Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B21/00—Nitrogen; Compounds thereof
  • C01B21/04—Purification or separation of nitrogen
  • C01B21/0405—Purification or separation processes
  • C01B21/0433—Physical processing only
  • C01B21/0438—Physical processing only by making use of membranes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/22—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion
  • B01D53/229—Integrated processes (Diffusion and at least one other process, e.g. adsorption, absorption)
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B21/00—Nitrogen; Compounds thereof
  • C01B21/04—Purification or separation of nitrogen
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C6/00—Methods and apparatus for filling vessels not under pressure with liquefied or solidified gases
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C7/00—Methods or apparatus for discharging liquefied, solidified, or compressed gases from pressure vessels, not covered by another subclass
  • F17C7/02—Discharging liquefied gases
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2256/00—Main component in the product gas stream after treatment
  • B01D2256/10—Nitrogen
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2210/00—Purification or separation of specific gases
  • C01B2210/0043—Impurity removed
  • C01B2210/0045—Oxygen
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2203/00—Vessel construction, in particular walls or details thereof
  • F17C2203/03—Thermal insulations
  • F17C2203/0375—Thermal insulations by gas
  • F17C2203/0379—Inert
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2221/00—Handled fluid, in particular type of fluid
  • F17C2221/01—Pure fluids
  • F17C2221/014—Nitrogen
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C2227/00—Transfer of fluids, i.e. method or means for transferring the fluid; Heat exchange with the fluid
  • F17C2227/04—Methods for emptying or filling
  • F17C2227/044—Methods for emptying or filling by purging

Definitions

• the invention relates to a device and a method for producing and distributing nitrogen, in particular for a liquefied gas transport vessel.
• a liquefied gas transport vessel such as liquefied natural gas, is generally equipped with a device for producing and distributing nitrogen, which nitrogen can be used by several consumers.
• a transport vessel is equipped with three types of nitrogen consumers.
• a first type (type I) of nitrogen consumer comprises means for supplying nitrogen to seals, for example compressor bearings of the ship.
• Compressors of the ship for example to pump evaporation gas, are equipped with sliding bearings guiding rotating parts. These bearings are housed in enclosures whose labyrinth type seals are supplied with nitrogen to prevent outside air pollutes the enclosure and disrupts the operation of the bearings.
• a second type (type II) of nitrogen consumer comprises means for purging fluid circulation lines, such as a liquefied gas circulation line of the vessel. To clean such a line and prevent liquefied gas remains in it, it is known to purge the line with nitrogen.
• a third type (type III) of nitrogen consumer comprises means for supplying nitrogen to isolation spaces, for example tanks for storing liquefied gas from the ship. Such tanks are indeed equipped with double wall which defines an isolation space which is supplied with nitrogen.
• the nitrogen requirement is different depending on the type of consumer.
• a type I consumer is supplied with nitrogen continuously with a flow rate generally between 25 and 70 Nm3 / h, and a relatively high pressure of the order of 5 barg. Continuous feeding is due to the fact that the seals must be supplied with nitrogen continuously.
• a type II consumer is supplied with nitrogen with a flow rate that can be significant but which is generally punctual, at a relatively high pressure of the order of 5 barg.
• a type III consumer is supplied with nitrogen with a large flow rate generally between 100 and 200 Nm3 / h, and at a relatively low pressure of the order of a few mbar. Feeding takes place on short and infrequent periods, especially during the cold-cooling operations of the tanks that precede their loading with liquefied gas.
• a device for producing and generating nitrogen comprises two nitrogen generators, each having an air inlet and a nitrogen outlet, a nitrogen storage buffer tank, and means for distributing nitrogen. nitrogen to supply nitrogen to consumers.
• the generators are arranged in parallel and are configured to operate in all or nothing mode (also called "start & stop”). There are two of them, a main generator and a relay generator, to ensure redundancy and to ensure the nitrogen filling of the buffer tank during the high nitrogen demand of consumers.
• the generators are oversized, that is to say they are configured to each be able to provide a flow of nitrogen sufficient to supply the largest consumer of nitrogen, in terms of flow, that is to say say the type III consumer.
• the buffer tank is intended to store the nitrogen produced and deliver it to consumers as needed.
• the generators are usually controlled so that the nitrogen pressure in the buffer tank reaches a maximum value. When nitrogen is consumed and the nitrogen pressure in the buffer tank decreases, at least one of the generators is controlled to produce nitrogen and increase the pressure in the buffer tank up to the maximum pressure value.
• the consumption profile of the type I consumer is stable and constant, as seen in the foregoing, and is not in adequacy with the cyclic operation of the buffer tank and the nitrogen generators.
• the present invention provides an improvement to the present technique, which is simple, effective and economical.
• the invention proposes a device for producing and distributing nitrogen, in particular for a liquefied gas transport vessel, comprising:
• Nitrogen distribution means for supplying nitrogen to at least two different consumers
• first nitrogen dispensing means leaving said buffer tank for feeding at least one of said consumers
• second nitrogen dispensing means leaving at least one of said generators, without passing through said buffer tank. for feeding at least one of said other consumers.
• the invention thus proposes that nitrogen produced by one or more generators reaches the second distribution means directly without passing through the reservoir.
• the first distribution means are supplied with nitrogen by the reservoir.
• the generators are not necessarily oversized, on the contrary, and can be less often solicited, which reduces the number of cycles "start &stop" and increases their lifespan.
• nitrogen air enriched in nitrogen. Atmospheric air includes, at sea level, about 78% (by volume) of nitrogen, 21% (by volume) of oxygen and traces of other gases. In the present application, “nitrogen” therefore means air comprising more than 78% by volume of nitrogen, and for example more than 80 or even 90% by volume. This level is preferably at least 97%.
• generators include at least two and for example three generators. At least some of the generators may have elements in common, such as a separator and / or a heater.
• the device according to the invention may comprise one or more of the following features, taken separately from one another or in combination with each other:
• said second nitrogen distribution means are connected directly to said outlets of at least one of said generators; in this application, the term "direct" connection, a connection only through a pipe possibly equipped with a valve,
• said outputs of said generators are connected together by a collector comprising a first output connected to an input of said buffer tank, and a second output connected to said second distribution means,
• said output of at least one of said generators is connected to an input of said buffer tank, and said output of at least one of said other generators is connected to said second distribution means; in this case, there is no fluid communication between the outputs of all the generators,
• said first distribution means are connected to said second distribution means, so that nitrogen stored in said buffer tank can supply said at least one other of said consumer, said output of at least one of said generators is connected to an input of said buffer tank by a valve,
• said valve is configured to be always on and to have a controlled variable flow rate as a function of a pressure P1 inside said buffer tank, and / or a pressure P2 at the outlet of at least one of said generators, and / or a supply pressure P3 of said first and / or second distribution means,
• At least some of said inputs of said generators are connected together and to a single air supply port, and / or at least some of said outputs of said generators are connected together and to a single port of nitrogen output,
• said consumers comprise means for supplying nitrogen to seals, in particular compressors of said vessel, means for supplying isolation spaces, in particular tanks for said vessel, and means for purging, particular supply lines of said vessel,
• said generators are configured to operate in all or nothing mode
• said generators are identical and dimensioned so as to each be able to feed alone one of said consumers whose consumption in terms of flow is intended to be stable and continuous.
• the present invention also relates to a method for producing and distributing nitrogen using a device as described above, comprising the steps of:
• the method according to the invention may comprise one or more of the following features or steps, taken separately from each other or in combination with each other:
• the buffer tank is fed with nitrogen during steps a) and b),
• the buffer tank is supplied with nitrogen through a valve whose flow rate is regulated as a function of a pressure P1 inside said buffer tank, and / or a pressure P2 at the outlet of at least one of said generators, and / or supply pressure P3 of said first and / or second distribution means,
• the invention proposes a device for producing and distributing nitrogen, in particular for a liquefied gas transport vessel, comprising:
• a buffer tank for storing nitrogen
• Nitrogen distribution means for supplying nitrogen to at least two different consumers
• Nitrogen recirculation has several advantages. On the one hand, it does not waste excess nitrogen, which is therefore reused. It also makes it possible to optimize the yield of nitrogen production by increasing the level of nitrogen enrichment of the gas produced. In fact, the air inlets of the generators receive, in addition to the ambient air, air already charged with nitrogen. The recirculation also makes it possible not to stop a generator, and therefore to limit the number of "start & stop" cycles, if the nitrogen flow produced by this generator is not very excessive. In other words, it may be preferable to run a generator to produce nitrogen and meet a need of a consumer, while producing a surplus of nitrogen with the same generator that will be recirculated and therefore recycled, rather than stop this generator and supply the consumer with nitrogen stored in the tank for example.
• the device according to the invention may comprise one or more of the following features, taken separately from one another or in combination with each other: the device is configured to recirculate nitrogen stored in the buffer tank, when the pressure in the latter exceeds a certain threshold,
• said recirculation line comprises at least a first valve configured to have a controlled variable flow rate as a function of a pressure P1 inside said buffer tank,
• said recirculation line comprises at least one non-return valve
• said recirculation line comprises at least one flow meter
• the device comprises a control system configured to receive information from said flowmeter and a pressure sensor of said buffer tank, and to consequently control said first valve as well as said generators,
• said output of at least one of said generators is connected to an input of said buffer tank by a valve
• said second valve is configured to be always on and to have a controlled variable flow rate as a function of a pressure P1 inside said buffer tank, and / or a pressure P2 at the output of at least one of said generators, and / or a supply pressure P3 of said dispensing means,
• control system is further configured to control said second valve
• said consumers comprise means for supplying nitrogen to seals, in particular compressors of said vessel, means for supplying isolation spaces, in particular vessels of said vessel, and means for purging, in particular supply lines of said vessel,
• the present invention also relates to a method for producing and distributing nitrogen using a device as described above, comprising the steps of:
• the method according to the invention may comprise one or more of the following features or steps, taken separately from each other or in combination with each other:
• said distribution means are supplied with nitrogen during steps a) and b), the rate of recirculation of nitrogen through said recirculation line is monitored and at least one of said generators is stopped when the value of this flow exceeds one predetermined threshold.
• the invention proposes a device for producing and distributing nitrogen, in particular for a liquefied gas transport vessel, comprising:
• nitrogen generators each comprising an air inlet and a nitrogen outlet, at least one of these generators comprising a compressor comprising an air compression rotor,
• a buffer tank for storing nitrogen
• Nitrogen distribution means for supplying nitrogen to at least two different consumers
• the nitrogen production of a generator is in particular a function of the frequency or the speed of the compressor rotor of this generator, and is therefore adjustable according to the needs of consumers.
• the rotor frequency of a generator can be reduced for example if the nitrogen requirement is not important, rather than resorting to the complete shutdown of the generator.
• the device according to the invention may comprise one or more of the following features, taken separately from one another or in combination with each other:
• said system is configured to be controlled according to a pressure P1 inside said buffer tank,
• At least some of said generators comprise, from upstream to downstream, from the inlet to the nitrogen outlet, said compressor, an air separator of fluid (s), such as water and / or oil, an air heater, and a filtration membrane configured to separate nitrogen from the rest of the air; in practice, membrane separation technologies work by retaining nitrogen and permeating the rest of the air components,
• said output of at least one of said generators is connected to an input of said buffer tank
• At least some of said inputs of said generators are connected together and to a single air supply port, and / or at least some of said outputs of said generators are connected together and to a single port of nitrogen output,
• the device comprises first nitrogen distribution means leaving said buffer tank for feeding at least one of said consumers, and second nitrogen distribution means leaving at least one of said generators, without passing through said buffer tank for supplying at least one other of said consumers,
• said variation system is configured to vary the frequency or the speed of said rotor of said at least one generator for supplying said second distribution means
• said consumers comprise means for supplying nitrogen to seals, in particular compressors of said vessel, means for supplying isolation spaces, in particular tanks for said vessel, and means for purging, particular supply lines of said vessel,
• said generators are configured to operate in all or nothing mode, and said generators are identical and dimensioned so as to each be able to feed alone one of said consumers whose consumption in terms of flow is intended to be stable and continuous.
• the present invention also relates to a method for producing and distributing nitrogen using a device as described above, comprising the steps of:
• the method according to the invention may comprise one or more of the following features or steps, taken separately from each other or in combination with each other:
• said buffer tank and said distribution means are simultaneously fed with nitrogen during steps a) and b),
• the invention proposes a device for producing and distributing nitrogen, in particular for a liquefied gas transport vessel, comprising:
• nitrogen generators each comprising an air inlet and a nitrogen outlet, at least one of these generators comprising a compressor comprising an air compression rotor, and
• the inventors have found that at a given nitrogen pressure delivered, the purity of dinitrogen increases when the flow rate decreases. So, for purity specified at 97% nominal rate of nitrogen, a reduction in the flow rate leads to over-quality nitrogen with upstream air turbocharging.
• the variation of the frequency or the speed of the rotor of the compressor of the nitrogen generator makes it possible to guarantee a sufficient production of nitrogen at a sufficient purity, while optimizing the air consumption of the generators.
• the buffer tank is used here as an additional source of nitrogen, the generators being connected directly to the consumers and thus configured to supply the consumers directly.
• main means of nitrogen distribution, means that are intended to convey the majority or all of the nitrogen flow rate produced by the generator (s) operating.
• secondary means of nitrogen distribution are intended to convey a minority portion of the nitrogen flow produced.
• the device according to the invention may comprise one or more of the following features, taken separately from one another or in combination with each other:
• said at least one compressor generator comprises, from upstream to downstream, from the inlet to the nitrogen outlet, said compressor, an air separator of fluid (s), such as water and / or oil, a heater, and a filtration membrane configured to separate nitrogen from the rest of the air; in practice, membrane separation technologies work by retaining nitrogen and permeating the rest of the air components,
• At least some of said inputs of said generators are connected together and to a single air supply port, and / or at least some of said outputs of said generators are connected together and to a single port of nitrogen output,
• said single nitrogen outlet port is connected, preferably by a valve, to an inlet of said buffer tank and to said main nitrogen distribution means,
• the device comprises secondary means for distributing nitrogen leaving said buffer tank for supplying at least some of said consumers, the main distribution means are connected to the secondary means of distribution by a valve,
• said consumers comprise means for supplying nitrogen to seals, in particular compressors of said vessel, means for supplying isolation spaces, in particular tanks for said vessel, and means for purging, particular supply lines of said vessel,
• said principal nitrogen distribution means feed directly at least said gasket nitrogen supply means, and said insulation space supply means,
• said main means for distributing nitrogen comprise at least one pressure and / or flow sensor, this sensor being connected to a control system of said frequency or speed variation system,
• said generators are identical and oversized so as to each be capable of supplying at least one of said consumers whose consumption in terms of flow is intended to be stable and continuous, when this generator is regulated at a load less than 100% at the hub said variation system.
• the present invention also relates to a process for the production and distribution of nitrogen using a device according to one of the preceding claims, comprising the steps of:
• the method according to the invention may comprise one or more of the following features or steps, taken separately from each other or in combination with each other:
• the frequency or the speed of the rotor of said at least one compressor generator is controlled so that the pressure or the flow rate is greater than or equal to a threshold value in said main means of nitrogen distribution, the threshold value of pressure in said main means of nitrogen distribution is 5 barg, and
• said buffer tank is fed with nitrogen if and only if the pressure measured in said main distribution means is greater than said pressure threshold value, and if the pressure measured in said buffer tank is lower than a lower limit value.
• Only one of the generators can be used to produce nitrogen, when the nitrogen flow demanded by said consumers is lower than the maximum nitrogen flow that can produce this generator alone.
• At least two of the generators or all the generators can be used to produce nitrogen, when the nitrogen flow required by said consumers is greater than the maximum nitrogen flow that can produce each of these generators, but that nitrogen flow The demand is lower than the maximum cumulated nitrogen rates that these generators can produce when operating simultaneously.
• At least two or all generators can be used to produce nitrogen, when the nitrogen flow demanded by said consumers is greater than the maximum cumulated nitrogen rates that can produce these generators when they operate simultaneously.
• the buffer tank can be used to provide a complementary nitrogen flow and sufficient to meet the demand of consumers, especially during a cooling of the tank to which these consumers are connected.
• a maximum flow of nitrogen is required by said consumers, and in particular by only one of said consumers, for the cold setting of a liquefied gas storage tank.
• the nitrogen flow rate may be requested by the consumer (s) for cooling the vessel without it having previously undergone inerting, the vessel being able to be brought to a temperature above -40 ° C. thanks to its nitrogen supply.
• the nitrogen flow rate may be requested by the consumer (s) for cooling the tank after it has undergone inerting, the tank may be brought to a temperature above -10 ° C or even 0 ° C thanks to its nitrogen supply.
• FIG. 1 is a schematic view of a device for producing and distributing nitrogen
• FIG. 2 is a schematic view of an embodiment of a device for producing and distributing nitrogen according to the invention
• FIGS. 3 to 5 are schematic views corresponding to FIG. 1 and illustrating steps of a method according to the invention
• FIG. 6 is a schematic view of an alternative embodiment of a device for producing and distributing nitrogen according to the invention.
• FIG. 7 is a schematic view of another alternative embodiment of a device for producing and distributing nitrogen according to the invention.
• FIG. 8 is a schematic view of another alternative embodiment of a device for producing and distributing nitrogen according to the invention.
• FIGS. 9 to 14 are diagrammatic views corresponding to FIG. 8 and illustrating steps of a method according to the invention.
• FIG. 15 is a diagram very schematically showing the nitrogen production of the generators of a device of the prior art, with respect to the nitrogen demand of a large consumer of nitrogen
• FIG. 16 is a diagram very schematically showing the nitrogen production of the generators of another device, with respect to the nitrogen demand of a large consumer of nitrogen, the generators being each here at a fixed rate
• FIG. 17 is a diagram very schematically showing the nitrogen production of the generators of the device of the invention, with respect to the nitrogen demand of a large consumer of nitrogen, the generators being each here variable flow, and
• FIG. 18 is a summary and comparative diagram of the devices of FIGS. 15 to 17.
• upstream and downstream refer to the flow of a fluid, such as a gas or a liquid, in a pipe or circuit.
• Figure 1 shows a device 10 for producing and distributing nitrogen, in particular for a liquefied gas transport vessel.
• the device 10 essentially comprises nitrogen generators 12 each having an air inlet 12a and a nitrogen outlet 12b, a nitrogen storage tank 14, and nitrogen distribution means 166. intended to supply nitrogen to consumers 18, 20 and 22.
• the generators 12 are two in number and are connected in parallel, their inputs 12a being connected together and connected to a single port 24 for supplying air to the generators. Their outputs 12b are connected together by a collector, and connected to an inlet 14a of the buffer tank 14.
• Each generator 12 comprises, from upstream to downstream, that is to say from the inlet 12a to the outlet 12b, an air compressor 26, a separator 28 of fluid air (s), such as water and / or oil, an air heater, and a filtration membrane 32 configured to separate nitrogen from the rest of the air.
• the compressor 26 of each generator is for example of the compression rotor type.
• the rotor is for example piston, screw or blade.
• the buffer tank 14 is equipped with a pressure relief valve 34, configured to allow the release of nitrogen contained in the tank 14 to the outside, when the pressure inside the tank 14 exceeds a predetermined threshold value, for example 1 1 barg.
• the buffer tank 14 is further equipped with a pressure sensor 36 configured to measure the nitrogen pressure, denoted P1, inside the tank 14.
• the buffer tank 14 also comprises a nitrogen outlet 14b connected by the distribution means 1 6 to the consumers 18, 20 and 22.
• the distribution means 1 6 here comprise expansion valves 38, 38 ', an inlet of which is connected to the output 14b, and an output of which is connected to a consumer 18, 20, 22.
• Each expansion valve is configured to be supplied upstream with nitrogen at any pressure (via the tank 14) and to deliver downstream a constant pressure to the corresponding consumer.
• the valves 38 connected to the consumers 20, 22 are configured to deliver nitrogen at a consumption pressure noted Pc1, which is for example 5 barg.
• the valve 38 'connected to the consumer 18 is configured to deliver nitrogen at a consumption pressure noted Pc2, which is for example 0.5 barg.
• the consumer 18 is type III and comprises, for example, nitrogen supply means for insulating spaces, for example tanks for storing liquefied gas from the ship.
• the consumer 20 is type II and comprises, for example, means for purging the vessel's fluid circulation lines.
• the consumer 22 is of type I and comprises means for supplying nitrogen to compressor ship seals. Types I, II and III have been presented in the foregoing.
• the device 10 further comprises a system 40 for controlling the generators 14, and in particular the generators compressors 26, in particular as a function of signals emitted by the pressure sensor 36.
• One of the generators 12 is considered a main generator and the other of the generators is considered a relay generator.
• Each generator is configured to operate in all or nothing mode, and is controlled by the system 40.
• the main generator is configured to produce nitrogen when the pressure in the tank 14, measured by the sensor 36, is between 6 and 9 barg.
• the relay generator is configured to produce nitrogen when the pressure in the tank 14, measured by the sensor 36, is between 5 and 8 barg.
• the system 40 controls the generators 14 according to the nitrogen requirements of the consumers so that the pressure P1 in the buffer tank is at a maximum value of about 10 barg.
• the system 40 actuates the main generator to produce nitrogen and fill the buffer tank 14.
• the system 40 actuates the main generators and relay to produce nitrogen and fill the buffer tank 14.
• This mode of operation ensures a maximum amount of nitrogen available in the reservoir buffer 14 but causes accelerated wear of the generators and thus a reduction in their life.
• These generators are also expensive because they are oversized (and identical) so that they can each be sufficient to supply the largest consumer of nitrogen, in terms of flow, namely the consumer 18 type III. For example, they each have a nitrogen production capacity of 150 Nm 3 / h at 10 barg.
• FIGS 2 to 5 illustrate a first embodiment of a device 1 10 according to the invention which essentially comprises the same elements as those of the device 10.
• the foregoing description in relation to the device 10 therefore applies in the device 1 10 to the extent that it does not contradict the following.
• the device 1 10 here comprises three generators 1 12 but could understand more.
• the generators 1 12 are connected in parallel, their inputs 1 12a being connected together and connected to a single port 124 and their outputs 1 12b being connected together and connected to an input 1 14a of the buffer tank 1 14.
• the generators 1 12 are here not oversized. They are identical and configured so that they are able to feed only the consumer type I 22, which has a stable consumption. In practice, each generator is preferably sized to produce a nitrogen flow rate slightly higher than the constant rate of nitrogen consumption of a type I consumer. They each have, for example, a nitrogen production capacity of 50 Nm 3. / h to 6 barg.
• Each generator 1 12 comprises, from upstream to downstream, that is to say from the inlet 1 12a to the outlet 1 12b, an air compressor 126, a separator 128 of fluid air (s) ), such as water and / or oil, an air heater 130, and a filtration membrane 132 configured to separate the nitrogen from the rest of the air.
• fluid air s
• the device 1 10 may comprise a separator 128 common to the three generators 1 12 , or only two of them.
• the device 1 10 may comprise a heater 130 common to the three generators 1 12, or only two of them.
• the outputs 1 12b of the generators 1 12 are connected by a valve 142 to the inlet 14a of the buffer tank 1 14.
• a pressure sensor 144 is provided upstream of the valve 142 and is used to measure the nitrogen pressure, noted P2 at the output of the generators 1 12.
• the buffer tank 1 14 is further equipped with two pressure sensors 136 and 146 configured to measure the pressure P1 inside the tank.
• the sensors 136, 146 can be replaced by one and the same sensor.
• the signals emitted by the sensors 144 and 136 are intended to be received by the system 140 which controls a means 148 for controlling the valve 142.
• the signals emitted by the sensor 146 are intended to be received by the system 140 which controls a means 150 controlling a valve 152 for recirculating nitrogen.
• the device 1 comprises a nitrogen recirculation line 154, an upstream end of which is connected to the nitrogen outlet 14b of the tank 1 14, and an opposite downstream end of which is connected to the inlets 1 12a of the generators 1 12. .
• the line 154 is equipped with the valve 152 as well as a non-return valve 156. It can also be equipped with a flowmeter 158 whose signals are intended to be transmitted to the system 140.
• the flow meter 158 makes it possible to know the amount of nitrogen produced in excess. In the case where the flow rate of nitrogen produced in excess and flowing in the line 154, is too large, the system 140 can control the shutdown of one of the generators January 12 when two generators are in operation.
• the means 150 is configured to actuate the valve 152 when the pressure in the tank 1 14, measured by the sensor 146, exceeds a certain threshold, for example of the order of 10 barg.
• Line 154 makes it possible, in the event of overproduction of nitrogen, to reuse the nitrogen produced in excess in order to avoid stopping the generators and thus to limit the number of "start & stop" cycles.
• the buffer tank 1 14 is equipped with a relief valve 134 and its outlet 1 14b is connected by first distribution means 1 1 6a to type II and III consumers, namely consumers 1 18 and 120.
• the distribution means 1 1 6a here comprise expansion valves 138, 138 'whose input is connected to the output 1 14b, and an output of which is connected to a consumer 1 18, 120.
• the device 1 10 further comprises second means 1 1 6b of direct distribution of nitrogen to the consumer type I, namely the consumer 122.
• These distribution means 1 1 6b here comprise an expansion valve 138 whose input is connected to the outputs 1 12b of the generators 1 12, and whose output is connected to the consumer 122.
• the outputs 1 12b of the generators 1 12 are thus connected together to form a first branch of a Y connector, a second branch of which is connected by the valve 142 to the inlet 1 14a of the reservoir, and a third branch of which is connected to the valve 138 and the consumer 122.
• the direct supply to the consumer 122 which requires a constant nitrogen flow over a relatively long period, avoids the many "start &stop" cycles of operation of the generators and therefore to limit their wear.
• the tank 1 14 can adopt a nitrogen storage function and have a storage pressure that varies between a minimum value and a maximum value, and not only a buffer function for which an operating pressure must be kept constant .
• the consumer supplied directly by the generators 1 12 could be the consumer 120 type II.
• Figures 3 to 5 illustrate steps of operation of the device
• the step shown in Figure 3 represents the direct supply of nitrogen to the consumer 122 and the recirculation of nitrogen if necessary.
• One of the generators 1 12 is actuated by the system 140 and produces nitrogen with a flow rate and a pressure sufficient to cover the needs of the type I consumer 122.
• the nitrogen pressure is equal to 5 barg downstream of the valve 138. means 1 1 6b and is greater than 5barg upstream of this valve.
• the excess nitrogen produced by the generator is sent to the buffer tank 1 14, through the valve 142 which remains open continuously.
• the valve 152 is opened and nitrogen is removed from the tank to reduce the pressure and return it to the inputs 1 12a of the generators.
• This nitrogen will therefore be reprocessed by the generators to increase the yield of nitrogen production of the device, that is to say the enrichment in nitrogen of the gas output of the generators.
• the step shown in FIG. 4 also represents the direct supply of nitrogen to the consumer 122 as well as the recirculation of nitrogen if necessary.
• Two of the generators 112 are operated by the system 140 and produce nitrogen with a flow rate and pressure sufficient to meet the needs of the Type I consumer 122, or even other consumers.
• the nitrogen pressure is equal to 5 barg downstream of the valve 138 of the means 1 1 6a and is greater than 5barg upstream of this valve.
• the excess nitrogen produced by the generator is sent to the buffer tank 1 14, through the valve 142 which is open.
• the valve 152 is opened and nitrogen is removed from the tank to reduce the pressure and the refer to inputs 1 12a of the generators.
• the nitrogen pressure in the reservoir 1 14 increases. Beyond the pressure threshold, the means 150 controls the opening of the valve 152 and thus the recirculation of a portion of the nitrogen contained in the reservoir so as to maintain its internal pressure at 10 barg. In the case where the recirculating nitrogen flow rate is below a threshold value, the generators are kept in operation. In the case where this flow rate is greater than this threshold value, one of the generators could be stopped by the system 140.
• the nitrogen pressure in the reservoir 1 14 decreases.
• the system can then control the activation of the third generator 1 12 to prevent the pressure in the tank reaches a minimum value, for example 1 barg.
• the device is however configured so that the pressure in the tank can go down as low, which was not the case in the prior art.
• the system 140 can control the activation of the heater of this generator. This allows the generator to be preheated for imminent operation.
• the step represented in FIG. 5 represents the nitrogen supply of the consumers 1 18 and 122.
• the consumer 1 18 requires a relatively large flow of nitrogen. This is particularly the case when cold and charging a tank of liquefied gas, the isolation space of the tank to be supplied with nitrogen with a high flow and low pressure.
• Two of the generators January 12 are actuated by the system 140 and produce nitrogen, part of which directly feeds the consumer 122 and the other portion supplies the buffer tank 1 14.
• the pressure in nitrogen is equal to 5 barg downstream of the valve 138 and is greater than or equal to 5 barg upstream of this valve.
• the nitrogen pressure is equal to 0.5 barg downstream of the valve 138 'and is greater than 0.5 barg upstream of this valve.
• the valve 142 is controlled so as to ensure that the pressure upstream of the valve 138 of the distribution means 1 1 6b, is always greater than 5barg.
• the valve 138 may be substantially closed so that all or almost all of the nitrogen produced by the generators feed the consumer 122.
• the valve 142 is preferably maintained bypass. This allows the buffer tank 1 14 to be supplied with nitrogen at any time and to rebalance the pressures upstream and downstream of the valve 142, that is to say in the nitrogen outlet manifold of the generators 1 12 and in the tank 1 14. If the nitrogen flow rate consumed is large and greater than the nitrogen flow rate produced by the generators 1 12, the pressure in the tank will decrease. If the nitrogen consumption stops or if the flow rate consumed is lower than the feed rate, then the pressure in the tank will increase until reaching a maximum value.
• the valve 142 is configured to be fully open when the pressure inside the tank is greater than 5 barg, and to be partially open when the pressure inside the tank is less than 5 barg, so that the pressure upstream of the valve is greater than or equal to 5 barg.
• valve 142 could be replaced by a two-state valve, all or nothing.
• An additional line connecting the generator outputs to the buffer tank inlet would then be necessary in parallel with the valve, so as to ensure fluid communication between the generator outputs and the buffer tank inlet even when the valve is closed. .
• FIG. 6 illustrates a second embodiment of a device 210 according to the invention which essentially comprises the same elements as those of the device 1 10.
• the foregoing description in relation with the device 1 10 therefore applies to device 210 to the extent that it does not contradict the following.
• FIG. 6 differs from that of FIGS. 2 to 5 in particular in that the first distribution means 21 6a are connected to the second distribution means 21 6b by a bypass line 260 equipped with a valve 262 and / or a check valve.
• the branch line 260 is configured to allow the passage of nitrogen from the distribution means 21 6a, and therefore from the buffer tank 1 14, to the consumer 122.
• the line 260 may have an upstream end connected to the distribution means 21 6a, just upstream of the valves 138, 138 ', and a downstream end connected to the distribution means 21 6b, just upstream of the valve 138.
• the outputs 212b of two of the generators 212 are here connected to the inlet 214a of the buffer tank 214 by a pipe without a valve to simplify the device 210.
• the device 210 also has no recirculation line even if it could understand it. a.
• the device 210 comprises at least one system 264 for varying the frequency or speed of the rotor of a compressor 226 of at least one of the generators 212 '.
• the system 264 may be controlled by the system 240. Alternatively, it may be manually controlled, the frequency or speed of the rotor being adjusted manually.
• the system 264 is associated with only one of the compressors whose output 212b 'is directly connected to the distribution means 21 6b and is not connected to the outputs 212b of the other generators.
• the outputs 212b of the other two generators are connected to the inlet 214a of the tank, as mentioned in the foregoing.
• FIG. 7 illustrates a third embodiment of a device 310 according to the invention which essentially comprises the same elements as those of the device 210.
• the foregoing description in relation to the device 210 therefore applies to the device 310 to the extent that it does not contradict the following.
• FIG. 7 differs from that of FIG. 6 in particular in that the device 310 comprises only first distribution means 31 6a, and therefore does not comprise second means for direct distribution of nitrogen from the outlets 312a.
• the distribution means 31 6a are therefore connected to the outlet 314b of the buffer tank 314 and to the set of consumers 318, 320 and 322 by the expansion valves 338, 338 '.
• the outputs 312b of the generators are all connected together and at the input 314a of the buffer tank.
• the device 310 comprises a means 366 for controlling the system 364 as a function, in particular, of the pressure in the buffer tank 314, measured by the pressure sensor 346.
• the generator associated with the system 364 may be undersized with respect to the other generators.
• This generator is for example similar to those 12, 212, 212 described above, while the other generators may be of the type used in the prior art (which are generally oversized).
• the invention proposes solutions to respond to the technical problem of accelerated wear of nitrogen generators due to their mode of operation in all or nothing or "start & stop”.
• FIGS. 8 to 14 illustrate another alternative embodiment of a device 410 according to the invention which essentially comprises the same elements as those of the device 10.
• the foregoing description in relation to the device 10 therefore applies to device 1 10 to the extent that it does not contradict the following.
• the device 410 here comprises two generators 412 but could understand more.
• the generators 412 are connected in parallel, their inputs 412a being connected together and connected to a single port 424 and their outputs 412b being connected together.
• Each generator 412 comprises, upstream to downstream, that is to say from the inlet 412a to the outlet 412b, an air compressor 426, a fluid separator 428 (s), such as water and / or oil, an air heater 430, and a filtration membrane 432 configured to separate the nitrogen from the rest of the air.
• a fluid separator 428 such as water and / or oil
• an air heater 430 and a filtration membrane 432 configured to separate the nitrogen from the rest of the air.
• membrane separation technologies work by retaining nitrogen and permeating the rest of the air components.
• Certain elements of the generators 412 can be communalised, as mentioned in the foregoing.
• the outputs 412b of the generators 412 are connected by a valve 442 to the inlet 414a of a buffer tank 414.
• the outlets 421b are also connected to main means 41 6b of nitrogen distribution to the consumers 418 and 422.
• the tank 414 can adopt a nitrogen storage function and have a storage pressure that varies between a minimum value and a maximum value, and not only a buffer function for which an operating pressure must be kept constant.
• An outlet 414b of the buffer tank 414 is further connected by secondary means 41 6a of nitrogen distribution to at least one of the consumers, here the consumer 418 type III.
• the buffer tank 414 may comprise another outlet 414c connected to the type II consumer 420.
• the main distribution means 41 6b are equipped with pressure sensors 444a, 444b and flow 445.
• a pressure sensor 444a and a flow sensor 445 are located just at the output of the generators 412, and the other pressure sensor 444b plus downstream.
• the sensors 444a, 444b are configured to measure pressures P1 and P2 of the nitrogen in the means 41 6b.
• the buffer tank 414 is further equipped with a pressure sensor 446a configured to measure a pressure P4 inside the tank.
• the secondary distribution means 416a are equipped with a pressure sensor 446b which is configured to measure a pressure P3.
• the distribution means 41 6a, 416b comprise, upstream of each consumer 418, 420, 422, an expansion valve 438, 438 ', 438 ".
• the main distribution means 41 6b comprise two respective supply lines of the consumers 418, 420, 422.
• the first line 41 6b1 extends from the outputs 412b of the generators 412 to the consumer 422 and is equipped with sensors 444a, 444b, and 445, and the valve 438.
• the second line 416b2 extends between the first line 41 6b1 and the consumer 418 and is equipped with the valve 438 'and another valve 462 disposed upstream of the valve 438 '.
• the second line 41 6b2 is connected to the first line 41 6b1, downstream of the sensors 444a, 444b, 445 and upstream of the valve 438.
• a third line 41 6b3 extends between the first line 416b1 and the consumer 420 and is equipped with the valve 438 "The line 41 6b3 is only connected to the output 414c of the buffer tank 414.
• the secondary distribution means 416a are connected to the second line 41 6b2 and downstream of the valve 462 and upstream of the valve 438 'These distribution means 41 6a are equipped with a valve 443.
• the signals emitted by the sensors 446a, 444b are intended to be received by control means 448a, 448b, which in turn control the valves 442 and 462.
• control means 448a, 448b which in turn control the valves 442 and 462.
• the signals emitted by the sensor 446b are intended to be received by a control means 448c which controls the valve 443 in function.
• the signals emitted by the sensors 444a, 445 are intended to be received by a control system 440 of a system 464 for varying the frequency or speed of the rotor of the compressor 426 of each generator 412.
• each compressor rotor is controlled as a function of the pressure and / or the flow rate of nitrogen flowing in the main distribution means 416b.
• each generator (all or nothing) has a capacity slightly greater than the regular consumer 422
• the generators 412 of the device 410 have higher capacities here, so that the variation system 464 can operate a low load generator ("low" regime) and responds to the demand of the regular consumer 422. And it is when the demand increases, for example by an additional need of the consumer 418, that the system 464 makes it possible to increase the production of the generator.
• the “low” regime corresponds for example to an operating point of 50Nm3 / h to 6 barg, which corresponds to approximately 30 to 50% of the rated capacity of the generator.
• This "low” diet responds to steady regular consumption, that is to say the consumer's need 422.
• FIG. 9 to 14 illustrate steps of operation of the device
• the step represented in FIG. 9 represents the direct supply of nitrogen to the consumer 422 or possibly to the consumer 418.
• One of the generators 412 is operated by the system 440 and produces nitrogen with sufficient flow and pressure to meet the need of the Type I consumer 422.
• the nitrogen pressure is equal to 5 barg downstream of the valve 438. means 41 6b and is greater than 5barg upstream of this valve.
• there is more nitrogen production surplus since it comes to drive the generator to produce what is requested.
• the consumer 418 can potentially consume a low or no flow, which then passes through the valves 462, 438 'which are open.
• the generator 412 compressor that operates can be at a load of 30 to 50% of its rated capacity. This charge is regulated by the system 440 as a function of the consumed flow rate measured by the sensor 444a.
• the sensor 445 makes it possible to ascertain the operating speed and that the valve 438 is well supplied with a pressure at least equal to 5 barg. Valves 442 and 443 are closed.
• the valve 462 is fully open for the small nitrogen demands of the consumer 418.
• FIG. 9 thus represents the state of the device in stable normal consumption.
• the step of FIG. 10 represents an increase in the nitrogen demand of the consumers 422 and 418.
• the pressure or the rate of production of nitrogen is greater than the previous stage.
• 440 system increases compressor load to meet the demand.
• Valves 442 and 443 are closed.
• the valve 462 is fully open for the small nitrogen demands of the consumer 418.
• the valve 438 ' is thus open.
• a single generator 412 operates in step 10 against two in the next step illustrated in Figure 1 1, which shows a state of the device corresponding to a large consumption.
• the two generators 412 are operated by the system 440 and produce nitrogen with a flow rate and pressure sufficient to meet the needs of the consumers 422 and 418.
• the consumer 418 here requires a relatively large flow of nitrogen. This is particularly the case when cold and charging a tank of liquefied gas, the isolation space of the tank to be supplied with nitrogen with a high flow and low pressure.
• Peak consumption corresponds to the case where the requested flow rate is greater than the total capacity of the two compressors (2x100%). When this consumption exceeds the capacity, the delivered pressure will fall.
• buffer tank 414 is used to supplement nitrogen production and maintain the required pressure demanded by consumers ( Figure 12).
• the nitrogen pressure in the tank 414 then decreases.
• the valve 443 opens and distributes the stored nitrogen to maintain sufficient pressure upstream of the valve 438 '.
• the valve 462 is closed progressively in order to maintain a sufficient pressure upstream of the valve 438.
• the valve 442 remains closed. We consider that the peak consumption is passed when the pressure P2 measured by the sensor 444b goes back to a sufficient value.
• the step represented in FIG. 14 represents the supply of nitrogen to the consumers and to the buffer tank 414.
• Two of the generators 412 are actuated by the system 440 and produce nitrogen, a portion of which supplies the consumer 422 and Another part supplies the buffer tank 414.
• the nitrogen pressure is equal to 5 barg downstream of the valve 438 and is greater than or equal to 5 barg upstream of this valve.
• the nitrogen pressure is equal to 0.5 barg downstream of the valve 438 'and is greater than 0.5 barg upstream of this valve.
• the nitrogen pressure in the tank 414 increases. Beyond the pressure threshold, the means 448c controls the opening of the valve 443.
• the tank 414 Under normal consumption, out of peak, the tank 414 must remain full, preferably at the highest pressure that can be produced by the generators 412, for example between 10 and 12 barg. If, and only if, the pressure P2 measured by the sensor 444b is greater than 5 barg and the pressure P4 measured by the sensor 446a is less than 8 barg (for example), then the valve 442 begins to open to allow supply the reservoir with nitrogen and thus increase its pressure. Both compressors can be used 100% to reach this maximum filling pressure of 10 to 12 barg.
• the valve 442 is in any case controlled so as to ensure that the pressure upstream of the valve 438 of the distribution means 416b is always greater than 5barg.
• the valve 438 may be substantially closed so that all or almost all of the nitrogen produced by the generators feed the consumer 122.
• FIG. 15 illustrates the prior art to the present invention and the fact that the generators are identical and oversized so as to be able to provide a nitrogen flow rate sufficient to feed the largest consumer of nitrogen, in terms of flow, that is, the type III consumer.
• N1 and N2 are respectively low and high levels of consumer nitrogen demand.
• Levels L1 and L2 are respectively the nitrogen production capacities of the two generators G1 and G2.
• the capacity L1 of the first generator makes it possible to cover the level N1 but not the level N2. To cover the level N2, it is necessary to operate simultaneously the two generators which then produce a nitrogen flow rate greater than N2 and which corresponds to the nitrogen flow rate (MAX) of the largest consumer of nitrogen type III.
• Figure 1 6 illustrates a similar case with three generators (G1, G2 and G3) instead of two as well as a buffer tank (RT).
• N1 and N2 are the low and high levels of nitrogen demand from consumers.
• Levels L1, L2 and L3 are respectively the nitrogen production capacities of the three generators.
• the capacity L1 of the first generator makes it possible to cover the level N1.
• the cumulative capacities L1, L2 and L3 make it possible to cover the level N2.
• the buffer tank is used to provide more nitrogen and to supplement the flow rate supplied up to the nitrogen (MAX) flow rate of the largest consumer of Type III nitrogen.
• Figure 17 illustrates one aspect of the invention and the fact that the device includes variable flow generators.
• one or more of the generators will supply nitrogen. If the nitrogen demand is low, only one of the generators is operated and the speed or frequency of its rotor is controlled to provide the requested flow rate. If the requested flow rate is greater than the maximum flow rate that a single generator can produce, both generators are operated.
• the accumulated capacities L1 and L2 of the generators are equal to N2.
• the buffer tank is used to provide an occasional surplus of flow required to satisfy the demand, and therefore the additional flow required to move from the N2 level to the MAX level.
• the level N2 corresponding to the flow rate requested by the type III consumer during a cooling of a tank.
• the tank can be emptied and brought to a temperature above -40 ° C.
• the tank can be filled again with liquefied gas. Before that, however, it is necessary to put it cold thanks to the type III consumer.
• the flow N2 thus corresponds to the flow rate necessary for the supply of this consumer.
• the MAX level corresponding to the flow rate requested by the same consumer during a cooling of a tank that has previously been inerted.
• the tank can be emptied and brought to a temperature above -10 ° C or even 0 ° C. It may undergo one or more inerting steps of injecting inert gas into the tank in order to evacuate the air that is there because of a maintenance operation for example carried out in the tank.
• the tank can be refilled with liquefied gas. Before that, however, it is necessary to put it cold thanks to the type III consumer.
• the NMAX flow thus corresponds to the flow rate necessary for the supply of this consumer.
• the level N1 may correspond to the rate demanded continuously by one or the other of the other consumers, for example that of type I.

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• 2017
  • 2017-07-19 FR FR1756857A patent/FR3069237B1/fr active Active
• 2018
  • 2018-05-29 WO PCT/EP2018/064111 patent/WO2019015836A1/fr active Application Filing
  • 2018-05-29 RU RU2020103348A patent/RU2756674C2/ru active
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