KR102302436B1 - Equipment for supplying a combustible gas to a gas consuming member and liquefying the combustible gas - Google Patents

Abstract

the present invention
- a hermetically insulated tank (2) intended to be filled with combustible gases in liquid-vapor equilibrium;
- a heat exchanger (10) disposed at a point higher than the tank and comprising a vaporization path (15) and a condensation path (12) separated from each other closed by a heat exchange wall;
- the input end of the condensing path is connected to a vapor collection circuit (13) located in the upper part (8) of the tank,
- the output end of the condensing path 14 is connected to the tank,
- the input of the vaporization path 15 is an installation 1 connected to the tank via a liquid input circuit 17 comprising an inlet located in the lower part 9 of the interior of the tank for drawing a stream of combustible gas in liquid state ) is about

Description

Equipment for supplying a combustible gas to a gas consuming member and liquefying the combustible gas

The present invention relates to a plant for handling combustible gases, for example liquefied natural gas (LNG).

More particularly, the present invention relates to a facility for supplying a combustible gas to a gas consuming member on the one hand and liquefying the combustible gas on the other hand.

Liquefied natural gas is stored in sealed and insulated tanks in liquid/vapor two-phase equilibrium at cryogenic temperatures. The insulating barrier of a liquefied natural gas storage tank is a site of heat flow that seeks to heat the contents of the tank, which is reflected by the evaporation of the liquefied natural gas. The gas from natural evaporation is usually fed to a gas consuming member to improve this. That is, in methane tankers, for example, the vaporized gas used to be supplied to a power train to propel the vessel or to a generator that supplies the electricity needed for the operation of onboard equipment. However, although this prior art allows to improve the gas from the natural evaporation of the tank, it does not make it possible to reduce the amount.

Further, when the combustible gas is formed into a gas mixture, the components of the vapor state resulting from natural evaporation are different from those of the liquid state, and also have a tendency to change with time. In particular, the vapor state from natural evaporation naturally has a higher composition than the liquid state, in the case of liquefied natural gas, the most volatile element such as nitrogen. As a result of this difference in composition, the calorific value of a gas from spontaneous evaporation, such as that of the remaining liquefied gas in the tank, varies with time when natural evaporation prevails. Accordingly, supplying the combustible gas with a significantly varying heat capacity to the consuming member is likely to cause incomplete combustion of the gas and operational defects and variable output for the gas consuming member.

US-A-2010/170297 discloses a device for the reliquefaction of gas from natural evaporation of an LNG tank. These devices include a heat exchange unit placed above the LNG tank to condense the gas from natural evaporation by heat exchange with a secondary cooling liquid such as liquid nitrogen. Equipment implemented to produce, cool, and liquefy nitrogen consumes energy.

JP 0960799 discloses an LNG storage facility having an LNG vaporization circuit and a circuit for recondensing gas from natural evaporation. The vaporization of LNG in the vaporization circuit is achieved by the heat supplied by the heater (24).

The idea forming the basis of the present invention is to propose a facility for supplying a combustible gas to a gas consuming member and for liquefying the combustible gas, which does not have at least some of the disadvantages of the prior art. A particular aspect of the present invention originates from the idea of using the liquid state of a combustible gas as a refrigerant in a heat exchanger to cool and condense a gas from natural evaporation.

According to one embodiment, the present invention is a facility for supplying a combustible gas to a gas consuming member and liquefying the combustible gas,

- a hermetically insulated tank comprising an interior space intended to be filled with combustible gas in liquid-vapor two-phase equilibrium;

- disposed at a point higher than the sealed insulated tank and comprising a vaporization path and a condensation path, wherein the vaporization path and the condensation path are formed by a heat exchange wall allowing heat to be transferred between the fluid contained in the condensation path and the fluid contained in the vaporization path. sealed and separated from each other, the vaporization path and the condensation path including a heat exchanger each including an input end and an output end,

- the input end of the condensing path is connected to the sealed and insulated tank by a vapor collection circuit comprising an inlet located above the interior space of the tank for drawing a first stream of combustible gas in vapor state of the interior space of the tank; The input end of the condensation path is disposed higher than the output end of the condensation path,

- the output end of the condensing path is connected to the internal space of the tank for discharging a liquid part of the first stream of combustible gas of the internal space of the tank by gravity, wherein the liquid part of the first stream of combustible gas is caused by condensation of the condensing path obtained,

- the input end of the vaporization path is connected to the sealed insulated tank by a liquid input circuit, the liquid input circuit being an inlet located at the bottom of the internal space of the tank for drawing a second stream of combustible gas in liquid state in the internal space of the tank and a circulation pump for discharging a second stream of combustible gas in a liquid state to the vaporization path;

- a vacuum pump is connected to the vaporization path to bring the vaporization path of the heat exchanger to a pressure less than the pressure prevailing in the vapor state of the sealed insulated tank,

- the output end of the vaporization path is connected to the gas consuming member for directing a vapor portion of a second stream of combustible gas to the gas consuming member, wherein the vapor portion of the second stream of combustible gas is at a pressure prevailing in the vapor state of the sealed insulated tank during operation A facility is provided which is obtained by vaporization of a combustible gas in a vaporization path placed at a pressure of less than.

According to one embodiment, such a facility may include one or more of the following features.

According to an embodiment, the output end of the vaporization path is disposed lower than the input end of the vaporization path. Thus, both the first stream of combustible gas in the condensing path and the second stream of combustible gas in the vaporization path perform a descending action, which facilitates the utilization of gravity, thereby maintaining circulation of these two streams. Moreover, the direction of this stream enables the same flow of heat exchange between the liquid state of the combustible gas used as the refrigerant and the gas from natural evaporation, thereby facilitating isothermal heat exchange by phase change. Preferably in this case the vaporization path is configured such that the second stream of combustible gas flows in the form of falling liquid films.

According to one embodiment, the vaporization path of the heat exchanger comprises a phase separation tank disposed at the bottom of the vaporization path, the phase separation tank comprising a bottom wall and sidewalls extending upwardly from the bottom wall, wherein the vaporization path output end is spaced above the bottom wall It is located through the side wall of the phase separation tank at the specified point. Such a phase separation tank makes it easy to separate the vapor fraction from the second stream of combustible gas from the fraction remaining liquid by gravity.

According to an embodiment, the purge circuit may pass through the bottom wall of the phase separation tank to discharge the liquid state from the phase separation tank by gravity. Thus, for example, in the case of an unvaporized portion from the second stream residue composed of the least volatile species (heavy) of the mixture, the removal of this liquid portion is facilitated, avoiding saturating or clogging the vaporization pathway.

According to one embodiment, the vaporization path of the heat exchanger is under a lower pressure, ie a pressure less than the pressure prevailing in the vapor phase of the closed insulated tank. Therefore, it is possible to further force the vaporization of the combustible gas in the vaporization path by the cumulative effect of heat supply to the condensation path and the reduced pressure in the vaporization path. Furthermore, since the reduced pressure moves the two-phase equilibrium temperature downward in the vaporization path, it is possible to increase the heat flow transferred from the vapor state in the condensation path to the gas located in the vaporization path.

In this case the absolute pressure in the vaporization path is preferably greater than 120 mbar absolute pressure. In fact, in order to prevent condensation of natural gas inside the vaporization path, it is preferable that the pressure inside the vaporization path is greater than the pressure corresponding to the triple point of the methane phase diagram. The pressure in the vaporization path may in particular be between 500 mbar absolute and 980 mbar absolute.

The apparatus further comprises a vacuum pump or pressure reducing pump connected to the vaporization path for placing the vaporization path of the heat exchanger at a pressure below the pressure prevailing in the vapor phase of the closed insulated tank.

According to an embodiment such a vacuum pump may be controlled as a function of a nominal flow rate or a nominal pressure. This nominal flow rate or pressure may be predetermined or generated by the gas consuming member.

According to the embodiment, the present facility may have one or more of the following features.

- the installation comprises a flow rate sensor for transmitting a signal representative of the flow rate of the vapor stream drawn through the inlet and delivered to the gas consuming member and a signal representative of the flow rate of that vapor stream and a function of the nominal flow rate generated by the gas consuming member and a control device for controlling the furnace vacuum pump.

- The installation comprises a pressure sensor for transmitting a signal indicating the prevailing pressure in the vaporization path and a control device for controlling the vacuum pump as a function of the signal indicating that pressure and the nominal pressure.

The connection between the output end of the vaporization path and the gas consuming member may be made directly or indirectly, depending on the requirements of the gas consuming member. According to one embodiment, the aforementioned vacuum pump is arranged between the output end of the vaporization path and the gas consuming element. According to another embodiment, a compressor is arranged between the output end of the vaporization path and the gas consuming member to provide a gaseous stream at a pressure exceeding the storage pressure of the tank.

According to one embodiment, the heat exchanger comprises a hermetically insulated envelope defining an interior space for receiving a condensation path, the envelope being arranged above the hermetic insulated tank, comprising a lower aperture communicating with the interior space of the hermetic and insulated tank; It constitutes the output stage of the condensing path.

This sealing and insulating envelope can be made in various ways, for example as an integral part of the upper wall of the tank, or alternatively in the form of an assembly attached to the upper wall of the tank.

According to one embodiment, the upper wall of the hermetically insulated tank has a hole connected to the lower hole of the envelope, the envelope further comprising a fixing clip arranged around the lower hole of the envelope, the fixing clip being arranged around the hole in the upper wall of the hermetically insulated tank is attached to the upper wall of

Preferably in this case the heat exchanger further comprises a collection pipe extending from the lower hole of the envelope to a point adjacent to the upper wall of the envelope and having a lower end located in the interior space of the tank and an upper end located in the interior space of the envelope, The pipe defines, within the interior space of the envelope, an interior space of the collection pipe forming a vapor collection circuit and an exterior space of the collection pipe forming a condensation path of the heat exchanger.

By this feature, the heat exchanger and vapor collection circuit can be formed in a relatively small volume integrated form while having a relatively small surface for exchange with the external environment, which limits the heat flow, which tends to increase spontaneous evaporation .

According to another embodiment, the apparatus further comprises a plurality of hermetically insulated tanks comprising an interior space intended to be filled with combustible gas in liquid-vapor two-phase equilibrium, wherein said vapor collection circuit There is a common collection circuit connecting the input of the condensing path to each of the tanks to collect the exiting gas. Thus, heat exchangers can be utilized together for a series of tanks.

According to that embodiment, the heat exchanger is

a plurality of tubes arranged in the outer space of the collecting pipe around the collecting pipe and parallel to the collecting pipe constituting the heat exchange wall of the heat exchanger,

an input distributor arranged in the interior space of the envelope and extending around the collection pipe, the input distributor having a bottom wall through which the top of each parallel tube is located;

an input tube constituting the input end of the vaporization path and extending through the envelope between the outside of the envelope and the input distributor;

an output case arranged in an outer space of the collection pipe around the collection pipe lower than the input chamber and having an upper wall through which the lower end of each parallel tube is located; and

It constitutes an output end of the vaporization path, and includes an output tube extending through the envelope between the output case and the outside of the envelope.

In order to maximize the output of heat exchange, it is necessary to form thermal contact over the maximum possible height of the outer envelope between the vaporization path and the worm path. Advantageously the input distributor is arranged higher than the top of the collecting pipe. The parallel tube can thus extend over substantially the same height as the collection pipe.

According to one embodiment, the tube parallel to the collection pipe has heat exchange vanes arranged on the outer surface of the tube parallel to the collection pipe.

According to one embodiment, the present invention provides a method for supplying a combustible gas to a gas consuming member and liquefying the combustible gas using the above-mentioned equipment,

- introducing a first stream of combustible gas in vapor state from the upper portion of the interior space of the hermetically insulated tank through the vapor collection circuit to the input end of the condensing path;

- sending a second stream of combustible gas in liquid state from the lower part of the internal space of the tank to the input end of the vaporization path using a circulation pump;

- heat exchange between the first stream of combustible gas in the condensing path and the second stream of combustible gas in the vaporization path to vaporize at least a portion of the second stream of combustible gas that was initially in a liquid state in the vaporization path, while vaporizing at least a portion of the second stream of combustible gas in the vaporization path condensing at least a portion of the first stream of combustible gas that was initially in a vapor state in

- directing by gravity the liquid portion of the first stream of combustible gas from the output end of the condensing path to the interior space of the tank and

- directing the vapor portion of the second stream of combustible gas from the output end of the vaporization path to the gas consuming member.

By the descending direction of the condensation path, the first stream of combustible gas cooled by heat exchange can flow by natural convection, ie by gravity, into the interior space of the tank, which prevents the formation of the suction of the vapor collection circuit. facilitating, maintaining the first stream without further mechanical action.

Preferably this process is carried out to vaporize all or substantially all of the second stream of combustible gas in the vaporization path. By forming a vapor state by forcible vaporization of the liquid stream brought from the bottom of the tank thereby, the content of the most volatile component is substantially equal to that of the liquid state of the gas stored in the tank. The concentration of the most volatile components of the vaporized gas stream is thus restrained and becomes substantially constant over time.

Also with these plants, the vaporization of liquefied gases can be carried out without the aid of an external heat source, in contrast to forced vaporization plants using seawater, intermediate liquids from motorization or combustion gases or heat exchange using specific burners. can

That is, the gas present in the upper part of the internal space of the tank acts as a heat source for the stream to be vaporized. The facility also provides a vapor stream while allowing the cooling and condensing of the vapor phase from spontaneous evaporation present in the upper part of the gas in the tank to limit spontaneous evaporation.

According to one embodiment, the present invention provides a ship comprising the aforementioned equipment.

According to one embodiment, the present invention provides a method for loading or unloading such a vessel, wherein the combustible gas is transported through an insulated pipeline, from an offshore or land-based storage facility to a hermetic insulated tank of a vessel, or a hermetic insulated tank of a vessel. It provides a method of delivery from a sea or land-based storage facility.

According to one embodiment, the present invention is a system for transporting combustible gas through an insulated pipeline and an insulated pipeline arranged to connect a tank installed in the hull of a ship to the aforementioned ship, sea or land-based storage facility. , a system comprising a pump for directing combustible gas from a sea or land-based storage facility to an enclosed insulated tank on a ship, or from an enclosed insulated tank on a ship to an offshore or land-based storage facility.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood and further objects, details, features and advantages will become more apparent from the following description of a plurality of specific embodiments, given merely for illustration and without limitation, with reference to the accompanying drawings.

1 is a schematic diagram of a facility for supplying a combustible gas to a gas consuming member and liquefying the combustible gas.
FIG. 2 is a perspective view showing a longitudinal cross-section of a heat exchanger that can be used in the facility of FIG. 1 .
FIG. 3 is a cross-sectional view of the heat exchanger taken along line III-III of FIG. 2 .
Figure 4 is an enlarged view of the heat exchange tube of the heat exchanger of Figure 2;
FIG. 5 is another embodiment of a facility similar to FIG. 1 , for supplying a combustible gas to a gas consuming member and for liquefying the combustible gas;
6 is a schematic diagram of a tank of a methane tanker including such a facility and a terminal for unloading the tank.

In the description and claims of the invention, the term "flammable gas" is of generic character and denotes, without preference to any one, a gas composed of a single pure substance or a mixture of gases composed of a plurality of components.

1 , an installation 1 is shown for providing, on the one hand, a combustible gas to one or more gas consuming elements and for liquefying the combustible gas on the other hand. Such a facility 1 may be installed on land or offshore structures. In the case of offshore structures, the installation 1 may be intended for liquefied natural gas cargo ships such as liquefied or regasified barges or methane tankers, and more generally for any vessel equipped with a gas consuming member. have.

The installation 1 shown in FIG. 1 is a steam output line 3 which can directly or indirectly supply various types of combustible gas consuming elements (not shown), in particular burners, generators and/or engines for propulsion of ships. ) is included.

These burners are integrated into the power plant. The power plant may in particular comprise a steam generating boiler. The steam may be intended to supply a steam turbine to generate energy and/or to a heating network of a vessel.

Such generators include, for example, diesel/natural gas mixed feed heat engines of DFDE (Dual-Fuel Diesel Electric) technology. These heat engines can burn a mixture of diesel and natural gas, or use either of these two combustible materials. The natural gas supplied to such a heat engine should have a pressure of several bar to several tens of bar, for example, 6 to 8 bar absolute pressure. For this purpose, one or more compressors 4 may be provided in the steam output line 3 .

An engine for propulsion of such a vessel is, for example, a dual fuel two-stroke low-speed engine of "ME-GI" technology developed by MAN. These engines use natural gas as a combustible material and a small amount of pilot fuel injected prior to injection of the natural gas to ignite. To feed these engines, natural gas must first be compressed to a high pressure between about 150 and 400 bar absolute, more specifically between 250 and 300 bar absolute. For this purpose, one or more compressors 4 may be provided in the steam output line 3 .

The plant (1) comprises a closed and insulated tank (2). According to one embodiment, the tank 2 is a membrane tank. By way of example such a membrane tank is disclosed in patent applications WO 140/57221, FR 2 691 520 and FR 2 877 638. Such membrane tanks are intended to store combustible gases at a pressure substantially equal to or slightly higher than atmospheric pressure. According to another alternative embodiment, the tank 2 may be a self-supporting tank, and in particular may have a parallelepiped, prism, sphere, cylinder or multi-pronged shape. Certain types of tanks 2 allow the storage of gases at significantly higher pressures than atmospheric pressure.

The tank 2 comprises an interior space 7 intended to be filled with combustible gas. Combustible gases are particularly liquefied natural gas (LNG), i.e. mainly methane and small amounts of ethane, propane, n-butane, i-butane, n-pentane, i-pentane, neopentane and one or more other hydrocarbons such as nitrogen. It may be a mixture of gases. The combustible gas may be ethane or liquefied petroleum gas (LPG), i.e. a mixture of hydrocarbons obtained from an oil refinery comprising essentially propane and butane.

The combustible gas is stored in the internal space 7 of the tank 2 in a liquid-vapor two-phase equilibrium state. That is, the gas exists in a vapor state in the upper part 8 of the tank 2 and in a liquid state in the lower part 9 of the tank 2 . This stratification is obtained naturally due to the specific density of each phase. The position of the liquid-vapor interface naturally depends on the fill height of the tank 2 . The equilibrium temperature of liquefied natural gas, which corresponds to its liquid-vapor two-phase equilibrium, is about -162°C when stored at atmospheric pressure.

On the upper wall 5 of the tank 2, the gas in the vapor state from the spontaneous evaporation of the upper part 8 of the tank 2 is liquefied, while the gas in the liquid state obtained from the lower part 9 of the tank 2 is liquefied. A heat exchanger 10 is shown that allows forcibly vaporizing the

To this end, the heat exchanger 10 has a gastight outer envelope 11 , preferably as thermal insulation to limit the flow of incoming heat from the surrounding environment, arranged above the upper wall 5 of the tank 2 . and the inner space 12 is at least two connecting parts,

- a vapor collection circuit (13) located at the top of the inner space (12) and sending combustible gas vapor to the upper end of the inner space (12);

- located at the bottom of the internal space 12, through the condensate return circuit 14 that collects the combustible gas deposited in the internal space 12 by gravity and returns it to the tank 2, It communicates with the upper part (8).

1 , the vapor collection circuit 13 and the condensate return circuit 14 pass through the upper wall 5 of the tank 2 , but other arrangements are possible, in particular in the case of the condensate return circuit 14 , for example the tank It is possible to pass through the side wall (6) at the upper part (8) of (2).

As indicated at 50 , the vapor collection circuit 13 may include several branches connected to several tanks, acting as a common collector connecting a series of tanks to the condensation path of the heat exchanger 10 . In this case, a valve (not shown) may be provided on each branch to isolate the tanks together.

The condensate return circuit 14 can likewise be connected to several tanks.

In order to withdraw heat from the inner space 12 , the heat exchanger 10 has a vaporization circuit 15 arranged in the inner space 12 , which is shown in the form of a coil, but its shape can be variously changed. . The vaporization circuit 15 is connected from the lower part 9 of the tank 2 to the input tube 17 connected to the input end of the vaporization circuit 15 passing through the circulation pump 16 and the outer envelope 11 airtightly. , a liquid combustible gas is supplied. By the latent heat of the combustible gas in the vapor state of the internal space 12, the gas in the liquid state circulating in the vaporization circuit 15 is vaporized, and the vapor state thus formed is vaporized passing through the outer envelope 11 fluidly It flows to an output line 3 connected to the output of the circuit 15 . For this purpose, the output terminal of the vaporization circuit 15 is preferably arranged lower than the input terminal of the vaporization circuit 15 . Therefore, the gas stream vaporized in the vaporization circuit 15 and the gas stream condensed in the inner space 12 are one of the effects of the circulation pump, the other only gravity and the difference in density between the liquid and vapor phases. It has the action of descending under the influence.

Since the liquid state is much denser than the vapor state, the consumption of vapor by condensation creates a permanent suction effect in the vapor collection circuit 13 , as indicated by arrow 19 . Therefore, there is generally no need to provide a circulation pump in the vapor collection circuit 13 .

To further force vaporization of the liquid combustible gas circulating through the vaporization circuit 15, the circuit may be placed under a lower pressure. For this purpose, as shown in FIG. 5 , for example, a vacuum pump 51 may be used instead of the compressor 4 . The vacuum pump 51 must be a cryogenic pump, that is, a pump capable of withstanding a cryogenic temperature of less than 150°C. It must also comply with ATEX regulations, ie it must be designed so that there is no risk of explosion. A pressure loss element, for example an expansion valve 45 , is also arranged at the input of the vaporization circuit 15 , preferably inside the outer envelope 11 .

1 shows another possible arrangement of the vapor collection circuit as a continuous line, which is arranged concentrically in the condensate return circuit 14 from the top 8 of the tank 2 to the top of the interior space 12 ( 113) is the form. In this case, the introduction of the gas in the vapor state takes place inside the collecting pipe 113 , and the condensate return flows in a circular space around the collecting pipe 113 in the condensate return circuit 14 . The rest of the operation is the same.

Although FIG. 1 shows a heat exchanger in which the vaporization path is contained and enclosed in the fluid of the condensing path, the reverse configuration is possible, ie the condensing path is contained and enclosed in the fluid of the vaporization path. Other configurations are also possible, such as a heat exchanger in which the two paths have substantially the same volume.

2 to 4, another embodiment of a heat exchanger is described. Elements similar or identical to those in FIG. 1 have reference numerals incremented by 100.

In FIG. 2 , the outer envelope 111 generally has a shape of a cylindrical bottle with a vertical axis, and is turned over so that its neck faces downward. More specifically, the main body defining the interior space 112 has a larger diameter than the condensate return tube 114 .

Here, the hermetic insulating wall is formed by two parallel layers of metal sheets spaced apart from each other, the space between the two being made up of a vacuum. Other types of insulation may be used.

The condensate return tube 114 has a diaphragm for absorbing heat shrinkage during temperature changes of the outer envelope 111 , particularly during operation. It is finished at the bottom by a fixing clip 21 for fixing to the upper wall of the tank (2).

A collection pipe 213 is arranged concentrically to the condensate return tube 114 from the end of the condensate return tube 114 and penetrates into the interior space 112 over most of its height. The upper end of the collection pipe 213 is open and is located in the upper part of the inner space 112 . In order to ensure the mechanical strength of the collecting pipe 213 in this position, a fixing member for attaching the collecting pipe 213 to the outer envelope 11 may be provided. For example, a fixing lug 22 is provided at the top of the collection pipe 213 and attached to the vaporization circuit 115 which is itself attached to the outer envelope 111 .

Hereinafter, the vaporization circuit 115 is described in more detail. This is essentially

- a circular or toric input distributor 23 arranged at the top of the inner space 112;

- a circular or annular output case 24 arranged at the bottom of the inner space 112 around the collecting pipe 213;

between the input distributor 23 and the output case 24 , preferably vertically, a plurality of vane tubes 25 extending parallel to the collecting pipe 213 .

The vane tube 25 passes through the bottom wall to the upper end 27 located in the circular chamber 26 of the input distributor 23 and the lower end located in the circular chamber 29 of the output case 24 through the cover wall ( 28), respectively. These constitute the heat exchange wall of the heat exchanger 110 , together allowing vaporized liquid vapor to flow down the vane tube 25 and gaseous condensation to flow down the interior space 112 .

The vane tubes 25 are distributed over the interior space 112 around the entire collection pipe 213, as partially shown in FIG. 3, to maximize the area for exchange between the two streams and to equalize the heat transfer.

4 shows two embodiments of a vane tube 25 . In the right figure, the tube body 30 is surrounded by vanes 31 spaced apart from each other and distributed over the entire length of the tube body 30 in the form of a disk extending across the tube body 30 .

In the left figure, the tube body 30 is in the form of a rectangular or polygonal blade extending parallel to the tube body 30 over the entire length of the tube body 30, and is distributed spaced apart from each other around the entire tube body 30 surrounded by vanes 32 .

In one variant (not shown) the vanes are omitted, which reduces the lateral volume of each tube, thereby increasing the number of tubes and allowing a large area to be obtained for exchange.

The circular chamber 26 of the input distributor 23 has a rectangular cross section and extends along the line of the vane tube 25 , ie along the perimeter of the collection pipe 213 . Furthermore, a conical wall is arranged in the center of the input distributor 23, the top of which is oriented towards the top of the collection pipe 213 and closes the center of the input distributor 23, whereby the vapor state is 213 forcing it to flow laterally towards the top of the vane tube 25 .

The input tube 117 extends laterally out of the outer envelope 111 from the circular chamber 26 . A hermetic weld or seal (not shown) may be provided around the input tube 117 in a passage passing through the outer envelope 111 to maintain its airtightness. The output tube 117 is connected to the circulation pump 16 via any suitable pipe, preferably with thermal insulation.

The output case 24 has a hollow toroid around the collection pipe 213 spaced therefrom. Its bottom wall 33 is concave to form a phase separation tank for collecting the non-vaporized portion of the liquid gas stream injected from the input tube 117 by gravity. A purge tube 34 located at the bottom of the bottom wall 33 allows this liquid portion to be drained, for example re-injected into the tank 2 . Furthermore, the output tube 103 extends laterally out of the outer envelope 111 from the circular chamber 29 . The output tube 103 is located in the circular chamber 29 above the concave bottom wall 33 so as not to collect the liquid phase. In practice, the fill height of the bottom wall 33 should be kept relatively low to prevent leakage of the liquid state into the output tube 103 . A hermetic weld or seal (not shown) is provided around the output tube 103 in a passage passing through the outer envelope 111 to maintain its airtightness. The output tube 103 is connected either directly to the combustible gas consuming member or via other gas processing equipment such as, for example, a compressor, heater, etc.

The fact that the vapor phase collected in the upper part 8 of the tank 2 during operation communicates with the upper end of the heat exchanger 110 via a collecting pipe 213 means first that the heat exchanger 110 is at substantially its entire height. and, secondly, ensuring that convective pumping/operation by condensation is ensured in the vapor state. This vapor state, which is relatively hot compared to the liquid state in the lower part 9 of the tank 2 , enters through the collection pipe 213 and reaches the top of the heat exchanger 110 . Accordingly, it comes into contact with the heat exchange surface of the vaporization circuit, that is, the tube 25, and begins to cool, which creates a first suction effect by thermal contraction of the steam, and then changes state by calculating the latent heat of vaporization, so that water droplets This is formed and falls by gravity onto the concave bottom wall 35 of the outer envelope 111, which creates a second suction effect. It is thus possible to omit the active pumping element for accompanying the circulation of the vapor phase.

In the vaporization circuit 115, the structure shown here has an input end at the top and an output end at the bottom, and uses a falling-film technique. The actuation thereby ensures that all components that can vaporize during the interval between entering the chamber 26 and reaching the chamber 29, under some volatile material that this film is easy to accommodate and will reach the bottom wall 33 in a liquid state. that it does not leave

A check valve 49 is preferably arranged in the purge tube 34 to close the purge tube 34 during normal operation of the facility, but intermittently open the purge tube 34 to release heavy substances. Remove this much liquid fraction. Removal of the liquid fraction may be accomplished by injecting gas under pressure into the input tube 117 , or by the effect of hydrostatic pressure of heavy matter that has only accumulated by gravity. This purge operation may also occur while the equipment is operating.

Alternatively, instead of check valve 49, valve 149 may be used on purge tube 34 to close purge tube 34 if necessary, and intermittently or continuously open purge tube 34 to allow heavy substances to pass through. Many liquid fractions can be removed. Removal of the liquid part can be effected by gravity when the valve is in the open position, only by the hydrostatic pressure of accumulated heavy substances. This purge operation may occur while the equipment is operating.

Alternatively, an out-of-tank pump (not shown) may be used to intermittently or continuously remove this residual liquid fraction. One of the advantages of this structure is that the risk of the vaporization circuit 115 becoming saturated with the liquid state is relatively limited, if the heat transferred by the vapor is insufficient to ensure vaporization of the liquid, without interfering with the vaporization process. Residual liquid state can be removed by reaching. The boiler vessel will be fed through the bottom so that the liquid end will not boil.

As in FIG. 5 , by placing the circuit under a lower pressure, it is possible to further force the vaporization of the liquid combustible gas reaching the vaporization circuit 115 . In this case, the purge device and its operation will be changed.

When the vaporization circuit 115 is placed under a lower pressure, a second valve 52 is added to the purge tube 34 upstream of the valve 149 to a buffer volume 53 which may take the form of a tube or reservoir. to form The actuation of the valves 52 and 149 alternate, first allowing the second valve 52 to open to fill the buffer space 53 with heavy material. Second valve 52 is then closed before valve 149 is opened, thereby evacuating the buffer volume by gravity before valve 149 is closed. The opening of valves 52 and 149 may be accomplished by injecting gas or by electronic control such as an electromagnetic valve.

The opening period of the valves 52 and 149 is directly related to the composition of the LNG, the greater the portion of heavy material in the LNG, the more frequently the valves 52 and 149 are opened.

The structure of the heat exchanger 110 enables heat exchange of parallel flows or co-currents. In theory, this type of heat exchange is less efficient than counter-current heat exchange. Specifically, in the heat exchange of two fluids, the two fluids enter the exchanger with a given temperature difference between the two fluids. If heat exchange occurs in the opposite direction of flow, the output temperature of one of the fluids will tend toward the input temperature of the other, and vice versa. On the other hand, in the same flow exchanger, the two fluids tend towards the mixing temperature.

This is not an obstacle to the correct operation of the heat exchanger 110 used as the evaporator-condenser. Specifically, in the heat exchanger, the portion of the spent heat is insignificant, and most of the heat transfer is isothermally performed by a phase change.

For example, if the vapor state of the combustible gas enters -100 ° C through the collection pipe 213, the portion of the heat that causes the vapor to drop to -160 ° C is about 130 kJ/kg, whereas the latent heat required for condensing it is 510 kJ /kg. That is, most of the heat transfer is isothermal. This also applies to the liquid state of the vaporization circuit 115 .

Referring to FIG. 6 , a cutaway view of a methane tanker 70 provided with a facility for supplying a combustible gas to a gas consuming member and liquefying the combustible gas as described above is disclosed. 6 shows a closed and insulated tank 71 of a generally prismatic shape as mounted on a double hull 72 of a ship. The wall of the tank 71 is a primary sealing barrier intended to come into contact with the LNG contained in the tank, a secondary sealing barrier arranged between the primary sealing barrier and the double hull 72 of the vessel and the primary sealing barrier and secondary and two insulating barriers respectively arranged between the hermetic barrier and between the secondary hermetic barrier and the double hull 72 .

As is known per se, the loading/unloading pipes 73 arranged on the upper deck of the vessel may be connected to the shore or harbor terminals by suitable connectors for the delivery of LNG to or from the tank 71 . .

6 shows an example of a coastal terminal comprising a loading and unloading station 75 , an underwater pipeline 76 and an onshore infrastructure 77 . The loading and unloading station 75 is a stationary offshore installation comprising a movable arm 74 and a tower 78 supporting the movable arm 74 . The movable arm 74 has a series of insulated hose pipes 79 that can be connected to a loading/unloading pipe 73 . The reversible movable arm 74 can fit any size tanker. A connecting pipeline (not shown) extends inside the tower 78 . The loading and unloading station 75 allows the tanker 70 to be loaded or unloaded from or to the land-based facility 77 . This facility comprises a liquefied gas storage tank 80 and a connecting pipeline 81 connected to a loading or unloading station 75 via an underwater pipeline 76 . The submersible pipeline 76 allows the transfer of liquefied gas between the loading or unloading station 75 and the land-based facility 77 over a large distance, eg, 5 km, which allows the tanker 70 to perform loading and unloading operations. Allow them to keep a long distance from the shoreline while on the go.

In order to generate the necessary pressure for the transfer of the liquefied gas, a pump mounted onboard pump of the vessel 70 and/or a pump installed at the shore-based facility 77 and/or a pump mounted at the loading and unloading station 75 is used. .

Although the invention has been described with respect to several specific embodiments, it is clear that it is not limited thereto, and includes all technical equivalents of the described means, and combinations thereof, provided that they fall within the scope of the invention.

The use of the verb "comprise" or "have" and its conjugations does not exclude the presence of elements or steps other than those recited in a claim.

Any reference signs placed between parentheses in a claim shall not be construed as limiting the claim.

Claims (17)

A facility (1) for supplying a combustible gas to a gas consuming member and liquefying the combustible gas, comprising:
- a closed insulated tank (2) comprising an interior space (7) intended to be filled with combustible gas in liquid-vapor two-phase equilibrium;
- disposed at a point higher than the sealed insulated tank, and comprising a vaporization path (15, 115) and a condensation path (12, 112), wherein the vaporization path and the condensation path are heated between the fluid contained in the condensation path and the fluid contained in the vaporization path. sealed and separated from each other by a heat exchange wall that allows this
- the input end of the condensing path is a vapor collection circuit comprising an inlet located in the upper part (8) of the interior space of the tank for drawing a first stream (19) of combustible gas in vapor state of the interior space of the tank ( 13, 113, 213) connected to the sealed and insulated tank, the input end of the condensing path is disposed higher than the output end of the condensing path,
- the output end of the condensing path 14, 114 is connected to the internal space of the tank for discharging the liquid part of the first stream of the combustible gas of the internal space of the tank by gravity, wherein the liquid part of the first stream of the combustible gas is condensed obtained by condensation of the path,
- the input ends of the vaporization path (15, 115) are connected to the sealed insulated tank by a liquid input circuit (17, 117), the liquid input circuit for drawing a second stream of combustible gas in liquid state in the interior space of the tank an inlet located in the lower part (9) of the interior space of the tank and a circulation pump (16) for discharging a second stream of combustible gas in liquid state into the vaporization path;
- a vacuum pump 51 is connected to the vaporization path 15 to place the vaporization path of the heat exchanger at a pressure below the pressure present in the vapor state in the internal space 7 of the sealed insulated tank,
- the output end of the vaporization path 3 , 103 is connected to the gas consuming member for directing the vapor portion of the second stream of combustible gas to the gas consuming member, wherein the vapor portion of the second stream of combustible gas during operation of the closed insulated tank Equipment obtained by vaporization of the combustible gas in the vaporization path (15, 115) placed at a pressure less than the pressure present in the vapor state in the interior space (7). According to claim 1,
The vacuum pump 51 is arranged between the output end of the vaporization path and the gas consuming member. According to claim 1,
The output end of the vaporization path (15, 115) is arranged lower than the input of the vaporization path. 4. The method of claim 3,
The vaporization path of the heat exchanger comprises a phase separation tank 33 disposed at the bottom of the vaporization path,
The phase separation tank includes a bottom wall and a side wall extending upwardly from the bottom wall,
The vaporization path output terminal 103 is a facility located through the side wall of the phase separation tank at a point spaced apart above the bottom wall. 5. The method of claim 4,
A facility further comprising a purge circuit (34) positioned through the bottom wall of the phase separation tank to be able to drain the liquid phase from the phase separation tank by gravity. 6. The method according to any one of claims 1 to 5,
Installation further comprising a compressor (4) arranged between the output of the vaporization circuit and the gas consuming member. 6. The method according to any one of claims 1 to 5,
The heat exchanger comprises a hermetically insulating envelope (11, 111) defining an interior space (12, 112) for receiving the condensation path,
The envelope is arranged above the sealed insulating tank, and comprises a lower hole (14, 114) communicating with the interior space of the sealed insulating tank, the equipment constituting the output end of the condensing path. 8. The method of claim 7,
The upper wall (5) of the sealed insulated tank has a hole connected to the lower hole of the envelope,
The envelope further comprises a retaining clip (21) arranged around the lower hole of the envelope,
The retaining clip is a fixture that is attached to the upper wall of a sealed insulated tank around a hole in the upper wall. 9. The method of claim 8,
The heat exchanger extends from the lower hole of the envelope to a point adjacent to the upper wall of the envelope (11, 111) and has a lower end located in the inner space of the tank and a collecting pipe having an upper end located in the inner space (12, 112) of the envelope ( 113, 213) further comprising,
The collection pipe defines, within the interior space of the envelope, an interior space of the collection pipe forming a vapor collection circuit and an exterior space of the collection pipe forming a condensation path of the heat exchanger. 10. The method of claim 9,
the heat exchanger
a plurality of tubes (55) arranged in the outer space of the collecting pipe around the collecting pipe and parallel to the collecting pipe constituting the heat exchange wall of the heat exchanger;
an input distributor 34 arranged in the interior space of the envelope and extending around the collection pipe and having a bottom wall through which the top of each parallel tube is located;
an input tube 117 constituting the input end of the vaporization path and extending through the envelope between the outside of the envelope and the input distributor;
an output case 24 arranged in the outer space of the collection pipe around the collection pipe lower than the input chamber, and having an upper wall through which the lower end of each parallel tube is located; and
A facility comprising an output tube (103) constituting an output end of the vaporization path and extending through the envelope between the output case and the outside of the envelope. 11. The method of claim 10,
The input distributor (23) is arranged higher than the top of the collecting pipe (213). 12. The method of claim 11,
The tube (25) parallel to the collection pipe (213) has heat exchange vanes (31, 32) arranged on the outer surface of the tube parallel to the collection pipe (213). 6. The method according to any one of claims 1 to 5,
Further comprising a plurality of hermetically insulated tanks comprising an interior space intended to be filled with combustible gas in liquid-vapor two-phase equilibrium,
The vapor collection circuit (13) is a common collection circuit connecting the input of the condensing path to each of the tanks for collecting the gas from the evaporation of each tank. A method for supplying a combustible gas to a gas consuming member and liquefying the combustible gas using the facility according to any one of claims 1 to 5, comprising:
- introducing a first stream (19) of combustible gas in the vapor state from the upper part (8) of the interior space of the hermetically insulated tank through the vapor collection circuit to the input end of the condensing path (12, 112);
- sending a second stream of combustible gas in liquid state from the lower part of the internal space of the tank to the input end of the vaporization path (15, 115) by means of a circulation pump (16);
- placing the vaporization path of the heat exchanger at a pressure less than the pressure present in the vapor state in the interior space (7) of the sealed insulated tank;
- heat exchange between the first stream of combustible gas in the condensing path and the second stream of combustible gas in the vaporization path, whereby the second stream of combustible gas in the vaporization path is placed at a pressure less than that present in the vapor phase of the sealed insulated tank condensing at least a portion of the first stream of combustible gas in the condensation path while vaporizing at least a portion of
- directing the liquid portion of the first stream of combustible gas from the output end of the condensing path (14, 114) by gravity into the interior space of the tank and
- directing the vapor portion of the second stream of combustible gas from the output end of the vaporization path to the gas consuming member. A vessel (70) comprising an installation (1) according to any one of claims 1 to 5. A method for loading or unloading a vessel (70) according to claim 15, comprising:
Combustible gases are transported via insulated pipelines (73, 79, 76, 81), from a marine or land-based storage facility (77) to a ship's sealed insulated tank (71), or from a ship's sealed insulated tank (71) at sea or A method of delivery to a land-based storage facility (77). A system for transporting a combustible gas, comprising:
A vessel (70) according to claim 15,
Insulated pipelines 73 , 79 , 76 , 81 arranged to connect a tank 71 installed on the hull of a ship to an offshore or land-based storage facility 77 and
Including a pump for introducing the combustible gas through an insulated pipeline, from a marine or land-based storage facility to an enclosed insulated tank (71) on a ship, or from an enclosed insulated tank (71) on a ship to an offshore or land-based storage facility. system.

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