil Co|LEAK DETECTION APPARATUS IN A CRYOGENIC TANK|
    FR2535831A1|1982-11-05|1984-05-11|Gaz Transport|Method to improve the thermal insulation of a tank intended for storing a liquefied gas and corresponding tank|
    FR2893700A1|2005-11-18|2007-05-25|Air Liquide|DEVICE AND METHOD FOR PROTECTING A CRYOGENIC RESERVOIR AND RESERVOIR COMPRISING SUCH A DEVICE|
    US3395548A|1966-11-07|1968-08-06|Mcmullen John J|Vessel for transporting liquefied gas at about ambient pressure|
    US3489311A|1967-05-25|1970-01-13|Aerojet General Co|Tanks for storage of liquefied gas|
    FR2502289B1|1981-03-19|1983-12-16|Applied Thermodynamics Lng Ser|
    JPS60101399A|1983-11-08|1985-06-05|Tokyo Gas Co Ltd|Method of transporting and storing liquefied combustible gas|
    CN87215896U|1987-12-05|1988-06-29|中国科学院三环新材料研究开发公司|Protection solid powder ball mill pot with inert gas and nitrogen gas|
    RU2082910C1|1991-11-13|1997-06-27|Александр Леонидович Гусев|Cryogenic reservoir and method of activation of chemical absorber before placing it in heat-insulated chamber of cryogenic reservoir|
    IT1264692B1|1993-07-08|1996-10-04|Getters Spa|GETTER COMBINATION SUITABLE FOR REVERSIBLE VACUUM INSULATING SHIRTS|
    RU2073814C1|1993-12-17|1997-02-20|Омское научно-производственное объединение "Сибкриотехника"|Method and device for evacuation of cryogenic insulation|
    JP4929654B2|2005-09-02|2012-05-09|トヨタ自動車株式会社|Hydrogen storage device|
    CN101367466B|2008-08-15|2011-11-23|李束为|Apparatus for storing and transporting oil products|
    CN101660889B|2009-09-17|2012-08-29|西安新竹防灾救生设备有限公司|Inert gas exploder|
    CA2812233A1|2010-09-30|2012-04-05|General Electric Company|Fuel storage system|
    FR2972242B1|2011-03-01|2014-10-17|Gaztransp Et Technigaz|FIXING INSULATING PANELS ON A CARRIER WALL ACCORDING TO A REPEATED PATTERN|
    FR2978749B1|2011-08-01|2014-10-24|Gaztransp Et Technigaz|INSULATING BLOCK FOR THE MANUFACTURE OF A TANK WALL|
    FR2978748B1|2011-08-01|2014-10-24|Gaztransp Et Technigaz|SEALED AND THERMALLY INSULATED TANK|FR3032776B1|2015-02-13|2017-09-29|Gaztransport Et Technigaz|MANAGEMENT OF FLUIDS IN A SEALED AND THERMALLY INSULATING TANK|
    FR3073601B1|2017-11-16|2019-11-22|Gaztransport Et Technigaz|DEVICE FOR INERTING A LIQUEFIED GAS STORAGE TANK FOR A TRANSPORT VESSEL OF THIS GAS|
    US11214282B2|2018-06-29|2022-01-04|Hyperloop Transportation Technologies, Inc.|Method and an article of manufacture for determining optimum operating points for power/cost and helium-air ratios in a tubular transportation system|
    US11235787B2|2018-06-29|2022-02-01|Hyperloop Transportation Technologies, Inc.|Tube transportation systems using a gaseous mixture of air and hydrogen|
    US11230300B2|2018-06-29|2022-01-25|Hyperloop Transportation Technologies, Inc.|Method of using air and helium in low-pressure tube transportation systems|
    US11242072B2|2018-06-29|2022-02-08|Hyperloop Transportation Technologies, Inc.|Method of using air and hydrogen in low pressure tube transportation|
    KR102229232B1|2019-09-04|2021-03-19|한라아이엠에스 주식회사|Gas safety system applied to fuel propulsion vessel|
    法律状态:
    2016-02-29| PLFP| Fee payment|Year of fee payment: 3 |
    2017-02-28| PLFP| Fee payment|Year of fee payment: 4 |
    2018-02-26| PLFP| Fee payment|Year of fee payment: 5 |
    2020-02-28| PLFP| Fee payment|Year of fee payment: 7 |
    2021-02-26| PLFP| Fee payment|Year of fee payment: 8 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1451416A|FR3017924B1|2014-02-21|2014-02-21|METHOD AND SYSTEM FOR INERTING A WALL OF A STORAGE TANK OF A LIQUEFIED FUEL GAS|FR1451416A| FR3017924B1|2014-02-21|2014-02-21|METHOD AND SYSTEM FOR INERTING A WALL OF A STORAGE TANK OF A LIQUEFIED FUEL GAS|
    AU2015220997A| AU2015220997B2|2014-02-21|2015-02-16|Method and system for inerting a wall of a liquefied fuel gas-storage tank|
    PCT/EP2015/053234| WO2015124536A2|2014-02-21|2015-02-16|Method and system for inerting a wall of a liquefied fuel gas-storage tank|
    CN201580008536.0A| CN106068418B|2014-02-21|2015-02-16|A kind of method and system for inerting liquefied fuel gas storage tank skin|
    JP2016550806A| JP6537518B2|2014-02-21|2015-02-16|Method and system for deactivating wall of liquefied fuel gas storage tank|
    RU2016131896A| RU2673837C2|2014-02-21|2015-02-16|Method and system for inerting wall of liquefied fuel gas-storage tank|
    SG11201606636VA| SG11201606636VA|2014-02-21|2015-02-16|Method and system for inerting a wall of a liquefied fuel gas-storage tank|
    KR1020167024518A| KR102302435B1|2014-02-21|2015-02-16|Method and system for inerting a wall of a liquefied fuel gas-storage tank|
    PH12016501564A| PH12016501564B1|2014-02-21|2016-08-05|Method and system for inerting a wall of a liquefied fuel gas-storage tank|
    [返回顶部]