Multi-stage cascade reaction process method and system for preparing ethylene and oxygen-containing compound through catalytic oxidation of mixed hydrocarbon of carbon 1 and carbon 2

Abstract

The invention relates to an ethylene preparation technology in organic chemical industry, in particular to a multi-stage cascade reaction process method and system for preparing ethylene and an oxygen-containing compound through catalytic oxidation of mixed hydrocarbon of carbon I and carbon II. According to the method and the system provided by the invention, conventional inert substances such as nitrogen or water and the like are not used as diluents in the raw materials, and oxygen in any reactor is nearly completely converted, namely the oxygen content in tail gas of each reactor is very low, and the process safety is high. The reactors can be connected in series in multiple stages, the raw material concentration in the raw materials can be flexibly adjusted, the two modes can flexibly adjust the raw material one-way conversion level of the device, and meanwhile the proportion of ethylene and oxygen-containing compounds such as acetic acid products can be adjusted so as to better adapt to market changes. The method and the system provided by the invention have the advantages of high ethylene molar selectivity and low raw material unit consumption. The method and the system provided by the invention have the advantages of low production energy consumption and less production wastes (mainly referring to carbon monoxide and carbon dioxide).

Description

Technical Field

[0001] The present invention relates to the technology for preparing ethylene and acetic acid in organic chemical industry, and in particular to a multi-stage series reaction process method and system for preparing ethylene and oxygen-containing compounds by catalytic oxidation of mixed hydrocarbons of carbon one and carbon two. Background Art

[0002] Ethylene is one of the world's largest consumer goods and chemicals, and the world's highest-yielding organic chemical raw material. It is known as the "mother of the petrochemical industry", a basic raw material for petrochemicals, and an important indicator of a country's petrochemical industry level. In 2022, the global ethylene production capacity reached 210 million tons, with an output of 197 million tons. Since the development and completion of the first cracking ethylene unit by Union Carbide in 1923, global ethylene production has relied mainly on steam cracking technology for nearly a hundred years. Today, more than 90% of the world's ethylene is produced by steam cracking. Depending on the reaction raw materials, the development of steam cracking technology can be roughly divided into two stages: the first stage is from the birth of steam cracking technology to the beginning of this century, naphtha, which has a price advantage and is easy to store and transport, has always been the main raw material for steam cracking; the second stage is since the US shale gas revolution in 2010, due to the substantial increase in the supply of low-carbon hydrocarbons such as ethane and the continuous decline in prices, steam cracking of ethylene using ethane as raw material has become the most competitive ethylene production process route. In addition, ethylene is currently the most productive organic chemical raw material, and it also consumes the most energy in production (production energy consumption is as high as 2.0×10 15 kJ / year) and the organic chemical product with the most associated greenhouse gases, so the innovation of its process technology will also have a profound impact on the global energy and environmental pattern. Although the comprehensive production cost of ethane cracking to ethylene is the lowest, the process is still a highly energy-intensive, highly polluting and strongly endothermic process, and the operating temperature usually needs to be above 900°C (Equation 1). Therefore, the development of a more advanced new process for ethylene production is of extremely important strategic significance. The technology for producing ethylene from low-carbon hydrocarbons such as ethane through catalytic oxidative dehydrogenation is a spontaneous energy-saving process that is not restricted by thermodynamic equilibrium and can theoretically be carried out at room temperature (Equation 2). Based on the important pillar status of ethylene in the national economy and the increasingly urgent global demand for environmental protection, it will be very necessary to develop new technologies for the targeted conversion of ethane to ethylene with low energy consumption and low carbon emissions.

[0003] Oxygen-containing compounds such as acetic acid (acetic acid) can not only be used in food processing, but also are an important chemical raw material intermediate. They are mainly used to produce compounds such as purified terephthalic acid (PTA), vinyl acetate, acetate esters, acetic anhydride and chloroacetic acid. They can be used as industrial solvents and raw materials for pesticides, medicines and dyes, and are widely used in fabric printing and dyeing, photographic drug manufacturing and the rubber industry. At present, the largest downstream demand for acetic acid is PTA, accounting for about 30% of total consumption, and it is an important chemical fiber raw material for the polyester industry. In 2020, China's acetic acid production and consumption accounted for 53.4% ​​and 45.8% of the world's total, respectively, making it the world's largest producer and consumer of acetic acid.

[0004] With the development of the acetic acid industry and the rapid expansion of its scale, the acetic acid production process has also been continuously updated. According to the different raw materials, the production process routes of acetic acid can be divided into acetylene, ethanol, ethylene, butane or light oil routes, and methanol routes. The acetylene, ethanol and ethylene raw material routes specifically oxidize acetylene, ethanol and ethylene to produce acetaldehyde, and then further oxidize acetaldehyde to produce acetic acid. The methanol route has become the main acetic acid production process at present with its mature technical advantages and cost advantages. The output of acetic acid produced by this method accounts for more than 90% of the total acetic acid production capacity, but the process is cumbersome, the investment cost is high, and the catalyst used contains iodine and is toxic. Therefore, it is necessary to find new process technologies. In 1978, Thorsteinson et al. reported the use of Mo-V catalysts to directly oxidize ethane to produce acetic acid under pressurized conditions, thus opening up the study of ethane selective oxidation to prepare acetic acid.

[0005] Direct dehydrogenation of ethane to ethylene process:

[0006] C2H6=C2H4+H2,△ r H m =136 kJ / mol…………………………………………Equation 1

[0007] Ethane oxidative dehydrogenation process to ethylene:

[0008] C2H6+0.5O2=C2H4+H2O,△ r H m =-104 kJ / mol………………………………Equation 2

[0009] The catalytic oxidation of low-carbon hydrocarbons to produce ethylene and oxygenated compounds has been widely studied in recent decades. The introduction of oxygen thermodynamically supports the formation of deep oxidation products such as CO and CO2, but also poses a great challenge to the safety of the process. Therefore, it is necessary not only to develop highly selective catalysts for the catalytic oxidation of low-carbon hydrocarbons to produce ethylene and oxygenated compounds, but also to carry out new process research. Public data show that at normal temperature and pressure, the explosion limit of ethane in air (i.e., ethane + oxygen + nitrogen) is 3.0%-15.5%, while the explosion limit in oxygen (i.e., ethane + oxygen) is expanded to 3.0%-66.0%. In particular, the catalytic oxidation of low-carbon hydrocarbons to produce ethylene and oxygenated compounds is usually a high-temperature and non-normal pressure process, so low-carbon hydrocarbons will inevitably have a wider explosion limit in oxygen (see Table 1). If the concentration of low-carbon hydrocarbons in the process of catalytic oxidation of low-carbon hydrocarbons to produce ethylene and oxygen-containing compounds is lower than its lower explosion limit (i.e., less than 3%), its concentration in the raw material will be too low, and a higher space-time yield of ethylene and oxygen-containing compounds cannot be obtained, which is obviously uneconomical. Therefore, the usual practice is to keep the ethane concentration above its upper explosion limit. Moreover, because the catalytic oxidation of low-carbon hydrocarbons to produce ethylene and oxygen-containing compounds is a highly exothermic process, as described in patents CN113860985A and CN113831207A, a large amount of diluent (such as nitrogen) must be used in the raw material in the conventional practice to reduce the process safety risk and improve the heat transfer efficiency. That is, the purpose is to take into account the important indicators affecting the economic efficiency of the process of catalytic oxidation of low-carbon hydrocarbons to produce ethylene and oxygen-containing compounds, such as ethylene selectivity, ethane conversion rate and ethylene space-time yield, while maintaining process safety. Patents CN105090575B, CN110963890A, CN110963879A, CN106660901B, CN105727975B, etc. all disclose methods of using inert gases such as water vapor, nitrogen, carbon dioxide, etc. as diluents. According to the existing public information, the addition of these diluents has brought challenges to the separation and industrial application of this technology: the advantage of using water vapor as a diluent gas is that the diluent gas and the product gas can be separated by cooling, and the separation energy consumption is lower than when nitrogen is used as a diluent. The disadvantage is that the presence of water vapor in the raw gas will greatly increase the selectivity of the by-product acetic acid, thereby reducing the effective utilization rate of the raw material ethane to produce ethylene; using CO2 as a diluent gas will cause a large amount of CO2 to be recycled back to the reactor after absorption and desorption. The decarbonization unit has high energy consumption, and the desorbed CO2 is a normal pressure gas. The energy consumption and equipment investment of compressing and recycling it back to the reactor are relatively high. A large amount of CO2 needs to be introduced during startup, and its material source is limited; using nitrogen as a diluent gas is usually beneficial to improving the selectivity of ethylene, but it will cause a large amount of nitrogen to be mixed with ethane and ethylene. If deep cold separation is adopted, it is necessary to increase the pressure to more than 3MPa and cool to below -100℃. The compressor has a large pressure ratio and the required cooling capacity is of high quality, resulting in a large number of equipment, high investment, and high energy consumption for separating nitrogen.Patents CN110225900A and CN110225901A also disclose the use of methane and at least other inert components as diluents (i.e., a mixture of two or more inert components). The increase in the types of inert components will inevitably increase the number of product separation equipment. Therefore, it is more meaningful to develop a new process for catalytic oxidation of low-carbon hydrocarbons to produce ethylene and oxygen-containing compounds using carbon-1 compounds (such as methane) and carbon-2 compounds (such as ethane) as raw materials and direct use of pure oxygen.

[0010] Table 1. Upper explosion limit of ethane in pure oxygen under various working conditions

[0011]

[0012] In the method and system of the present invention, if there are multiple reactors, the connection relationship between the reactors is in series. Existing public information shows that the conventional connection mode between reactors in the art is parallel connection, such as CN110225900A discloses that its reaction unit "may include one or more reactors, such as those operated in parallel", and CN112142547A also discloses that the connection relationship between the reactors is parallel connection. Summary of the invention

[0013] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a multi-stage series reaction process method and system for preparing ethylene and oxygen-containing compounds by catalytic oxidation of mixed hydrocarbons of carbon one and carbon two, wherein only a mixture of carbon one compound and carbon two compound is used as the raw material, and only oxygen is needed as the oxidant, and a strategy of adding oxygen in stages is optionally adopted, and the reactors are optionally connected in a multi-stage series to achieve the preparation of ethylene and oxygen-containing compounds (such as acetic acid), that is, oxygen without any diluent is used, and the mixed hydrocarbon and oxygen are mixed in a certain proportion under safe operating conditions, and then continuously pass through a multi-stage series oxidation catalyst bed to generate a catalytic oxidation reaction, and then undergo a subsequent conventional multi-stage separation to finally obtain ethylene that meets the national standard for industrial ethylene (GB / T7715-2014) and industrial oxygen-containing compounds such as glacial acetic acid (acetic acid product (GB / T 1628-2020). The method and system provided by the present invention can ensure process safety on the one hand, and high selectivity and space-time yield of ethylene products on the other hand, ultimately achieving the purpose of reducing raw material unit consumption and comprehensive energy consumption. On the other hand, based on the selected carbon-one compound (such as methane) having the highest constant pressure specific heat capacity characteristic (see Table 2), the mixed hydrocarbon catalytic oxidation reaction process can be stably operated at a higher load.

[0014] Table 2. Specific heat capacity of common substances at constant pressure (400°C)

[0015]

[0016] The inventors have realized that in the catalytic oxidation reaction of mixed hydrocarbons, the use of a high ethylene selectivity catalyst as described in patent CN105080575B (application number CN2014101988672) and suitable reaction conditions (such as a low ratio of oxygen to ethane) are crucial to the heat control of the reaction process. For example, when the low carbon hydrocarbon is ethane, the four oxidation reactions described below occur, and the heat release intensities of side reaction 1, side reaction 2, and side reaction 3 are 5.7 times, 8.3 times, and 13.7 times that of the main reaction, respectively. This is exactly one of the starting points of the present invention.

[0017] Main reaction: C2H6+0.5O2=C2H4+H2O, △ r H m =-104 kJ / mol

[0018] Side reaction 1: C2H6+1.5O2=C2H4O2+H2O, △ r H m =-591 kJ / mol

[0019] Side reaction 2: C2H6+2.5O2=2CO+3H2O, △ r H m =-863 kJ / mol

[0020] Side reaction 3: C2H6+3.5O2=CO2+3H2O, △ r H m =-1429 kJ / mol

[0021] The present invention is achieved through the following technical solutions:

[0022] One of the technical solutions of the present invention is to provide a multi-stage series reaction process method for preparing ethylene and oxygen-containing compounds by catalytic oxidation of mixed hydrocarbons of carbon one and carbon two, wherein the raw gas contains mixed hydrocarbons of carbon one and carbon two as raw materials, and the oxidant is oxygen, the carbon one includes methane, and the carbon two includes ethane.

[0023] Based on the above technical solution, further, the reactor is a fixed bed reactor. If the number of reactors is 2 or more, the reactors are connected in series, and oxygen needs to be added before each reactor.

[0024] Based on the above technical solution, further, the method includes the following steps:

[0025] 1) Preheat the C1 compound (such as methane) and C2 compound (such as ethane) and oxygen streams respectively, mix them, and enter the reactor together for oxidation reaction to obtain the final reaction process product gas a. If there are two or more reactors, the mixed stream mixed with the added oxygen at the outlet of the preceding reactor enters the subsequent reactor to continue oxidation reaction to obtain the final reaction process product gas a;

[0026] 2) The final reaction product a gas described in step 1) is subjected to rapid cooling treatment to remove acetic acid and water, and obtain a process product gas b from which acid water is removed. The acetic acid therein is recovered or treated with acid water. The rapid cooling treatment, removal of acetic acid and water, recovery of acetic acid or treatment with acid water can be carried out by any conventional technology in the art;

[0027] 3) removing oxygen from the process product gas b in step 2) to obtain a process product gas c. The oxygen removal process may be carried out using any conventional technology in the art, including but not limited to catalytic oxidation technology;

[0028] 4) The process product gas c described in step 3) is subjected to a carbon dioxide removal treatment to obtain a process product gas d. The carbon dioxide removal treatment can be carried out by any conventional technology in the art, including but not limited to washing with an organic amine first and then washing with an alkali;

[0029] 5) drying, multi-stage compression and cryogenic treatment of the process product gas d described in step 4) to obtain the process product gas e. The drying, multi-stage compression and cryogenic treatment can adopt any conventional technology in the art;

[0030] 6) The process product gas e in step 5) is subjected to ethane removal treatment to obtain process product gas f at the top of the tower and ethane at the bottom of the tower. The so-called ethane removal treatment can be carried out by any conventional technology in the art.

[0031] 7) returning the ethane described in step 6) to the ethane preheater of step 1) for preheating and continuing oxidation reaction as a raw material;

[0032] 8) The process product gas f described in step 6) is subjected to ethylene distillation treatment to obtain process product gas g at the top of the tower and ethylene at the bottom of the tower. The ethylene distillation treatment can be carried out using any conventional technology in the art.

[0033] 9) The process product gas g described in step 8) is subjected to methane removal treatment to obtain tail gas at the top of the tower and methane at the bottom of the tower. The methane removal treatment can be carried out using any conventional technology in the art.

[0034] 10) returning the methane described in step 9) to the methane preheater of step 1) for preheating, and then mixing with the ethane stream and the oxygen stream and entering the reactor;

[0035] 11) treating the tail gas in step 9). The tail gas treatment may be carried out by any conventional technique in the art, including but not limited to flare treatment.

[0036] Based on the above technical solution, further, in the step 1), the mixed raw material entering the first reactor contains only carbon one compounds (such as methane).

[0037] Based on the above technical scheme, further, the catalytic reaction of mixed hydrocarbon oxidation to produce ethylene and oxygen-containing compounds is carried out in a multi-stage series reactor, and the multi-stage series reactor includes a special case of only one fixed bed reactor, and the reactor is a fixed bed reactor, preferably a shell-and-tube fixed bed reactor.

[0038] Based on the above technical solution, further, the molar ratio of carbon one to carbon two in the mixed hydrocarbon of carbon one and carbon two is 0.01-80:1, preferably 10-60:1, and more preferably 20-50:1.

[0039] Based on the above technical solution, further, the mass ratio of oxygen to the total amount of inflammable and explosive substances in the mixed raw material at the inlet of the reactor is 0.01 to 0.55:1. The inflammable and explosive substances described in the present invention include but are not limited to methane, ethane, ethylene, carbon monoxide and acetic acid; if it is the first reactor, it refers to methane and ethane; if it is the second or subsequent series reactor, it refers to ethylene, acetic acid, CO and unreacted remaining methane and ethane in the product. The inlet temperature of any fixed bed reactor is 100°C to 400°C, preferably 150°C-300°C; the inlet pressure of any fixed bed reactor is 0.10 to 1.0MPa, preferably 0.20-0.70MPa.

[0040] Based on the above technical solution, further, when the number of reactors is 2 or more, the single-pass conversion rate of mixed hydrocarbons and the product content of oxygen-containing compounds (such as acetic acid) will be significantly increased.

[0041] Based on the above technical scheme, further, after the acetic acid is recovered in step 2), the acetic acid flow meets the national standard for industrial glacial acetic acid (GB / T 1628-2020).

[0042] Based on the above technical solution, further, after the ethylene distillation treatment in step 8), the ethylene logistics complies with the national standard for industrial ethylene (GB / T 7715-2014).

[0043] The second technical solution of the present invention is to provide a system for catalytic oxidation of C1 and C2 mixed hydrocarbons to produce ethylene and oxygen-containing compounds for the above process, such as Figure 1 As shown, it mainly includes:

[0044] A preheater for preheating an oxygen stream, a C2 compound (such as ethane) stream and a C1 compound (such as methane) stream, comprising an oxygen preheater (901-1), an ethane preheater (901-2) and a methane preheater (901-3);

[0045] For hot mixing the raw material flow through the reactor (903-1) filled with a mixed hydrocarbon oxidation catalyst, and the subsequent possible reactor (903-i), i is 2-3, preferably 2 and 3;

[0046] A quench unit (902-1), such as a quench cooler, for quenching the process product gas stream from the last reactor;

[0047] an acid water removal unit (904), such as an acid water removal device, for quenching and removing acid water from the process product gas stream a;

[0048] A unit (905) for removing oxygen from the process gas product stream b, such as an oxygen removal device;

[0049] A unit (906) for removing CO2 from the process gas product stream c; a unit (806), such as a CO2 removal device;

[0050] A unit (907) for drying, multi-stage compression and cryogenic treatment of the process gas product stream d, such as drying, multi-stage compression and cryogenic treatment equipment;

[0051] A unit (908) for removing ethane from the process gas product stream e, such as an ethane removal device;

[0052] A unit (909) for treating the process gas product stream f with ethylene distillation, such as an ethane removal unit;

[0053] A unit (910) for removing methane from the process gas product stream g, such as a methane removal device.

[0054] In general, compared with the existing disclosed technologies, the characteristics and advantages of the present invention are:

[0055] a) By using the method and system provided by the present invention, conventional inert substances such as nitrogen or water are not used as diluents in the raw materials; oxygen in any reactor is nearly completely converted, that is, the oxygen content in the tail gas after each reactor is very low.

[0056] b) The reactors can be connected in series in multiple stages, which means that the ethane single-pass conversion level and product selectivity of the device can be flexibly adjusted as needed, that is, the ratio of ethylene and oxygen-containing compounds (such as acetic acid) products can be adjusted at the same time to better adapt to market changes.

[0057] c) Using the method and system provided by the present invention, the mixed hydrocarbon catalytic oxidation reaction on the catalyst can be operated with high stability.

[0058] d) By utilizing the method and system provided by the present invention, the single-pass conversion rate of the mixed hydrocarbons can be flexibly adjusted by adjusting the concentration of the mixed hydrocarbons in the feed.

[0059] e) The method and system provided by the present invention have high ethylene molar selectivity and low raw material unit consumption.

[0060] f) The method and system provided by the present invention have a short production route, a simple product composition, low production energy consumption, and low carbon (mainly carbon monoxide and carbon dioxide) emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 The present invention is a schematic diagram of the system structure of a multi-stage series process for producing ethylene and oxygen-containing compounds by catalytic oxidation of mixed C1 and C2 hydrocarbons.

[0062] Figure 1 Explanation of logistics numbers: a represents the output after the last reactor (including but not limited to unconverted ethane, unconverted oxygen, ethylene, acetic acid, carbon monoxide, carbon dioxide, water and methane); b represents the process gas logistics after the removal of acid water; c represents the process product gas logistics after the removal of oxygen; d represents the process product gas logistics after the removal of CO2; e represents the process product after drying, multi-stage compression and cryogenic treatment; f represents the process product gas logistics after the ethylene distillation tower, and the polymerization-grade product ethylene is distilled out at the bottom of the tower; g represents the process gas product logistics flowing out from the top of the methane distillation tower, which is mainly carbon monoxide, and the methane distilled out at the bottom of the tower is recycled. For other logistics, please refer to the text description in the attached figure.

[0063] Figure 1 Explanation of equipment numbers: 901-1 represents an oxygen preheater; 901-2 represents an ethane preheater; 901-3 represents a methane preheater; 902-1 represents a quenching equipment unit; 903-1 represents the first fixed bed reactor, 903-i represents the i-th fixed bed reactor that may exist, and i takes the values ​​of 2 and 3; 904 represents an acid water removal equipment unit, 905 represents an oxygen removal equipment unit; 906 represents a CO2 removal equipment unit; 907 represents a drying, multi-stage compression and cryogenic treatment unit; 908 represents an ethane removal tower; 909 represents an ethylene distillation tower; 910 represents a methane removal unit.

[0064] Figure 2 The present invention is a schematic diagram of the system structure of a single reactor process for producing ethylene and oxygen-containing compounds by catalytic oxidation of mixed C1 and C2 hydrocarbons.

[0065] Figure 2 Explanation of logistics numbers: a represents the output after the reactor (including but not limited to unconverted ethane, unconverted oxygen, ethylene, acetic acid, carbon monoxide, carbon dioxide, water and methane); b represents the process gas logistics after the removal of acid water; c represents the process product gas logistics after the removal of oxygen; d represents the process product gas logistics after the removal of CO2; e represents the process product after drying, multi-stage compression and cryogenic treatment; f represents the process product gas logistics after the ethylene distillation tower, and the polymerization-grade product ethylene is distilled out at the bottom of the tower; g represents the process gas product logistics flowing out from the top of the methane distillation tower, which is mainly carbon monoxide, and the methane distilled out at the bottom of the tower is recycled. For other logistics, please refer to the text description in the attached figure.

[0066] Figure 2 Explanation of equipment numbers: 901-1 represents oxygen preheater; 901-2 represents ethane preheater; 901-3 represents methane preheater; 902-1 represents quenching equipment unit; 903 represents fixed bed reactor; 904 represents acid water removal equipment unit, 905 represents oxygen removal equipment unit; 906 represents CO2 removal equipment unit; 907 represents drying, multi-stage compression and cryogenic treatment unit; 908 represents ethane removal tower; 909 represents ethylene distillation tower; 910 represents methane removal unit.

[0067] Figure 3 The present invention is a schematic diagram of the system structure of a dual-reactor series process for catalytic oxidation of C1 and C2 mixed hydrocarbons to produce ethylene and oxygen-containing compounds.

[0068] Figure 3 Explanation of logistics numbers: a represents the output after the second reactor (including but not limited to unconverted ethane, unconverted oxygen, ethylene, acetic acid, carbon monoxide, carbon dioxide, water and methane); b represents the process gas logistics after the removal of acid water; c represents the process product gas logistics after the removal of oxygen; d represents the process product gas logistics after the removal of CO2; e represents the process product after drying, multi-stage compression and cryogenic treatment; f represents the process product gas logistics after the ethylene distillation tower, and the polymerization-grade product ethylene is distilled out at the bottom of the tower; g represents the process gas product logistics flowing out from the top of the methane distillation tower, which is mainly carbon monoxide, and the methane distilled out at the bottom of the tower is recycled. For other logistics, please refer to the text description in the attached figure.

[0069] Figure 3Explanation of equipment numbers: 901-1 represents an oxygen preheater; 901-2 represents an ethane preheater; 902-1 represents an ethane and oxygen mixer connected to the first fixed bed reactor, and 902-2 represents a mixer for product gas and added oxygen from the second fixed bed reactor; 903-1 represents the first fixed bed reactor, and 903-2 represents the second fixed bed reactor; 904 represents an acid water removal equipment unit; 905 represents an oxygen removal equipment unit; 906 represents a CO2 removal equipment unit; 907 represents a drying, multi-stage compression and cryogenic treatment unit; 908 represents an ethane removal tower; 909 represents an ethylene distillation tower; 910 represents a methane removal unit. DETAILED DESCRIPTION

[0070] In the description of the present invention, the number of reactors is expressed as "multi-stage", including the case where only one reactor is used.

[0071] In the description of the present invention, pressure is a commonly used term, and its real meaning is "pressure intensity", which indicates absolute pressure (absolute pressure).

[0072] In the description of the present invention, the hierarchy is reduced as follows: system→unit→device.

[0073] In the following embodiments, unless otherwise specified, the devices, equipment or processing technologies used are all commonly used devices or commonly used technologies in the art.

[0074] In the description of the present invention, it is necessary to further explain that the structures, proportions and sizes shown in the drawings of the present specification are all expressed in a concise manner, and are only used to match the contents disclosed in the specification so that people familiar with the technology can understand and read them, but are not used to limit the limiting conditions that the present invention can be implemented, so they have no technical substantive significance. Any structural modification, proportional relationship change or size adjustment, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the present invention. The terms used in the present invention to indicate the orientation or position relationship, such as "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., refer to the orientation or position relationship based on the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to describe the order of the equipment before and after, and cannot be understood as indicating or implying their relative importance.

[0075] In the description of the present invention, for the clarity of the process diagram, the heat exchange process is not specifically identified, such as the heat released during the oxidation reaction of the mixed hydrocarbons of C1 and C2 is recovered to heat various raw materials to achieve the purpose of preheating the raw materials.

[0076] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection, or an integral connection, or a mechanical connection, or an electrical connection, or a direct connection, or an indirect connection through an intermediate medium, or the internal connection of two elements, or a combination of any of the above connections. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0077] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0078] The following is a detailed description of a multi-stage series process method and system for producing ethylene and oxygen-containing compounds by catalytic oxidation of mixed C1 and C2 hydrocarbons according to the present invention.

[0079] Example 1

[0080] like Figure 2As shown, fresh ethane with a flow rate of 41.266kg / sec and recycled ethane with a flow rate of 43.865kg / sec are mixed and preheated, and methane with a flow rate of 45.454kg / sec, and oxygen with a flow rate of 31.999kg / sec is preheated and fully mixed with ethane and then enters the fixed bed reactor for oxidation reaction. The fixed bed is a shell and tube fixed bed reactor. The shell and tube fixed bed reactor is divided into a hot side and a cold side. The mixed gas composed of ethane and oxygen enters the hot side of the shell and tube fixed bed reactor. The hot side is filled with an annular catalyst, and its active component is MoVTeNbO described in patent CN2014101988672; the circulating molten salt is sent to the cold side of the shell and tube fixed bed reactor, and after absorbing the heat released by the oxidation reaction, it is used as a circulating molten salt and then cooled by a heat exchanger, and then circulated back to the cold side of the shell and tube fixed bed reactor. The molten salt can be selected from any molten salt system known to those skilled in the art, preferably potassium and sodium nitrates and nitrites. Ethane and oxygen react in the reactor to produce ethylene, acetic acid, carbon monoxide, carbon dioxide, water and methane. The reactor discharge also contains unconverted ethane and trace oxygen, including ethylene flow rate 35.805kg / sec, ethane flow rate 43.925kg / sec, oxygen 4.664kg / sec, acetic acid 3.57kg / sec, CO1.705kg / sec, CO21.433kg / sec, water 26.368kg / sec and methane 45.050kg / sec. The reactor inlet feed temperature is 190℃, and the molten salt operating temperature is 310℃.

[0081] After the heat of the reactor discharge is recovered, it passes through the acid water removal unit, oxygen removal unit, CO2 absorption unit, and subsequent cooling and drying, multi-stage compression, and then enters the ethane separation and circulation unit and the final ethylene distillation unit. The above separation process belongs to the conventional technology in this field. Finally, a glacial acetic acid product with a purity of 99.5% (national standard for industrial glacial acetic acid) can be obtained.<GB / T 1628-2020> ) and 99.7% purity polymer grade ethylene products containing very small amounts of ethane (National Standard for Industrial Ethylene<GB / T 7715-2014> ).

[0082] Through the process described in this embodiment, the oxygen conversion rate is 98.0%, the ethylene selectivity is 91.2%, the ethylene space-time yield is 1.64 kg ethylene / kg catalyst / hour, the comprehensive energy consumption is 253 kg standard oil / t ethylene, and the unit consumption of ethane raw material is 1.15 kg ethane / kg ethylene.

[0083] Example 2

[0084] like Figure 2As shown, ethane with a flow rate of 102.237 kg / sec (including ethane recycled with a flow rate of 60.368 kg / sec) is mixed and preheated, and methane with a flow rate of 36.364 kg / sec, and oxygen with a flow rate of 31.999 kg / sec is preheated and fully mixed with ethane and then enters the fixed bed reactor for oxidation reaction, and the fixed bed is a shell and tube fixed bed reactor. The shell and tube fixed bed reactor is divided into a hot side and a cold side, and a mixed gas composed of ethane and oxygen enters the hot side of the shell and tube fixed bed reactor, and the hot side is filled with an annular catalyst, and its active component is MoVTeNbO described in patent CN2014101988672; the circulating molten salt is sent to the cold side of the shell and tube fixed bed reactor, and after absorbing the heat released by the oxidation reaction, it is cooled by a heat exchanger as a circulating molten salt and circulated back to the cold side of the shell and tube fixed bed reactor. The molten salt can be selected from any molten salt system known to those skilled in the art, preferably potassium and sodium nitrates and nitrites. Ethane and oxygen react in the reactor to produce ethylene, acetic acid, carbon monoxide, carbon dioxide, water and methane. The reactor discharge also contains unconverted ethane and trace oxygen, including ethylene flow rate 36.489kg / sec, ethane flow rate 60.422kg / sec, oxygen 4.372kg / sec, acetic acid 3.796kg / sec, CO 1.61kg / sec, CO21.391 kg / sec, water 26.667kg / sec and methane 35.864kg / sec. The reactor inlet feed temperature is 190℃, and the molten salt operating temperature is 310℃.

[0085] After the heat of the reactor discharge is recovered, it passes through the acid water removal unit, oxygen removal unit, CO2 absorption unit, and subsequent cooling and drying, multi-stage compression, and then enters the ethane separation and circulation unit and the final ethylene distillation unit. The above separation process belongs to the conventional technology in this field. Finally, a glacial acetic acid product with a purity of 99.5% (national standard for industrial glacial acetic acid) can be obtained.<GB / T 1628-2020> ) and 99.7% purity polymer grade ethylene products containing very small amounts of ethane (National Standard for Industrial Ethylene<GB / T 7715-2014> ).

[0086] After the process described in this embodiment, the oxygen conversion rate is 98.5%, the ethylene selectivity is 91.3%, the ethylene space-time yield is 1.62 kg ethylene / kg catalyst / hour, the comprehensive energy consumption is 197 kg standard oil / ton ethylene, and the unit consumption of ethane raw material is 1.13 kg ethane / kg ethylene.

[0087] Example 3

[0088] like Figure 2As shown, fresh ethane with a flow rate of 44.333kg / sec and recycled ethane with a flow rate of 92.015kg / sec are mixed and preheated, and methane with a flow rate of 18.182kg / sec, and oxygen with a flow rate of 31.999kg / sec is preheated and fully mixed with ethane and then enters the fixed bed reactor for oxidation reaction. The fixed bed is a shell-and-tube fixed bed reactor. The shell-and-tube fixed bed reactor is divided into a hot side and a cold side. The mixed gas composed of ethane and oxygen enters the hot side of the shell-and-tube fixed bed reactor. The hot side is filled with an annular catalyst, and its active component is MoVTeNbO described in patent CN2014101988672; the circulating molten salt is sent to the cold side of the shell-and-tube fixed bed reactor, absorbs the heat released by the oxidation reaction, and is then cooled by a heat exchanger as a circulating molten salt and circulated back to the cold side of the shell-and-tube fixed bed reactor. The molten salt can be selected from any molten salt system known to those skilled in the art, preferably potassium and sodium nitrates and nitrites. Ethane and oxygen react in the reactor to produce ethylene, acetic acid, carbon monoxide, carbon dioxide, water and methane. The reactor discharge also contains unconverted ethane and trace oxygen, including ethylene flow rate 38.258kg / sec, ethane flow rate 92.032kg / sec, oxygen 2.953kg / sec, acetic acid 4.722kg / sec, CO1.313 kg / sec, CO21.331kg / sec, water 27.937kg / sec h and methane 17.982kg / sec. The reactor inlet feed temperature is 190℃, and the molten salt operating temperature is 310℃.

[0089] After the heat of the reactor discharge is recovered, it passes through the acid water removal unit, oxygen removal unit, CO2 absorption unit, and subsequent cooling and drying, multi-stage compression, and then enters the ethane separation and circulation unit and the final ethylene distillation unit. The above separation process belongs to the conventional technology in this field. Finally, a glacial acetic acid product with a purity of 99.5% (national standard for industrial glacial acetic acid) can be obtained.<GB / T 1628-2020> ) and 99.7% purity polymer grade ethylene products containing very small amounts of ethane (National Standard for Industrial Ethylene<GB / T 7715-2014> ).

[0090] After the process described in this embodiment, the oxygen conversion rate is 99.5%, the ethylene selectivity is 90.3%, the ethylene space-time yield is 1.65kg ethylene / kg catalyst / hour, the comprehensive energy consumption is 115kg standard oil / ton ethylene, and the unit consumption of ethane raw material is 1.16kg ethane / kg ethylene.

[0091] Example 4

[0092] like Figure 3As shown, fresh ethane with a flow rate of 74.207 kg / sec, recycled ethane with a flow rate of 62.109 kg / sec are mixed and preheated, and methane with a flow rate of 18.182 kg / sec, and oxygen with a flow rate of 31.999 kg / sec are preheated and fully mixed with ethane before entering the first fixed bed reactor for oxidation reaction. The fixed bed is a tube-in-tube fixed bed reactor. The oxygen added to the second fixed bed reactor has a flow rate of 21.951 kg / sec, and enters together with the product gas from the first fixed bed reactor for oxidation reaction. The tubular bed fixed bed reactor is divided into a hot side and a cold side. A mixed gas composed of ethane and oxygen enters the hot side of the tubular bed fixed bed reactor. The hot side is filled with an annular catalyst, and its active component is MoVTeNbO described in patent CN2014101988672; the circulating molten salt is sent to the cold side of the tubular bed fixed bed reactor, and after absorbing the heat released by the oxidation reaction, it is cooled by a heat exchanger as a circulating molten salt and circulated back to the cold side of the tubular bed fixed bed reactor. The molten salt can be selected from any molten salt system known to those skilled in the art, preferably potassium and sodium nitrates and nitrites. Ethane and oxygen react in the reactor to produce ethylene, acetic acid, carbon monoxide, carbon dioxide, water and methane. The reactor discharge also contains unconverted ethane and trace oxygen, including ethylene flow rate 64.426kg / sec, ethane flow rate 62.109kg / sec, oxygen 5.309kg / sec, acetic acid 7.908kg / sec, CO 2.199kg / sec, CO2 2.229kg / sec, water 46.785kg / sec and methane 17.482kg / sec. The reactor inlet feed temperature is 190℃, and the molten salt operating temperature is 310℃.

[0093] After the heat of the reactor discharge is recovered, it passes through the acid water removal unit, oxygen removal unit, CO2 absorption unit, and subsequent cooling and drying, multi-stage compression, and then enters the ethane separation and circulation unit and the final ethylene distillation unit. The above separation process belongs to the conventional technology in this field. Finally, a glacial acetic acid product with a purity of 99.5% (national standard for industrial glacial acetic acid) can be obtained.<GB / T 1628-2020> ) and 99.7% purity polymer grade ethylene products containing very small amounts of ethane (National Standard for Industrial Ethylene<GB / T 7715-2014> ).

[0094] After the process described in this embodiment, the oxygen conversion rate is 97.7%, the ethylene selectivity is 90.1%, the ethylene space-time yield is 1.68kg ethylene / kg catalyst / hour, the comprehensive energy consumption is 102kg standard oil / ton ethylene, and the unit consumption of ethane raw material is 1.17kg ethane / kg ethylene.

[0095] Comparative Example 1

[0096] According to the document "Research Progress on Comprehensive Energy Consumption Analysis of Steam Cracking Process for Ethylene Production" published by Li Jianhua et al. in Energy Conservation in 2008, the current more mature mainstream ethylene production process is steam cracking: when ethane is used as raw material, its comprehensive energy consumption is 17-21 GJ / t ethylene (typical value), which is converted into standard oil as 398-492 kg standard oil / t ethylene (typical value); when naphtha is used as raw material, its comprehensive energy consumption is 26-31 GJ / t ethylene (typical value), which is converted into standard oil as 609-726 kg standard oil / t ethylene (typical value), which are significantly higher than the comprehensive energy consumption of the process described in the present invention.

[0097] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be included in the claims of the present invention.

Claims

1. A multi-stage series reaction process for preparing ethylene and oxygen-containing compounds by catalytic oxidation of mixed C1 and C2 hydrocarbons, characterized in that: The raw material gas contains mixed hydrocarbons of carbon one and carbon two as raw materials, and the oxidant is oxygen; the carbon one includes methane, and the carbon two includes ethane.

2. The process according to claim 1, characterized in that: The reactor is a fixed bed reactor. If the number of reactors is 2 or more, the reactors are connected in series, and oxygen needs to be added before each reactor.

3. The process according to claim 1, characterized in that: The method comprises the following steps: 1) The ethane stream, the oxygen stream and the methane stream are preheated and mixed respectively, and then enter the reactor together to undergo oxidation reaction to obtain the process product gas a of the final reaction; if there are two or more reactors, the mixed stream is mixed with the added oxygen at the outlet of the preceding reactor to obtain the mixed stream, and enters the subsequent reactor to continue the oxidation reaction to obtain the process product gas a of the final reaction; 2) subjecting the final reaction product gas a described in step 1) to rapid cooling treatment to remove acetic acid and water, and obtaining a process product gas b from which acid water is removed, wherein the acetic acid is recovered or subjected to acid water treatment; 3) subjecting the process product gas b described in step 2) to deoxygenation treatment to obtain a process product gas c; 4) removing carbon dioxide from the process product gas c in step 3) to obtain a process product gas d; 5) drying, multi-stage compression and cryogenic treatment of the process product gas d in step 4) to obtain a process product gas e; 6) removing ethane from the process product gas e in step 5) to obtain a process product gas f at the top of the tower and ethane at the bottom of the tower; 7) returning the ethane described in step 6) to the ethane preheater of step 1) for preheating and continuing oxidation reaction as a raw material; 8) subjecting the process product gas f in step 6) to ethylene distillation to obtain process product gas g at the top of the tower and ethylene product at the bottom of the tower; 9) subjecting the process product gas g in step 8) to methane removal to obtain methane at the bottom of the tower and tail gas at the top of the tower; 10) returning the methane described in step 9) to the methane preheater of step 1) for preheating, and then mixing with the ethane stream and the oxygen stream and entering the reactor; 11) treating the tail gas in step 9).

4. The method according to claim 1 or 3, characterized in that: The molar ratio of carbon one to carbon two in the mixed hydrocarbon of carbon one and carbon two is 0.01-80:1, preferably 10-60:1, and more preferably 20-50:

1.

5. The process according to claim 1, 2 or 3, characterized in that: The catalytic reaction of mixed hydrocarbon oxidation to produce ethylene and oxygen-containing compounds is carried out in a multi-stage series reactor, and the multi-stage series reactor includes a special case of only one fixed bed reactor. The reactor is a fixed bed reactor, preferably a shell-and-tube fixed bed reactor.

6. The process according to claim 1, 2 or 3, characterized in that: The mass ratio of oxygen to the total amount of inflammable and explosive substances at the reactor inlet is 0.01 to 0.55:1, and the inflammable and explosive substances include methane, ethane, ethylene, carbon monoxide and acetic acid; the inlet temperature of any fixed bed reactor is 100°C to 400°C, preferably 150°C-300°C; the inlet pressure of any fixed bed reactor is 0.10 to 1.0 MPa, preferably 0.20-0.70 MPa.

7. The process according to claim 2, characterized in that: When there are more than two reactors, the single-pass conversion rate of mixed hydrocarbons and the content of acetic acid product will increase significantly.

8. The process according to claim 3, characterized in that: In step 3), the deoxidation treatment includes catalytic oxidation technology; In step 4), the carbon dioxide removal treatment includes first washing with an organic amine and then washing with an alkali; In step 11), the waste gas treatment includes torch treatment.

9. The process according to claim 3, characterized in that: After the acetic acid is recovered in step 2), the acetic acid stream meets the national standard for industrial glacial acetic acid (GB / T1628-2020); It is characterized in that after the ethylene distillation treatment in step 8), the ethylene flow meets the national standard for industrial ethylene (GB / T7715-2014).

10. A system for catalytic oxidation of C1 and C2 mixed hydrocarbons to produce ethylene and oxygen-containing compounds for use in the process according to any one of claims 1 to 9, characterized in that: Mainly include: Preheaters (901-1, 901-2 and 901-3) for preheating oxygen, ethane and methane streams; For hot mixing the raw material flow through the reactor (903-1) filled with a mixed hydrocarbon oxidation catalyst, and the subsequent possible reactor (903-i), i is 2-3; A quench cooler (902-1) for rapidly cooling the process product gas from the last reactor; an acid water removal unit (904) for removing acid water from the process product gas stream a; An oxygen removal unit (905) for removing oxygen from the process product gas stream b; A unit (906) for removing CO2 from the process gas product stream c; A unit (907) for drying, multi-stage compression and cryogenic treatment of the process gas product stream d; A unit (908) for removing ethane from the process gas product stream e; A unit (909) for subjecting the process gas product stream f to ethylene distillation treatment; A unit (910) for removing methane from the process gas product stream g.

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