CN107285985B - Hydrogen and ethylene co-production process and device - Google Patents
Hydrogen and ethylene co-production process and device Download PDFInfo
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- C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
- C07C2/76—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation of hydrocarbons with partial elimination of hydrogen
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- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
- C01B3/22—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of gaseous or liquid organic compounds
- C01B3/24—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of gaseous or liquid organic compounds of hydrocarbons
- C01B3/26—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of gaseous or liquid organic compounds of hydrocarbons using catalysts
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- C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
- C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
- C01B3/56—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with solids; Regeneration of used solids
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- C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
- C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
- C01B2203/042—Purification by adsorption on solids
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- C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
- C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
- C01B2203/0465—Composition of the impurity
- C01B2203/048—Composition of the impurity the impurity being an organic compound
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- C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
- C01B2203/06—Integration with other chemical processes
- C01B2203/062—Hydrocarbon production, e.g. Fischer-Tropsch process
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- C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
- C01B2203/12—Feeding the process for making hydrogen or synthesis gas
- C01B2203/1205—Composition of the feed
- C01B2203/1211—Organic compounds or organic mixtures used in the process for making hydrogen or synthesis gas
- C01B2203/1235—Hydrocarbons
- C01B2203/1241—Natural gas or methane
Abstract
The invention provides a co-production process and a co-production device of hydrogen and ethylene, wherein the process comprises the following steps: carrying out methane dehydrogenation reaction on feed gas containing methane to obtain product gas containing hydrogen, ethylene, heavy component hydrocarbons and unreacted methane, and separating the product gas to obtain a hydrogen product and an ethylene product; the hydrogen content of the product gas is above 35% by volume, and the separation comprises: (a) separating heavy component hydrocarbons in the product gas to obtain a heavy component product and a mixed gas I containing hydrogen, ethylene and methane; (b) boosting the pressure of the mixed gas I, and then carrying out first pressure swing adsorption separation to obtain ethylene-rich gas containing methane and mixed gas II containing hydrogen and methane; (c) pressurizing the ethylene-rich gas, and then carrying out cold separation to obtain an ethylene product and a methane tail gas I; and carrying out second pressure swing adsorption separation on the mixed gas II to obtain a hydrogen product and a methane tail gas II. The process and the device can reduce the cost of raw materials and obtain high-purity hydrogen.
Description
Technical Field
The invention relates to the field of hydrocarbon processing, in particular to a co-production process of hydrogen and ethylene and a device used in the co-production process of the hydrogen and the ethylene.
Background
Currently, steam cracking is an important process for producing ethylene, the raw materials of Asian steam cracking are mainly naphtha, light diesel oil and the like, and the U.S. generally takes ethane as the raw material. The cracking of the aforementioned raw materials produces not only ethylene but also hydrogen, methane, and propylene as by-products, and therefore, it is necessary to separate the products to obtain ethylene, propylene, and hydrogen, etc., with high purity. The content of hydrogen in the cracking gas formed when the chemical products are prepared by cracking naphtha, ethane and other raw materials is lower, the content of other components such as ethylene and propylene is higher, and the separation of the products is realized by a cryogenic separation process.
CN104030875A discloses a method for separating and refining catalytic cracking dry gas, which comprises pressurizing catalytic cracking dry gas, and separating the pressurized dry gas into ethylene-rich dry gas (desorbed gas) and concentrated gas by a first pressure swing adsorption tower; the concentrated gas enters a second pressure swing adsorption tower and is separated into hydrogen and second desorption gas; mixing and pressurizing the ethylene-rich gas and the second desorption gas, separating by a membrane separation method to obtain a permeation gas and a non-permeation gas, and separating the non-permeation gas by a cryogenic separation system to respectively obtain ethane, ethylene, propylene and the like; the cryogenic separation system uses an ethylene rectifying tower, an ethylene crude distillation tower, a propylene rectifying tower and the like and corresponding refrigeration equipment. The yield and purity of various gas components are improved by adopting the technology of combining pressure swing adsorption, membrane separation and cryogenic separation.
However, with the rapid development of global economy, the demand for chemical products is rising day by day, and due to the increasing shortage of petroleum resources, the raw material resources such as naphtha and light diesel oil, which are raw materials for producing chemical products, face an increasingly serious shortage situation. While natural gas and shale gas are increasingly paid more attention as cleaner energy sources, with the technical progress, the exploitation cost of the energy sources is greatly reduced, and the utilization route of utilizing the main component methane as a chemical raw material is gradually attractive. Among them, a technology for converting methane into a chemical product by using a catalytic dehydrogenation technology is receiving attention.
Generally, catalytic dehydrogenation of methane produces a product gas comprising primarily hydrogen, ethylene, benzene, naphthalene, and some unreacted methane. The proportion of hydrogen therein is generally in the range from 40 to 95% by volume. For the new material system, the industry continues to use the traditional cryogenic separation process, but the hydrogen content produced by the methane dehydrogenation process is high, and in order to separate high-purity products, the cryogenic separation system needs a plurality of separation devices and corresponding refrigeration systems, which results in huge investment on the cryogenic separation system, and the purity of the hydrogen cannot be guaranteed (usually only about 95%). Therefore, a new production and processing technology which is suitable for a system containing high-concentration hydrogen and has a simple separation process needs to be developed.
Disclosure of Invention
The present invention is directed to solving the above problems of the prior art, and thus provides a process for co-producing hydrogen and ethylene, and an apparatus for use in the process.
In order to achieve the above object, a first aspect of the present invention provides a process for co-producing hydrogen and ethylene, the process comprising: carrying out methane dehydrogenation reaction on feed gas containing methane to obtain product gas containing hydrogen, ethylene, heavy component hydrocarbons and unreacted methane, and separating the product gas to obtain a hydrogen product and an ethylene product; wherein the hydrogen content of the product gas is 35% by volume or more, and the separating comprises the steps of:
(a) separating heavy component hydrocarbons in the product gas to obtain a heavy component product and a mixed gas I containing hydrogen, ethylene and methane;
(b) boosting the pressure of the mixed gas I, and then carrying out first pressure swing adsorption separation to obtain ethylene-rich gas containing methane and mixed gas II containing hydrogen and methane;
(c) pressurizing the ethylene-rich gas, and then carrying out cold separation to obtain an ethylene product and a methane tail gas I; and carrying out second pressure swing adsorption separation on the second mixed gas to obtain a hydrogen product and a methane tail gas II.
In a second aspect, the present invention provides an apparatus for use in the above process for co-producing hydrogen and ethylene, the apparatus comprising: the reaction unit is used for carrying out methane dehydrogenation reaction on the feed gas containing methane to obtain a product gas, and the separation unit is used for separating the product gas to obtain a hydrogen product and an ethylene product; wherein, the separating element includes that it sets gradually according to material flow direction: the device comprises a heavy component removing unit, a mixed gas first pressure raising unit, a first pressure swing adsorption unit, an ethylene-rich gas pressure raising unit and a cold separation unit, wherein a second pressure swing adsorption unit is arranged at the downstream of the first pressure swing adsorption unit; the ethylene-rich gas pressure rising unit is connected with the bottom of the first pressure swing adsorption unit, and the second pressure swing adsorption unit is connected with the top of the first pressure swing adsorption unit.
The co-production process of hydrogen and ethylene adopts the raw material gas containing methane as the raw material, and reduces the raw material cost compared with naphtha and light diesel oil as the raw materials; more importantly, compared with the traditional cryogenic separation process, the process provided by the invention has the advantages that the purity of the obtained hydrogen is high (more than 99%), the process is short, the energy consumption is low, and the adopted device also has the advantage of low investment.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.
Fig. 1 shows a flow diagram of a co-production process of hydrogen and ethylene according to an embodiment of the invention.
Description of the reference numerals
U1-reaction unit; u2-heavies removal unit; u3-mixed gas-pressure increasing unit; u4-first pressure swing adsorption unit; u5-ethylene-rich gas pressure rising unit; u6-cold separation unit; u7-second pressure swing adsorption unit; u8-methane boosting unit; 101-a methane-containing feed gas; 102-product gas; 201-heavy ends product; 301-mixed gas I after pressure boosting; 401-ethylene rich gas; 501-ethylene-rich gas after pressure boosting; 601-ethylene product; 602-methane tail gas one; 701-hydrogen production; 702-methane tail gas two; 801-methane tail gas II after pressure boosting.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
According to a first aspect of the present invention, there is provided a process for the co-production of hydrogen and ethylene, the process comprising: carrying out methane dehydrogenation reaction on feed gas containing methane to obtain product gas containing hydrogen, ethylene, heavy component hydrocarbons and unreacted methane, and separating the product gas to obtain a hydrogen product and an ethylene product; wherein the hydrogen content of the product gas is 35% by volume or more, and the separating comprises the steps of:
(a) separating heavy component hydrocarbons in the product gas to obtain a heavy component product and a mixed gas I containing hydrogen, ethylene and methane;
(b) boosting the pressure of the mixed gas I, and then carrying out first pressure swing adsorption separation to obtain ethylene-rich gas containing methane and mixed gas II containing hydrogen and methane;
(c) pressurizing the ethylene-rich gas, and then carrying out cold separation to obtain an ethylene product and a methane tail gas I; and carrying out second pressure swing adsorption separation on the second mixed gas to obtain a hydrogen product and a methane tail gas II.
In the present invention, the raw material gas containing methane is not particularly limited, and may be any raw material gas in the art for producing hydrocarbons from methane as a main raw material, such as methane gas or natural gas, rock leaf gas, biogas, etc. in which methane is mixed with other hydrocarbons. Generally, the methane content of the methane-containing feed gas may be in the range of from 5 to 100 volume%. Preferably, the methane content of the methane-containing feed gas is in the range of 80 to 100 vol%. More preferably, the methane-containing feed gas is methane gas.
According to the invention, the methane dehydrogenation reaction is usually carried out in the presence of a methane dehydrogenation catalyst, and methane is converted into products such as hydrogen, ethylene, heavy component hydrocarbons and the like through selective catalysis of the catalyst, so as to obtain the product gas. Preferably, the heavy component hydrocarbons produced by the dehydrogenation of methane contain benzene and/or naphthalene. The methane dehydrogenation catalyst can be selected according to the type of heavy component hydrocarbon to be generated, and can be selected from Mo/phosphorus-containing pentasil zeolite catalyst prepared by CN1174757A, Mo/HZSM-5 catalyst prepared by CN1102359A, Zn/HZSM-5 catalyst and the like. According to a preferred embodiment of the invention, the Methane dehydrogenation catalyst may also be chosen from the documents Xiao guang Guo et al, Direct, innoxious conversion of Methane to Ethylene, aromatic and Hydrogen; science 344,616(2014) silicide lattice-confined single-site iron catalyst prepared
(
The catalyst is characterized by a single-site iron insertion in SiO2In the matrix), in which case the heavy hydrocarbons produced include benzene and naphthalene.
The preparation method specifically comprises the following steps: reacting ferrous silicate with SiO in air at a temperature of 1973K2(from quartz) fusion followed by HNO3Is leached and dried at a temperature of 353K.
In the present invention, the reaction conditions of the methane dehydrogenation reaction can be selected with reference to the prior art. For example, the reaction conditions of the methane dehydrogenation reaction may include: the temperature is 200 ℃ and 1500 ℃, and the pressure is from normal pressure to 3.0 MPaG. Preferably, the reaction conditions of the methane dehydrogenation reaction include: the temperature is 700 ℃ and 1300 ℃, and the pressure is from normal pressure to 2.0 MPaG.
The co-production process of hydrogen and ethylene has a very good separation effect on high-concentration cracking dry gas with the hydrogen content of more than 35 volume percent, namely, high-purity hydrogen and ethylene products can be obtained. In the present invention, the hydrogen content of the product gas may be generally 35 to 95% by volume. From the viewpoint of further improving the yields of hydrogen and ethylene, it is preferable that the content of hydrogen in the product gas is 40 to 80% by volume.
In the present invention, the separation of the product gas is achieved through steps (a) to (c) to obtain the ethylene product and the hydrogen product in high purity.
In the step (a), the separation of the heavy component hydrocarbons can be performed by utilizing the principle of absorption-desorption separation and selecting according to the types of the heavy component hydrocarbons. In addition, the specific operating conditions for separating the heavy component hydrocarbons in the product gas are conventional in the art and will not be described herein.
In the present invention, step (a) removes the heavier hydrocarbons, resulting in a reduced pressure of the resulting gas mixture as compared to the product gas. In order to satisfy the pressure swing adsorption condition, in step (b), the first mixed gas needs to be pressurized, and the pressure of the first mixed gas can be 1.0-6.0 MPaG. Preferably, the pressure increase is such that the pressure of the first mixture is 1.5-4.5 MPaG.
In step (b), the first pressure swing adsorption separation may be performed in a first pressure swing adsorption tower, for example, by passing through a bed layer filled with an adsorbent, so that the heavier components of ethylene and a small amount of methane in the first mixed gas are absorbed by the adsorbent, and then passing through a bed layer filled with the adsorbent, and then desorbing and discharging from the bottom of the adsorption tower after pressure reduction to obtain an ethylene-rich gas containing methane, while the unabsorbed hydrogen and methane are discharged from the top of the adsorption tower to obtain a second mixed gas containing hydrogen and methane. Wherein the conditions of the first pressure swing adsorption separation may be conventional in the art and well known to those skilled in the art. The adsorbent used may be selected from zeolites and the like. In addition, the ethylene-rich gas inevitably contains hydrogen that is not separated, in addition to the methane component.
In order to obtain the ethylene product with high purity, the step (c) comprises the steps of pressurizing the ethylene-rich gas, then carrying out cold separation, and utilizing the rectification principle to realize the separation of ethylene and methane in a cold separation unit so as to obtain the ethylene product and the methane tail gas I. Wherein the pressure increase is such that the pressure of the ethylene-rich gas may be in the range of 1.0 to 4.0 MPaG. The conditions of the cold separation may include: the temperature is-140 deg.C to 30 deg.C, and the pressure is 1.0-4.0 MPaG. Depending on the conditions of the dehydrogenation reaction of methane and the aforementioned separation operation, the purity of ethylene in the ethylene product obtained by cold separation may be generally 80 to 99.99 mol%.
Step (c) of the present invention further comprises subjecting the second mixed gas to a second pressure swing adsorption separation, which may be performed in a second pressure swing adsorption tower, wherein methane is selectively absorbed by the adsorbent through a bed layer filled with the adsorbent, and methane tail gas two is obtained at the bottom of the adsorption tower through pressure reduction and flushing by reverse discharge, while non-adsorption phase hydrogen is discharged from the top of the adsorption tower to obtain a hydrogen product. Likewise, the conditions of the second pressure swing adsorption separation may also be conventional in the art and well known to those skilled in the art. The adsorbent used may be zeolite or the like. The purity of the hydrogen in the obtained hydrogen product can reach more than 99.9 volume percent.
In addition, in order to avoid the waste of methane gas and save the production cost, the co-production process of hydrogen and ethylene of the present invention preferably further comprises: pressurizing the methane tail gas, and recycling the methane tail gas for the methane dehydrogenation reaction or serving as fuel for the methane dehydrogenation reaction; and/or
And boosting the pressure of the methane tail gas II, and recycling the methane tail gas II for the methane dehydrogenation reaction or serving as fuel for the methane dehydrogenation reaction.
In this case, the pressure is raised so that the pressure of the methane tail gas one and the methane tail gas two may be 0.05 to 0.5MPaG, respectively.
According to a second aspect of the present invention, there is provided an apparatus for use in the above-described process for co-producing hydrogen and ethylene, as shown in fig. 1, the apparatus comprising: the reaction unit U1 and the separation unit, the reaction unit U1 is configured to perform a methane dehydrogenation reaction on the feed gas containing methane to obtain a product gas, and the separation unit is configured to separate the product gas to obtain a hydrogen product and an ethylene product; wherein, the separating element includes that it sets gradually according to material flow direction: the device comprises a heavy component removal unit U2, a mixed gas-pressure boosting unit U3, a first pressure swing adsorption unit U4, an ethylene-rich gas-pressure boosting unit U5 and a cold separation unit U6, wherein a second pressure swing adsorption unit U7 is further arranged at the downstream of the first pressure swing adsorption unit U4; the ethylene-rich gas pressure boosting unit U5 is connected with the bottom of the first pressure swing adsorption unit U4, and the second pressure swing adsorption unit U7 is connected with the top of the first pressure swing adsorption unit U4.
The product gas can be contacted with a solvent to remove heavy component hydrocarbons, in order to make the heavy component hydrocarbons fully contacted, the reaction unit U1 can be connected with the bottom of the heavy component removing unit U2 to make the product gas enter, and the solvent enters from the top of the heavy component removing unit U2. In addition, the top of the heavy component removal unit U2 for obtaining the first mixed gas may be connected to a pressure increasing unit U3, so that the first mixed gas is discharged from the top for pressure increase.
Specifically, the separation of the product gas by the separation unit is realized by the following modes: firstly, separating the product gas by using a heavy component removing unit U2 to obtain a heavy component product and a mixed gas I; then, the mixed gas I is pressurized by the mixed gas I pressurizing unit U3, and then the mixed gas I is separated by the first pressure swing adsorption unit U4 to obtain the ethylene-rich gas and the mixed gas II; subsequently, an ethylene-rich gas pressure boosting unit U5 boosts the pressure of the ethylene-rich gas, and then a cold separation unit U6 is utilized to separate the ethylene-rich gas, so that an ethylene product and a methane tail gas I are obtained; and separating the second mixed gas by using a second pressure swing adsorption unit U7 to obtain a hydrogen product and a methane tail gas II.
In the present invention, the reaction unit U1 may be provided with a reactor containing a catalyst so that the methane dehydrogenation reaction is performed in the presence of a methane dehydrogenation catalyst. The first pressure swing adsorption unit U4 and the second pressure swing adsorption unit U7 of the present invention may be pressure swing adsorption towers, respectively.
According to the invention, in order to achieve reuse of the methane obtained after separation, it is preferred that the apparatus further comprises: a methane boosting unit U8 disposed downstream of the cold separation unit U6 and/or the second pressure swing adsorption unit U7. The methane pressure boosting unit U8 is used for boosting the pressure of the methane tail gas I separated by the cold separation unit U6 and/or the methane tail gas II separated by the second pressure swing adsorption unit U7.
In the present invention, the mixed gas-pressure increasing unit U3, the ethylene-rich gas-pressure increasing unit U5 and the methane pressure increasing unit U8 for increasing pressure may be compressors, respectively.
The device used in the co-production process of hydrogen and ethylene combines the heavy component hydrocarbon separation unit, the pressure swing adsorption unit and the cold separation unit, and avoids the need of using various rectifying devices and corresponding refrigeration equipment and refrigerants for cryogenic separation, so that not only can high-purity hydrogen and ethylene be obtained, but also the device has the characteristic of low equipment investment.
According to an embodiment of the present invention, the co-production process of hydrogen and ethylene can be performed according to the flow scheme shown in fig. 1, and the flow scheme of the process comprises the following steps:
(1) carrying out methane dehydrogenation reaction on a feed gas 101 containing methane in a reaction unit U1 to obtain a product gas 102;
(2) enabling the product gas 102 to enter a heavy component removal unit U2 for absorption, desorption and separation to obtain a heavy component product 201 and a mixed gas I containing hydrogen, ethylene and methane;
(3) the mixed gas is boosted to 1.0-6.0MPaG, preferably 1.5-4.5MPaG, more preferably 2.0MPaG through a mixed gas first boosting unit U3 to obtain a boosted mixed gas first 301, and then the boosted mixed gas first 301 is sent to a first pressure swing adsorption unit U4 for separation to obtain an ethylene-rich gas 401 containing methane and a mixed gas second containing hydrogen and methane;
(4) the ethylene-rich gas 401 is pressurized to 1.0-4.0MPaG, preferably 3.2MPaG, by an ethylene-rich gas pressurization unit U5 to obtain pressurized ethylene-rich gas 501, and then separated by a cold separation unit U6 to obtain an ethylene product 601 and a methane tail gas I602; sending the second mixed gas to a second pressure swing adsorption unit U7 for separation to obtain a hydrogen product 701 and a second methane tail gas 702;
(5) and (3) boosting the pressure of the second methane tail gas 702 to 0.05-0.5MPaG, preferably 0.15MPaG, through a methane boosting unit U8 to obtain a second boosted methane tail gas 801, and sending the second boosted methane tail gas 801 back to the reaction unit U1 for methane dehydrogenation reaction.
The present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.
In the following examples, the dehydrogenation catalyst is described in Direct, Nonexative conversion of methane to Ethylene, Aromatics and Hydrogen; prepared by Xiao guang Guo et al, Science 344,616(2014)
Example 1
Hydrogen and ethylene were produced according to the process scheme shown in FIG. 1. The main composition and condition parameters of the various streams are shown in table 1. In reaction unit U1, the reaction temperature for the methane dehydrogenation reaction was 1050 ℃, and the pressure was 0.05 MPaG.
TABLE 1
As can be seen from Table 1, the purity of the hydrogen product 701 obtained by the co-production process of hydrogen and ethylene of the present invention is up to 99% or more, and the purity of the ethylene product 601 is even close to 100%, thus the process of the present invention can produce high-purity hydrogen and ethylene.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (9)
1. A process for the co-production of hydrogen and ethylene, the process comprising: carrying out methane dehydrogenation reaction on feed gas containing methane to obtain product gas containing hydrogen, ethylene, heavy component hydrocarbons and unreacted methane, and separating the product gas to obtain a hydrogen product and an ethylene product; wherein the hydrogen content of the product gas is 35% by volume or more, and the separating comprises the steps of:
(a) separating heavy component hydrocarbons in the product gas to obtain a heavy component product and a mixed gas I containing hydrogen, ethylene and methane;
(b) boosting the pressure of the mixed gas I, and then carrying out first pressure swing adsorption separation to obtain ethylene-rich gas containing methane and mixed gas II containing hydrogen and methane;
(c) pressurizing the ethylene-rich gas, and then carrying out cold separation to obtain an ethylene product and a methane tail gas I; carrying out second pressure swing adsorption separation on the second mixed gas to obtain a hydrogen product and a methane tail gas II;
wherein the methane content in the methane-containing feed gas is 80-100 vol%.
2. The process of claim 1 wherein the heavy hydrocarbon fraction comprises benzene and/or naphthalene; the reaction conditions of the methane dehydrogenation reaction include: the temperature is 200 ℃ and 1500 ℃, and the pressure is from normal pressure to 3.0 MPaG.
3. The process of claim 1, wherein in step (b), the pressure is increased such that the pressure of the first mixed gas is 1.0-6.0 MPaG.
4. The process of claim 3, wherein in step (b), the pressure is increased such that the pressure of the first mixed gas is 1.5-4.5 MPaG.
5. The process of claim 1, wherein in step (c), the pressure is increased such that the pressure of the ethylene-rich gas is from 1.0 to 4.0 MPaG; the operating conditions of the cold separation include: the temperature is-140 deg.C to 30 deg.C, and the pressure is 1.0-4.0 MPaG.
6. The process of any one of claims 1-5, wherein the process further comprises: pressurizing the methane tail gas, and recycling the methane tail gas for the methane dehydrogenation reaction or serving as fuel for the methane dehydrogenation reaction; and/or
And boosting the pressure of the methane tail gas II, and recycling the methane tail gas II for the methane dehydrogenation reaction or serving as fuel for the methane dehydrogenation reaction.
7. The process of claim 6, wherein the pressure is increased such that the pressure of the first methane tail gas and the second methane tail gas is 0.05-0.5MPaG, respectively.
8. An apparatus for use in a process for the co-production of hydrogen and ethylene according to any one of claims 1 to 7, the apparatus comprising: the reaction unit (U1) is used for carrying out methane dehydrogenation reaction on the feed gas containing methane to obtain a product gas, and the separation unit is used for separating the product gas to obtain a hydrogen product and an ethylene product; wherein, the separating element includes that it sets gradually according to material flow direction: the device comprises a heavy component removing unit (U2), a mixed gas first pressure boosting unit (U3), a first pressure swing adsorption unit (U4), an ethylene-rich gas pressure boosting unit (U5) and a cold separation unit (U6), wherein a second pressure swing adsorption unit (U7) is further arranged at the downstream of the first pressure swing adsorption unit (U4); the ethylene-rich gas pressure rising unit (U5) is connected with the bottom of the first pressure swing adsorption unit (U4), and the second pressure swing adsorption unit (U7) is connected with the top of the first pressure swing adsorption unit (U4).
9. The apparatus of claim 8, wherein the apparatus further comprises: a methane boosting unit (U8) disposed downstream of the cold separation unit (U6) and/or the second pressure swing adsorption unit (U7).
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