JP5411496B2 - Method and apparatus for diluting a liquefied natural gas stream - Google Patents

Description

  The present invention relates to a method and apparatus for extracting a natural gas liquid from a liquefied natural gas (LNG) stream (liquefied natural gas stream) to dilute the liquefied natural gas stream. The resulting dilute liquefied natural gas stream can be, for example, a liquid phase and / or a vapor phase utilized for subsequent regasification.

  In the present specification and claims, the term “deriching” is used as an opposite term for enrichment or enrichment to remove hydrocarbon compounds higher than methane, ie, “stoichiometric”. It is understood to include the meaning of “rip” or “thinner”. The term “natural gas liquid” is understood to include higher hydrocarbons than methane, such as ethane, ethylene, propane, propylene, butane and isomer variants thereof, and butylene and isomer variants thereof.

BACKGROUND OF THE INVENTION Liquefied natural gas usually contains higher hydrocarbon compounds such as various isomeric forms of ethane, propane, and butane in addition to methane. These additional compounds have a higher calorie than methane. Different standards for liquefied natural gas are required in various markets, particularly regarding the amount of heat.

Thus, to meet pipeline standards requiring low heat, it may be necessary to dilute the liquefied natural gas stream in the regasification facility before sending the regasification stream to the grid.
One method of dilution is to recover a natural gas liquid from a liquefied natural gas stream.

  US Pat. No. 6,604,380 discloses such a natural gas liquid recovery method. In the disclosed method, the liquefied natural gas feed stream is split. With particular reference to FIG. 2 of this patent, a portion of the split stream is heated in a heat exchanger, thereby partially vaporized and then fed to the feed separator. A bottom stream rich in natural gas liquid is withdrawn from the feed separator and guided to the path of the second separation process including the stabilizer. The other part of the split flow passes through this heat exchanger path and is supplied as external reflux to the second separation process at a very low temperature of about -157 ° C (-250 ° F). The methane-rich overhead vapor stream is withdrawn from the feed separator and stabilizer and combined into a heat exchanger where it is cooled against the portion of the split feed stream.

WO 2004/109180 discloses a method for treating LNG in a plant. In the plant, pressurized LNG is vaporized by a heat source and then expanded to work in an open power cycle.
It has been found that the above method is not always efficient.
US Pat. No. 6,604,380 WO 2004/109180 Article by Joseph Cho et al. "Innovative gas processing with various LNG sources", LNG Journal January / February 2005, pp 23-27.

SUMMARY OF THE INVENTION The object of the present invention is to minimize the above problems.
It is a further object of the present invention to provide an alternative method for diluting a liquefied natural gas stream.

One or more of the above objects or other objects provide a method according to the present invention for extracting a natural gas liquid from a liquefied natural gas stream to dilute the liquefied natural gas stream, comprising at least the following steps: Is achieved. That is, this method
Heating a feed stream comprising a liquefied natural gas stream in a first heat exchanger array to form an intermediate feed stream;
Dividing the intermediate feed stream into at least a first portion and a second portion;
Passing the first portion through a distillation column and supplying the first portion via a first feed point;
Passing the second part through a second heat exchanger arrangement, wherein the second part is further heated, and then the heated second part is fed to the distillation column via a second feed point;
Removing the natural gas liquid-containing liquid stream from the bottom of the distillation column;
A process of taking the top vapor stream from the top of the distillation tower,
The overhead vapor stream is passed through a second heat exchanger arrangement, where the overhead vapor stream is cooled by a second portion of the intermediate feed stream to form an intermediate dilute stream, and then the intermediate dilute stream Passing at least a portion through the first heat exchanger arrangement and further cooling with the raw material stream to form a dilute natural gas product stream;
including. Here, during cooling of the overhead vapor stream in the second heat exchanger arrangement, the vapor stream is partially condensed to form an intermediate condensate and an intermediate vapor, at least a portion of the intermediate condensate being Via three feed points, it is passed to the distillation column and the intermediate steam is passed to the first heat exchanger arrangement.

  An advantage of the present invention is that it gives more flexibility in the choice of temperature distribution in the distillation column, thereby facilitating efficient control of process conditions in the distillation column.

  Furthermore, it has been found that the use of an intermediate dilute stream to generate a reflux stream significantly improves natural gas liquid recovery. The overhead vapor stream from the distillation column is partially condensed during cooling in the second heat exchanger, so that the intermediate dilute stream contains intermediate condensate and intermediate steam, the intermediate condensate being the third feed point. Can be passed through to the distillation column, and the intermediate steam can be passed through the first heat exchanger arrangement.

  A further advantage is that the intermediate condensate is rich in heavy components including natural gas liquids. This condensate is re-supplied to the distillation column as internal reflux instead of being supplied to the first heat exchanger arrangement. Thus, the recovery rate of natural gas liquid is significantly improved.

  By selecting relative cooling in the first and second heat exchanger arrangements, an intermediate temperature can be selected in the intermediate dilute stream where the condensate composition can be made to order.

  Another advantage of the present invention is that heating and cooling are respectively performed in at least two stages upstream and downstream of the distillation column. Thus, the intermediate stream obtained between at least two stages is effective for using the present method in addition to the fully heated and cooled streams, respectively.

  One method of utilizing an intermediate feed stream is to use it as an external reflux that is not as cold as the original feed stream but is cooler than the portion fed to the distillation column via the second feed point.

  It has been found that an external reflux stream having a temperature as low as liquefied natural gas (around -157 ° C or below -140 ° C) is generally not required to effectively separate natural gas liquid components from liquefied natural gas. It was. An advantage of the present invention is that the temperature of the external reflux can be selected higher than the feed stream, for example higher than -140 ° C. As a result, devices such as distillation columns or reboilers (if equipped) can be miniaturized and less power is consumed in the reboiler. Thus, high quality coldness in the feed stream is sufficient for recondensing dilute natural gas.

  Depending on the amount of heat applied to the first heat exchanger arrangement and the pressure of the feed stream, the intermediate feed stream may be completely liquid or partially vaporized.

  When the feed stream heating step in the first heat exchanger arrangement includes a partial vaporization step of the feed stream, whereby the intermediate feed stream comprises a mixture of a liquid intermediate feed fraction and a vaporous intermediate feed fraction, at least liquid The intermediate raw material fraction is advantageously divided into at least the first part and the second part. Since the vaporous intermediate feed fraction is relatively cool compared to the temperature after the second heating, it is already relatively lean from the natural gas liquid and does not require further distillation. This fraction can be mixed in or with the final product stream.

  In a further aspect, the present invention provides a dilute natural gas stream obtained by the method of the present invention and an apparatus suitable for carrying out the present invention.

Preferred embodiments for the apparatus can be derived from the preferred embodiments and / or detailed description of the embodiments described below.
The features of the invention described above and other features will be further described by way of example and with reference to the accompanying non-limiting drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings, FIGS. 1 and 2 show an overview of system processes and apparatus incorporated for illustrative purposes, but not all features of the present invention.
FIG. 3 shows an outline of the system process and apparatus of the present invention.

FIG. 4 outlines a preferred embodiment of the present invention combining the system steps of FIG. 2 with the system steps of FIG.
For purposes of this description, like numerals correspond to like parts. The symbols corresponding to the lines are also used to refer to the respective flows that flow through these lines.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of an apparatus for extracting a natural gas liquid from a liquefied natural gas stream and diluting the liquefied natural gas stream. The raw material line 1 can be connected to a supply source of liquefied natural gas. An optional pump 3 is provided in the raw material line 1 and its high-pressure outlet is able to communicate with the first heat exchanger array 5 via the line 2.

  The intermediate raw material line 7 is fluidly connected to the outlet 6 of the first heat exchanger array 5 provided with the distributor 14. The distributor 14 has two outlets connected to the lines 17 and 19. If desired, the distributor 14 has more than two outlets. The line 17 is connected to the distillation column 21 via an optional first control valve 23 and a first supply point 25 provided at the upper portion of the distillation column 21. The other line 19 is connected to the distillation column 21 except for the second heat exchanger array 26 and the other via the line 20. The line 20 can optionally include a second control valve 27 and a second supply point 29. In this manner, the first outlet 6 of the first heat exchanger array 5 can be circulated with the second heat exchanger array 26. The line 17 passes through a path that bypasses the second heat exchanger array 26. The second supply point 29 of the distillation column 21 is preferably arranged to be lower than the first supply point 25 in a gravitational manner.

  The distillation column 21 has a lower part with a discharge port 31 for taking out the liquid stream 35 from the column 21. An optional reboiler 33 may be provided in the line 35 connected to the outlet 31. The reboiling return line 37 feeds back from the reboiler 33 to the lower part of the distillation column 21. The optional reboiler 33 may be integrated with the distillation column 21 instead of the external arrangement shown. Line 38 is connected to line 35 or to an optional reboiler 33 for natural gas liquid discharge.

  The distillation column 21 also has an upper part with a top vapor outlet 39. The tower top steam outlet 39 can communicate with the first heat exchanger array 5 via the second heat exchanger array 26. Line 40 extends between overhead vapor outlet 39 and second heat exchanger array 26 and connects to line 48, and line 48 is between second heat exchanger array 26 and first heat exchanger array 5. It extends and is connected via a second outlet 41 of the first heat exchanger array 5 to a line 55 downstream of the first heat exchanger array 5.

  Line 55 may be provided with an optional pump 65 that discharges to line 67 to increase the pressure at which the diluted liquefied natural gas is produced at a certain pressure in accordance with local standards. Line 67 is the title “Innovative gas processing with various LNG sources” by Joseph Cho et al., LNG Journal January / February, 2005, pp23-27, the contents of which are incorporated by reference from 2005 to pp23-27. It can be connected to any kind of regasification system, including known systems.

  The apparatus can extract a natural gas liquid from a liquefied natural gas stream to dilute the liquefied natural gas stream. An optional bypass line 59 may be provided to fluidly connect the high pressure outlet of the pump 3 upstream of the line 1 or the first heat exchanger array 5 with the line 55 downstream of the first heat exchanger array 5. The optional bypass line 59 can include a control valve 61. By the bypass line 59, the diluting array can be bypassed and the extraction of the natural gas liquid can be avoided.

  The apparatus of FIG. 1 works as follows during operation. A feed stream containing a liquefied natural gas stream is fed via feed line 1 and heated in the first heat exchanger array 5 by the intermediate dilute stream in line 48 to form an intermediate feed stream 7. Prior to feeding the feed stream 1 to the first heat exchanger array 5, the feed stream can be pressurized or its pressure can be increased using an optional pump 3. This is particularly useful when liquefied natural gas is supplied at or near normal pressure.

  The intermediate feed stream 7 is divided into at least a first part 17 and a second part 19 in the distributor 14. The first portion 17 is passed through the distillation column 21 and fed into the column via the first feed point 25. The pressure and temperature can be controlled using the control valve 23.

  The second portion 19 of the intermediate feed stream 7 is passed through a second heat exchanger arrangement 26 where the second portion is further heated by the overhead stream in line 40. The further heated stream is then fed to the distillation column 21 via the line 20 and the second feed point 29. The pressure can be controlled using the control valve 27.

  During further heating in the second heat exchanger arrangement 26, the second portion 19 of the intermediate feed stream 7 is at least partially vaporized. It is generally recommended to evaporate to a molar fraction of at least 60%.

  If the temperature of the first part 17 can be lower than the temperature of the second part 19, the first part 17 acts as an external reflux stream in this distillation process. The first portion 17 helps to scrub the natural gas liquid from the vapor generated in the second portion 19 and optional reboiler 33. If the first supply point 25 is preferentially positioned higher than the second supply point 29, scrubbing is facilitated.

  The natural gas liquid-containing liquid stream is then withdrawn into the line 35 from the lower part of the distillation column 21 via the outlet 31. Optionally, the liquid stream is heated and partially fed back to the bottom of the distillation column 21 via line 37 to form some vapor containing relatively light molecules. The remainder is discharged to line 38 as natural gas liquid.

  On the other side of the distillation column 21, a top vapor stream 40 is taken from the top of the column 21. The overhead vapor stream 40 is a dilute stream that contains primarily methane and sometimes other components such as ethane and the remainder of the propane.

  The overhead vapor stream 40 is passed to the second heat exchanger arrangement 26, where the overhead vapor stream is cooled by the intermediate feed stream to form an intermediate dilute stream 48, which is then the intermediate diluted stream. At least a portion is passed through the first heat exchanger array 5 and further cooled by the feed stream 1 to form a dilute natural gas product stream 55. The product stream 55 can be fully recondensed.

  Optionally, product stream 55 is combined with a detour stream extracted from feed stream 2 via line 59. The product stream pressure in line 55 can then be raised to a desired pressure level by optional pump 65. Pump 65 is generally more energy efficient because the flow in line 55 is generally sufficiently susceptible to condensation. The product stream is discharged from line 67 and can then be further processed (not shown), for example regasification, which converts the product stream to a gaseous stream by heating. Some possible regasification methods are described in the LNG Journal January / February 2005 article.

  Although not strictly necessary, in order to ensure that the product stream in the line 55 leaving the outlet 41 of the first heat exchanger arrangement 5 is not only sufficiently recondensed, but is also supercooled to a satisfactory level, The line 40 can be provided with an optional compressor (not shown) so that a sufficient margin can be provided. The installation of the compressor is not very important when a substantial amount of the feed stream 2 is diverted via the line 59. This is because the product stream leaving the first heat exchanger array 5 is directly subjected to heat exchange.

  The advantage of having two heat exchanger arrangements 5, 26 is that the intermediate streams 7 and / or 48 are useful for use in the present method. In the embodiment of FIG. 1, a part of the intermediate stream 7 (first part 17) is not as cold as the feed stream 1 but is fed to the distillation column 21 via the second feed point 29 (second part 19). It is used as a lower temperature external reflux. With an appropriate balance of heating capacity in the first heat exchanger array 5 vs. the second heat exchanger array 26, the reflux stream 17 and the one possible with the method described in US Pat. No. 6,604,380 Furthermore, improved temperature control for the heated feed stream 20 is achieved. Such increased flexibility allows efficient control of process conditions in the distillation column 21 and achieves the desired separation of the top stream 40 and bottom stream 38 for selected natural gas liquid components. .

  FIG. 2 shows a gas / liquid separator 9 (based on the embodiment shown and described above for FIG. 1 and arranged at the connection between the first outlet 6 of the first heat exchanger arrangement 5 and the distributor 14. In the claims, "second gas / liquid separator" is indicated. This gas / liquid separator is provided here in the form of a raw material separation vessel 9. The first outlet 6 of the first heat exchanger array 5 is connected to the raw material separation container 9. The raw material separation container 9 has a bottom outlet 11 and a top outlet 13. The bottom outlet 11 is connected to a distributor 14 via a line 15. The top outlet 13 is fluidly connected to a line 48 via a line 15 upstream of the first heat exchanger array 5.

  The embodiment of FIG. 2 works as follows. When the feed stream is heated in the first heat exchanger array 5, the feed stream can be partially vaporized. Vapor is withdrawn from the top outlet 13 and combined with the intermediate dilute stream in line 48. This combined stream is then further cooled and recondensed together in the first heat exchanger array 5 by the feed stream 2.

  Since the temperature is still relatively low, the vapor mainly contains more dilute components such as methane. Components such as propane, which have a higher calorific value, are still essentially sufficient, together with ethane and methane, in this liquid phase. The vaporized fraction does not need to be further distilled and can be mixed with the distillation stream in line 48 and recondensed in the first heat exchanger arrangement 5.

  The mole fraction of steam can range from 1 to 90%. The higher the steam mole fraction, the lower the mass load downstream of the extractor. In this respect, the composition of the normal liquefied natural gas is preferably 50 mol% or more in the vapor phase. On the other hand, the higher the mole fraction of the vapor, the lower the natural gas liquid recovery rate because the material separation in the separation vessel is not as high as in the case of the distillation column 21. In this respect, the mole fraction of steam is preferably 80% or less.

  The liquid withdrawn from the bottom outlet 11 of the separator 9 is guided to the distributor 14, where a part of the liquid is sent as an external reflux to the distillation column 21 via line 17, whereby a second heat exchanger arrangement. Detour 26.

  The advantage of this embodiment is that the external reflux can be fully effective as a scrubbing medium because it is completely liquid. The temperature of the external reflux is lower than the temperature of the portion fed to the distillation column via the second feed point 29, but not as low as the temperature of the original feed stream 1. The temperature can be controlled in a joint (co) dependency that arbitrarily controls the amount of expansion at the control valve 23 by selecting the amount of heat exchange in the first heat exchanger array 5.

  An advantage of the optional control valves 23, 27 is that the distillation column 21 is operated at a lower pressure than the raw material separator 9, thereby improving the separation efficiency of the natural gas liquid component in the column 21.

  Still referring to FIG. 2, an optional top compressor 63 may be provided between the top vapor outlet 39 of the distillation column 21 and the second heat exchanger array 26. This can compensate for any pressure drop across the valves 23, 27, thus allowing the pressure in the line 48 to reach the pressure level set by the feed flow in the line 7.

  The top stream 40 is always sufficiently vaporous thanks to the distillation column 21, whereas the product stream can be multiphase downstream of the second heat exchanger array 26, so that the second heat exchanger array It is preferable to arrange the compressor 63 upstream of 26.

  Alternatively, line 57 can include an expansion device such as a Joule-Thompson valve (not shown) to reduce the pressure in line 57 to the pressure in line 48. 1 and FIG. 2 have been described above. FIG. 3 is based on the embodiment shown and described with reference to FIG. 1, and the top steam outlet 39 of the distillation column and the first heat exchanger arrangement are shown in FIG. 5 with an internal reflux system in the connecting line 48 between the two. The reflux system shown here has a gas / liquid separator (referred to as “first gas / liquid separator” in the claims) provided in the form of a reflux separation vessel 43. The reflux separation vessel 43 is arranged in the line 48 downstream of the second heat exchanger array 26 and is connected to the second heat exchanger array 26 via the line 42. Separator 43 has a bottom outlet 45 and a top outlet 47. The bottom outlet 45 is connected to the distillation column 21 via a line 49 and a third supply point 51 for supplying a reflux stream. An optional control valve 53 can be provided in the line 49. In general, the temperature of the reflux stream 49 is lower than the temperature of the further heated feed stream 20 and gravitationally lower than the first supply point 25, so that the third supply point 51 is more gravitational than the second supply point 29. It is best to place it higher.

The top outlet 47 of the reflux separation vessel 43 is fluidly connected to the first heat exchanger array 5 via a line 48.
In operation, when a liquefied natural gas feed stream containing methane, ethane and propane is fed to the process, most of the propane is recovered in the distillation column 21. If the remaining propane components that may be present in the overhead vapor stream 40 are condensed in the second heat exchanger 26, the selective recovery of propane can be increased. The intermediate condensate 49 is extracted from the reflux separation vessel 43 and fed back to the distillation column 21 as a cold reflux stream. Propane also has the opportunity to leave the process via outlet 31.

  Since the second heat exchanger arrangement 26 only brings the intermediate dilute stream to an intermediate temperature, the material selectivity of the reflux stream is made as ordered by this temperature selection and by any pressure drop at the optional valve 53. it can. Furthermore, it is avoided that methane or ethane is unnecessarily circulated through the distillation column, thereby only consuming energy and not increasing the production of dilute natural gas leaving the process via line 55.

  Comparing the system process of FIG. 1 (not including all the features of the present invention) and the system process of FIG. 3 (according to the present invention), the calculation based on the prediction of the propane recovery rate shows that the method using the system process of FIG. While the propane recovery rate of 69% was obtained under the predetermined process conditions, the method according to the system process of FIG. 3 gave a propane recovery rate of 90% under the same predetermined process conditions.

  The mole fraction of steam can usually be 50-95%. The higher the mole fraction of steam, the less and better the amount of dilute components circulating in the reflux loop. In this respect, 60 mol% or more is preferably a vapor phase. On the other hand, the higher the molar fraction of the vapor, the less the natural gas liquid component is recondensed and the feedback to the distillation column 21, so the recovery rate of the natural gas liquid becomes lower. In this regard, the most common liquefied natural gas composition preferably has a vapor mole fraction of 90% or less.

  FIG. 4 is a schematic diagram of a preferred embodiment of the present invention combining the methods and apparatus shown in FIGS. For the detailed description, reference is made to the description of FIGS.

  Table I below shows the recommended lower and upper limits of the temperature and pressure of the flow through the various lines in this method, as well as the normal values of temperature and pressure for specific operating examples.

In the examples shown in Table I, the vapor mole fraction in line 7 was 66% and in line 20 it was 69%. The vapor mole fraction in line 20 was 75%. Based on mass balance calculations, the apparatus and method of FIG. 4 was expected to provide an efficient means for recovering natural gas liquid components from a liquefied natural gas feed stream with a recovery rate exceeding 90%. .
In the context of the present invention, the heat exchanger arrangement can comprise one heat exchanger or a plurality of heat exchangers in parallel and / or in series.

It does not include all the features of the present invention, but outlines the system processes and equipment taken for illustrative purposes. It does not include all the features of the present invention, but outlines the system processes and equipment taken for illustrative purposes. The outline of the system | strain process and apparatus of this invention is shown. Fig. 4 shows a schematic of a preferred embodiment of the present invention combining the system steps of Fig. 2 with the system steps of Fig. 3;

Explanation of symbols

1 liquefied natural gas stream or feed stream 5 first heat exchanger array 6 outlet of first heat exchanger array 7 intermediate feed stream 9 second gas / liquid separator 11 outlet of second gas / liquid separator 14 distributor 15 Liquid intermediate feed fraction 17 First portion 19 of the intermediate feed stream Second portion 20 of the intermediate feed stream Heated second portion 21 Distillation tower 25 First feed point 26 Second heat exchanger array 29 Second feed point 35 Natural gas liquid Containing liquid stream or natural gas liquid 39 Overhead steam outlet 40 Overhead steam stream 43 First gas / liquid separator or first separator 45 First separator outlet 47 First separator outlet 48 Intermediate dilute stream 49 At least a part of the intermediate condensate 51 Third feed point 55 Product stream of diluted natural gas 57 Steam intermediate raw material fraction 63 Compressor

Claims (11)

In a method of diluting a liquefied natural gas stream (1) by removing hydrocarbon compounds higher than methane in the form of a natural gas liquid (35) from the liquefied natural gas stream,
Heating a feed stream (1) comprising a liquefied natural gas stream in a first heat exchanger array (5) to form an intermediate feed stream (7);
Dividing the intermediate feed stream (7) into at least a first part (17) and a second part (19);
Passing the first part (17) through the distillation column (21) and supplying the first part (17) via the first feed point (25);
The second part (19) is passed through a second heat exchanger array (26), where the second part is further heated,
Next, supplying the heated second part (20) to the distillation column (21) via the second supply point (29),
Removing the natural gas liquid-containing liquid stream (35) from the lower part of the distillation column (21);
Removing the top vapor stream (40) from the top of the distillation column (21);
The overhead vapor stream (40) is passed through a second heat exchanger arrangement (26) where the overhead vapor stream (40) is cooled by the second part (19) of the intermediate feed stream (7) A dilute stream (48) is formed and then at least a portion of the intermediate dilute stream is passed through a first heat exchanger array (5) and further cooled by a feed stream (1) to produce dilute natural gas. Forming the logistics (55);
And during cooling of the overhead vapor stream (40) in the second heat exchanger arrangement (26), the vapor stream is partially condensed to form intermediate condensate and intermediate vapor, the intermediate condensate At least a portion of (49) is passed to the distillation column (21) via a third feed point (51) and the intermediate steam is passed to the first heat exchanger arrangement (5).   The step of heating the raw material stream in the first heat exchanger arrangement (5) includes a step of partially vaporizing the raw material stream, whereby the intermediate raw material stream (7) is a liquid intermediate raw material fraction and a vaporous intermediate raw material fraction. And at least the liquid intermediate feed fraction (15) is divided into at least the first part and the second part (17, 19).   The mixture is passed through the raw material separation vessel (9), from which the liquid intermediate raw material fraction (15) and the vaporous intermediate raw material fraction (57) are divided into the at least first part and the second part (17, 19). The method according to claim 2, wherein each is extracted before performing. The method according to any one of claims 1 to 3, wherein the second supply point (29) is arranged at a position gravitationally lower than the first supply point (25). The method according to any one of the preceding claims, wherein the third supply point (51) is at a position that is gravitationally lower than the first supply point (25). The method according to any one of the preceding claims, wherein the third supply point (51) is at a position that is gravitationally higher than the second supply point (29). The method according to any one of the preceding claims, wherein the overhead vapor stream (40) is compressed before passing through the second heat exchanger arrangement (26). The method according to any one of claims 1 to 7, wherein the dilute natural gas product stream is subsequently regasified. In an apparatus for diluting a liquefied natural gas stream (1) by removing hydrocarbon compounds higher than methane in the form of a natural gas liquid (35) from the liquefied natural gas stream,
A liquefied natural gas stream comprising a discharge outlet (6) for an intermediate feed stream (7) formed by heating a feed stream (1) comprising a liquefied natural gas stream in a first heat exchanger arrangement (5) Raw material stream containing (
1) the first heat exchanger arrangement (5) arranged for receiving;
A second heat exchanger array (26) in communication with the outlet (6) of the first heat exchanger array (5);
It has at least first, second and third supply points (25, 29, 51), is provided with a discharge outlet (31) for removal of the natural gas liquid-containing liquid stream (35) in the lower part and at least in the upper part. A distillation column (21) with a top steam outlet (39) that can communicate with the first heat exchanger array (5) via a second heat exchanger array (26);
A first outlet connected to the first supply point (25) of the distillation column (21) and a second outlet (29) connected to the second supply point (29) of the distillation column (21) via the second heat exchanger array (26). A distributor (14) having two outlets and connected to the outlet (6) of the first heat exchanger array (5); and the first separator (43) is a third feed point (51 ) And an outlet (47) capable of communicating with the first heat exchanger array (5), downstream of the top steam outlet (39) and in the second heat exchanger array ( 26) and a first gas-liquid separator (43) between the first heat exchanger arrangement (5);
The device.   The second gas-liquid separator (9) with an inlet connected to the outlet (6) of the first heat exchanger arrangement (5) and a bottom outlet (11) connected to the distributor (14). 9. The apparatus according to 9.   The apparatus according to claim 9 or 10, further comprising a compressor (63) between the outlet (39) of the distillation column (21) and the second heat exchanger array (26).