Ethylene production plant and method for producing ethylene using the same

Abstract

The present application relates to an ethylene production apparatus and a method for producing ethylene using the same. The ethylene production equipment comprises a steam cracking furnace used for carrying out steam cracking on added raw materials; the ethylene treatment unit is communicated with the steam cracking furnace; the depropanizing tower is communicated with the steam cracking furnace; the hydrogenation reactor is communicated with the top of the depropanizing tower; the demethanizing tower is communicated with the hydrogenation reactor; the deethanization tower is communicated with the tower kettle of the demethanization tower; the ethylene tower is communicated with the tower top of the deethanization tower; one end of the ethylene production unit is communicated with the tower kettle of the ethylene tower, the other end of the ethylene production unit is communicated with the hydrogenation reactor, and the ethylene production unit is used for deoxidizing the ethane-containing product from the tower kettle of the ethylene tower. According to the ethylene production equipment and method, a steam cracking process is coupled with a process for preparing ethylene through oxidative dehydrogenation of ethane, so that under the condition of not transforming the equipment, partial structural problems of existing products are solved, energy consumption and carbon emission are reduced, and investment and production cost are greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of ethylene systems, in particular to ethylene production equipment and a method for producing ethylene using the ethylene production equipment. Background Art

[0002] Ethylene is one of the world's most produced chemical products. The ethylene industry is the core of the petrochemical industry, with its products accounting for over 75% of petrochemical output and occupying a crucial position in the national economy. Ethylene (CH2=CH2) can be produced from a variety of chemical feedstocks, the most common of which are ethane, propane, and naphtha. While its production processes are diverse, the differences between them are relatively small, a key characteristic that distinguishes the ethylene industry from other chemical products. The vast majority of ethylene is produced globally through cracking, with steam cracking being the most important route for producing ethylene. In recent years, there has been a clear trend towards diversification and lighter ethylene feedstocks globally. The successful development of shale gas in the United States has not only provided low-cost feedstock for US ethylene but has also influenced global ethylene feedstock trends, increasing the diversity of ethylene feedstock options. The significant domestic ethylene shortage and high dependence on crude oil imports highlight the importance of diversified olefin feedstocks. Factors such as feedstock availability, price levels, and production processes give ethane cracking and coal / methanol to olefins projects their respective advantages.

[0003] The ethylene cracking process is one of the main methods for ethylene production, whereby hydrocarbons such as naphtha, liquid hydrocarbons, and light hydrocarbons are decomposed into ethylene and other byproducts using a catalyst or thermal cracking method under appropriate temperature and pressure. The ethylene cracking reaction is the process by which the carbon-carbon bonds in the ethane molecule are broken to produce ethylene and alkane cracking products. The key to the cracking reaction is the formation and cracking of alkyl radicals. During the cracking process, ethane molecules are heated to high temperatures to decompose into ethylene and alkane cracking products. This process is a free radical reaction that requires high temperatures and a catalyst. Currently, the main existing method for ethylene production is steam cracking, which suffers from high energy consumption and large carbon emissions. Summary of the Invention

[0004] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of protection of this application.

[0005] This application provides an ethylene production device and a method for producing ethylene using the ethylene production device. The ethylene production device and method provided herein couple a steam cracking process with an ethane oxidative dehydrogenation process to produce ethylene. These methods are used in the production of light olefins. Without modifying the equipment, they address some structural issues of existing products, reduce energy consumption and carbon emissions, and significantly lower investment and production costs.

[0006] In one aspect, the present application provides an ethylene production plant, comprising:

[0007] A steam cracking furnace, used for steam cracking the added raw materials to obtain a first product;

[0008] an ethylene processing unit, which is in communication with the steam cracking furnace, and is used for quenching, compressing, alkali-washing and drying the first product;

[0009] a depropanizer, which is in communication with the ethylene processing unit and obtains a second product at the top of the depropanizer;

[0010] a hydrogenation reactor connected to the top of the depropanizer, wherein the second product is subjected to a hydrogenation reaction in the hydrogenation reactor to obtain a third product, wherein the third product comprises methane, hydrogen, ethane, ethylene, propylene and propane;

[0011] a demethanizer, which is in communication with the hydrogenation reactor and is used to remove methane and hydrogen from the third product;

[0012] a deethanizer, which is connected to the bottom of the demethanizer and is used to extract ethane and ethylene from the third product;

[0013] an ethylene tower, which is connected to the top of the deethanizer and is used to separate ethane and ethylene in the third product, and ethylene is output through the top of the ethylene tower; and

[0014] An ethylene production unit, one end of which is connected to the bottom of the ethylene tower and the other end of which is connected to the hydrogenation reactor, is used to perform an oxidative dehydrogenation reaction on the third product containing ethane from the bottom of the ethylene tower to obtain a mixture containing ethylene and unreacted ethane, and to allow the mixture to enter the hydrogenation reactor.

[0015] In an embodiment of the present application, the ethylene production equipment further includes a propylene tower, which is connected to the bottom of the deethanizer and is used to extract propylene from the third product in the bottom of the deethanizer. The bottom of the propylene tower is connected to the steam cracking furnace and is used to send the third product in the bottom of the propylene tower to the steam cracking furnace.

[0016] In an embodiment of the present application, the methane and hydrogen in the demethanizer are output through the top of the demethanizer.

[0017] In an embodiment of the present application, the ethylene production equipment further comprises a debutanizer, which is connected to the bottom of the depropanizer and is used to separate the fourth product at the bottom of the depropanizer into mixed C4 and pyrolysis gasoline.

[0018] In an embodiment of the present application, the ethylene production equipment further comprises a drying unit, one end of the drying unit being connected to the hydrogenation reactor and the other end being connected to the demethanizer, and the drying unit being used to dry, condense and separate the third product output from the hydrogenation reactor.

[0019] In an embodiment of the present application, the raw material includes one or more of naphtha, liquid hydrocarbons and light hydrocarbons, the first product includes ethylene, propylene, butadiene, hydrogen, methane, acetylene, ethane, propyne, propadiene, vinyl propyne, butane, butene, and the second product includes ethylene, propylene, butadiene, hydrogen, methane, acetylene, ethane, propyne, propadiene, vinyl propyne.

[0020] In an embodiment of the present application, the ethylene processing unit includes a quenching tower, a compressor section and an alkaline washing dryer connected in series in sequence, wherein the quenching tower is connected to the steam cracking furnace, and the alkaline washing dryer is connected to the depropanizer; the ethylene production unit includes an ethane oxidative dehydrogenation reactor, an acetic acid separator and a gas removal device connected in series in sequence, wherein the ethane oxidative dehydrogenation reactor is connected to the bottom of the ethylene tower, and the gas removal device is connected to the hydrogenation reactor.

[0021] In another aspect, the present application provides a method for producing ethylene using the above-mentioned device, the method comprising:

[0022] (1) steam cracking the raw material in a steam cracking furnace to obtain a first product;

[0023] (2) quenching, compressing, alkali washing, and drying the first product by an ethylene processing unit connected to the steam cracking furnace;

[0024] (3) processing the first product through a depropanizer connected to an ethylene processing unit, obtaining a second product at the top of the depropanizer and a fourth product at the bottom of the depropanizer;

[0025] (4) subjecting the second product to a hydrogenation reaction in a hydrogenation reactor connected to the top of the depropanizer to obtain a third product, wherein the third product comprises methane, hydrogen, ethane, ethylene, propylene, and propane;

[0026] (5) removing methane and hydrogen from the third product through a demethanizer connected to the hydrogenation reactor;

[0027] (6) extracting ethane and ethylene from the third product through a deethanizer connected to the bottom of the demethanizer;

[0028] (7) separating ethane and ethylene in the third product by an ethylene tower connected to the top of the deethanizer, and outputting ethylene through the top of the ethylene tower; and

[0029] (8) subjecting the third product containing ethane from the bottom of the ethylene tower to an oxidative dehydrogenation reaction through an ethylene production unit to obtain a mixture containing ethylene and unreacted ethane, and allowing the mixture to enter the hydrogenation reactor, wherein one end of the ethylene production unit is connected to the bottom of the ethylene tower and the other end is connected to the hydrogenation reactor.

[0030] In an embodiment of the present application, the method further comprises extracting propylene from the third product in the bottom of the deethanizer through a propylene tower connected to the bottom of the deethanizer, and sending the third product in the bottom of the propylene tower to the steam cracking furnace by connecting the bottom of the propylene tower to the steam cracking furnace; or

[0031] The method further comprises outputting methane and hydrogen through the top of the demethanizer; or

[0032] The method further comprises separating the fourth product at the bottom of the depropanizer into mixed C4 and pyrolysis gasoline through a debutanizer connected to the bottom of the depropanizer; or

[0033] The method further includes drying, condensing and separating the third product output from the hydrogenation reactor through a drying unit, wherein one end of the drying unit is connected to the hydrogenation reactor and the other end is connected to the demethanizer.

[0034] In an embodiment of the present application, the raw materials include one or more of naphtha, liquid hydrocarbons and light hydrocarbons, the first product includes ethylene, propylene, butadiene, hydrogen, methane, acetylene, ethane, propyne, propadiene, vinyl propyne, butane, and butene, and the second product includes ethylene, propylene, butadiene, hydrogen, methane, acetylene, ethane, propyne, propadiene, and vinyl propyne; the ethylene processing unit includes a quenching tower, a compressor section and an alkaline washing dryer; the ethylene production unit includes an ethane oxidative dehydrogenation reactor, an acetic acid separator and a gas removal device.

[0035] The technical solution provided by this application brings at least the following beneficial effects: the recycled ethane from the steam cracking furnace is used as the raw material for the ethane oxidative dehydrogenation process to produce ethylene. After the ethane oxidative dehydrogenation reaction, water washing, deoxygenation, compression, alkali washing and drying, the reaction products, including C2 and light components below C2 and part of the C3 components, enter the hydrogenation reactor in the steam cracking process to produce ethylene. The reaction products are dried, condensed and separated before entering the demethanizer. Methane and hydrogen are obtained at the top of the tower. The bottom of the tower enters the deethanizer. The top gas of the deethanizer enters the ethylene tower to separate the products ethylene and ethane. Ethane serves as the raw material for the ethane oxidative dehydrogenation process to produce ethylene, replacing the process route of entering the steam cracking furnace in the steam cracking process. The bottom product of the deethanizer enters the propylene tower, and the propylene product is obtained at the top of the propylene tower. The propane in the bottom of the propylene tower is returned to the steam cracking furnace as a circulating raw material. The steam cracking process for producing ethylene uses a pre-depropanization separation process. Naphtha, light hydrocarbons, and recycled propane react in a steam cracking furnace at a specific dilution ratio. The cracked gas undergoes rapid cooling, compression, alkali washing, and drying before entering a depropanizer. The depropanizer overhead gas is mixed with the product from the ethane oxidative dehydrogenation process and fed into a hydrogenation reactor. The depropanizer's bottom product enters a debutanizer to separate mixed C4 and pyrolysis gasoline, and the recycled ethane enters the cracking furnace for reaction. This application leverages the compatibility of the ethane oxidative dehydrogenation process with conventional ethane steam cracking. For conventional steam cracking production lines with a capacity of 600,000 to 1.5 million tons per year, this process controls the recycled ethane flow rate to between 4.69 kg / sec (kilograms per second) and 10 kg / sec (kilograms per second). The reaction operating temperature of the recycled ethane is controlled between 360°C and 380°C, and the reaction pressure is controlled between 0.1 MPa and 20 MPa, thereby achieving a controlled ethylene production rate of 3.47 kg / sec (kilograms per second) in the ethylene tower. This coupled process can increase ethylene production with an overall energy consumption of less than 250 kgEo / t (kilograms of standard oil per ton), while also improving recycled ethane conversion and ethylene selectivity. This high reaction conversion rate saves significant steam and fuel, significantly reducing equipment energy consumption. Furthermore, the production of acetic acid as a byproduct adds additional economic value, which can be sold or used in downstream equipment. Furthermore, the CO2 (carbon dioxide) produced in the ethane oxidative dehydrogenation reactor can be recovered and used downstream or captured.

[0036] This application addresses the high energy consumption and carbon emissions of steam cracking. It allows for flexible adjustment of ethylene processing loads based on ethylene market fluctuations, and the addition of acetic acid as a byproduct creates additional economic value. The ethylene and acetic acid produced are well-suited to processes for producing EVA resin, polyester (PET), ethyl acetate, and similar derivatives, which require these raw materials. This allows for expansion of ethylene production capacity based on traditional steam cracking, with low investment costs.

[0037] The added economic value of a 1 million ton / year ethylene plant ranges from 15% (for low-yield acetic acid) to 24% (for high-yield acetic acid). CO2 emissions are reduced by 8%, and the comprehensive energy consumption for increased ethylene production is less than 250 kgEo / t (kilograms of standard oil per ton). The total production cost per ton of increased ethylene production is approximately RMB 5,000. Based on an ethylene market price of RMB 7,500 / ton, this represents an annual profit of RMB 250 million. This technology can also significantly reduce carbon emissions for refineries and other enterprises, promoting their green, low-carbon development. This technology is widely applicable to domestic refineries and other enterprises, with promising application prospects and high expectations for commercialization. Fully implemented within the group, it is expected to generate annual efficiency gains of RMB 2.5 billion, and nationwide, it is expected to generate annual efficiency gains of RMB 12.5 billion, significantly contributing to energy conservation and carbon reduction for refineries and other enterprises.

[0038] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. Other advantages of the present application can be realized and obtained by the solutions described in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings are used to provide an understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0040] Figure 1 is a block diagram of an ethylene production apparatus according to an embodiment of the present invention.

[0041] Figure 2 is a flow chart of an ethylene production method according to an embodiment of the present invention.

[0042] 1-steam cracking furnace, 2-depropanizer, 3-hydrogenation reactor, 4-demethanizer, 5-deethanizer, 6-ethylene tower, 7-propylene tower, 8-debutanizer, 9-ethylene processing unit, 10-ethylene production unit, 11-drying unit, 91-quenching tower, 92-compressor section, 93-alkali washing dryer, 101-ethane oxidative dehydrogenation reactor, 102-acetic acid separator, 103-gas removal equipment. DETAILED DESCRIPTION

[0043] To make the purpose, technical solutions and advantages of this application more clear, the embodiments of this application will be described in detail below. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other in any way.

[0044] The embodiment of the present application provides an ethylene production device, comprising: a steam cracking furnace for steam cracking a feedstock to obtain a first product; an ethylene processing unit connected to the steam cracking furnace, the ethylene processing unit being used to quench, compress, alkali-wash and dry the first product; a depropanizer connected to the ethylene processing unit, obtaining a second product at the top of the depropanizer; a hydrogenation reactor connected to the top of the depropanizer, causing the second product to undergo a hydrogenation reaction in the hydrogenation reactor to obtain a third product, the third product comprising methane, hydrogen, ethane, ethylene, propylene and propane; a demethanizer connected to the hydrogenation reactor, for removing methane and hydrogen from the third product; a deethanizer connected to the bottom of the demethanizer and for extracting ethane and ethylene from the third product; an ethylene tower connected to the top of the deethanizer and for separating ethane and ethylene from the third product, with ethylene output through the top of the ethylene tower; and an ethylene production unit, one end of the ethylene production unit being connected to the bottom of the ethylene tower and the other end being connected to the hydrogenation reactor, the ethylene production unit being used to perform an oxidative dehydrogenation reaction on the third product containing ethane from the bottom of the ethylene tower to obtain a mixture containing ethylene and unreacted ethane, and allowing the mixture to enter the hydrogenation reactor.

[0045] The present application fully utilizes the compatibility of the ethane oxidative dehydrogenation process and the traditional ethane steam cracking process. By coupling the steam cracking process with the ethane oxidative dehydrogenation to ethylene process, the overall energy consumption of the increased ethylene product can be reduced, and the conversion rate of the circulating ethane and the ethylene selectivity can be improved. The reaction conversion rate is high, and a large amount of steam and fuel are saved. The energy consumption of the equipment is significantly reduced, which greatly reduces investment and production costs.

[0046] Figure 1 is a block diagram of an ethylene production apparatus according to an embodiment of the present invention.

[0047] like Figure 1 In an exemplary embodiment of the present application, an ethylene production plant is provided, comprising:

[0048] The steam cracking furnace 1 is used to steam crack the raw materials to obtain the first product;

[0049] an ethylene processing unit 9, which is in communication with the steam cracking furnace 1 and is used for quenching, compressing, alkali-washing and drying the first product;

[0050] a depropanizer 2, which is connected to the ethylene processing unit 9, and obtains a second product at the top of the depropanizer 2;

[0051] a hydrogenation reactor 3 connected to the top of the depropanizer 2, wherein the second product undergoes a hydrogenation reaction in the hydrogenation reactor 3 to obtain a third product, wherein the third product comprises methane, hydrogen, ethane, ethylene, propylene, and propane;

[0052] a demethanizer 4, which is in communication with the hydrogenation reactor 3 and is used to remove methane and hydrogen from the third product;

[0053] a deethanizer 5, which is connected to the bottom of the demethanizer 4 and is used to extract ethane and ethylene from the third product;

[0054] an ethylene tower 6, which is connected to the top of the deethanizer 5 and is used to separate ethane and ethylene in the third product, and ethylene is output through the top of the ethylene tower 6; and

[0055] An ethylene production unit 10, one end of which is connected to the bottom of the ethylene tower 6 and the other end of which is connected to the hydrogenation reactor 3, is used to perform an oxidative dehydrogenation reaction on the third product containing ethane from the bottom of the ethylene tower 6 to obtain a mixture containing ethylene and unreacted ethane, and to allow the mixture to enter the hydrogenation reactor 3.

[0056] The ethane from the bottom of the ethylene tower 6 is used as the raw material for the ethane oxidative dehydrogenation process to produce ethylene, replacing the process route of entering the steam cracking furnace 1 in the steam cracking process. The ethane is recycled into the cracking furnace for reaction, which has a high reaction conversion rate, saves a lot of steam and fuel, and significantly reduces the energy consumption of the device.

[0057] In an embodiment of the present application, the ethylene production equipment further includes a propylene tower 7, which is connected to the bottom of the deethanizer 5 and is used to extract propylene from the third product in the bottom of the deethanizer 5. The bottom of the propylene tower 7 is connected to the steam cracking furnace 1 and is used to deliver the third product in the bottom of the propylene tower 7 to the steam cracking furnace 1.

[0058] In the embodiment of the present application, the methane and hydrogen in the demethanizer 4 are output through the top of the demethanizer.

[0059] In an embodiment of the present application, the ethylene production equipment further includes a debutanizer 8, which is connected to the bottom of the depropanizer 2 and is used to separate the fourth product at the bottom of the depropanizer 2 into mixed C4 and pyrolysis gasoline.

[0060] In an embodiment of the present application, the ethylene production apparatus further includes a drying unit 11, one end of which is connected to the hydrogenation reactor 3 and the other end of which is connected to the demethanizer 4. The drying unit 11 is used to dry, condense, and separate the third product output from the hydrogenation reactor 3. Preferably, the drying unit 11 is a dryer.

[0061] In an embodiment of the present application, the raw materials include one or more of naphtha, liquid hydrocarbons and light hydrocarbons, the first product includes ethylene, propylene, butadiene, hydrogen, methane, acetylene, ethane, propyne, propadiene, vinyl propyne, butane, butene, and the second product includes ethylene, propylene, butadiene, hydrogen, methane, acetylene, ethane, propyne, propadiene, vinyl propyne.

[0062] In the embodiments of the present application, Figure 1 As shown, the ethylene processing unit 9 includes a quenching tower 91, a compressor section 92 and an alkaline washing dryer 93 connected in series, wherein the quenching tower 91 is connected to the steam cracking furnace 1, and the alkaline washing dryer 93 is connected to the depropanizer 2; the ethylene production unit 10 includes an ethane oxidative dehydrogenation reactor 101, an acetic acid separator 102 and a gas removal device 103 connected in series, wherein the ethane oxidative dehydrogenation reactor 101 is connected to the bottom of the ethylene tower, and the gas removal device 103 is connected to the hydrogenation reactor 3.

[0063] The present invention provides a method for producing ethylene using the above-mentioned device, the method comprising:

[0064] (1) steam cracking the raw material in a steam cracking furnace to obtain a first product;

[0065] (2) quenching, compressing, alkali washing, and drying the first product by an ethylene processing unit connected to the steam cracking furnace;

[0066] (3) processing the first product through a depropanizer connected to an ethylene processing unit, obtaining a second product at the top of the depropanizer and a fourth product at the bottom of the depropanizer;

[0067] (4) subjecting the second product to a hydrogenation reaction in a hydrogenation reactor connected to the top of the depropanizer to obtain a third product, wherein the third product comprises methane, hydrogen, ethane, ethylene, propylene, and propane;

[0068] (5) removing methane and hydrogen from the third product through a demethanizer connected to the hydrogenation reactor;

[0069] (6) extracting ethane and ethylene from the third product through a deethanizer connected to the bottom of the demethanizer;

[0070] (7) separating ethane and ethylene in the third product by an ethylene tower connected to the top of the deethanizer, and outputting ethylene through the top of the ethylene tower; and

[0071] (8) subjecting the third product containing ethane from the bottom of the ethylene tower to an oxidative dehydrogenation reaction through an ethylene production unit to obtain a mixture containing ethylene and unreacted ethane, and allowing the mixture to enter the hydrogenation reactor, wherein one end of the ethylene production unit is connected to the bottom of the ethylene tower and the other end is connected to the hydrogenation reactor.

[0072] Figure 2 is a flow chart of an ethylene production method according to an embodiment of the present invention.

[0073] like Figure 2 In an exemplary embodiment of the present application, a method for producing ethylene using the above-mentioned device is provided, the method comprising:

[0074] S101: steam cracking the raw material in a steam cracking furnace to obtain a first product;

[0075] S102: quenching, compressing, alkali washing, and drying the first product through an ethylene processing unit connected to the steam cracking furnace;

[0076] S103: processing the first product through a depropanizer connected to an ethylene processing unit, obtaining a second product at the top of the depropanizer and a fourth product at the bottom of the depropanizer;

[0077] S104: hydrogenating the second product in a hydrogenation reactor connected to the top of the depropanizer to obtain a third product, wherein the third product comprises methane, hydrogen, ethane, ethylene, propylene, and propane;

[0078] S105: removing methane and hydrogen from the third product through a demethanizer connected to the hydrogenation reactor;

[0079] S106: extracting ethane and ethylene from the third product through a deethanizer connected to the bottom of the demethanizer;

[0080] S107: Separating ethane and ethylene in the third product through an ethylene tower connected to the top of the deethanizer, and outputting ethylene through the top of the ethylene tower; and

[0081] S108: The third product containing ethane from the bottom of the ethylene tower is subjected to an oxidative dehydrogenation reaction by an ethylene production unit to obtain a mixture containing ethylene and unreacted ethane, and the mixture is introduced into the hydrogenation reactor, wherein one end of the ethylene production unit is connected to the bottom of the ethylene tower and the other end is connected to the hydrogenation reactor.

[0082] In an embodiment of the present application, the method further includes extracting propylene from the third product in the bottom of the deethanizer through a propylene tower connected to the bottom of the deethanizer, and sending the third product in the bottom of the propylene tower to the steam cracking furnace by connecting the bottom of the propylene tower to the steam cracking furnace.

[0083] In an embodiment of the present application, the method further comprises outputting methane and hydrogen through the top of the demethanizer.

[0084] In an embodiment of the present application, the method further comprises separating the fourth product at the bottom of the depropanizer into mixed C4 and pyrolysis gasoline by a debutanizer connected to the bottom of the depropanizer.

[0085] In an embodiment of the present application, the method further includes drying, condensing and separating the third product output from the hydrogenation reactor by a drying unit, wherein one end of the drying unit is connected to the hydrogenation reactor and the other end is connected to the demethanizer.

[0086] In an embodiment of the present application, the raw materials include one or more of naphtha, liquid hydrocarbons and light hydrocarbons, the first product includes ethylene, propylene, butadiene, hydrogen, methane, acetylene, ethane, propyne, propadiene, vinyl propyne, butane, and butene, and the second product includes ethylene, propylene, butadiene, hydrogen, methane, acetylene, ethane, propyne, propadiene, and vinyl propyne; the ethylene processing unit includes a quenching tower, a compressor section and an alkali washing dryer connected in series, wherein the quenching tower is connected to the steam cracking furnace, and the alkali washing dryer is connected to the depropanizer; the ethylene production unit includes an ethane oxidative dehydrogenation reactor, an acetic acid separator and a gas removal device connected in series, wherein the ethane oxidative dehydrogenation reactor is connected to the bottom of the ethylene tower, and the gas removal device is connected to the hydrogenation reactor.

[0087] In the above embodiment, the recycled ethane from the steam cracking furnace is used as the raw material for the ethane oxidative dehydrogenation process to produce ethylene. After ethane oxidative dehydrogenation reaction, water washing, deoxygenation, compression, alkali washing and drying, it passes through a depropanizer. The first product of the reaction product including C2 and light components below C2 and part of the C3 components is sent to the hydrogenation reactor in the steam cracking process to produce ethylene. The generated second product is dried, condensed and separated and then enters the demethanizer. Methane and hydrogen are obtained at the top of the tower. The third product in the bottom of the tower enters the deethanizer. The top gas of the deethanizer enters the ethylene tower to separate the product ethylene and recycled ethane. The recycled ethane is used as the raw material for the ethane oxidative dehydrogenation process to produce ethylene, replacing the process route of entering the steam cracking furnace in the steam cracking process. The process of circulating ethane entering the cracking furnace for reaction has a high reaction conversion rate, saves a lot of steam and fuel, and significantly reduces the energy consumption of the device.

[0088] In the above embodiment, before the step of sending the recycled ethane to the hydrogenation reactor for hydrogenation reaction, the step also includes: subjecting the recycled ethane to ethane oxidative dehydrogenation reaction, water washing, deoxygenation, compression, alkali washing and drying treatment.

[0089] This scheme leverages the compatibility of ethane oxidative dehydrogenation and conventional ethane steam cracking processes. For conventional steam cracking lines with capacities ranging from 600,000 to 1.5 million tons per year, the recycle ethane flow rate is controlled between 4.69 kg / sec (kilograms per second) and 10 kg / sec (kilograms per second). The operating temperature of the recycle ethane is controlled between 360°C and 380°C, and the reaction pressure is controlled between 0.1 MPa and 20 MPa. This achieves a controlled ethylene production rate of 3.47 kg / sec (kilograms per second) in the ethylene column. This coupled process reduces the overall energy consumption for increased ethylene production to less than 250 kgEo / t (kilograms of oil equivalent per ton), improves the conversion rate of recycle ethane, and significantly reduces ethylene selectivity. The high conversion rate, significant steam and fuel savings, and significant reductions in plant energy consumption are achieved. Furthermore, the production of acetic acid as a byproduct offers added economic value, which can be sold or used in downstream facilities. The CO2 (carbon dioxide) produced by the ethane oxidative dehydrogenation reactor can be recovered and used downstream or captured.

[0090] Compared to steam cracking, this proposed process, which recycles ethane into the cracking furnace for reaction, achieves high conversion rates, saves significant amounts of steam and fuel, and significantly reduces energy consumption. Coupled with traditional steam cracking, this process allows for flexible adjustment of ethylene processing loads to adapt to market fluctuations. The coupled steam cracking and ethane oxidation process has been simulated and analyzed using process simulation software, demonstrating its feasibility and reliability. This process also provides case studies and detailed data for industrial production.

[0091] Although the embodiments disclosed in this application are as described above, the contents described are merely embodiments adopted to facilitate understanding of this application and are not intended to limit this application. Any person skilled in the art to which this application belongs may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in this application. However, the scope of patent protection of this application shall still be based on the scope defined by the attached claims.

Claims

1. An ethylene production plant, characterized in that: include: A steam cracking furnace, used for steam cracking the added raw materials to obtain a first product; an ethylene processing unit, which is in communication with the steam cracking furnace, and is used for quenching, compressing, alkali-washing and drying the first product; a depropanizer, which is in communication with the ethylene processing unit and obtains a second product at the top of the depropanizer; a hydrogenation reactor connected to the top of the depropanizer, wherein the second product is subjected to a hydrogenation reaction in the hydrogenation reactor to obtain a third product, wherein the third product comprises methane, hydrogen, ethane, ethylene, propylene and propane; a demethanizer, which is in communication with the hydrogenation reactor and is used to remove methane and hydrogen from the third product; a deethanizer, which is connected to the bottom of the demethanizer and is used to extract ethane and ethylene from the third product; an ethylene tower, which is connected to the top of the deethanizer and is used to separate ethane and ethylene in the third product, and the ethylene is output through the top of the ethylene tower; as well as An ethylene production unit, one end of which is connected to the bottom of the ethylene tower and the other end of which is connected to the hydrogenation reactor, is used to perform an oxidative dehydrogenation reaction on the third product containing ethane from the bottom of the ethylene tower to obtain a mixture containing ethylene and unreacted ethane, and to allow the mixture to enter the hydrogenation reactor.

2. The ethylene production equipment according to claim 1 further comprises a propylene tower, which is communicated with the tower kettle of the deethanizer and is used to extract propylene from the third product in the tower kettle of the deethanizer, and the tower kettle of the propylene tower is communicated with the steam cracking furnace and is used to deliver the third product in the tower kettle of the propylene tower to the steam cracking furnace.

3. The ethylene production equipment according to claim 1, wherein: The methane and hydrogen in the demethanizer are output through the top of the demethanizer.

4. The ethylene production equipment according to claim 1, further comprising a debutanizer, which is communicated with the bottom of the depropanizer and is used to separate the fourth product at the bottom of the depropanizer into mixed C4 and pyrolysis gasoline.

5. The ethylene production equipment according to claim 1, further comprising a drying unit, one end of which is connected to the hydrogenation reactor and the other end of which is connected to the demethanizer, and the drying unit is used to dry, condense and separate the third product output from the hydrogenation reactor.

6. The ethylene production plant according to claim 1, wherein: The raw materials include one or more of naphtha, liquid hydrocarbons and light hydrocarbons, the first product includes ethylene, propylene, butadiene, hydrogen, methane, acetylene, ethane, propyne, propadiene, vinyl propyne, butane and butene, and the second product includes ethylene, propylene, butadiene, hydrogen, methane, acetylene, ethane, propyne, propadiene and vinyl propyne.

7. The ethylene production plant according to claim 1, wherein: The ethylene processing unit includes a quenching tower, a compressor section and an alkaline washing dryer connected in series, wherein the quenching tower is connected to the steam cracking furnace, and the alkaline washing dryer is connected to the depropanizer; the ethylene production unit includes an ethane oxidative dehydrogenation reactor, an acetic acid separator and a gas removal device connected in series, wherein the ethane oxidative dehydrogenation reactor is connected to the bottom of the ethylene tower, and the gas removal device is connected to the hydrogenation reactor.

8. A method for producing ethylene using the ethylene production equipment according to any one of claims 1 to 7, characterized in that: The method comprises: (1) steam cracking the raw material in a steam cracking furnace to obtain a first product; (2) quenching, compressing, alkali washing, and drying the first product by an ethylene processing unit connected to the steam cracking furnace; (3) processing the first product through a depropanizer connected to an ethylene processing unit, obtaining a second product at the top of the depropanizer and a fourth product at the bottom of the depropanizer; (4) subjecting the second product to a hydrogenation reaction in a hydrogenation reactor connected to the top of the depropanizer to obtain a third product, wherein the third product comprises methane, hydrogen, ethane, ethylene, propylene, and propane; (5) removing methane and hydrogen from the third product through a demethanizer connected to the hydrogenation reactor; (6) extracting ethane and ethylene from the third product through a deethanizer connected to the bottom of the demethanizer; (7) separating ethane and ethylene in the third product by an ethylene tower connected to the top of the deethanizer, and outputting ethylene through the top of the ethylene tower; and (8) subjecting the third product containing ethane from the bottom of the ethylene tower to an oxidative dehydrogenation reaction through an ethylene production unit to obtain a mixture containing ethylene and unreacted ethane, and allowing the mixture to enter the hydrogenation reactor, wherein one end of the ethylene production unit is connected to the bottom of the ethylene tower and the other end is connected to the hydrogenation reactor.

9. The method according to claim 8, wherein The method further comprises extracting propylene from the third product in the bottom of the deethanizer through a propylene column connected to the bottom of the deethanizer, and sending the third product in the bottom of the propylene column to the steam cracking furnace by connecting the bottom of the propylene column to the steam cracking furnace; or The method further comprises outputting methane and hydrogen through the top of the demethanizer; or The method further comprises separating the fourth product at the bottom of the depropanizer into mixed C4 and pyrolysis gasoline through a debutanizer connected to the bottom of the depropanizer; or The method further includes drying, condensing and separating the third product output from the hydrogenation reactor by a drying unit, wherein one end of the drying unit is connected to the hydrogenation reactor and the other end is connected to the demethanizer.

10. The method according to claim 8, wherein The raw materials include one or more of naphtha, liquid hydrocarbons and light hydrocarbons; the first products include ethylene, propylene, butadiene, hydrogen, methane, acetylene, ethane, propyne, propadiene, vinyl propyne, butane and butene; the second products include ethylene, propylene, butadiene, hydrogen, methane, acetylene, ethane, propyne, propadiene and vinyl propyne; the ethylene processing unit includes a quench tower, a compressor section and an alkali washing dryer; the ethylene production unit includes an ethane oxidative dehydrogenation reactor, an acetic acid separator and a gas removal device.

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