KR20180124775A - Device and process for cooling liquefied gas and/or natural boil-off gas of liquefied gas - Google Patents

Abstract

The present invention relates to a device and a process for cooling liquefied gas and/or natural boil-off gas of liquefied gas and, more specifically, relates to a device (10) for cooling liquefied gas for a power generation unit (12) installed on a ship, which selectively comprises: a main storage tank (14) for liquefied gas (14a); a first separation drum (24) for cooled liquefied gas (24a); a decompression unit (26) of the first drum relevant to the main tank; an evaporation means (18, 19) installed in a first duct and/or an input unit of the first duct; and a means (22, 30, 32, 34, 40) to supply the cooled liquefied gas accommodated in the first drum to the main tank to cool gas accommodated in the main tank.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a device and a method for cooling a natural vaporized gas of a liquefied gas and / or a liquefied gas,

The present invention relates to an apparatus and a method for cooling a liquefied gas and / or a natural vaporized gas of a liquefied gas, particularly for a power generating unit installed on a ship, such as a ship carrying an liquefied gas or operating with a liquefied gas .

The prior art includes in particular the documents WO-A1-2012 / 089891, FR-A1-2 920 484, WO-A1-2005 / 058684 and WO6A1-2016 / 075399.

Over long distances, the gas is generally liquefied by cooling the gas from atmospheric pressure to a cryogenic temperature, e. G. -163 占 폚, to facilitate transport of gas, such as natural gas (e.g., liquefied natural gas- LNG). The liquefied gas is then loaded on a special vessel.

For example, in ships carrying LNG carrier-type liquefied gas, a power generation unit is installed to meet the working energy demand of the ship, in particular to generate electricity for ship propulsion and onboard equipment.

Such a device usually comprises a thermal machine using the gas supplied by the evaporator; The gas is obtained from the conveying liquefied gas which is cargo stored in one tank or a plurality of tanks of the ship.

Document FR-A-2 837 783 discloses a method of providing an evaporator and / or other system that provides propulsion power using a pump submerged in the bottom of one of the tanks of the vessel.

To limit the evaporation of the liquefied gas, the accepted method is to store the gas inside the tank and keep the gas on the vapor-liquid equilibrium curve of the gas, thereby raising the evaporation temperature of the gas. Thus, the liquefied gas can be stored at a higher temperature, which limits evaporation of the liquefied gas.

However, the natural evaporation of the gas can not be avoided, and the gas generated by this phenomenon is referred to as natural evaporation gas and is denoted by its abbreviation NBOG (in contrast, the forced evaporation gas is denoted by FBOG). The gas which naturally evaporates from the tank of the boat is generally used to power the above apparatus. If the amount of natural evaporation gas is insufficient to meet the demand of the combustible gas of the apparatus (first case), a pump submerged in the tank operates to provide more combustible gas after forced evaporation. If the amount of evaporated gas is too large for the required amount of the apparatus (second case), excess gas is burned in the gas-fired unit substantially, which leads to loss of flammable gas.

According to the current technology, the tank is perfected such that the natural evaporation rate (or BOR) of the liquefied gas is gradually lowered, while the performance of the ship's machinery has increased. This results in a significant difference between the gas naturally produced by evaporation and the gas required by the ship's power plant in both the first case and the second case described above.

Thus, interest in a solution for the cooling of liquefied gas contained in a storage tank, such as a re-liquefying or cooling unit, and the treatment of BOG generated within the tank, as disclosed in WO-A1-2016 / 075399 Is increasing. An idea contradictory to this document is to propose a liquefied gas cooling device which limits the natural evaporation of the liquefied gas while maintaining the liquefied gas in a thermodynamic state that provides for the continual storage of the liquefied gas. However, the heat exchange techniques disclosed herein are costly and very inefficient, and other disadvantages and features will be discussed in detail below.

In addition, various parameters, such as the motion and ambient conditions of the liquid, affect the occurrence of NBOG. Depending on the type of operation and the speed of the ship, the power requirements of the marine transportation vessel vary greatly. Therefore, it may be difficult to implement an efficient BOG processing solution because the amount of excessive NBOG can vary greatly.

The present invention proposes to perfect the present technology in a simple, effective and cost effective manner.

In the first embodiment, the present invention proposes, in particular, a liquefied gas cooling apparatus used for a power generating unit installed on a ship,

Optionally, a main storage tank for liquefied gas,

- a first drum having a first input connected to a first end of the first duct and for separating cooled liquefied gas, wherein a second end of the first duct, preferably at the bottom of the main tank, The first duct being submerged in the liquefied gas contained in the main tank, the first duct being capable of supplying liquefied gas to the first drum,

Pressure reducing means of said first drum associated with said main tank, said pressure reducing means being arranged to provide, in said first drum, an operating pressure which is lower than the pressure inside said main tank,

At least a portion of the liquefied gas supplied to the first drum, referred to as evaporation gas, and at least another portion (e.g., the remainder) of the liquefied gas, referred to as cooled liquefied gas, And evaporation means provided at the input of the first duct and / or the first drum to cool to a saturation temperature of pressure, wherein the first drum is configured to separate the evaporated gas and the cooled liquefied gas And

And means for supplying cooled liquefied gas contained in said first drum to said main tank for cooling gas which is contained in said main tank and is in the form of liquefied and / or gaseous form.

In this case, the liquefied gas is used to cool the liquefied gas contained in the main tank and regulate the temperature of the liquefied gas after it is cooled or cooled more than before.

The first drum serves as a vacuum evaporator (VE) and is preferably associated with a first compressor, which acts as a vacuum evaporator compressor. In a known manner, the evaporation or decompression of the gas releases the cooling energy. Therefore, the evaporation means can be regarded as a cooling means. In addition, the evaporation means, decompression means and decompression means are considered to have the same meaning for the purposes of the present invention. According to the present invention, the evaporation means is installed in the first duct and / or the connection input portion between the first duct and the first drum. The first drum may constitute (additional) evaporation means, as described below.

The present invention therefore proposes to replace the heat exchanger of the previous invention with a vacuum evaporator to improve the cooling capacity and to improve the cooling of the gas, in the form of liquid and / or gas contained in the main tank.

The main tank is optional because it can be regarded as part of the device according to the invention or can be excluded from the device according to the invention. For example, the device may be provided without a main tank, and therefore the main tank is not part of the device. In another form, for example, the device installed on the vessel is coupled to the main tank, and thus the main tank is part of the device according to the invention.

Preferably, there is no associated heat exchanger in the expansion or evaporation phase (a disadvantage of the heat exchanger is that it causes loss of cold air due to the pinch effect). Prior art relies on a heat exchanger, in which the light part is completely evaporated due to the heat exchanger evaporating the lighter part of the gas remaining in liquid form after depressurization. However, decompression and heat exchangers are not enough to evaporate heavier parts.

In the present application, the expression of being heavier and lighter means, respectively, a gas having a high molar mass and a gas having a low molar mass. In one embodiment, the liquefied gas is liquefied natural gas. In this case, the lighter gas is methane. Liquefied natural gas may contain some nitrogen as a lighter portion. In the case of liquefied natural gas, small heavier parts include propane, butane and ethane (which evaporate at higher temperatures or, for example, pressures below the operating pressure). In the liquefied gas, the heavy portion corresponds to 5.2% to 49.8% of the total mass of the liquefied gas. The heavy gas is characterized by having a molar mass that is 25 to 500% higher than the light gas.

This device offers a variety of advantages, including:

- Simplified configuration and control that depends on the cooling process that can occur entirely outside the main tank, and more secure operation,

- improving efficiency by eliminating the pinch effect which may occur in heat exchangers according to the prior art, as disclosed in WO-A1-2016 / 075399; Considering the operating pressure and the associated temperature drop, the 1 to 2 DEG C pinch effect corresponds to a cold power loss of approximately 15%

Cooling power is generated in the form of cooled liquefied gas that can be sent and used to meet various needs and even stored for future use; This is particularly advantageous because, instead of the low temperature power, cooling power can be generated by recovering the energy of the forced evaporation gas during the step where NBOG is matched with the step in which hot power is required,

On the other hand, considering the typical size of the main tank installed on the vessel, the amount of gas stored in the tank, and the size of the cooling equipment as disclosed in the above-mentioned earlier application, The low temperature output is not sufficient for storage and subsequent use of the gas,

- only the liquefied gas which is phase separated in said drum and only the gas which can be used in said apparatus is sucked by the decompression unit, such as a compressor; There is no risk of damaging the compressor by the droplet sucked by the compressor; Given the operating pressure range, temperature and composition of the liquefied gas, in most cases the liquefied gas is not entirely evaporated in the heat exchanger, such as that disclosed in the previous application above; For example, at 120 mbar, the liquid ratio in the initial configuration varies from 0.12 to 32%, and at 800 mbar (the pressure of 950 mbar can not be considered due to the pinch effect in the heat exchanger, as proposed in the previous invention) , In the range of 0.8 to 92% (largely changed due to the different composition of the liquefied gas)

In the previous application, all the flow required to supply the device, i. E., The consumer, must pass through the compressor, which means that only the required amount in the forced evaporative gas is used to fill the output of the natural evaporative gas The invention is not necessarily so; Thus, the capacity of the compressor is reduced, thereby reducing initial investment and operating costs; Moreover, it is generally more efficient to limit the circulating flow in the device, since each component of the device generates a loss; Finally, the proposed device is easier to connect to conventional consumable devices installed on the vessel, and it limits the environmental impact by providing greater flexibility in designing machinery that operates with flammable gas carried by the vessel;

- Preferably, the drum is disposed outside the main tank, so that the apparatus can be operated more safely and more easily.

Overall, this device reduces the total energy used for evaporation by 31-38%, compared with conventional equipment installed on ships, where additional BOG is generated by a pump supplying the liquefied gas to the heat exchanger. The main purpose is to generate cold by recovering the evaporative energy consumed in the ship in general. Depending on the characteristics of the ship, in particular the speed profile of the ship, the efficiency of the ship's machinery, etc., the said device is capable of detecting the heat generated during the ship's voyage (including the ship's return, commercial operation and waiting time before entering the canal) Up to 175%.

The pressure in the main tank may vary depending on the depth inside the tank due to the hydrostatic pressure.

In the present application, the expression " bottom " of a tank or barrel is considered to indicate a position less than one meter from the bottom wall of the tank, and the bottom wall is closest to the center of the earth during its operation. Is preferably as close as possible to the floor (so that the distance to the floor may be difficult to prepare to operate the pump too close to the floor) so that one pump or a plurality of pumps will work at the lowest possible filling height . ≪ / RTI >

According to the invention, the device can comprise one or several of the following features individually or in combination:

The first drum is a separating and / or expanding drum;

At least a portion of the first drum and / or at least a portion of the first duct, and / or at least a portion of the evaporation means are housed or received within the main tank;

The first drum is configured to receive only liquefied gas;

The pressure of the liquefied gas in the first duct is preferably higher than the hydrostatic pressure generated by the locked portion of the first duct inside the main tank;

The diameter of said first duct, before said decompression means, is preferably reduced as much as possible (cooling loss limit) in order to limit the cooling of the liquefied gas in the duct;

Preferably, the first duct is configured to be able to maintain a liquid form until the gas recovered from the main tank reaches the decompression means; Although the pressure in the first duct is lowered due to the fact that the immersion depth is reduced, the pressure is kept high enough to keep all of the gas in liquid form;

- at the input of the decompression means, the pressure of the first duct is, for example, approximately 1 bar; The liquefied gas that has only received a small amount of heat inside the first duct is maintained at a temperature (e.g., about -160 DEG C) that is maintained in liquid form at about 1 bar;

The evaporation means comprises a valve, for example a Joule-Thomson (JT) valve and / or a portion of a first duct, particularly disposed downstream from the valve;

- evaporation of the recovered liquefied gas preferably takes place in said part of the first duct (preferably in a proportion, or in a proportion of 80%, even in a proportion of 90%), immediately after said valve; The liquefied gas is also cooled in a first portion of the duct due to reduced pressure (spontaneous depressurisation) due to " flash "evaporation;

- this part of the duct can have a larger diameter than the part of the first duct arranged before the valve, in particular to ensure sufficient flow, since the evaporated gas takes up a larger volume;

In another form, if the duct portion between the valve and the first drum is reduced or absent, evaporation may occur predominantly (even at a rate greater than 80%) in the first drum; In this case, if the first drum is sufficiently large, the operation can be non-continuous; Then, in particular, it is necessary to wait for the liquefied gas evaporation and cooling process to end, at a temperature just below the boiling temperature at the new pressure, after the depressurization ("flash") of the secondary tank described below, There will be; In this case, the valve, for example the JT valve, may be replaced by a simple two-state valve (an on-off valve, in other words, a fully open or fully closed valve);

The pressing means comprises at least a first compressor connected to the first gas output of the first drum and at least one output having one output capable of supplying a combustible gas to the device, At least a portion of the evaporation gas inside the first drum can be sucked and an operating pressure can be applied to the first drum; In another form or as an additional feature, the decompression means comprises at least one pump having an input connected to the fluid output of the first drum; In this form, at least one compressor can be used to suck the evaporated gas contained in the first drum;

The feeding means comprises a second duct having a first end connected to the second cooled liquefied gas of the first drum and at least one second end designed to reach the main tank, Inject at least a portion of the cooled liquid gas of the first drum into the main tank; The connection between the first drum and the main tank, made by the second duct, may be direct or indirect; In other words, the second duct may include another fluid communication component or may be associated with the other fluid communication component, or it may be divided into a plurality of parts, with the components disposed between them; This may be true for all ducts mentioned for the purposes of the present invention;

The gas in liquid and / or gaseous form can be injected, in particular through the second duct, into the main tank; A mixture of gas and vapor may be injected into the main tank; When this mixture is re-injected into the bottom of the vat, the gas portion of the mixture will likely be re-condensed due to the hydrostatic pressure of the gas and the temperature of the liquefied natural gas inside the main tank; This can slow the pressure drop in the main tank;

The device comprises a first duct which is designed to be submerged in the liquefied gas contained in the main tank, preferably at the bottom of the barrel, for circulating the liquefied gas through the first tank to the first drum, And a first pump connected to the second end; In another aspect, the apparatus does not include a first pump; For example, when the first drum and the first duct are disposed inside the main tank;

The apparatus includes a second pump connected to the second duct for circulating at least a portion of the cooled liquefied gas from the first drum to the main tank through the second duct; In another form, for example, in the case of interrupted operations in which the first drum is supplied with the liquefied gas to a predetermined charge height and then decompressed to cool the liquefied gas and cause partial evaporation, 2 pump is not required and this will cause a pressure rise in the first drum until it reaches a value which is generally similar to the pressure in the main tank, which will be sufficient to make the second pump optional;

The first duct has an on-off valve which can be closed when a loss of pressure occurs in the first drum;

The first pump or the second pump may be a fuel pump or a bilge pump installed on the ship; This kind of pump typically provides a maximum flow rate of about 25-30 t / h; In another form, a pump with a higher maximum flow rate can be used, in particular, to provide a maximum flow rate of 300 t / h and even preferably a maximum flow rate of 2'500 t / h for the first pump have;

A unit formed by the first drum, the first compressor and the first pump forms a vacuum evaporation unit (or vacuum evaporator-VE); Generally, in the present invention, a unit formed by a drum, a compressor and a pump is regarded as a vacuum evaporation unit;

The evaporation means is preferably configured to lower the gas pressure to the operating pressure of the first drum;

The second output of the first compressor is connected to a second compressor having an output capable of supplying a combustible gas to the device;

The second duct comprises a plunger submerged in the liquefied gas contained in the main tank and / or an atomizer boom in the main tank to inject cooled liquefied gas into the main tank, or the plunger and / Connected to the boom; The injection of the cooled liquefied gas may be carried out on the gas and / or the liquefied gas contained in the main tank;

A second output of the drum is connected to a first input of a secondary tank for supplying cooled liquefied gas to the secondary tank and for storing the cooled liquefied gas in the secondary tank;

The secondary tank is configured to receive the cooled liquefied gas at a pressure higher than the operating pressure of the first drum; The secondary tank may be over-pressured with respect to the first drum, e.g., under atmospheric pressure; The secondary tank can be made cheaper, especially since it can be used to store a significant amount of gas; This is the advantage of the secondary tank; Thus, the cooled gas can be accumulated in the first tank when the demand of the device exceeds the natural evaporation, and when the demand of the device is less than the natural evaporation, the cooled gas is introduced into the main vat Can be injected;

The cooled liquefied gas contained in the secondary tank can be regarded as over-cooled liquefied gas; The expression " sub-cooled " means that the gas is at a temperature below the boiling temperature (i. E., The saturation temperature) at the pressure the gas is receiving; In the secondary tank, the liquefied gas is under pressure which can be regarded as over-cooled;

- the secondary tank acts as a heat exchanger for cooling the fluid, in particular the BOG;

The second pump is disposed between the second output of the first drum and the first input of the secondary tank;

The secondary tank comprises a first output for at least a portion of the cooled liquefied gas connected to the second duct and the second duct is adapted to send at least a portion of the cooled liquefied gas from the secondary tank to the main tank Can be used for;

The apparatus comprising at least one heat exchange circuit, wherein the at least one heat exchange circuit cools the fluid circulating in the heat exchange circuit by at least a portion of the cooled liquefied gas stored in the secondary tank or from the secondary pump ≪ / RTI > The heat exchange circuit may be disposed in the secondary tank, attached to the secondary tank, coupled with the secondary tank, or removed from the secondary tank; The cooled liquefied gas duct may be used, for example, to replace the role of the heat exchange circuit, which may be part of a complete heat exchanger; In another form, the cooled liquefied gas used to cool the fluid circulating in the heat exchange circuit may come from another source, such as, for example, a main tank or a first drum;

The combination of said secondary tank and said heat exchanging circuit may be combined with a natural evaporation gas (e.g. a temperature of -80 ° C to -160 ° C, or more precisely -100 ° C to + At a temperature of 140 DEG C, the effect of the pinch associated with the heat exchanger relative to the temperature difference between the liquid gas and the vapor phase gas at the secondary tank input is relatively small, allowing reprocessing of the natural vaporized gas with good yields and; Naturally, the same advantages are achieved through the exchange of the cooled gas of the primary tank or the first drum when there is no secondary tank; In other words, the cooled liquefied gas may be stored in the secondary tank, the first drum and / or the main tank;

The heat exchange circuit comprises an input connected to the natural evaporation gas output of the main tank; In this situation, the heat exchange circuit is particularly advantageous in that, due to the fact that due to the fact that the liquid gas is cooled, the pinch effect associated with the heat exchanger is relatively small relative to the temperature difference between the natural evaporation gas and the liquid gas, Can be used to reprocess natural vaporization gases;

The input of the circuit is connected to the output of at least one compressor, such as the first compressor or the second compressor, which is supplied with natural evaporation gas from the output of the main tank; So that the natural evaporation gas is compressed before it enters the heat exchanger or the cooled liquid gas heat exchange circuit (this raises the temperature of the natural evaporation gas);

Said input of said circuit being connected to said output of at least one compressor, such as said first compressor or said second compressor, provided in the first circuit of a first heat exchanger, said first heat exchanger being connected to said output A secondary circuit having one input connected to said natural vaporizing gas output of said tank and one output connected to said input of said first compressor or said second compressor; The natural vaporized gas recovered from the main tank will be heated as it passes through the secondary circuit, which is not a problem as the gas must be heated in any case if the gas is used to meet the demand of the apparatus; Preferably, there is a preliminary (or alternatively between) all natural evaporation gases (including those used to supply fuel to the apparatus) and a compressed portion of the natural vaporization gas Exchange (this exchange is preliminary because the natural evaporation gas is hotter than the cooled liquefied gas);

The heat exchange circuit comprises an output connected to the input of the second drum and the second drum comprises a first cooled liquefied gas output connected to the second duct for injecting cooled liquefied gas into the main tank And; In another form, the device can be configured to reinject, for example, the gas portion in the mixture into the main tank at the bottom of the barrel, wherein the gas portion is pressurized by the hydrostatic pressure of the gas and the temperature of the liquefied gas in the main tank Will tend to re-agglomerate under the influence of;

The second drum is a phase separation drum;

The output of the circuit is connected to the input of the second drum by means of a valve, such as a Joule-Thomson valve (known as the abbreviation JT), to lower the temperature of the gas by adiabatic expansion; Thus, the natural evaporation gas can be expanded; On both sides of the heat exchanger or heat exchange circuit, pressurization / depressurization can be used to achieve a lower natural evaporation gas temperature and consequently a larger amount of natural evaporation gas to condense;

The apparatus comprises an input connected to the first duct, as well as a primary circuit having an input connected to the output of the third pump and a cooled liquefied gas output, submerged in the liquefied gas of the main tank, And a second heat exchanger including a secondary circuit having a connected output;

The second heat exchanger is not immersed in the liquefied gas of the main tank and is not installed in the main tank;

An output of the primary circuit of said second heat exchanger is connected to an input of said secondary tank to supply cooled liquefied gas to said secondary tank;

The device does not include any components other than the pump and / or duct which is immersed in the liquefied gas contained in the main tank;

The liquefied gas comprises at least one " pure " portion comprising a pure gas or body, and comprises at least one pure portion of the cooled liquefied gas and the vaporized gas. If the liquefied gas is a liquefied natural gas, the pure portion may be made of methane.

In this application, the expression " pure " is used to denote a single chemical entity or chemical species, rather than a combination of several chemical entities or species. For example, the pure gas is a light gas or a heavy gas.

The present invention relates to a ship, and more particularly to a ship used for conveying liquefied gas, comprising at least one apparatus of the above kind.

The present invention also relates to a liquefied gas cooling method for a power generating unit, particularly installed in a ship, using the above kind of apparatus,

- recovering the liquefied gas contained in the main tank and recovered at the collection temperature and circulated in said first duct,

A portion of the collected gas evaporates due to the expansion effect and the remaining portion of the collected gas remains a liquid and is cooled to a temperature lower than the collection temperature since the collected gas is cooled to the saturation temperature at the expansion pressure, Expanding the recovered gas at an expansion pressure lower than the saturated vapor pressure of the gas collected at the collection temperature,

- filling the first drum with a liquefied gas and separating the evaporated gas from the cooled liquefied gas in the first drum, in particular by gravity,

- supplying D to the apparatus with at least a portion of the vaporized gas contained in the first drum, and

Cooling the liquefied gas contained in the main tank using the cooled liquefied gas contained in the first drum to cool the gas contained in the main tank,

And a control unit.

The saturated vapor pressure is the pressure at which the gas phase of a given object in a closed system is in equilibrium with the liquid or solid phase of the given object at a given temperature.

According to the present invention, instead of using cooling and depressurization of the evaporation enclosure and heat exchange between the evaporation enclosure and the liquefied gas inside the drum to cool the liquefied gas injected into the main tank, Evaporation is carried out and the resulting cooled liquid portion returns to the main tank. The main advantage lies in the elimination of the pinch effect due to the heat exchange between the evaporation enclosure and the liquefied gas in the drum.

In one embodiment, the liquefied gas collected comprises a pure gas, such as, for example, methane. In this case, the liquefied gas circulating in the first duct may be a mixture containing pure gas, such as, for example, liquefied natural gas containing methane.

According to the present invention, the method can include one or more of the following features individually or in combination:

- cooling the gas contained in the main tank, step E comprising circulating cooled liquefied gas in the second duct and injecting into the main tank;

The method comprising the step of spraying a droplet of cooled liquefied gas into the gas contained in the main tank, wherein the electrons are disposed above the height of the liquefied gas contained in the main tank,

The method comprising compressing the gas discharged from the first output of the first drum;

The pressure inside the first drum is between 120 and 950 mbar and / or the pressure inside the main tank is between 20 and 700 mbar, especially between 20 and 350 mbar, or between 20 and 250 mbar for a pressure tank, and / or the evaporation rate generated by the expansion is from 0.94 to 15, 18%, and / or the flow rate in the first duct is from 18.09 to 374.7 t / h, and / And / or the secondary tank has an internal volume or capacity of 1312 to 86037 m < ³ >, and / or a liquefied gas or natural evaporation The temperature of the cooled gas after cooling of the gas is between -159 and -180, 4 ° C, and / or the evaporation rate generated by the expansion of the compressed natural vaporization gas is 81.63 to 100%;

The method comprising the steps of: after expansion of the liquefied gas which can be partially or fully evaporated in the first drum and before liquefaction, the liquefied gas collected in the main tank is preheated by heat exchange with the fluid circulating in the primary circuit ≪ / RTI >

The method comprises precooling the liquefied gas collected in the main tank by heat exchange with a fluid circulating in the secondary circuit, prior to injection into the secondary tank;

The method comprises cooling the gas discharged from the first compressor or the second compressor by heat exchange with the cooled liquefied gas contained in the secondary tank;

The method comprises pre-cooling the gas discharged from the first compressor or the second compressor by heat exchange with the natural vaporized gas collected in the main tank before the gas is cooled inside the secondary tank;

- the method comprises pre-heating the natural evaporation gas collected in the main tank before it is compressed in the first compressor or the second compressor;

- the method comprises the step of lowering the pressure and / or the temperature of the gas supplied to the second drum before filling the second drum;

The method comprising the step of injecting cooled liquefied gas into the main tank through the second duct; This injection step contributes to cooling the liquefied gas contained in the main tank to limit the production of BOG;

The method comprising the step of transferring the gas from the second drum to the second compressor; The gas may be used in the apparatus before compression of the gas.

The present invention also relates to a method in which a combustible gas is supplied to a power generating unit, in particular a vessel, using the above-mentioned kind of apparatus,

- collecting the liquefied gas contained in the main tank, recovered from the first duct at the collection temperature,

A portion of the collected gas evaporates due to the expansion effect and the remaining portion of the collected gas remains a liquid and is cooled to a temperature lower than the collection temperature since the collected gas is cooled to the saturation temperature at the expansion pressure, Expanding the recovered gas at an expansion pressure lower than the saturated vapor pressure of the gas collected at the collection temperature,

- C filling the first drum, and in particular by gravity, separating the liquefied gas from the cooled liquid gas in the first drum,

- a step F in which the secondary tank is supplied with the cooled liquefied gas from the first drum and the cooled liquefied gas is stored in the secondary tank,

A step G in which a natural vaporizing gas is collected in the main tank and the gas is preheated,

- step H in which the evaporating gas from the first drum and the preheated natural evaporating gas are compressed,

- step I in which the compressed gas is supplied to the apparatus

And a control unit.

According to the present invention, the method can include one or more of the following features individually or in combination:

Step A, Step B, Step C and Step F are continuous;

At the same time as step G, or simultaneously with step A, step B, step C, step F and step G, simultaneously with step A, step B, step C and step F, the method comprises cooling the liquefied gas contained in the main tank , The cooled liquefied gas is collected from the secondary tank and injected into the main tank;

- The cooled liquefied gas is injected directly into the liquefied and / or vaporized gas of the main tank.

In the second embodiment, the present invention proposes a natural evaporative gas cooling apparatus for a power generation unit installed on a ship,

- optionally, a primary liquefied gas storage tank comprising a first natural vaporized gas output,

- liquefied gas cooling unit,

A secondary cooled liquefied gas tank configured to store liquefied gas that is cooled by said cooling unit, and

A first heat exchange circuit comprising an input connected to said first output of said main tank for circulating a natural vaporized gas inside said circuit, said natural evaporation gas passing through said first heat exchange circuit being connected to said secondary tank And is configured to cooperate with the secondary tank to be cooled by the cooled liquefied gas stored in the secondary tank or from the secondary tank.

The main tank is optional because it can be regarded as forming part of the device according to the invention or can be excluded from the device according to the invention. For example, the device may be provided without a main tank, and therefore the main tank is not part of the device. In another form, the device is associated with the main tank, for example once installed in the vessel, and thus forms part of the device according to the invention.

Thus, the solution is to cool the BOG and to:

- limiting the capacity of the means to be implemented for cooling purposes for what is required for the treatment of excessive NBOGs than is required to handle the maximum of NBOG production;

- optimizing the utilization of this means, which can be used continuously, if necessary, since cold sources such as cooled liquefied gas can be stored; and

- to ensure that the cooling power produced is used properly when needed

For example, to improve the BOG process with a device that meets the needs of the ship.

The solution applies to all means performed to cool the fluid. In this case, the fluid is BOG which exits the tank, is cooled in the secondary tank and is finally returned to the cooled state in the tank.

According to the invention, the device can comprise one or several of the following features individually or in combination:

A first drum having an input connected to the output of said first circuit for supplying a re-condensed spontaneous vapor to form a natural evaporated gas cooled and a cooled liquefied gas in said first drum, The drum includes a first natural vaporized gas output and a second cooled liquefied gas output connected to the main tank for injecting cooled liquefied gas into the main tank;

The second tank is configured to receive the cooled liquefied gas at a pressure higher than the operating pressure of the first drum;

The apparatus comprises at least a first compressor having one input connected to the main span and / or to the first spontaneous vapor output from the spontaneous vapor output of the first drum;

The cooling means comprises a second heat exchange circuit which is operated by heat exchange with liquefied gas in the secondary tank or liquefied gas from the secondary tank and in which the cooling fluid ≪ / RTI > The cooled liquefied gas is thus generated directly in the secondary tank;

Said cooling means comprising:

And a second drum having one input connected to the first end of the first duct, the second end of the first duct being immersed in the liquefied gas contained in the main tank, the first duct being connected to the liquefied gas To the second drum, and

And a second duct having one end connected to the first cooled liquefied gas output from the second drum and another end connected to the secondary tank for supplying the cooled liquefied gas to the secondary tank ;

The second drum is a separation and / or expansion drum;

The apparatus comprises a secondary circuit having an input connected to the first duct and an output connected to the first drum as well as a primary circuit having an input connected to the liquefied gas output of the main tank and a cooled liquefied gas output, The first heat exchanger having a first heat exchanger;

The second heat exchanger is not immersed in the liquefied gas of the main tank and is not installed in the main tank;

An output of the primary circuit of said second heat exchanger is connected to an input of said secondary tank to supply cooled liquefied gas to said secondary tank;

The apparatus does not include any components other than the pump and / or duct which is immersed in the liquefied gas contained in the main tank;

The input of the primary circuit is connected to a third pump submerged in the liquefied gas of the main tank;

The apparatus comprises:

A first pump connected to the second end of the first duct and immersed in the liquefied gas contained in the main tank for circulating the liquefied gas from the main tank to the second drum through the first duct, And

And a second pump connected to said second duct for circulating cooled liquefied gas from said second drum to said secondary tank;

Said first duct comprises said evaporation means;

The apparatus comprises at least a second compressor having one input connected to the first natural vaporizing gas output from the main tank;

The second compressor comprises an output connected to an input of the first circuit;

The input of the second compressor is also connected to the second gas output of the second drum and / or to the second gas output of the first drum;

The input of the second compressor is connected to the output of the first compressor;

The first compressor or the second compressor comprises in particular an output capable of supplying a combustible gas to the device;

The input of the first circuit is connected to the output of the first compressor or the second compressor by the primary circuit of the second heat exchanger and the second heat exchanger is connected to the first natural evaporation gas output And a secondary circuit having one input connected to the first compressor and one output connected to the input of the first compressor or the second compressor:

The secondary tank is connected to a first end of a third cooled liquefied gas duct having a second end connected to the main tank and the third duct is connected to at least a portion of the cooled liquefied gas from the secondary tank Can be moved to the main tank;

The third duct comprises a plunger immersed in the liquefied gas contained in the atomizer boom and / or the main tank disposed in the main tank to inject cooled liquefied gas into the main tank;

The input of the first circuit is connected to the output of at least one compressor, such as the first compressor or the second compressor, which is provided in the primary circuit of the second heat exchanger, and the second heat exchanger A secondary circuit having one input connected to the first natural vaporizing gas output of the main tank and one output connected to the input of the first compressor or the second compressor; Thus, a preliminary exchange between all the natural evaporation gases (a portion of which is supplied to the apparatus) and the compressed portion of the natural evaporation gas (the excess portion that is not used by the apparatus and is re-condensed) It is preliminary because the gas is hotter than the cooled liquefied gas);

The apparatus does not include any components other than the pump and / or duct which is immersed in the liquefied gas contained in the main tank.

The above-mentioned effects and advantages with respect to the features of the apparatus of the first embodiment of the present invention can of course be applied to the same features of the apparatus of the second embodiment of the present invention, and conversely, the features of the apparatus of the second embodiment of the present invention The advantages and advantages described above can be applied to the same features of the apparatus of the first embodiment of the present invention.

The present invention relates to a ship, in particular a ship used for conveying liquefied gas, comprising at least one apparatus of the above kind.

According to the present invention, the method can include one or more of the following features individually or in combination:

- the method comprises:

The step of compressing the gas discharged from the first output of the main tank, and / or

The step of compressing the gas discharged from the second output portion of the first drum, and / or

≪ RTI ID = 0.0 > a < / RTI > step of compressing the gas discharged from the second output of the second drum

/ RTI >

The method comprises pre-cooling the compressed gas by heat exchange with natural vaporizing gas collected in the main tank and circulated in the secondary circuit of the second heat exchanger before the compressed gas is cooled inside the secondary tank Include;

- the method comprises precooling the natural evaporation gas collected in the main tank by heat exchange with the fluid circulating in the primary circuit of the second heat exchanger before it is compressed;

- the method comprises cooling the liquefied gas contained in the secondary tank;

The method comprises the step of expanding the liquefied gas such that a portion of the liquefied gas is evaporated by an expansion effect and the remaining portion of the liquefied gas is maintained in liquid and cooled.

- the method comprises the step of the second drum being filled and said vapor being separated from said cooled liquid gas in said first drum, in particular by gravity;

- the method comprises the step of supplying cooled liquefied gas to the secondary tank;

The method comprising the steps of: after expansion of the liquefied gas and prior to injecting the liquefied gas into the second drum, the liquefied gas collected in the main tank is subjected to heat exchange with the fluid circulating in the primary circuit of the first heat exchanger ≪ / RTI >

The method comprising the steps of: prior to injecting the liquefied gas collected in the main tank into the secondary tank, liquefied gas collected in the main tank is preheated by heat exchange with the fluid circulating in the secondary circuit of the first heat exchanger Lt; / RTI >

The advantages and advantages of the method according to the first embodiment of the present invention can of course be applied to the same features and steps of the method of the second embodiment of the present invention. Conversely, in the second embodiment of the present invention The advantages and advantages mentioned above with respect to the features and steps of the method of the present invention can of course be applied to the same features and steps of the method of the first embodiment of the present invention.

The present invention relates to a method for cooling a vaporized gas of a liquefied and / or liquefied gas for a power generating unit, which is installed on a ship, using the apparatus of the above kind,

- a step A where cooled liquefied gas is prepared in said secondary tank

- step B where cooled liquefied gas is collected in said secondary tank,

- the step C in which the cooled liquefied gas is injected into the evaporative gas and / or the liquefied gas contained in the main tank,

And a control unit.

The present invention also relates to a method for supplying a combustible gas to a power generating unit installed on a ship, using the above-mentioned kind of apparatus,

The method includes monitoring at least one parameter of gas consumption by the unit,

- if the value of said parameter exceeds a predetermined threshold, the cooled liquefied gas is prepared and stored, in particular in said secondary tank,

And when the value of the parameter is smaller than a predetermined threshold value, excessive natural evaporation gas made in the main tank is recondensed.

The method may also include the step of cooling the gas contained in the main tank with the cooled liquefied gas to limit the generation of the natural vaporized gas.

The predetermined threshold value may vary, for example, while the ship is navigating. Functionally, the threshold can be matched to the NBOG flow rate to be extracted from the main tank to avoid having to regulate the pressure inside the main tank.

Preferably, the cooled liquefied gas is prepared when the amount of natural evaporation gas production is insufficient to meet the gas consumption amount of the unit.

Preferably, the liquefied gas is cooled by a process of collection, expansion and phase separation of the liquefied gas contained in the main tank.

There are several ways to retard natural evaporation: for example, by injecting cooled liquid gas into the cylinder (e.g., into a cooled liquid gas atomizer boom in the main tank, or simply through the output of the main tank) ), Or by cold exchange between the natural vaporized gas and the cooled gas, which provides a re-condensation of the natural vaporized gas (optionally, the natural vaporized gas can be returned to the tank) That is, by heat exchangers), the natural evaporation can be delayed.

The fact that the liquid gas is over-cooled prevents the generation of evaporative gas when natural evaporation has to be retarded. Storage can meet a significant reconditioning demand with a limited capacity secondary tank (e.g., the liquefaction unit is very expensive and the cost of the liquefaction unit depends on the capacity of the liquefaction unit).

In another form, cooled gas is stored in the main tank in order to condense the natural vaporized gas in the main tank, particularly when the amount of available natural vaporization gas is greater than the demanded amount of the unit. This cooled gas is more dense than the rest of the gas in the main vat, so that it can be used, for example, below the height of the liquid output or heat exchanger at the bottom of the main tank, It is necessary to cool / recondense the natural evaporation gas with the liquid gas. For example, a heat exchanger may be installed in this location, or piping may be used to deliver the cooled gas stored in that location to the heat exchanger (e. G., A heat exchanger disposed outside the tank) Can be provided.

Preferably:

The natural vaporization gas is condensed by heat exchange with the cooled liquefied gas, and / or

The natural vaporization gas is compressed before the heat exchange, and / or

- the natural vaporization gas is depressurized before the heat exchange, and / or

- The natural evaporation gas is phase separated after the decompression.

The features and steps of the apparatus and method of the first embodiment of the present invention can be combined with the features and steps of the apparatus and method of the second embodiment of the present invention and conversely the apparatus and method of the second embodiment of the present invention Features and steps may be combined with features and steps of the apparatus and method of the first embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood and other details, features and advantages of the present invention will become more apparent from the following description, given by way of non-limiting example, and with reference to the accompanying drawings, in which: FIG.
1 is a schematic view of a first embodiment of a device according to the invention, installed in a ship,
- Figures 2 to 6 are schematic views according to figure 1 showing the steps of the method according to the invention,
7 is a schematic view of a second embodiment of a device according to the invention, installed on a ship,
8 is a schematic view of a third embodiment of a device according to the invention, installed on a ship,
9 and 10 are schematic views of a fourth embodiment of the device according to the invention, which is installed in the ship and which shows the steps of the method according to the invention,
11 is a schematic view of a fifth embodiment of a device according to the invention, mounted on a ship,
12 is a schematic view of a sixth embodiment of a device according to the invention, installed on a ship,
13 is a schematic view of a seventh embodiment of a device according to the present invention installed on a ship;

1 shows a first embodiment device 10 according to the invention which can be considered to provide for the cooling of the liquefied gas and / or the cooling of the natural evaporation gas of the liquefied gas.

The device 10 is particularly suitable for supplying a combustible gas to, but not exclusively, a ship, such as a ship carrying liquefied gas. Thus, the device 10 can be used to supply a combustible gas to the power generation unit 12, particularly on a ship.

The vessel includes one tank 14 or several tanks 14 used to store the liquefied gas. The gas is, for example, a mixture of various gases containing methane or methane. The tank 14 or each tank 14 can receive the gas in liquid form at a predetermined pressure and temperature, for example at a temperature of atmospheric pressure and -160 ° C. One or several tanks 14 of the vessel may be connected to the power generation unit 12 by means of the apparatus 10 according to the invention. The number of tanks is not limited. For example, the number of tanks may be one to six. Each tank 14 may have a capacity of 1'000 to 50'000 m ³ .

In the following, the term " tank " should be understood as " tank or individual tank ".

The tank 14 receives the liquefied gas 14a and the gas 14b generated by the natural evaporation of the liquefied gas 14a inside the tank 14. [ Naturally, the liquefied gas 14a is stored at the bottom of the tank 14, while the vapor 14b is above the height of the liquefied gas within the tank, schematically indicated by the letter N.

Herein, " LNG " refers to liquefied gas, i.e., liquid gas, " BOG " refers to a vapor gas or vapor, " NBOG " refers to natural vapor, a forced boil-off gas; These abbreviations are known to those skilled in the art, as these abbreviations reflect commonly used English terms in the art.

In the embodiment shown in Figure 1 it is preferred that the pumps 16a and 16b are immersed in the LNG of the tank 14 and that the LNG is the sole source of the pumps 16a and 16b, Respectively.

In this case, there are two pumps 16a and 16b. The pump 16a is connected to the lower end of the duct 18. The pump 16b is connected to the lower end of the duct 20. In another form, for example to achieve redundancy of the pump 16a and the pump 16b, or to use an existing pump which is a sprayer pump already present in the vessel (in this case , The function of the pump 16b may be provided by four atomizer pumps, each of the four atomizer pumps already present in four separate tanks), there may be an additional pump of each kind.

The duct 20 includes an upper end connected to the LNG droplet atomizer boom 22 disposed in the upper portion of the tank 14 above the height N. [ The LNG droplet sprayer boom 22 is configured to spray an LNG droplet to the NBOG. This is used to recondite the NBOG in the tank 14. The pump 16b is configured to circulate the LNG in the duct 20 from the bottom of the tank 14 to the LNG droplet atomizer boom 22 and ensure that the LNG is sprayed in the form of droplets. In fact, while the NBOG can circulate in the duct, there may be expansion space in the main tank.

The pump 16a directs the LNG in the duct 18 from the bottom of the tank 14. For example, to the drum 24 connected to the upper end of the duct 18. The duct 18 is provided with a decompression unit 19, such as a JT valve, to reduce the pressure of the LNG circulated in the duct 18 before the LNG reaches the drum 24. Preferably, the decompression unit 19 is configured to lower the pressure of the LNG circulating in the duct 18 to the operating pressure of the drum 24. [ The decompression unit 19 includes, for example, a JT valve (as described below).

When the LNG circulating in the duct 18 passes through the decompression unit 19, the LNG is partially evaporated before the LNG is supplied to the drum 24.

The drum 24 is thus designed to receive the partially vaporized LNG from the tank 14. The operating pressure inside the drum 24 is lower than the storage pressure of the LNG in the tank 14. [ Feeding the LNG to the drum 24 may lead to additional evaporation of the LNG which causes the generation of FBOG inside the drum 24 and cooling of the LNG remaining in the drum, Liquefied gas " The drum 24 receives the gas in liquid form at a predetermined temperature and pressure.

The drum 24 receives the gas 24b generated by the forced evaporation of the liquefied gas 14a from the tank 14 as well as the cooled liquefied gas 24a. Naturally, the cooled liquefied gas 24a (or LNG) is stored at the bottom of the tank 24 while the evaporated gas 24b (or FBOG) is stored in the drum 24, Is higher than the height of the liquefied gas inside.

The drum 24 includes three fluid communication ports, namely, an LNG input connected to the duct 18, an FBOG output, and an LNG output.

The FBOG output is coupled to an input of a compressor 26 that includes one output coupled to compressor 28. The compressors 26, 28 can be either independent compressors or two compression stages of a single compressor. Thus, the compressors 26 and 28 may be related to each other.

The compressor 26 is used in this case to operate the operating pressure inside the drum 24. Thus, the compressor 26 is configured to depressurize the drum 24 relative to the tank 14. The pressure differential therebetween may be sufficient to circulate the LNG from the tank 14 to the drum 24. In this case, it is understood that the pump 16a is optional. The condition imposed on the drum 24 by the compressor 26 is set to generate LNG in the expansion drum.

The LNG can be moved from the LNG output of the drum 24 to the LNG input of the secondary tank 30 when the amount of LNG in the drum 24 is very large and the membrane is about to reach a threshold level.

In this case, the drum 24 and the secondary tank 30 are connected by, for example, a duct 31 provided with a valve 33 and a pump 35. The pump 35 is configured to circulate the LNG from the drum 24 to the secondary tank 30. The pump 35 is particularly useful when the tank 30 is in an excessively pressurized condition with respect to the drum 24. The secondary tank 30 receives the LNG at a predetermined pressure and temperature.

The secondary tank 30 is configured to store excessive LNG generated in the drum 24. The secondary tank 30 receives the gas 30b generated by the natural evaporation of the liquefied gas 14a from the tank 14 as well as the cooled liquefied gas 30a. Naturally, the cooled liquefied gas 30a (or LNG) is stored at the bottom of the tank 30, while the evaporated gas 30b is stored at the bottom of the tank 30, Is above the height of the liquefied gas.

The secondary tank 30 includes an LNG output section. In the example shown, this output is connected by a duct 32 to the tank 14 or to the atomiser boom 22 of each tank 14 on one side and to the LNG of the tank on the other And is connected to the plunger 34 which is or is locked. It is therefore understood that the atomizer boom 22 can supply the LNG to spray the LNG droplets to the BOG of the tank 14 and the plunger 34 can supply LNG to inject the LNG directly into the LNG of the tank 14. [ .

The duct 32 may be connected to the LNG output of the secondary tank 30 via a valve 36. The duct may be connected to the plunger 34 and the boom 22 by a three-way valve 38.

The secondary tank 30 is used to cool a fluid, such as gas or liquid, which in this case is BOG from the main tank 14. In this case, the heat exchange circuit 40 is coupled to the secondary tank 30. [ The term " this combination " is to be understood in its broadest sense in the present specification, and the heat exchange circuit 40 may be a coiled duct locked to the LNG accommodated in the secondary tank 30. In another form, the heat exchange circuit (40) may be disposed outside the tank (30). The heat exchange circuit 40 is configured to perform heat exchange between the fluid circulating in the heat exchange circuit 40 and the LNG accommodated in the secondary tank 30. The fluid circulating in the heat exchange circuit (40) is generally higher in temperature than the LNG cooling the fluid circulating in the heat exchange circuit (40). The heat exchange circuit includes an input unit and an output unit.

The input of the heat exchange circuit 40 is in this case connected to the BOG output 45 of the main tank 14, which is arranged in the upper part of the main tank. The BOG output 45 of the tank 14 is connected to the secondary circuit input 42a of the heat exchanger 42 and one output of the heat exchanger is connected to one of the inputs of the input or compressor 28 It is connected.

The output of the compressor 28 is generally connected to the unit 12 to supply a combustible gas to the unit 12. [ A portion of the combustible gas exiting the compressor 28 may be collected and carried by a duct 44 which may be connected to the output of the compressor 28 by a three way valve 46.

Compressor 28 is configured to compress the gas (e.g., NBOG from the tank) at an operating pressure adapted for use in unit 12.

The duct 44 is connected to the primary circuit input 42b of the heat exchanger 42 and one output of the heat exchanger 42 is connected to the input of the heat exchange circuit 40.

The output of the heat exchange circuit 40 is connected to the drum 50 by a duct 48, which is separate from the drum 24. The duct 48 includes a valve 52, which is preferably a Joule-Thomson valve, to lower the temperature of the gas by adiabatic expansion.

Joule-Thomson expansion is characterized by slow and slow liquefaction, which is achieved when gas flows through a buffer (usually cotton wool or raw silk) with pressure differential across the lateral sides of a horizontal insulated pipe. stationary laminar expansion. For real gases, Joule-Thomson expansion usually results in temperature changes: this is known as the Joule-Thomson effect. The heat exchanger 42, the heat exchange circuit 40 and the valve 52 cools and partially re-condenses the BOG.

The drum 50 is used to separate the BOG 50b remaining in the gaseous form from the (re-) condensed BOG 50a before supplying the (re-) condensed BOG to the tank 14. [ Naturally, the re-condensed BOG 50a is stored at the bottom of the drum 50 while the evaporation gas 50b (or BOG) is stored in the drum 50, It is above the height of the gas.

The drum 50 includes three fluid communication ports, namely, a BOG input connected to the duct 48, a BOG output in the gaseous state, and a BOG output condensed (again). In this case, the BOG output portion in the gaseous state is connected to the input portion of the compressor 28. In this case, the (re) condensed BOG output is connected to the plunger 34, the duct 32 and / or the atomizer boom 22 in order to inject the (re) condensed BOG into the tank 14.

The vacuum evaporation unit formed by the following elements, the pump 16a, the depressurization unit 19, the drum 24 and the compressor 26, Is used to recover the latent heat of vaporization, which is generally consumed in the evaporator, according to the cooling power used to cool the LNG contained in the main tank 14. [

The LNG generates cooling power, which can be stored in the secondary tank 30 when it is not needed, for example, the amount of NBOG generated is insufficient to meet the demand.

The operating pressure of the drum 24 is lower than the operating pressure of the tank 14 and the operating pressure of the tank 14 is in the range of -20 mbarg to 250 mbarg (gauge mbar), or -20 to 350 mbar, or -20 to 700 mbar. The operating pressure of the drum 24 is preferably from 300 to 800 mbar (absolute mbar).

The LNG is carried from the tank 14 to the drum 24 in a reduced pressure state as compared to the tank 14 in a saturation equilibrium similar to the storage pressure of the LNG in the tank 14. [ Therefore, when the LNG is decompressed by the decompression unit 19, it is overheated, and in order to reach the saturated equilibrium state, the LNG releases excessive heat by evaporation. The LNG is then separated from the LNG and FBOG inside the drum 24, at a rate primarily determined by the operating pressure of the drum 24.

For example, at an operating pressure of 300 mbar, the evaporation rate of the LNG supplied to the drum 24 is 9.5 to 10%. At 800 mbar, the evaporation rate is 2.3 to 3%. The remaining portion is the liquid cooled to a temperature that matches the saturated equilibrium state at the operating pressure of the drum 24. [ For example, at an operating pressure of 300 mbar, the LNG is cooled to a temperature of -172 to -175 ° C (a temperature drop of -12 to -15 ° C), and at 800 mbar the LNG is cooled to a temperature of -163 to -164 ° C -4 < 0 > C).

The LNG can then be discharged by the pump 35, preferably into the secondary tank 30. The pump 35 may be used to increase the pressure of the LNG. When the LNG is stored in the secondary tank 30, the cooling power can be maintained.

During operation, the evaporated portion of the LNG supplied to the drum 24 is accumulated inside the drum. In order to adjust the pressure inside the drum 24 to a predetermined value (for example, 300 to 800 mbara), preferably, the FBOG generated inside the drum 24 is continuously discharged. This is done by a compressor 26 which compresses the input pressure to match the operating pressure of the drum 24 and an output pressure that is similar to the storage pressure of the LNG in the tank 14, 24) of the gas. The gas subjected to this treatment is easy to use as it is at the same pressure as the pressure of the NBOG generated in the tank 14 and can be supplied to the compressor 28 together with the NBOG. The compressor 28 is configured to generate a combustible gas that can be used directly by the unit 12, for example, to supply fuel to the propulsion engine of the ship.

In order to satisfy the gas consumption of the unit 12, the NBOG generated in the tank 14 is conveyed to the compressor 28 by the above-described apparatus 10 and is compressed at its operating pressure in this compressor. Additional BOG required to meet demand is generated by the evaporation of the LNG fed to the drum 24 and subsequently to the compressor 26 and the compressor 28. The pump 16a may prove to be necessary to supply the LNG from the tank 14 to the drum 24, in particular if the depth or height N of the tank is between 10 and 50 m - in this case the drum 24 ) May be insufficient to passively circulate the LNG in the duct 18.

Thus, the drum 24, together with the NBOG, must be supplied with a sufficient flow of LNG to meet the combustible gas consumption demand of the unit 12. For example, the additional FBOG flow rate generated in the drum 24 may be 0 to 4000 kg / h. Therefore, the flow rate from the tank 14 to the drum 24 may be 0 to 17.5 t / h, depending on the composition of the LNG and the operating pressure of the drum 24. [

The LNG generated in the drum 24 is stored in the secondary tank 30. The secondary tank 30 is configured to store and maintain the LNG and is thus preferably insulated. The pressure inside the secondary tank 30 is, for example, from 0.3 bara to 10 bara, and this value is given some flexibility for pressure management. The temperature of the LNG in the secondary tank 30 is close to the temperature of the LNG in the drum 24 and is, for example, -175 to -161 占 폚. The LNG contained in the secondary tank 30 can be transported to the atomizer boom 22 through the duct 32 and the LNG droplet from the atomizer boom 22 can be transported to the drum 30 during the excess NBOG step, Is sprayed to the BOG contained in the tank 14 to cool the BOG: it may be injected back into the LNG of the tank by the plunger 34 to cool the LNG directly.

The NBOG produced in excess of the demand of the unit (12) is collected and sent to the compressor (28). The NBOG is then sent back to the heat exchange circuit 40 of the secondary tank 30 through the valve 46 and the NBOG in the heat exchange circuit is subjected to heat exchange with the previously stored LNG Lt; / RTI > The excess NBOG is then sent to the valve 52 and through this valve is depressurized to reach a pressure close to the storage pressure inside the tank 14. For example, if the tank is an atmospheric tank, the excess NBOG may be reduced to reach a pressure of 0 to 1 barg. The excess NBOG is then fed to the drum 50 and phase separated in this drum 50 to form a (re) condensed BOG and a gaseous BOG. The BOG in the gaseous state is sent to the compressor 28 through the duct 51 in the same manner as the NBOG produced in the tank 14. The (re-) condensed BOG is injected into the tank 14 for LNG storage.

Figures 2-6 illustrate the operating steps of the apparatus of Figure 1, and the operating steps correspond to the different speed steps of the vessel with this apparatus.

The liquefied gas cooling method is described in three steps:

1. When the volume of the NBOG is insufficient, also referred to as the FBOG stage (FIGS. 2 and 3), for example when the ship's sailing speed requires more BOG to fill the NBOG generated in the tank 14 . Additional BOG or FBOG is supplied by the device 10 and cold power is generated.

2. Steps where excess NBOG is created (Figs. 4 and 5), for example when the ship is slowing down or anchored; Excessive NBOG should be handled in a safe and environmentally friendly manner.

3. The step of cooling the main tank 14 of the vessel (Figure 6), e.g., before loading after return crossing, during which the tank 14 is close to being empty So BOG management is generally not necessary).

1. Inadequate level of NBOG, also referred to as the FBOG phase (Figures 2 and 3).

Figure 2 shows the detailed steps of the first step, during which the FBOG and NLG are jointly created by the device.

In order to regulate the pressure in the tank 14, the NBOG is collected in the tank and through the output 45, a pressure that can be used by the unit 12, for example, about 6-7 bars, 15-17 bars Or to a compressor 28 that produces combustible gas at a pressure of 300-315 bars. The LNG is sent from the tank 14 to the decompression unit 19 through the duct 18 by the pump 16a in order to fill the amount of gas and satisfy the consumption of the unit 12. In this decompression unit, The pressure of the LNG is reduced until the operating pressure of the drum 24 is reached. The LNG reaches the drum 24 at the operating pressure of the drum 24 and due to the shift of the saturated equilibrium state caused by the pressure difference between the drum 24 and the tank 14, ( Flash phenomenon), and the remaining portion is cooled to the saturation temperature of the LNG at the operating pressure of the drum. As described above, a sufficient flow rate must be collected from the tank 14. The FBOG contained in the drum 24 is then discharged and compressed by the compressor 26 to reach the LNG storage pressure in the tank 14. The FBOG is then compressed again by the compressor 28 to reach the pressure required by the unit 12. In order to prevent the drum 24 from becoming overfilled, the LNG in the drum, particularly when the LNG fill rate of the drum reaches a given threshold, for example 50% Lt; / RTI >

3 shows other detailed steps of the first stage, during which LNG is stored in the secondary tank 30.

If the capacity of the secondary tank 30 is not sufficient to store the produced LNG, the LNG of the tank 14 may be supplied to the secondary tank 30 in order to cool the LNG of the tank 14 below the LNG saturation temperature at the storage pressure inside the tank 14. [ The accommodated LNG can be transported to the bottom of the tank 14 through the duct 32 and the plunger 34.

2. Steps where excess NBOG is created (Figures 4 and 5)

Figure 4 shows the detailed steps of the second step during which the excess BOG recondensates.

The NBOG made in the tank 14 is more than sufficient to meet the demand of the unit 12. In order to regulate the pressure inside the tank 14, BOG is collected from this tank and supplied to the compressor 28 to reach the operating pressure of the unit 12. Excess BOG that can not be used by the apparatus is sent from the output of the compressor 28 to the heat exchanger 42 and heat exchanged with the cold NBOG collected directly from the tank 14 through the output 45 in the heat exchanger . Excess BOG is then sent to the heat exchange circuit 40 of the secondary tank 30 and is again cooled in the heat exchange circuit through heat exchange with the LNG stored in the tank, as described above. The excess BOG is then depressurized by the valve 52 and fed to the drum 50 where it is heated by the heat exchanger 42, the heat exchange circuit 40 and the valve 52, The condensed BOG is separated from the gaseous BOG. The remaining gaseous BOG is sent back to the compressor 28 to supply fuel to the unit 12.

Figure 5 shows the detailed steps of the second stage, during which LNG is sprayed.

The LNG contained in the secondary tank 30 may be directed to the atomizer boom 22 through the duct 32 to directly recondition the BOG contained in the tank 14 instead of recondensing the excess NBOG through the dedicated line .

3. The stage where the main tank 14 of the ship is cooled (Fig. 6).

Figure 6 shows the detailed steps of the last step.

Typically, the liquefaction terminal, on which the cargo is loaded on the vessel, is designed so that the interior of the tank 14 is cooled to a cold temperature prior to the loading operation, in order to limit the amount of LNG in which flash evaporation occurs. in need. This is generally accomplished by spraying the LNG already contained in the tank 14 with the boom 22 and the associated pump 16b to cool the BOG contained in the tank. In the apparatus 10, this operation is performed by supplying LNG from the secondary tank 30, which is cooler than the LNG contained in the tank 14, to the boom 22. Likewise, if the BOG contained in the tank 14 is insufficient to supply fuel to the unit 12, the LNG contained in the secondary tank 30 can be regenerated in the same manner as in the first step.

Fig. 7 shows another embodiment of a device different from that shown in Fig. 1 in that it includes another heat exchanger 60. Fig. The heat exchanger 60 includes two circuits, a primary circuit 60a and a secondary circuit 60b.

The secondary circuit 60b includes an input connected to the duct 19, downstream from the decompression unit 19. The secondary circuit 60b includes an output connected to the LNG input of the drum 24.

The primary circuit 60a includes an input connected to the pump 16b via a three-way valve and the atomizer boom 22 of the tank 14, respectively. The primary circuit 60a includes an output connected to the LNG input of the secondary tank 30.

The secondary circuit 60b is a cold circuit and the fluid circulates in the secondary circuit and in this case the decompressed LNG is reheated by circulation in the circuit resulting in evaporation (in the FBOG). The primary circuit 60a is a hot circuit and the fluid circulates in the primary circuit and in this case the LNG coming out of the tank 14 is cooled by circulation in the circuit. However, the circuit 60 can not evaporate heavier components (ethane, propane, etc.). It is believed that the depressurization at the downstream portion from the secondary circuit 60b lowers the evaporation temperature and generates the FBOG through heat exchange with the LNG that is collected from the vat and circulated in the primary circuit. Evaporation into the FBOG requires the heat supplied by the circulating LNG in the primary circuit, which is the cooling source for cooling the LNG circulating in the primary circuit.

The LNG is sent from the tank 14 to the decompression unit 19 by the pump 16a and circulated in the secondary circuit or the low temperature circuit of the heat exchanger 60. [ In the meantime, the LNG is sent by the pump 16b from the tank to the primary circuit or high temperature circuit of the heat exchanger 60. Thus, the heat exchange between the circuits is:

- The reduced pressure and partially vaporized LNG are heated and subsequently sent to the drum for subsequent evaporation so that the LNG is phase separated,

- Cool the LNG supplied to the secondary tank (30), and in the secondary tank the LNG is stored for future use.

The apparatus then operates as described initially with respect to Figures 1-6. The effects of the heat exchanger 60 are as follows:

The pump 16a may be sized to circulate only a predetermined maximum amount of LNG to form an FBOG sufficient to meet the demand of the unit 12, in addition to the NBOG. This operation can be performed by a fuel pump provided on the ship in general,

The capacity of the drum 24 can be reduced (only the flow of additional FBOG can be used to meet the demand of the combustible gas of the unit 12), since the LNG feed can be less important,

Due to the temperature pinch effect in the heat exchanger, the cooling power production is reduced (approximately 15% loss based on 500 mbar operating pressure)

- This solution reduces the flow rate of the LNG and the circulating LNG, thus reducing the power consumption of the pump, which reduces the power consumption of the system.

Figure 8 shows another embodiment of the apparatus 110 according to the present invention, which may be considered to provide for the cooling of the liquefied gas and / or the cooling of the liquefied natural gas of the liquefied gas.

The device 110 is particularly suitable for supplying combustible gas to, but not exclusively, a vessel, such as a ship carrying liquefied gas. Thus, the apparatus 110 can be used to supply a combustible gas to the power generation unit 112, which is installed on the ship.

The vessel includes one tank 114 or several tanks 114 used to store the liquefied gas. The gas is, for example, a mixture of various gases containing methane, or methane, such as liquefied natural gas. The tank 114 or each tank 114 can receive gas in liquid form at a predetermined pressure and temperature, for example, at atmospheric pressure and at a temperature of -160 占 폚. One or several tanks 114 of the vessel may be connected to the power generation unit 112 by means of the apparatus 110 according to the invention. The number of tanks is not limited. For example, the number of tanks may be one to six. Each tank 114 may have a capacity of 1'000 to 50'000 m ³ .

In the following, the term " tank " should be understood as " tank or individual tank ".

The tank 114 receives the liquefied gas 114a and the gas 114b generated by the natural evaporation of the liquefied gas 114a within the tank 114. [ Naturally, the liquefied gas 114a is stored at the bottom of the tank 114, while the evaporation gas 114b is above the height of the liquefied gas within the tank, schematically indicated by the letter N.

"BOG" refers to evaporative gas or vapor gas, "NBOG" refers to natural evaporation gas, and "FBOG" refers to forced vaporization gas Lt; / RTI > These abbreviations are known to those skilled in the art, as these abbreviations reflect commonly used English terms in the art.

In the embodiment shown in FIG. 8, the tank 114 includes an LNG droplet atomizer boom 122 disposed above the height N above the tank. The LNG droplet sprayer boom 122 is configured to spray the LNG droplet to the BOG. This is used to refill the BOG in the tank 14.

In this case, the apparatus 110 includes a cooling unit 170 coupled with a secondary tank 130 used for storage of LNG.

The cooling unit 170 includes, for example, a heat exchange circuit 172 coupled with the secondary tank 130. The secondary tank 130 receives the LNG at a predetermined pressure and temperature.

The secondary tank 130 is configured to store the LNG. Thus, the secondary tank 130 accommodates not only the cooled liquefied gas 130a but also the gas 130b generated by the natural evaporation of the liquefied gas 130a. Naturally, the cooled liquefied gas 130a (or LNG) is stored at the bottom of the tank 130, while the evaporated gas 130b is present above the height of the liquefied gas, do.

The secondary tank 130 includes an LNG output section. In the illustrated example this output is connected by duct 132 to tank 114 or to atomizer boom 122 of each tank 114 on the one hand and to spray boom 122 of tank 114 on the other hand, And is connected to the plunger 134, which is contained or locked in the LNG. It is understood that the atomizer boom 122 can supply the LNG to spray the LNG droplets to the BOG of the tank 114 and the plunger 134 can supply LNG to inject the LNG directly into the LNG of the tank 114 .

The duct 132 may be connected to the LNG output of the secondary tank 130 via a valve 136. The duct may be connected to the plunger 134 and the boom 122 by a three-way valve 138.

The secondary tank 130 is used to cool a fluid, such as gas or liquid, which in this case is BOG from the main tank 114. In this case, another heat exchange circuit 140 is coupled to the secondary tank 130. The combination of the respective circuits 140 and 172 and the secondary tank 130 should be understood in the broadest sense herein and the circuits 172 and 140 are coils of the LNG enclosed in the secondary tank 130, . In other versions, the circuits may be located external to the tank 130. The heat exchange circuit 140 is configured to perform heat exchange between the fluid circulated in the heat exchange circuit 140 and the LNG stored in the secondary tank 130. The fluid circulating in the heat exchange circuit 140 is generally higher in temperature than the LNG cooling the fluid circulating in the heat exchange circuit 140. The heat exchange circuit includes an input unit and an output unit.

The input of the heat exchange circuit 140 is in this case connected to the BOG output 145 of the main tank 114, which is arranged in the upper part of the main tank. The BOG output 145 of the main tank 114 is connected to the secondary circuit input 142a of the heat exchanger 142 and one output of the heat exchanger is connected to the input of the input or compressor 128 have.

The output of the compressor 28 is connected to the unit 112 generally to provide a combustible gas to the unit 112. A portion of the combustible gas from the compressor 128 may be collected and transported by a duct 144 that may be connected to the output of the compressor 128 by a three way valve 146.

The compressor 128 is configured to compress the gas at an operating pressure adjusted for use in the unit 112.

The duct 140 is connected to the primary circuit input 142b of the heat exchanger 142 and one output of the heat exchanger 142 is connected to the input of the heat exchanger 140. [

The output of the heat exchange circuit 140 is connected to the drum 150 by a duct 148. The duct 148 includes a valve 152, such as a Joule-Thomson valve, to lower the temperature of the gas by adiabatic expansion.

The heat exchanger 142, the heat exchange circuit 140 and the valve 152 condense (or, in other words, liquefy) a portion of the BOG.

The drum 150 is used to separate the (re-) condensed BOG from the remaining BOG in gaseous form.

The drum 150 is thus not only re-condensed BOG 150a (by means of a condensation line including, for example, heat exchanger 142, heat exchange circuit 140 and valve 152) And a BOG 150b in a gaseous state. Naturally, the re-condensed BOG 150a is stored at the bottom of the drum 150, while the gaseous BOG 150b is located at the bottom of the drum 150, Above the height.

The drum 150 includes three fluid communication ports, namely, a BOG input connected to the duct 148, a BOG output in the gaseous state, and a liquid BOG output. In this case, the condensed BOG output is connected to the input of the compressor 126 by the duct 151. In this case, the liquid BOG output is connected to the plunger 134, the duct 132 and / or the atomizer boom 122 to store the LNG in the tank 114.

9 shows a device 110 of another embodiment that is different from that shown in Fig. 8 due to the cooling unit 170. Fig.

The cooling unit 170 is submerged in the LNG of the tank 114 and preferably includes a pump 116a disposed at the bottom of the tank to ensure that the LNG is the only feed.

The pump 116a is connected to the lower end of the duct 118. The duct 118 includes an upper end connected to the LNG input of the secondary tank 130 for supplying the LNG to the tank. The duct 118 extends through or includes a cold generator, such as a vacuum evaporator, which may include a drum coupled with a compressor, as shown in the previous embodiment.

The pump 116a is configured to circulate the LNG from the bottom of the tank 114 to the secondary tank 130 in the duct 118 in order to supply the LNG to the secondary tank 130 and store the LNG in the tank.

In the arrangement shown in Figures 8 and 9 there is a solution to integrate the cooling means 170 into the environment of the vessel in order to make the most of this equipment as possible to meet the needs of the ship. The cooling means 170, when in use,

9, the LNG is sent from the tank 114 to the cooling unit 170 by the pump 116a, where the LNG is cooled and injected into the secondary tank 130 And the LNG is stored in the secondary tank; If the capacity of the secondary tank 130 is not sufficient for storage purposes then the LNG can be sent to the duct 132 and then sent through the plunger 134 into the tank 114, ) Can cool the LNG inside;

8, since the cooling unit 170 is in direct contact with the LNG, in order to generate the LNG, the cooling unit 170 directly cools the LNG stored in the secondary tank 130 And the like.

In both cases, the result is that the LNG is stored in the secondary tank 130. The temperature of the LNG is preferably -180 to -160 캜, which usually corresponds to an LNG temperature drop of -0.5 to -20 캜. By applying heat to the secondary tank 130, a part of the LNG can be evaporated and the BOG 130b can be generated. When the pressure inside the secondary tank 130 reaches a predetermined threshold value, the pressure inside the secondary tank 130 can be adjusted by removing a part of the BOG using the compressor 126. [ The design of the secondary tank 130 may be used for its purposes and features, such as a capacity of 50 to 500 m ³ for the management of BOG during voyage, or for a period of two to five days when the vessel is anchored, It depends on the capacity of 1'500 to 10'000 m ³ for BOG management. The pressure inside the secondary tank 130 is, for example, from 0.3 bara to 10 bara, which is given some flexibility for the purposes of pressure and control of the evaporative gas 130b.

The cooling unit 170 may be operated independently of the above solution and its environment. Preferably, the cooling unit 170 operates continuously, regardless of whether cooling power is immediately required or not.

The LNG may be directed to the tank 114 by the duct 132 and the plunger 134 to regulate the pressure or temperature of the LNG contained in the tank 114, for example.

Typically, the pressure in the tank 114 is regulated by collecting the NBOG from the tank 114 by sucking the NBOG using the compressor 126, through the NBOG output 145 of the tank 114. The NBOG coming from the compressor 126 is then used to feed the unit 112. If the load imposed on the unit is not sufficient to consume all NBOGs, there is an excessive NBOG to be processed. In this case, as described above, it is desirable to affect only the excess NBOG rather than affecting the LNG or all of the NBOG contained in the tank 114. According to this solution, an excessive NBOG is transferred from the compressor 126 to the heat exchanger 126 at an operating pressure of the unit 112 (e.g., 6-7 bars or 15-17 bars or 300-315 bars, depending on the type of unit installed in the vessel) And is cooled by heat exchange with the NBOG collected by the NBOG output 145 of the tank 114 in the heat exchanger. Excess NBOG is then sent to the heat exchange circuit 140 of the tank 130 and cooled by heat exchange with the LNG contained in the tank 130 in this heat exchange circuit. The excess NBOG is then depressurized by the JT valve 152 to reach the operating pressure of the drum 150 before being supplied to the drum 150. [ The drum 150 is regulated to a pressure close to the storage pressure of the tank 114. Due to the arrangement of the BOG condensation line (this BOG condensation line includes heat exchanger 142, heat exchange circuit 140, JT valve 152 and drum 150), a portion of the excess NBOG condenses . Finally, the condensed NBOG collected in the drum 150 is re-injected into the tank 114 through the plunger 134. [ By (re) condensing NBOG, the pressure of the NBOG inside the tank 114 can be reduced.

The advantages of this device vary and include the following advantages:

The cooling unit 170 can operate continuously with average capacity and handle all of the excess NBOG. Typically, the size of the cooling unit 170 is such that it is capable of operating at a lower capacity or at an average capacity to handle a maximum NBOG and then to produce an actual change in excess NBOG, If the capacity is exceeded, NBOG is lost. With the apparatus 110, the cooling unit 170 can be sized according to the average excess capacity of the NBOG while being able to handle all of the excess NBOG. For conventional ships, the average amount of excess NBOG is 25-30% of the maximum amount of excess NBOG. On the one hand, the capacity to absorb the cooling power output and, on the other hand, the change in the demand for cooling power is reduced by the secondary tank 130, which can store the LNG at a lower temperature than the LNG stored in the tank 114 / RTI > In this way, the cooling power is concentrated in the LNG and is ready to be used when needed, while it is weakened inside a fairly large volume of the tank 114 according to the previous embodiment.

Typically, cooling power is used to spray LNG to the tank 114. By this process, the vapor phase inside the tank 114 is cooled and partly condensed. In terms of energy, this is not an ideal situation, since a portion of the excess NBOG may be used to fuel the unit 112. According to the apparatus 110, a portion of the NBOG is used to supply fuel to the unit 112, and the cold power is used only for the excess NBOG. For ordinary vessels, the gas consumption during the anchoring period is 15 to 30% of NBOG.

- the compressor 126 provided in the vessel compresses the excess NBOG to the input pressure of the unit 112 (typically a pressure of 6-7 bars, a pressure of 15-17 bars or a pressure of 300-315 bars) , Phase separation occurs and is cooled by the LNG before returning to the main tank 114. This is more efficient than spraying the LNG onto the vapor of the main tank 114, because the process can be used to cool the excess NBOG at lower temperatures and to condense more of the excess NBOG due to pressure differences.

- certain cooling methods can be used under certain conditions. For example, the above-described vacuum evaporator can generate cold air from additional FBOG needed in addition to the NBOG that supplies the unit 112 with fuel. According to the apparatus 110, the generated cold power can be used at a required time and place.

9 and 10 show the operating steps of the device of FIG. 9, which of course can be applied to the device of FIG. 8 and can be fitted with different speed steps of the ship with this device.

1. Adjustment of the state (pressure and temperature) in the tank - Figure 9;

2. Processing of excessive NBOG - Figure 10.

1. Adjustment of the state (pressure and temperature) in the tank - Fig.

If the secondary tank 130 does not require LNG supply from the tank 114 (e.g., if the energy demand is met by another power source) and the state of the tank 114 (e.g., The LNG stored in the secondary tank 130 is supplied to the LNG stored in the tank 114 through the duct 132 and the plunger 134. In this case, Lt; / RTI >

2. Processing of excessive NBOG - Figure 10.

As noted above, the excess NBOG can be handled by circulating the excess NBOG through a condensation line formed by the heat exchanger 142, the heat exchange circuit 140, the JT valve 152 and the drum 150 have.

Figure 11 shows an alternative solution.

The compressor 126 may be used to send a NBOG to a pressure that can be used by the unit 112 because the apparatus requires gas supply at a typical input pressure that is higher than the storage pressure inside the tank 114. [ During this compression, the NBOG is heated. Preferably, a heat exchanger 142 is used to recover a portion of the cool air exiting the tank 114. This solution increases the performance level, but this is neither essential nor essential. Therefore, this is eliminated from the embodiment shown in Fig. One output of the three way valve 146 is directly connected to the input of the heat exchange circuit 140 and the NBOG output 145 is connected directly to the input of the compressor 126.

Fig. 12 shows a device of another embodiment different from the device shown in Fig. 9 in that it includes another heat exchanger 180. Fig. The heat exchanger 180 includes two circuits, a primary circuit 180a and a secondary circuit 180b.

The secondary circuit 180b includes an output connected to the LNG input of the tank 130 for re-injection of the LNG into the tank 130 after a heat exchange process with the fluid circulating in the primary circuit of the heat exchanger 180, And an input connected to the LNG-pumped pump 182 housed in the inlet 130. The primary circuit 180 may be integrated into the heat exchange circuit 140 described above.

The primary circuit 180a is a high temperature circuit and the fluid circulates in this primary circuit, in this case the compressed BOG is cooled by circulation in the circuit. The secondary circuit 180b is a low temperature circuit and the fluid circulates in this secondary circuit, in which case the LNG coming out of the tank 330 is cooled by circulation in the circuit.

13 also shows that the drum 24 and the secondary tank 30 are integrated so as to form and define one cylinder 90 for the forced evaporation of the LNG from the tank 14 and the storage of the LNG thus produced 1 shows another embodiment of the device 10 different from that shown in Fig.

Table 1 below provides examples of the values of the various operating parameters of the device according to the invention in different ranges (large range, middle range, and optimum range).

Big range Intermediate range Optimal range Pressure (mbara) 120 950 300 800 500 600 After the decompression (decompression unit 19)
ratio(%) 14.86 to 15.18 0.94 to 1.97 9.58 to 10.2 2.38-3.37 6.06 to 6.87 4.68 to 5.57 Of the cooling gas provided by the pump 35
Flow rate (t / h) 15.35 to 31.08 138 to 371.6 24.23 to 51.42 79.32 to 197.7 37.37 to 84.69 46.81 to 109.9 The flow rate (t / h) of the gas provided by the pump 16a 18.09 to 34.95 140.8 to 374.7 26.99 to 55.48 82.11 to 202.6 40.14 to 89 49.58 to 114.4 (M ³ ) of the secondary tank 30 when it is directly connected to the boom 22, 1907 to 2120 20021 to 86037 2964 to 3483 10476 to 16799 4595 to 5810 5810 to 7611 The secondary tank 30 for recondensing BOG
Size (m ³ ) 1312 to 1778 3506 to 32049 1714 to 2915 2989 to 12136 2160 to 5164 2405 to 7224 The temperature of the BOG cooled by the circuit 40 (in degrees Celsius) -178.2 to -180.4 -160.6 to -159 -172.6 to -170.5 -162.5 to -161 -167.6 to -165.7 -165.7 to -164 The ratio (%) of recondensed BOG after expansion caused by valve 52 93.16 to 100 81.63 to 98.86 87.94 to 100 82.49 to 100 85 to 100 84 to 100

Table 2 provides the same parameter types, but this time the liquefied natural gas is the most common liquefied gas composition, especially a mixture of gases containing methane or methane.

Big range Intermediate range Optimal range Pressure (mbara) 120 950 300 800 500 600 The ratio (%) of the evaporated gas after the depressurization (depressurization unit 19) 14.86 to 15.18 0.94 to 1.97 9.58 to 10.2 2.38-3.37 6.06 to 6.87 4.68 to 5.57 Of the cooling gas provided by the pump 35
Flow rate (t / h) 15.35 to 19.88 138 to 261.1 24.23 to 32.59 19.32 to 142.9 37.37 to 53.56 46.81 to 70.44 The flow rate (t / h) of the gas provided by the pump 16a 18.09 to 22.86 140.8 to 264 26.99 to 35.59 82.11 to 2146 40.14 to 56.59 49.58 to 73.48 And the second tank 30 when it is directly connected to the boom 22
Size (m ³ ) 1907 to 2028 20021 to 42375 2964 to 3317 10476 to 14470 4595 to 5504 5810 to 6750 The size (m ³ ) of the secondary tank 30 for reconditioning BOG, 1312 to 1523 3506 to 5944 1714 to 2090 2989 to 4482 2160 to 2811 2405 to 3268 The temperature of the BOG cooled by the circuit 40 (in degrees Celsius) -179.1 to -180 -160.6 to -159.5 -172.6 to -171.1 -162.5 to -161.4 -167.6 to -166.1 -165.7 to -164.7 Of the re-condensed BOG after expansion caused by the valve 52
ratio(%) 100 92.47 to 98.86 98.69 to 100 93.59 to 100 96.26 to 100 95.24 to 100

Depending on the charge height of the main tank, the hydrostatic pressure at the bottom end of the duct 18 is varied (the pump is maintained at approximately the same depth).

The temperature of the liquefied gas in the drum 24 is, for example, the same as "the temperature (° C.) of the BOG cooled by the circuit 40" minus 2 ° C., which corresponds to the "pinch effect" of the heat exchanger.

The following equation is used to calculate the ratio of the evaporated gas after depressurization:

X = (H1, u-H1, d) / (Hv, d-H1, d)

Wherein:

X is the mass fraction of the evaporated liquid,

Hl, d (J / Kg) is the upstream liquid enthalpy at the upstream temperature and pressure,

Hv, d (J / Kg) is the enthalpy of the vapor at the downstream pressure, which corresponds to the saturation temperature, and

Hl, d (J / Kg) is the enthalpy of the residual liquid at the upstream pressure, which corresponds to the saturation temperature.

Claims (17)

1. An apparatus (10, 110) for cooling a liquefied gas supplied to a power generating unit (12, 112)
- a main tank (14, 114) for storing liquefied gas (14a, 114a)
- a first drum (24) for separating cooled liquefied gas (24a), having a first input connected to a first end of a first duct (18, 118), the second end of the first duct The first duct being submerged in the liquefied gas contained in the main tank, the first duct being capable of supplying liquefied gas to the first drum,
- a pressure reducing unit (26, 126) of said first drum associated with said main tank, said pressure reducing unit being configured to provide an operating pressure in said first drum that is lower than the pressure inside said main tank,
At least a portion of the liquefied gas supplied to the first drum and at least another portion of the liquefied gas is cooled to a saturation temperature of the operating pressure in the first drum, And an evaporator unit (18, 19, 118) installed in the input section, the first drum being configured to separate the evaporative gas from the cooled liquefied gas, and
- means (22, 30, 32, 34, 40, 122, 130, 132, 134, 140) for supplying the cooled liquefied gas contained in the first drum to the main tank for cooling the gas contained in the main tank (10, 110). ≪ / RTI > 2. The apparatus according to claim 1, wherein the decompression unit comprises one input connected to the first gas output of the first drum (24) and a second input connected to the output of the first drum (24) 1 compressors (26, 126), said first compressor being capable of sucking at least a portion of said evaporating gas in said first drum and capable of operating said operating pressure in said first drum (10, 110). 3. A method according to claim 1 or 2, wherein said feeding means comprises a first end connected to a second cooled liquefied gas output of said first drum (24) and at least a second end connected to said main tank (14, 114) And a second duct (32, 132) having an end, said second duct being capable of injecting at least a portion of the cooled liquefied gas exiting said first drum into said main tank ). The method of claim 3,
Connected to the second end of the first duct (18, 118), preferably at the bottom of the barrel, for circulating the liquefied gas to the first drum (24) through the first duct A first pump 16a, 116a designed to be immersed in the liquefied gas contained in the main tanks 14, 114, and /
- a second pump (35) connected to said second duct (32) for circulating at least a portion of said cooled liquefied gas from said first drum to said main tank through said second duct Device (10,110). 5. The system of claim 3 or 4, wherein the second output of the first drum (24) is connected to the first input of a secondary tank (30, 130) to supply cooled liquefied gas to the tank Wherein the secondary tank is configured to receive the cooled liquefied gas at a pressure greater than the operating pressure. ≪ Desc / Clms Page number 17 > 6. The system of claim 5, wherein the secondary tank (30, 130) comprises a first output for at least a portion of the cooled liquefied gas connected to the second duct (32, 132) And at least a portion of the gas can be used to pass from the secondary tank to the main tank (14, 114). 7. A circuit according to claim 5 or 6, comprising at least one heat exchange circuit (40, 140), said circuit being connected to at least a portion of said cooled liquefied gas stored in said secondary tank, (10, 110). ≪ / RTI > The device (10, 110) according to claim 7, characterized in that the heat exchange circuit (40, 140) comprises an input connected to the natural evaporation output (45, 145) of the main tank (14, 114). 9. The compressor of claim 8, wherein said input of said circuit (40, 140) comprises at least one compressor (26, 28, 126). ≪ / RTI > 10. The apparatus according to claim 9, wherein the second heat exchanger (60) further comprises a primary circuit (60a) having an input section connected to the output of the third pump (16b) immersed in the liquefied gas of the main tank (14) , And a secondary circuit (60b) having an input connected to said first duct (18) and an output connected to said first drum (24). In particular, as a vessel used for conveying liquefied gas,
Characterized in that it comprises at least one device (10, 110) according to any one of the claims 1 to 10. A liquefied gas cooling method for a power generation unit (12, 112), in particular a ship, using an apparatus (10, 110) according to one of the claims 1 to 10,
- recovering the liquefied gas contained in the main tank and recovered at the collection temperature and circulated in said first duct,
A portion of the collected gas evaporates due to the expansion effect and the remaining portion of the collected gas remains a liquid and is cooled to a temperature lower than the collection temperature at an expansion pressure lower than the saturated vapor pressure of the gas collected at the collection temperature A step B for expanding the recovered gas,
- filling the first drum (24) and separating the evaporated gas from the cooled liquid gas in the first drum, in particular by gravity,
- supplying D to the apparatus with at least a portion of the vaporized gas contained in the first drum, and
Cooling the liquefied gas contained in the main tank using the cooled liquefied gas contained in the first drum to cool the gas contained in the main tank,
And cooling the liquefied gas. 13. An apparatus as claimed in claim 12, wherein, in order to cool the gas contained in the main tank, step E comprises circulating the cooled liquefied gas in the second duct and injecting And cooling the liquefied gas. 14. The method of claim 13,
- the gas from the first output of the first drum is compressed
And cooling the liquefied gas. 15. The method according to any one of claims 12 to 14,
The pressure inside the first drum is between 120 and 950 mbar, and / or
The pressure inside the main tank is 20 to 700 mbar, 20 to 350 mbar, or 20 to 250 mbar, and / or
- the evaporation rate caused by expansion is 0.94 to 15, 18%, and / or
- the flow rate in said first duct is 18.09 to 374.7 t / h, and / or
- the cooled liquefied gas flow rate in said first drum is between 15.35 and 371.6 t / h. 16. The apparatus according to any one of claims 12 to 15, wherein the apparatus is a device defined in claim 10,
After the expansion of the liquefied gas which can be partially or fully evaporated in the first drum and prior to injection, the liquefied gas collected in the main tank is preheated by heat exchange with the fluid circulating in the primary circuit And cooling the liquefied gas. 17. The method of claim 16,
And precooling the liquefied gas collected in the main tank by heat exchange with a fluid circulating in the secondary circuit, before being injected into the secondary tank.

Images