JPH10114502A - Separation of hydrogen and methane from gaseous hydrocarbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably decrease the power of a refrigerator by dimishing the refigerant energy for separating hydrogen and methane as compared with the conventional method and to increase the output by eliminating the problem that an existing demethanton tower control the production rate. SOLUTION: Gaseous hydrogen is recovered from a high-pressure current of gaseous hydrocarbons contg. hydrogen in a hydrogen separator S-1. The gaseous hydrocarbons are successively cooled in at least two temp. zones arranged in series and separated into into gas and liq., the condensate is supplied to a methane separation stage (predemethanation tower T-1 or demethanation tower T-2), the uncondensed gas is supplied to the succeeding temp. zone, gaseous methane is recovered in the methane separation stage, and a condensate substantially free of methane is recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for separating hydrogen and methane from gaseous hydrocarbons.
The present invention relates to a method for efficiently separating hydrogen and methane from gaseous hydrocarbons containing hydrogen, methane, ethylene and ethane obtained at the time of, for example, thermal cracking of a hydrocarbon oil.

[0002]

2. Description of the Related Art Conventionally, hydrogen, methane, ethane, propane, and the like obtained by pyrolyzing hydrocarbon oils such as naphtha, etc.
There is known a method of separating hydrogen and methane from a gaseous hydrocarbon containing ethylene, propylene, and the like by a cryogenic separation method. An example of such a method is a method described in Japanese Patent Publication No. 3-53289.

The above method is performed as follows using the process of the flow diagram shown in FIG. The gaseous hydrocarbon is converted into a high-pressure gas stream by the compressor (C-1), and then cooled by a water cooler (W-1) and heat exchangers (H-1) to (H-1).
In -4), cooling is performed sequentially. Then, the hydrocarbon mixture condensed in the respective temperature zones of these heat exchangers is separated from the uncondensed gas in the corresponding gas-liquid separators (D-1) to (D-4).

The separated liquid extracted from the bottom of the gas-liquid separator (D-1) is supplied to a gas-liquid contactor (T-1) (pre-demethanizer) to be purified. The distillate gas in the gas-liquid contact device is extracted from the top of the tower, cooled by the heat exchanger (H-6), and then supplied to the medium-pressure rectification tower (T-2) (demethanizer). . The separated liquid extracted from the bottom of the gas-liquid separators (D-2) to (D-4) is supplied to the demethanizer (T-2).

[0005] A methane-based fraction obtained from the top by being purified by the demethanizer (T-2) is cooled by a heat exchanger (H-5), and then cooled by a gas-liquid separator (D). -5)
By this, an uncondensed gas mainly composed of methane and a condensate are separated, and a part of the condensate is returned to the demethanizer (T-2). From the bottom of the demethanizer (T-2), a hydrocarbon mixture containing ethylene and a hydrocarbon having a higher boiling point is obtained.

[0006] The uncondensed gas in the gas-liquid separator (D-4) is further cooled by the heat exchanger (H-7), and is not condensed in the gas-liquid separator (D-6). It is separated into condensate mainly composed of gas and methane.

[0007]

However, in the above method, since a large amount of hydrogen is contained in the gaseous hydrocarbon sent to the cooling step, ethylene is condensed.
It is necessary to lower the temperature of each separator. For this reason, the refrigerant used in each refrigerant heat exchanger requires a lower temperature and a larger amount. Furthermore, the gas-liquid separators (D-1) to (D
Since the amount of the separated liquid separated by -4) and the amount of methane contained therein are large, the liquid load in the demethanizer (T-2) is large. Therefore, when the production volume is to be increased, the capacity of the demethanizer is the rate-limiting factor (bottleneck).

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to significantly reduce the power of a refrigerator by reducing the refrigerant energy required for separating hydrogen and methane from the conventional method. Another object of the present invention is to provide a method for solving the problem that the existing demethanizer is production-limited, thereby achieving an increase in production.

[0009]

That is, the gist of the present invention is a method for separating hydrogen and methane from a high-pressure gas stream of a gaseous hydrocarbon containing at least hydrogen, methane, ethane and ethylene, 1) prior to cooling said hydrogen-containing gaseous hydrocarbon, recovering hydrogen gas from said high-pressure gas stream of hydrogen-containing gaseous hydrocarbon using a hydrogen separator capable of substantially separating only hydrogen gas; (2) In at least two or more temperature zones arranged in series, the above-mentioned gaseous hydrocarbons are sequentially cooled and separated into gas and liquid in each temperature zone, and the separated condensate is subjected to a methane separation step. And the uncondensed gas is supplied to the next temperature zone,
(3) A method for separating hydrogen and methane from gaseous hydrocarbons, wherein in the methane separation step, a methane gas is recovered and a condensate containing substantially no methane is recovered.

In a preferred embodiment of the present invention, in addition to the above configuration, the methane separation step of (3) above comprises a pre-demethanizer and a demethanizer, and the above-mentioned (3) is carried out using a dephlegmator. 2) recovering a gas substantially free of ethylene from the uncondensed gas in the final temperature zone of the sequential cooling step, separating a condensate rich in ethylene components, and separating the condensate into a demethanizer; The high-boiling hydrocarbon component substantially free of methane is recovered from the condensate obtained in the sequential cooling step (2) and the low-boiling component gas rich in methane is separated from the condensate obtained in the sequential cooling step in the pre-demethanizer column. Then, the separated gas is supplied to a demethanizer, in which a methane gas is recovered and a condensate substantially free of methane is recovered.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings. FIG. 1 is a process flow diagram showing an example of a preferred embodiment of the present invention, and FIG. 2 is a process flow diagram showing another embodiment of the present invention. In each figure, C-1 is a compressor, W-1 is a water cooler, S-1 is a hydrogen separator, H-1 to H-7 are heat exchangers, D-1 to D-6.
Is a gas-liquid separator, T-1 is a pre-demethanizer, T-2 is a demethanizer, and DEP-1 is a dephlegmator.

The process shown in FIG. 1 mainly includes a compressor (C-1), a hydrogen separator (S-1), and a water cooler (W-
1), heat exchangers (H-1) to (H-6), gas-liquid separators (D-1) to (D-3) and (D-5), a pre-demethanizer (T-1), It consists of a demethanizer (T-2) and a dephlegmator (DEP-1).

In the present invention, a gaseous hydrocarbon containing at least hydrogen, methane, ethylene and ethane is used as a raw material gas. In particular, gaseous hydrocarbons obtained by thermal decomposition of naphtha or the like are preferably used. The hydrogen-containing gaseous hydrocarbon is compressed by the compressor (C-1) to form a high-pressure gas stream. Incidentally, SO _x and CO ₂ present in the gaseous hydrocarbon is to contact treatment with an alkali solution after the compression process or compression, it is preferable to remove these acidic gases.

The preferred pressure of the high pressure gas stream is 20
５０50 kg / cm ² G (about ^{2 to} 5 MPa). If the pressure is less than 20 kg / cm ² G (about 2 MPa), the high pressure gas stream will eventually need to be cooled to a temperature below −160 ° C. If the pressure exceeds 50 kg / cm ² G (about 5 MPa), the power required for compressing the gas is increased more than necessary, and in any case, it is uneconomical.

First, before cooling the hydrogen-containing gaseous hydrocarbon, the hydrogen separator recovers hydrogen gas from the high-pressure gas stream of the hydrogen-containing gaseous hydrocarbon in the hydrogen separator (S-1). Separate hydrocarbons. Hydrogen separator (S-
The temperature of the hydrogen-containing gaseous hydrocarbon in 1) is usually 5
0-250 ° C.

In the present invention, "before cooling of a hydrogen-containing gaseous hydrocarbon" means "before cooling for cryogenic separation necessary for separating methane, ethylene, etc." Cooling from the naphtha decomposition temperature to a temperature that is easy to handle, cooling against temperature rise due to compression, or cooling in the process of previously separating high-boiling hydrocarbons having 3 or more carbon atoms may be performed in advance.

As the hydrogen separator (S-1), a separation membrane capable of selectively permeating and separating hydrogen in gaseous hydrocarbons is preferably used. As the separation membrane, a metal membrane capable of selectively permeating hydrogen from gaseous hydrocarbons, particularly a palladium membrane, a palladium alloy membrane or a platinum membrane is suitably used. These metal films are preferably used while being held by a support member such as silica, alumina, or a mixture thereof.

Since the hydrogen separated by the hydrogen separator (S-1) is substantially only hydrogen, it can be used not only as a fuel but also as a raw material for a hydrogenation reaction in an adjacent plant. .

Next, in at least two or more temperature zones arranged in series, the above-mentioned gaseous hydrocarbon is sequentially cooled to separate gas and liquid in each temperature zone. Then, the separated condensate is supplied to the pre-demethanizer (T-1) and the demethanizer (T-2). In this case, the condensate separated in the first temperature zone by gas-liquid separation is usually supplied to a pre-demethanizer (T-
The condensate separated into gas and liquid in the second and subsequent temperature zones is supplied to the demethanizer (T-2). Uncondensed gas is supplied to the next temperature zone.

The temperature zones in which the above-mentioned gas-liquid separation is performed are defined as the heat exchangers (H-1) to (H-3) and the gas-liquid separators (D-1) to (D- The process shown in FIG. 1 has three temperature zones for performing gas-liquid separation. That is, the gaseous hydrocarbon whose hydrogen concentration has been reduced by the separation membrane is sequentially cooled by the water cooler (W-1) and the heat exchangers (H-1) to (H-3).
The condensed liquid is sequentially separated by the gas-liquid separators (D-1) to (D-3).

The high-pressure gas stream having passed through the separation membrane is cooled to room temperature by a water cooler (W-1), and is cooled by a heat exchanger (H-).
1) to (H-3), the gas-liquid separator (D)
-1) to (D-3) are successively separated into condensed liquids. At this time, the cooling temperature of the heat exchangers (H-1) to (H-3) depends on the hydrogen separator (S-1). The temperature is set within a specific temperature range according to the amount of separated hydrogen. For example, a heat exchanger (H-
At the outlet of 1), in the temperature range of -20 ° C to -40 ° C,
−40 ° C. to −70 ° C. at the outlet of the heat exchanger (H-2)
-7 at the outlet of the heat exchanger (H-3) in the temperature range of
The amount of heat exchange with the refrigerant is adjusted so as to be in a temperature range of 0 ° C. to −90 ° C.

By the above temperature setting, each gas-liquid separator (D
-1) to (D-3) and the amount and composition of the condensate in the dephlegmator (DEP-1) described below can be adjusted. As a result, the amount of refrigerant used in the heat exchanger can be reduced and the temperature of the refrigerant can be increased, so that the power of the refrigerator can be reduced, and the amount of liquid supplied to the demethanizer (T-2) can be reduced. In addition, the throughput of gaseous hydrocarbons can be increased. Further, the reduction in the amount of uncondensed gas supplied to the dephlegmator apparatus not only allows the downsizing of the dephlegmator apparatus, but also improves the separation performance of the dephlegmator apparatus.

The heat exchanger (H-1) contains refrigerant propylene, and the heat exchangers (H-2) to (H).
In -5), refrigerant liquid ethylene is used as a refrigerant source for the low-temperature side liquid.

-20 ° C to-
The high-pressure gas stream cooled to a temperature range of 40 ° C. is subjected to gas-liquid separation by a gas-liquid separator (D-1). The separated condensate is supplied to the upper part of the pre-demethanizer (T-1).
This condensate contains a lot of relatively high boiling hydrocarbons but also contains methane. For example, when a naphtha pyrolysis gas is used, the bottom liquid containing about 10 to 25 mol% of methane and containing substantially no methane in the pre-demethanizer (T-1) and the top of methane-rich column It is separated into distillate gas.

The pre-demethanization tower (T-1) is provided with a plate or a packing for gas-liquid contact in the tower, similarly to a normal rectification tower. When the condensate supplied to the tower falls in the tower, the liquid that has reached the lower part of the tower is heated by a heating source (not shown) at the bottom of the tower and is brought into countercurrent contact with the upward flow of hydrocarbons generated. Then, methane evaporates and high-boiling components condense. The bottom liquid is withdrawn from the bottom. The methane-rich distillate gas passes through a heat exchanger (H-6), and then is demethanized (T-2).
Is supplied to the upper stage.

The uncondensed gas in the gas-liquid separator (D-1) is supplied to a heat exchanger (H-2) and is supplied from -40.degree.
After being cooled to a temperature range of ° C., it is supplied to a gas-liquid separator (D-2) to be separated into gas and liquid. The separated condensate is withdrawn from the bottom of the column and supplied to the demethanizer (T-2).

On the other hand, the uncondensed gas is supplied to a heat exchanger (H-3).
And cooled to a temperature range of -70 ° C to -90 ° C, and then supplied to a gas-liquid separator (D-3) for gas-liquid separation. The separated condensate is withdrawn from the bottom of the column and supplied to the demethanizer (T-2).

Next, a dephlegmator (DEP-
In 1), a gas substantially free of ethylene is recovered from the uncondensed gas in the final temperature zone, and a condensate rich in ethylene is separated, and the separated condensate is demethanized ( T-2). That is, the uncondensed gas in the gas-liquid separator (D-3) is cooled by the heat exchanger (H-4) as necessary, and then supplied to the dephlegmator (DEP-1).

The dephlegmator (DEP-1)
The supplied gas is separated into a gas containing methane as a main component and a condensate rich in an ethylene component. The condensate rich in ethylene component is withdrawn from the bottom of the column and supplied to the demethanizer (T-2). The dephlegmator (DEP-1)
An upper rectification tower heat exchange section (20R) comprising a plurality of vertically provided indirect heat exchange passages and a lower drum (20D) for collecting the condensate cooled by gravity and cooled by the upper rectification tower heat exchange section. . Dephlegmator (DEP-
The supply to 1) is preferably carried out below.

The above dephlegmator (DEP-
When the uncondensed gas supplied to 1) passes through the upper rectification tower heat exchange section (20R) upward, it is cooled by another refrigerant (not shown) and partially condenses and flows down. As a result, in the upper rectification tower heat exchange part (20R), the ascending gas and the condensate perform direct gas-liquid contact heat exchange, the gradually flowing condensate is rich in ethylene, and the ascending gas is methane. It will be rich.

When the uncondensed gas supplied to the dephlegmator apparatus (DEP-1) contains a large amount of hydrogen as in the prior art, the hydrogen acts as a scavenging gas,
Although it interferes with the condensation of ethylene, in the present invention, since the hydrogen has been removed in advance by the hydrogen separator (S-1), the separation by the dephlegmator is performed efficiently.

The temperature of the uncondensed gas in the upper rectification column heat exchange section (20R) in the dephlegmator apparatus (DEP-1) falls within the temperature range of -90 ° C to -110 ° C, and the condensate in the lower drum section (20D). The temperature is set in a temperature range of -70 ° C to -85 ° C. As a result, the amount of condensate extracted from the lower drum portion (20D) is reduced as compared with the condensate separated by the conventional gas-liquid separator shown in FIG. ) Can be reduced.

As a result, the throughput of the raw material gas can be increased by the capacity of the existing demethanizer, and the amount of the ethylene liquid, which is the refrigerant liquid required in the cryogenic separation, can be greatly reduced. The power required for the machine (not shown) can be greatly reduced. The uncondensed gas obtained from the dephlegmator (DEP-1) has a high methane concentration. The high-pressure gas temperature at the outlets of the heat exchangers (H-1) to (H-3) does not need to be reduced as compared with the conventional case, and the cooling efficiency can be improved.

On the other hand, in the pre-demethanizer (T-1), a high-boiling hydrocarbon component substantially free of methane is recovered, a gas of a low-boiling component rich in methane is separated, and the separated gas is removed. Is supplied to the demethanizer (T-2). The distillate gas extracted from the top of the pre-demethanizer (T-1) usually contains about 40 to 50% of methane and about 40 to 50% of ethylene. Compared to other demethanizer feed liquids, the content of methane is high and the proportion of ethylene is low. The methane-rich distillate gas is cooled in the heat exchanger (H-6) and then supplied to the demethanizer (T-2).

Next, in the demethanizer (T-2), a methane gas is recovered and a condensate substantially containing no methane is recovered. The demethanizer (T-2) is a rectification column filled with trays or packings used in ordinary cryogenic separation, and separates methane and ethylene. At the top of the demethanizer tower (T-2), a heat exchanger (H-5) for cooling the distillate gas with the circulating refrigerant ethylene liquid and condensing most of the gas into the reflux liquid of this tower. ) And a gas-liquid separator (D-
5) is provided.

In the demethanizer tower (T-2), the condensate and distillate supplied to the tower are returned from the gas-liquid separator (D-5) to this tower. The fraction is rectified by the action of the reflux liquid and the heating action of the bottom liquid by a heating source (not shown) at the bottom, and is removed from the bottom as a condensate containing ethylene as a main component substantially containing no methane. The distillate gas taken out from the top of the demethanizer (T-2) is cooled by the heat exchanger (H-5) and then substantially contains ethylene in the gas-liquid separator (D-5). Is separated as a distillate gas mainly composed of methane.

The preferred pressure of the pre-demethanizer (T-1) and the dephlegmator (DEP-1) is 15 to 4
The range is 0 kg / cm ² G (about 1.5 to 4 MPa). The pressure of the demethanizer (T-2) is usually determined by the pre-demethanizer (T-1) and the dephlegmator (DEP-
1) slightly lower pressure, preferably pre-demethanizer (T
-1) and 0.1 to 10 kg / cm ² G (about 0.01 to 1 MPa) from the dephlegmator (DEP-1)
It is in the low pressure range.

In the most preferred embodiment of the present invention, as described above, the uncondensed gas in the last gas-liquid separation performed by cooling sequentially is separated by a dephlegmator, and the methane separation step is performed by using a pre-demethanizer. Although it is an embodiment configured from a demethanizer, the present invention also includes an embodiment using a dephlegmator device in another gas-liquid separation step, an embodiment not using a dephlegmator device, a pre-demethanizer, Embodiments that do not use are also included in the present invention.

For example, as shown in FIG. 2, instead of the dephlegmator (DEP-1) of FIG. 1, a heat exchanger (H-
4) and a gas-liquid separation device (D-4) can also be provided. In this case, the temperature zone at the outlet of the heat exchanger (H-4) is preferably adjusted to -90 to -115 ° C.

[0040]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention.

Example 1 A simulation result in the case of separating hydrogen and methane from gaseous hydrocarbons by the process of the flow diagram shown in FIG. 1 is shown below. The simulation program is ASPENPLUS (ASPEN TECHNOLOGY,
INC.).

As raw material gases, 15 mol% of hydrogen, 31 mol% of methane, 33 mol% of ethylene, 7 mol% of ethane,
A naphtha pyrolysis gas consisting of 10 mol% of propylene and 4 mol% of other hydrocarbons was used as a model.

Further, a separation membrane is installed in the hydrogen separator (S-1), a 21-stage plate tower is installed in the pre-demethanizer (T-1), and a 41-stage plate is installed in the demethanizer (T-2). It was a tower. Here, the performance of the separation membrane was such that only hydrogen gas was selectively permeated, and the permeation amount of the membrane was 748 kmol / H.

The raw material gas passes through a compressor (C-1) and is supplied to a source (34).
The gas is supplied to the hydrogen separator (S-1) as a high-pressure gas stream of kg / cm ² G (about 3.5 MPa) and 91 ° C. In the hydrogen separator (S-1), 75% of the hydrogen in the raw material gas is separated and collected. The raw material gas after hydrogen separation is supplied to a water cooler (W
-1), after cooling to 15 ° C., the heat exchanger (H
-1), cooled to -23 ° C. and gas-liquid separator (D
-1). The uncondensed gas in the gas-liquid separator (D-1) is cooled to -61 ° C. in the heat exchanger (H-2), and then supplied to the gas-liquid separator (D-2). The condensate in (D-1) is supplied to the pre-demethanizer (T-1).

The uncondensed gas in the gas-liquid separator (D-2) is cooled to −81 ° C. in the heat exchanger (H-3), and then supplied to the gas-liquid separator (D-3). The condensate in the liquid separator (D-2) is supplied to the demethanizer (T-2). The uncondensed gas in the gas-liquid separator (D-3) is cooled by the heat exchanger (H-4) and then supplied to the dephlegmator (DEP-1), where it is cooled.
The condensate in 3) is supplied to the demethanizer (T-2).

The above dephlegmator (DEP-
The uncondensed gas supplied to 1) is cooled and decomposed when passing upward through the upper rectification tower heat exchange section (20R), and falls. As a result, in the upper rectification tower heat exchange section (20R), the rising gas and the condensate directly perform gas-liquid contact exchange, and the gradually falling condensate is rich in ethylene, and the rising gas is methane. Be rich.
The methane-rich distillate gas is extracted from the top of the tower and then heated to room temperature and recovered. On the other hand, the condensate rich in ethylene in the dephlegmator (DEP-1)
It is supplied to the demethanizer (T-2).

On the other hand, the condensate supplied to the above-mentioned pre-demethanizer (T-1) is separated into a methane-rich distillate gas and a bottom liquid substantially containing no methane. Then, the methane-rich distillate gas is cooled and condensed in the heat exchanger (H-6), and then supplied to the demethanizer (T-2), where the bottom liquid substantially containing no methane ( High boiling point hydrocarbon component)
Is recovered.

The demethanizer (T-2) is a rectification column used for ordinary cryogenic separation. At the top, the gas discharged from the top is cooled and a part thereof is condensed. A heat exchanger (H-5) for converting the reflux liquid into unrefined gas and a heat-exchanger (D-5) for separating the reflux liquid and uncondensed gas are provided.

In the demethanizer (T-2), the condensate in the gas-liquid separator (D-2) and the gas-liquid separator (D-3)
Liquid, dephlegmator (DEP-1)
And the methane-rich condensate obtained in the heat exchanger (H-6).

Then, the distillate gas taken out from the top of the demethanizer (T-2) is cooled by a heat exchanger (H-5), and then cooled by a gas-liquid separator (D-5). Is separated as a distillate gas containing methane as a main component substantially free of methane, and then heated to room temperature and recovered. A condensate containing ethylene as a main component is recovered from the bottom of the demethanizer (T-2).

In the heat exchanger (H-1), a propylene refrigerant is used as a refrigerant in the heat exchanger (H-1).
In -5), calculation was performed assuming that an ethylene refrigerant was used. Table 1 shows the operating conditions and the calculation results of the material balance in the steady state.

[0052]

[Table 1]

Comparative Example 1 A simulation was performed in the same manner as in Example 1, except that the process was changed to the process shown in FIG. Table 2
Figure 2 shows the operating conditions and the material balance calculation results in the steady state.

[0054]

[Table 2]

Table 3 shows a comparison between the horsepower of the refrigerator and the supply amount to the demethanizer in Example 1 and Comparative Example 1.

[0056]

[Table 3]

Example 2 The procedure of Example 1 was repeated, except that the process shown in FIG. 2 was used. Table 4 shows the operating conditions and the calculation results of the material balance in the steady state. Table 5 shows a comparison between Example 2 and Comparative Example 1.

[0058]

[Table 4]

[0059]

[Table 5]

[0060]

According to the present invention described above, since the temperature of the gas-liquid separator can be set higher than that of the conventional method, the refrigerant pressure higher than that of the conventional method can be used. It can be set high and the chiller power can be reduced. Therefore, a great economic benefit can be obtained by the power saving of the refrigerator according to the present invention. Furthermore, when a dephlegmator is used in combination, the amount of methane supplied to the demethanizer can be reduced. That is, in the case of an existing plant, more raw material gas can be processed than in the current situation, and in the case of a new plant, the size of the demethanizer can be reduced.

[Brief description of the drawings]

FIG. 1 is a process flow diagram illustrating an example of a preferred embodiment of the present invention.

FIG. 2 is a process flow diagram illustrating another embodiment of the present invention.

FIG. 3 is a prior art process flow diagram.

[Explanation of symbols]

 C-1: Compressor W-1: Water cooler S-1: Hydrogen separator H-1 to H-7: Heat exchanger D-1 to D-6: Gas-liquid separator T-1: Pre-demethane Tower T-2: Demethanizer DEP-: Dephlegmator

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10G 53/02 C10G 53/02 F25J 3/02 F25J 3/02 B 101 101

Claims (11)

[Claims] 1. A method for separating hydrogen and methane from a high-pressure gas stream of a gaseous hydrocarbon containing at least hydrogen, methane, ethane and ethylene, comprising: (1) cooling the hydrogen-containing gaseous hydrocarbon. Prior to recovering hydrogen gas from the high pressure gas stream of hydrogen-containing gaseous hydrocarbons using a hydrogen separator that can substantially separate only hydrogen gas,
(2) In at least two or more temperature zones arranged in series, the above-mentioned gaseous hydrocarbons are sequentially cooled and separated into gas and liquid in each temperature zone, and the separated condensate is subjected to a methane separation step. And the uncondensed gas is supplied to the next temperature zone. (3) In the methane separation step, methane gas is recovered and a condensate containing substantially no methane is recovered. For separating hydrogen and methane from water. 2. The method according to claim 1, wherein a gas / liquid separation is performed by installing a dephlegmator in at least one or more temperature zones in the sequential cooling step (2). 3. The method according to claim 2, wherein a gas substantially free of ethylene is recovered from the uncondensed gas in the final temperature zone of the sequential cooling step (2) by using a dephlegmator device. A method in which a condensate rich in components is separated, and the separated condensate is supplied to a methane separation step. 4. The method according to claim 1, wherein the methane separation step (3) comprises a pre-demethanizer and a demethanizer, wherein the pre-demethanizer is obtained by the sequential cooling step (2). From the condensate, a high-boiling hydrocarbon component substantially free of methane is recovered, and a low-boiling component gas rich in methane is separated, and the separated gas is supplied to a demethanizer, where A method for recovering methane gas and recovering a condensate substantially free of methane. 5. The method according to claim 4, wherein the low-boiling component gas separated in the pre-demethanizer is cooled and then supplied to the demethanizer. 6. The method according to claim 1, wherein the methane separation step (3) comprises a pre-demethanization tower and a demethanization tower, and the deflation is performed in at least one temperature zone in the sequential cooling step (2). A method of installing a gmeter and performing gas-liquid separation. 7. The method according to claim 6, wherein a gas substantially free of ethylene is recovered from the uncondensed gas in the final temperature zone of the sequential cooling step (2) by using a dephlegmator apparatus. The condensate rich in components is separated, and the separated condensate is supplied to a demethanizer, where methane is substantially removed from the condensate obtained in the sequential cooling step (2). A high-boiling hydrocarbon component not contained is recovered and a low-boiling component gas rich in methane is separated, and the separated gas is supplied to a demethanizer, where methane gas is recovered and methane is substantially recovered. To collect condensate that is not contained in water. 8. The method according to claim 7, wherein the low-boiling component gas separated in the pre-demethanizer is cooled and then supplied to the demethanizer. 9. The method of claim 1, wherein the hydrogen separator is a metal membrane that can selectively permeate hydrogen. 10. The method according to claim 1, wherein the high-pressure gas stream of the hydrocarbon as the raw material is obtained by compressing a gaseous hydrocarbon obtained by pyrolyzing naphtha with a compressor. 11. The method according to claim 1, wherein the high-pressure gas stream of the hydrocarbon as a raw material compresses a gaseous hydrocarbon obtained by pyrolyzing naphtha with a compressor, and further has a carbon number of 3 or more. The method obtained by condensing and removing the high-boiling hydrocarbons of the above.