Controllable acetylene pre-hydrogenation method and application

Abstract

The invention relates to the research field of acetylene selective hydrogenation, discloses a controllable acetylene front-hydrogenation method and application, and particularly discloses a method for producing ethylene from an acetylene mixed material in cracking gas generated by an ethylene cracking device by adopting a front-deethanization front-hydrogenation process. The acetylene mixed material mainly comprises hydrogen, acetylene, ethylene, ethane, methane, a small amount of carbon monoxide and the like. In a catalytic selective hydrogenation reactor system, a hydrogenation inlet material is contacted with a selective hydrogenation catalyst, and under controllable reaction conditions, acetylene in the hydrogenation inlet material is completely hydrogenated to produce a hydrogenation effluent. In order to cope with the change of the cracking gas of the cracking device, the method adopts controllably added crude hydrogen and / or dry hydrogen and optional carbon monoxide as regulation and control means to improve the ethylene selectivity and the operation stability and prevent the occurrence of temperature runaway and alkyne leakage.

Description

Technical Field

[0001] The invention relates to the research field of acetylene selective hydrogenation, and in particular to a controllable acetylene pre-hydrogenation method and application. Background Art

[0002] Ethylene is one of the most important basic raw materials for petrochemicals, and ethylene products account for more than 75% of petrochemical products. Ethylene can be used to make polyethylene, polyvinyl chloride, ethylene oxide / ethylene glycol, styrene, vinyl acetate, etc. These products can be used for packaging, construction, textiles, surfactants and other purposes. The production capacity of ethylene is a symbol of the development level of a country's petrochemical industry. There are many methods for producing ethylene, including steam cracking, catalytic cracking, coal / methanol to olefins, ethane cracking to ethylene, ethanol dehydration, etc. Among them, ethylene produced by steam cracking of petroleum hydrocarbons accounts for more than 90% of the world's total ethylene production. However, the acetylene produced in the production and separation process of hydrocarbon cracking to produce ethylene will reduce the polymerization efficiency of downstream polymerization catalysts, affect the quality of polymerization products, and bring safety hazards to the production and processing of downstream products. The carbon distillate mainly composed of ethylene obtained by steam cracking of petroleum hydrocarbons (various hydrocarbons or mixtures such as ethane, propane, C4 light hydrocarbons, naphtha, etc.) contains about 0.5% to 2.5% acetylene. With the advancement of downstream process technology, the requirements for the acetylene content in ethylene products are becoming more and more stringent. In the 1960s, the acetylene content in ethylene was required to be less than 10 ppmv, in the 1970s it was required to be less than 2 ppmv, and since the late 1980s it has been required to be less than 1 ppmv. Currently, catalytic selective hydrogenation technology is mostly used in industrial production to remove acetylene contained in the carbon distillation fraction. This technology has the advantages of simple process flow and high ethylene yield.

[0003] The separation process of producing ethylene by steam cracking of petroleum hydrocarbons is mainly divided into three categories of technologies, including sequential separation technology, pre-depropanization pre-hydrogenation technology, and pre-deethanization pre-hydrogenation technology. Pre-deethanization pre-hydrogenation technology is more suitable for light hydrocarbon cracking raw materials, has low comprehensive energy consumption, low power of cracking gas compressor, and is widely used. The present invention mainly relates to the selective hydrogenation process of acetylene in the pre-deethanization pre-hydrogenation technology. In the pre-deethanization pre-hydrogenation process, the carbon distillation fraction at the top of the deethanizer tower mainly contains hydrogen, carbon monoxide, acetylene, ethylene, ethane, etc. The carbon distillation fraction itself contains the hydrogen required for the reaction, as well as a high content of carbon monoxide that inhibits the hydrogenation activity. Therefore, the pre-hydrogenation process has the advantage of high selectivity, and at the same time there is a potential risk of temperature runaway.

[0004] Research on pre-deethanization pre-hydrogenation reactor systems usually focuses on developing catalysts with better performance. Acetylene hydrogenation catalysts usually use precious metals Pd, Ru, and Rh as active components, and are prepared by adding various additives including alkali metals, alkaline earth metals, etc., selecting suitable carriers including alumina, silica, etc., and through impregnation, spraying, and other methods. Patent CN112679306A discloses a selective hydrogenation method for carbon two post-hydrogenation process using crude hydrogen as the hydrogen source. The reaction process conditions in a single-stage fixed bed reactor are: inlet temperature 65-130°C, pressure 1.5-3.0MPa, gas volume space velocity 1500-4000h 1 , the volume content of ethylene in the catalytic reaction material is 70% to 93%, the volume content of acetylene is 0.6% to 1.3%, the volume content of carbon three fraction is 0.01% to 0.5%, and the hydrogen-acetylene ratio in the reactor inlet material is 23. The hydrogenation method uses a catalyst containing at least Pd, Ag, Ni, and Cu, and the carrier uses alumina with a bimodal pore distribution structure. The loading of Ni, Cu and part of Pd adopts a microemulsion method, and most of Pd, Ni and Cu enter the macropores of the catalyst during loading. The loading of part of Pd adopts a supersaturated impregnation method, and due to the capillary siphon effect, most of Pd enters the small pores on the surface of the carrier. The loading of Ag adopts a saturated impregnation method. The selective hydrogenation method of the invention has excellent anti-coking performance. Patent CN116020374A discloses an acetylene hydrogenation reactor and a method for controlling temperature thereof. The hydrocarbon gas feed pipeline containing alkynes is connected to the top of the first section of the reactor; the first emergency cooler is arranged on the branch pipeline where the feed circulating water cooler of the first section of the reactor is located and is located downstream of the feed circulating water cooler of the first section of the reactor or is connected to the feed circulating water cooler of the first section of the reactor or is separately arranged on the third branch pipeline; a discharge pipeline is arranged at the bottom of the first section of the reactor to connect to the top of the second section of the reactor; a second discharge pipeline is arranged at the bottom of the second section of the reactor to connect to the top of the third section of the reactor; regulating valves are arranged on the pipelines where all heaters and coolers are located, and are all connected to the temperature control element, the rapid cooling interlock signal and the parking interlock signal. Through the control method of the present invention, abnormal working conditions can be eliminated as soon as possible, the reactor can quickly resume production, the interlock parking caused by temperature runaway can be reduced or even eliminated, and the efficiency of the device can be increased.

[0005] At present, the ethylene production capacity at home and abroad is increasing rapidly. With the increase in the scale of ethylene plants and the change in the raw materials of ethylene plants, the acetylene hydrogenation performance requirements of the C2 hydrogenation reactor system are getting higher and higher. The scale of ethylene plants has expanded from an average of about 300,000 tons / year in the 1960s and 1970s to the current average scale of more than 1 million tons / year, and the scale of a single ethylene plant has even reached 1.5 million tons / year. The increase in the scale of ethylene plants has put higher and higher requirements on the performance of acetylene selective hydrogenation in the C2 fraction. The catalytic selective hydrogenation process of acetylene hydrogenation requires good selectivity and stability, as well as operability, to meet the "safe, stable, full and excellent" operation requirements of ethylene plants. Summary of the invention

[0006] In the pre-deethanization pre-hydrogenation process, the catalytic hydrogenation reactor system usually adopts one-stage or two-stage hydrogenation without a spare reactor. When the carbon II fraction feed is stable, the acetylene hydrogenation reactor system can operate smoothly. Due to changes in the production capacity of the ethylene unit, the switching of cracking raw materials, and changes in the operating conditions of the cracking process, the feed conditions of the catalytic hydrogenation reactor system vary greatly. Changes in feed conditions will affect the smooth operation of the catalytic hydrogenation reactor system, affecting ethylene selectivity and catalyst operating life. When the concentration of hydrogen or carbon monoxide in the carbon II fraction changes significantly, the catalytic hydrogenation reactor system is prone to acetylene leakage or temperature runaway, affecting the continuous production of the ethylene unit.

[0007] In order to solve the problems in the prior art, the present invention provides a method and application of controllable acetylene pre-hydrogenation. In the separation process of hydrocarbon cracking products, the carbon distillation fraction from the top of the deethanizer tower mainly includes hydrogen, carbon monoxide, acetylene, ethylene, and ethane. In the catalytic hydrogenation reactor system, the hydrogenation inlet material contacts with a selective hydrogenation catalyst. Under appropriate reaction conditions, all the acetylene in the hydrogenation inlet material is hydrogenated to produce a hydrogenation effluent. In order to cope with the changes in the cracking gas of the cracking unit, controllable raw hydrogen and / or dry hydrogen, as well as optional carbon monoxide, are used as control means to improve ethylene selectivity and operational stability, and avoid acetylene leakage and temperature runaway.

[0008] A first aspect of the present invention is to provide a method for controllable acetylene pre-hydrogenation, the method comprising:

[0009] Using the carbon distillate extracted from the top of the deethanizer as a hydrogenation material raw material, according to the change of the hydrogen and / or carbon monoxide content in the carbon distillate, before entering the hydrogenation reactor, inputting crude hydrogen and / or dry hydrogen, and optionally inputting carbon monoxide, into the carbon distillate to obtain a hydrogenation material with hydrogen and / or carbon monoxide content within a target range;

[0010] The hydrogenated material is contacted with a catalytic hydrogenation catalyst to perform a hydrogenation reaction, and the acetylene in the hydrogenated material is subjected to a hydrogenation reaction to produce a hydrogenation effluent;

[0011] The crude hydrogen contains 80% to 100% by volume of hydrogen, 500 to 20,000 ppmv of carbon monoxide, and a balance gas;

[0012] The dry hydrogen contains 80% to 100% by volume of hydrogen and a balance of gas.

[0013] The balancing gas in the present invention includes but is not limited to methane.

[0014] The carbon distillate extracted from the top of the deethanizer of the present invention generally comes from: the hydrocarbon cracking raw material is cracked at high temperature to produce cracking gas, the cracking gas enters the deethanizer for light and heavy component separation after the pre-processing steps such as quenching, compression, alkali washing, drying, etc., and the light component carbon distillate is extracted from the top of the deethanizer. The hydrocarbon cracking raw material is cracked at high temperature to produce cracking gas, and the cracking gas mixture enters the deethanizer for light and heavy component separation after the pre-processing steps such as quenching, compression, alkali washing, drying, etc. It is preferred that before the cracking gas enters the deethanizer for light and heavy component separation, the cracking raw material is subjected to arsenic removal treatment so that the cracking raw material does not contain arsenic. According to the source of the cracking raw material, a dechlorination treatment process can also be set. After various necessary treatment processes such as dearsenic removal and dechlorination, the cracking raw material enters the cracking furnace for high-temperature cracking. The cracking raw material will not damage the cracking furnace, and the cracking gas will not damage various hydrogenation catalysts used in the subsequent separation process, especially acetylene hydrogenation catalysts. Steam cracking raw materials generally include various hydrocarbons or mixed hydrocarbons such as ethane, propane, C4 light hydrocarbons, naphtha, etc. In addition to steam cracking, cracked gas obtained by catalytic cracking is also suitable for the cracked gas and its composition described in the present invention. The present invention does not impose any restrictions on the source of the cracked gas.

[0015] The composition of the cracked gas after cracking of different cracking raw materials will change. For example, compared with naphtha as cracking raw material, light hydrocarbon cracking raw material can produce cracked gas with a higher concentration of hydrogen and a lower concentration of carbon monoxide. Changing the cracking process conditions, such as changing the cracking temperature and cracking depth, will affect the product distribution of the cracking reaction and change the content of key components such as hydrogen, carbon monoxide, and acetylene in the cracked gas. After the cracking furnace has been running for a period of time, the coke produced by hydrocarbon cracking is deposited on the wall of the furnace tube, affecting heat transfer, increasing the system pressure, and even blocking the pipeline, so regular decoking is required. The furnace can be shut down for decoking, cutting off the feed and outlet cracking gas of the cracking furnace, or online decoking can be used, switching between different raw materials during decoking. The shutdown and charging of the cracking furnace, as well as the switching of cracking raw materials will cause changes in the content of hydrogen or carbon monoxide in the cracked gas, causing fluctuations in the carbon two hydrogenation reaction system.

[0016] In order to reduce the coking of the cracking furnace, it is often used to add coking inhibitors to the cracking raw materials. There are many types of coking inhibitors, such as sulfur-containing compounds such as mercaptans, dimethyl disulfide, and diphenyl disulfide. These operations can also control the carbon monoxide content in the cracking products. Carbon monoxide is a poison for carbon two hydrogenation catalysts. Controlling the sulfur content of the cracking furnace is conducive to properly controlling the reaction rate of the acetylene hydrogenation catalyst and preventing acetylene leakage or temperature runaway. General cracking raw materials such as naphtha contain sulfur, but light hydrocarbons such as ethane, propane, and carbon four need to be appropriately injected with various organic sulfurs to inhibit the formation of carbon monoxide. The acetylene hydrogenation reactor will fluctuate before and after sulfur injection.

[0017] Usually, during the initial use of the acetylene hydrogenation catalyst, the activity of the fresh catalyst can be suppressed by directly injecting carbon monoxide into the cracking gas. Before the hydrogenation feed is transported to the catalytic hydrogenation reactor system, an appropriate amount of carbon monoxide can be added to the cracking gas. Oxygen-containing compounds such as methanol and ethanol can also be injected. This method of injecting oxygen-containing compounds is a relatively indirect method. The carbon monoxide content cannot be accurately determined. Alcohols contained in the cracking gas may also reduce the activity of the acetylene hydrogenation catalyst.

[0018] After the cracking raw materials are cracked, quenched, and compressed, the composition of the cracking gas is relatively complex. It contains useful components such as ethylene and propylene, as well as a small amount of non-hydrocarbon impurities such as H2S, CO2, and H2O. These non-hydrocarbon impurities will not only reduce the quality of products such as ethylene and propylene, but also affect the normal progress of the separation process. In industry, sodium hydroxide solution is usually used to remove a small amount of H2S and CO2 in the cracking gas so that the acid gas content in the cracking gas meets the requirements. Molecular sieves are usually used as adsorbents for cracking gas drying. Molecular sieve adsorbents have the advantages of high dehydration efficiency and long service life, and are most widely used in industry. Molecular sieves can also be used to remove polar impurities such as methanol that may be contained in the cracking gas to prevent these impurities from reducing the performance of subsequent acetylene hydrogenation catalysts.

[0019] The light component carbon distillate is extracted from the top of the deethanizer, mainly including hydrogen, carbon monoxide, acetylene, ethylene, ethane, etc. The carbon distillate enters the catalytic hydrogenation reactor system for selective hydrogenation reaction. Usually, the process of removing hydrogen and carbon monoxide from the cracked gas after alkali washing without distillation separation, that is, hydrogenation to remove alkynes is called the pre-hydrogenation process. For the pre-hydrogenation process, since the raw material contains carbon monoxide, the selectivity of the catalytic hydrogenation reaction system is higher, and the catalyst can usually be used for one maintenance cycle, without setting up spare catalysts and regeneration facilities. However, the pre-hydrogenation process has the risk of temperature runaway or alkyne leakage, and there is only one control method for the inlet temperature. Changes in the content of hydrogen or carbon monoxide have a greater impact on the catalytic hydrogenation reactor system. Compared with the pre-hydrogenation process, the process of first separating light fractions such as hydrogen and methane contained in the cracked gas and then hydrogenating the separated carbon distillate is called the post-hydrogenation process. The amount of hydrogen in the C2 post-hydrogenation process is quantitatively added according to the amount of acetylene in the feed, and can be adjusted according to actual conditions. The operation is well controllable and has many adjustment methods. However, the overall selectivity of the post-hydrogenation process is not high, and the catalyst needs to be switched and regenerated regularly.

[0020] In the pre-deethanization pre-hydrogenation process, the volume content of acetylene in the carbon distillate extracted from the top of the deethanizer is about 2000-10000 ppmv, the volume content of hydrogen is about 15%-50%, the volume content of carbon monoxide is about 100-3000 ppmv, and it also contains some methane, ethane, ethylene, etc. The presence of highly unsaturated hydrocarbon impurity acetylene will reduce the activity of the polymerization catalyst, increase the consumption of the polymerization catalyst, and deteriorate the properties of the polymer. Industrial production requires that the content of alkynes contained in polymerization-grade ethylene is less than 2ppmv; in the production of low-pressure polyethylene, the content of acetylene in ethylene is required to be less than 0.1ppmv. The method of catalytic selective hydrogenation of the carbon distillate extracted from the top of the deethanizer has the advantages of simple process flow, low energy consumption, and no environmental pollution. Among the various acetylene selective hydrogenation process flows, the carbon monoxide content in the carbon distillate in the pre-deethanization pre-hydrogenation process flow is the lowest, the hydrogen content is the highest, and the leakage of acetylene or temperature rise is more likely to occur.

[0021] According to a preferred embodiment of the present invention, the carbon distillate contains at least hydrogen, carbon monoxide, acetylene, ethylene and ethane; more preferably,

[0022] The volume content of acetylene in the carbon distillate is 200-10000 ppmv, the volume content of hydrogen is 15%-50%, and the volume content of carbon monoxide is 100-3000 ppmv.

[0023] According to the change of hydrogen or carbon monoxide content in the carbon distillation fraction, the crude hydrogen and / or dry hydrogen and the optional amount of carbon monoxide that can be controllably added are adjusted, the hydrogenation inlet material is contacted with a selective hydrogenation catalyst, and under appropriate reaction conditions, all the acetylene in the hydrogenation inlet material is hydrogenated to produce a hydrogenation effluent.

[0024] In the existing pre-hydrogenation process, when the feed of the catalytic hydrogenation reactor is determined, the reactor inlet temperature is the only means of adjustment. By adjusting the inlet temperature of each section of the reactor system, the conversion rate and selectivity of the multi-stage reactor can be changed. Generally, the reaction temperature conditions of the catalyst are determined by comprehensive judgment based on the performance of the catalyst itself, the operating time, and the raw material conditions.

[0025] Hydrocarbon cracking feedstocks usually include various hydrocarbons or mixtures such as ethane, propane, C4 light hydrocarbons, naphtha, etc. In the original design of the ethylene production unit, the catalytic hydrogenation reactor system operates under relatively stable feedstock conditions, and the concentration of hydrogen or carbon monoxide in the cracked gas changes very little. However, affected by the supply of hydrocarbon feedstocks in the market, or by production changes in upstream refineries, the raw materials introduced into the cracking section may change frequently, as well as changes in cracking process conditions, switching operations of cracking furnaces, etc., which ultimately lead to changes in the concentration of hydrogen or carbon monoxide entering the catalytic hydrogenation reaction system, which is no longer consistent with the original design. According to the changes in the content of hydrogen or carbon monoxide in the carbon two fraction, adjusting the amount of controllable crude hydrogen or dry hydrogen or carbon monoxide can increase the adjustment means of the pre-deethanization pre-hydrogenation reaction and improve ethylene selectivity and operational stability.

[0026] When the cracking feedstock is switched from heavier hydrocarbon feedstock to lighter hydrocarbon feedstock, the hydrogen concentration in the cracking gas will increase. The increase in hydrogen concentration in the cracking gas will lead to a decrease in the ethylene selectivity of the acetylene hydrogenation reaction at a constant inlet temperature. The rapid increase in ethylene hydrogenation will lead to the possibility of temperature runaway in the catalytic hydrogenation reaction system. By increasing the carbon monoxide concentration in the cracking gas to suppress the activity of the catalyst and reduce the ability to hydrogenate olefins, the risk of temperature runaway in the acetylene hydrogenation reaction system can be reduced. Conversely, when the cracking feedstock is switched from lighter hydrocarbon feedstock to heavier hydrocarbon feedstock, the hydrogen concentration in the cracking gas will decrease. The decrease in hydrogen concentration in the cracking gas will lead to a decrease in the acetylene conversion rate of the acetylene hydrogenation reaction at a constant inlet temperature, and there is a risk of acetylene leakage, resulting in unqualified ethylene products. By increasing the hydrogen concentration in the cracking gas to increase the activity of the catalyst, the risk of acetylene leakage can be reduced and the stable operation of the carbon two hydrogenation reaction system can be maintained.

[0027] Similarly, when the carbon monoxide concentration in the cracking gas increases, the acetylene conversion rate of the acetylene hydrogenation reaction at a constant inlet temperature will decrease, and there will be a risk of acetylene leakage, resulting in unqualified ethylene products. By increasing the hydrogen concentration in the cracking gas to improve the activity of the catalyst, the risk of acetylene leakage can be reduced and the stable operation of the carbon two hydrogenation reaction system can be maintained. Conversely, when the carbon monoxide concentration in the cracking gas decreases, the ethylene selectivity of the acetylene hydrogenation reaction at a constant inlet temperature will decrease, and the rapid increase in olefin hydrogenation will cause the acetylene hydrogenation reaction system to have a risk of temperature runaway. By increasing the carbon monoxide concentration in the cracking gas to improve the selectivity of the catalyst and reduce the ability to hydrogenate olefins, the risk of temperature runaway in the acetylene hydrogenation reaction system can be reduced and the operation can be maintained stable.

[0028] Hydrogen and carbon monoxide are the two most critical parameters affecting the stable operation of the pre-deethanization pre-hydrogenation reaction system. The use of fast gas chromatography can quickly and accurately determine the hydrogen and carbon monoxide content in the carbon distillation fraction, as well as the hydrogen and carbon monoxide content in the hydrogenation inlet material, so as to adjust the controllable addition of crude hydrogen and / or dry hydrogen, and the optional carbon monoxide.

[0029] Adjusting the content of hydrogen or carbon monoxide in the carbon distillate can be achieved by increasing or decreasing the amount of crude hydrogen or dry hydrogen or carbon monoxide that can be controllably added. The controllably added crude hydrogen and / or dry hydrogen, as well as the optional carbon monoxide, become an adjustment means for the selective hydrogenation reactor system, and are no longer limited to only the adjustment means of the hydrogenation reactor inlet temperature. The controllably added crude hydrogen consists of about 80% to 100% volume content of hydrogen, 500 to 20000 ppmv volume content of carbon monoxide, and balance methane, etc. The controllably added dry hydrogen consists of about 80% to 100% volume content of hydrogen, and balance methane, etc. Crude hydrogen and dry hydrogen are mainly derived from the self-production of the ethylene device, and can also be introduced from outside the device. In the ethylene device, crude hydrogen is generally removed by methanation reaction until the carbon monoxide content is less than 5 ppmv, that is, dry hydrogen. Low-temperature methanation catalysts are often used, and medium-high temperature or high-temperature methanation catalysts can also be used. The volume content of carbon monoxide that can be controlled is 100%, which mainly comes from cylinder gas or gas storage tank.

[0030] According to a preferred embodiment of the present invention, the input of crude hydrogen and / or dry hydrogen, and the selective input of carbon monoxide, are adjusted according to the following changes in the hydrogen and / or carbon monoxide content in the carbon distillation fraction:

[0031] (1) for every 5% increase in the volume content of hydrogen in the carbon dioxide fraction, crude hydrogen or crude hydrogen and carbon monoxide are introduced into the carbon dioxide fraction, so that the volume content of carbon monoxide in the hydrogenated material increases by 0 to 500 ppmv, preferably by 50 to 300 ppmv, compared with the volume content of carbon monoxide in the carbon dioxide fraction;

[0032] (2) for every 500 ppmv increase in the carbon monoxide content in the carbon distillate, dry hydrogen is introduced into the carbon distillate so that the hydrogen content of the hydrogenated material increases by 0 to 5% by volume, preferably by 1 to 3% by volume, compared with the hydrogen content in the carbon distillate;

[0033] (3) When the hydrogen content in the carbon distillation fraction is reduced, dry hydrogen is introduced into the carbon distillation fraction to make up 50% to 120% of the reduced amount of hydrogen in the hydrogenation material;

[0034] (4) when the carbon monoxide content in the carbon dioxide fraction is reduced, by inputting crude hydrogen or crude hydrogen and carbon monoxide into the carbon dioxide fraction, 50% to 150% of the reduced amount of carbon monoxide is supplemented in the hydrogenated material;

[0035] (5) When the content of one of carbon monoxide and hydrogen in the carbon distillation fraction increases and the content of the other decreases, firstly make adjustment according to (1) or (2) based on the increased content, then calculate the decrease in the decreased content and make adjustment according to (3) or (4).

[0036] According to a preferred embodiment of the present invention, the volume content of hydrogen in the hydrogenation material is 15% to 50%, and the volume content of carbon monoxide is 100 to 3000 ppmv.

[0037] According to a preferred embodiment of the present invention, the change in the content of hydrogen and / or carbon monoxide in the carbon distillation fraction is determined by monitoring the content of hydrogen and / or carbon monoxide in the carbon distillation fraction; and / or,

[0038] The change in the content of hydrogen and / or carbon monoxide in the hydrogenated material is determined by monitoring the content of hydrogen and / or carbon monoxide in the hydrogenated material, preferably monitoring the content of hydrogen and / or carbon monoxide at the inlet of the reactor.

[0039] By determining the hydrogen or carbon monoxide content of the hydrogenation inlet material, the catalytic hydrogenation reactor system can be operated at a substantially stable reaction temperature. The reaction temperature is controlled by increasing or decreasing the temperature of the hydrogenation inlet material in the carbon two fraction heat exchange unit before contacting the selective hydrogenation catalyst.

[0040] Catalysts all have corresponding temperature ranges, and the reaction temperature range of catalysts is between the qualified temperature and the runaway temperature. The qualified temperature is the temperature of acetylene at the outlet of the catalytic hydrogenation reactor system at the qualified index. After passing through the catalytic hydrogenation reactor system, the acetylene content in the reaction effluent exceeds the specifications of the product ethylene. For example, when the acetylene content in the reaction effluent exceeds 2ppmv, it no longer meets the specification requirements of the ethylene product. In this case, it is called acetylene leakage. The runaway temperature is the temperature at which ethylene reacts rapidly in the catalytic hydrogenation reactor system. The situation in which the bed temperature increases rapidly and cannot be stabilized and controlled is called runaway. During runaway, a large amount of hydrogenation reaction occurs on the catalyst, and the reaction heat cannot be removed in time. Rapid cooling is required to suppress the reaction.

[0041] The inlet temperature is controlled according to the hydrogen or carbon monoxide content in the hydrogenation inlet material, and the inlet temperature is adjusted according to the catalyst operation time and the ethylene selectivity. The inlet temperature also depends on the flow rate of the hydrogenation inlet material, the inlet acetylene concentration, the presence of pollutants or poisons, and the performance of the hydrogenation catalyst itself.

[0042] Control the temperature of the hydrogenation inlet material to reduce or prevent temperature runaway or acetylene leakage. In the carbon two fraction heat exchange unit, the temperature of the hydrogenation inlet material is controlled by adjusting the flow rate of the heating or cooling medium of the heat exchanger, adjusting the flow rate of the heat exchange unit bypass, and other means. Various existing adjustment methods are applicable to the present invention.

[0043] According to a preferred embodiment of the present invention, the temperature of the hydrogenated material is adjusted according to the content of hydrogen and / or carbon monoxide in the hydrogenated material; preferably, the temperature of the hydrogenated material is adjusted by heat exchange.

[0044] According to a more preferred embodiment of the present invention, the temperature of the hydrogenated material is reduced by 0 to 5°C, preferably 1 to 4°C, for every 5% volume increase in the hydrogen content in the hydrogenated material;

[0045] For every 5% volumetric decrease in the hydrogen content in the hydrogenated material, the temperature of the hydrogenated material increases by 0-5°C, preferably 1-4°C.

[0046] According to a more preferred embodiment of the present invention, the temperature of the hydrogenated material increases by 0 to 2°C, preferably 0.5 to 1.5°C, for every 200 ppmv increase in the carbon monoxide content in the hydrogenated material;

[0047] For every 200 ppmv decrease in the carbon monoxide content in the hydrogenated material, the temperature of the hydrogenated material is reduced by 0-2°C, preferably 0.5-1.5°C.

[0048] By adopting the above method, the catalytic hydrogenation reactor system has a variety of controllable operating conditions, has high ethylene selectivity and operating stability, and has neither temperature runaway nor alkyne leakage. By adopting the method of the present invention, a stable concentration of hydrogen or carbon monoxide in the hydrogenation inlet material can be obtained in time. The control means of the catalytic hydrogenation reactor system is increased from a single reaction inlet temperature control to hydrogen concentration, carbon monoxide concentration, and inlet temperature control.

[0049] The process flow of pre-hydrogenation of carbon 2 usually adopts one or more stages of hydrogenation, and can adopt the reaction type of isothermal bed or adiabatic bed. The number of reactor sections or heat exchange types can be arbitrarily combined, and the reactors can be operated in series or in parallel. Reasonable control of the acetylene conversion rate of each section in the multi-stage hydrogenation can obtain better ethylene selectivity and operation cycle. Usually, the acetylene conversion rate in the first hydrogenation reaction bed is controlled at 50% to 100%, preferably 60% to 90%. Under the condition that the acetylene content in the carbon 2 fraction is less than 0.3%, one-stage hydrogenation can be used, and the acetylene conversion rate reaches 100%. In the pre-deethanization pre-hydrogenation process, the reaction conditions of the catalytic selective hydrogenation reactor are: reaction temperature of 20 to 120°C, reaction pressure of 1.0 to 4.0 MPa, gas phase volume space velocity of 2000 to 20000 h -1The volume content of hydrogen in the hydrogenation inlet material is 15% to 50%, and the volume content of carbon monoxide is 100 to 3000 ppmv.

[0050] According to a preferred embodiment of the present invention, when the acetylene content in the carbon distillate is less than 0.3% by volume, one-stage hydrogenation is adopted;

[0051] When the acetylene content in the carbon distillate is higher than 0.3% by volume, a first stage hydrogenation and at least one stage hydrogenation downstream of the first stage hydrogenation are included, wherein the acetylene conversion rate after the first stage hydrogenation reaction is 50% to 100%, preferably 60% to 90%.

[0052] According to a preferred embodiment of the present invention, the conditions of the hydrogenation reaction include: a hydrogenation reaction temperature of 20 to 120°C, and / or a reaction pressure of 1 to 4 MPa, and / or a catalyst gas phase volume space velocity of 2000 to 20000 h -1 and / or,

[0053] The acetylene content in the hydrogenation effluent is less than or equal to 5 ppmv, preferably less than or equal to 2 ppmv, more preferably less than or equal to 0.5 ppmv, most preferably less than or equal to 0.1 ppmv.

[0054] According to a preferred embodiment of the present invention, the catalytic hydrogenation catalyst comprises an active component, an auxiliary agent and a carrier, wherein the active component is a metal element of Group VIIIB, preferably at least one of Pd, Ru and Rh, and / or the active component is 0.003% to 0.3% of the total weight of the carrier in terms of the weight of the metal element; the auxiliary active component is one or more of Ag, Bi, Ga, K, La, F, In, Ni, Pt, Pb, Zn, Fe, Si, Ce and Sn; and / or the carrier is an inorganic carrier, preferably at least one of alumina, silicon oxide and activated carbon. The adsorption capacity of acetylene on these catalysts is stronger than that of ethylene, and selective hydrogenation can be performed to generate more ethylene and less ethane and oligomers. A commercial pre-deethanization pre-hydrogenation catalyst BC-H-21 (composed of Pd-auxiliary agent / alumina) and the like can be used.

[0055] The second aspect of the present invention is to provide a method for producing ethylene by cracking and separating hydrocarbon raw materials, comprising:

[0056] The hydrocarbon cracking feedstock is cracked to produce cracking gas, the cracking gas is subjected to a pre-processing step, the pre-processing step includes cooling, compression, alkali washing, and drying, and then enters a deethanizer to separate light and heavy components; the light component is extracted from the top of the deethanizer to obtain a carbon II fraction, and the carbon II fraction is subjected to a hydrogenation reaction using the acetylene pre-hydrogenation method described in the first aspect to obtain a hydrogenation effluent;

[0057] Preferably, the hydrocarbon cracking feedstock includes at least one hydrocarbon or a mixture of ethane, propane, C4 light hydrocarbons, and naphtha.

[0058] As mentioned above, at least one of the following conditions changes, including: a change in the composition of the hydrocarbon cracking feedstock, a change in the cracking conditions, a change in the pre-processing conditions, so that the hydrogen and / or carbon monoxide content in the carbon II fraction changes.

[0059] By adopting the above method, the catalytic hydrogenation reactor system has a variety of controllable operating conditions, high ethylene selectivity and operating stability, and neither temperature runaway nor acetylene leakage.

[0060] Compared with the prior art, the advantages of the present invention are:

[0061] A method for producing ethylene by using a pre-deethanization and pre-hydrogenation process on an acetylene mixture in cracked gas produced by an ethylene cracking unit. The acetylene mixture mainly includes hydrogen, acetylene, ethylene, ethane, methane, and a small amount of carbon monoxide. Due to changes in the production capacity of the ethylene unit, the switching of cracking raw materials, and changes in the operating conditions of the cracking process, the feed conditions of the catalytic hydrogenation reactor system vary greatly. The changes in the feed conditions will affect the smooth operation of the catalytic hydrogenation reactor system, and affect the ethylene selectivity and the operating life of the catalyst. When the concentration of hydrogen or carbon monoxide in the carbon distillation fraction changes significantly, the catalytic hydrogenation reactor system is prone to acetylene leakage or temperature runaway, affecting the continuous production of the ethylene unit.

[0062] The method of the present invention adopts controllable raw hydrogen and / or dry hydrogen, and optional carbon monoxide input regulation means to improve ethylene selectivity and operation stability, and prevent the occurrence of runaway temperature and acetylene leakage.

[0063] The control method of the present invention is more direct and targeted, and has the advantages of fast response, simplicity, directness, stability and controllability. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The accompanying drawings are used to further understand the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0065] Attached Figure 1 :A controllable selective hydrogenation method for polyunsaturated hydrocarbons. The process diagram schematically describes the process of producing olefins from hydrocarbon feedstocks through a cracking and separation process. It includes: 1 cracking feedstock; 2 hydrocarbon cracking unit; 3 cracking gas; 4 deethanizer feed; 5 deethanizer; 6 carbon 2 fraction; 7 carbon 3 and above fraction; 8 heat exchange unit; 9 hydrogenation inlet material; 10 catalytic hydrogenation reactor system; 11 hydrogenation effluent; 20 crude hydrogen; 30 dry hydrogen; 40 carbon monoxide.

[0066] The hydrocarbon cracking raw material 1 can be any hydrocarbon, mainly light hydrocarbon raw materials, including ethane, propane, butane, naphtha, etc. The hydrocarbon cracking raw material 1 is operated in the cracking unit 2 at a certain temperature, pressure, and space velocity to produce cracking gas 3. The cracking gas 3 includes one or more cracking products, such as but not limited to ethylene, propylene, butene, ethane, propane, hydrogen, carbon monoxide, acetylene, methylacetylene, propadiene, methane, acidic gas, etc. The cracking gas 3 is subjected to a heat recovery cooling process in the quenching unit and the steam and heavy hydrocarbon components are removed, and then the acidic gas is removed by compression and alkaline washing, and then enters the subsequent separation system after drying. The tower feed mixture 4 is distilled and separated in the pre-deethanizer 5, and the light component carbon two fraction 6 is produced from the top of the tower, and the heavy components 7 of carbon three and above are produced from the bottom of the tower. The top carbon two fraction 6 is adjusted in temperature by the heat exchange unit 8 and enters the catalytic hydrogenation reactor system 10 for hydrogenation and deacetylation reaction. The hydrogenation inlet material 9 includes hydrogen, carbon monoxide, acetylene, ethylene, ethane, methane, etc. Under the action of the selective hydrogenation catalyst, all the acetylene in the hydrogenation feed 9 is hydrogenated to generate a hydrogenation effluent 11, and the hydrogenation effluent 11 enters the ethylene distillation system to obtain an ethylene product. Crude hydrogen 20 or dry hydrogen 30 or carbon monoxide 40 is mainly used to adjust the content of hydrogen or carbon monoxide in the carbon distillation fraction 6.

[0067] The catalytic hydrogenation reactor system 10 includes one or more hydrogenation reactors. The catalytic hydrogenation reactor system 10 can use any known catalyst for selective hydrogenation of acetylene, which is widely available. The catalytic hydrogenation reactor system 10 also includes one or more analyzers, such as a gas chromatograph, to measure the hydrogen concentration and carbon monoxide concentration in the carbon distillation fraction 6 and the hydrogenation inlet material 9, and can also measure the concentrations of various components such as acetylene and ethylene. The acetylene hydrogenation reaction must be carried out within a reasonable temperature window, without acetylene leakage or temperature runaway. The previous adjustment method only has the only adjustment means of adjusting the reaction temperature of the hydrogenation inlet material 9. The present invention changes the hydrogen or carbon monoxide concentration in the hydrogenation inlet material 9 by adjusting the amount of crude hydrogen 20, dry hydrogen 30, and carbon monoxide 40. The operating performance of the catalytic hydrogenation reactor system 10 can be adjusted by adjusting the temperature, carbon monoxide concentration, and hydrogen concentration in the catalytic hydrogenation reactor system 10. DETAILED DESCRIPTION

[0068] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0069] In the present invention, the method for detecting the specific composition of the hydrogenation feedstock and the hydrogenation effluent is: using FID and TCD detectors, and adopting an external standard method or area normalization to analyze the composition.

[0070] The calculation method of acetylene conversion is:

[0071]

[0072] The ethylene selectivity is calculated as:

[0073]

[0074] In the following examples, the gas phase space velocity is the volume space velocity; and the reaction pressure is the gauge pressure.

[0075] Comparative Example 1:

[0076] The hydrogenation feedstock (light carbon distillation fraction taken from the top of the deethanizer) including hydrogen, carbon monoxide, acetylene, ethylene and ethane is contacted with the acetylene selective hydrogenation BC-H-21 catalyst (composed of Pd-promoter / alumina) in a fixed bed reactor at a gas phase volume space velocity of 10000h -1 , the reaction pressure is 3.3MPa. The volume composition of key components hydrogen, carbon monoxide, acetylene and ethylene is shown in Table 1, wherein the inlet acetylene content is 4200ppmv and the inlet ethylene volume content is 45%. The temperature of hydrogenation inlet material 9 is 55 degrees. Under such conditions, the acetylene conversion rate is 100% and the ethylene selectivity is 72%.

[0077] The hydrogenation feedstocks in the embodiments and comparative examples of the present invention are all from Figure 1 The feed 4 of the middle deethanizer is distilled and separated in the deethanizer 5, and the light component carbon distillate 6 extracted from the top of the tower contains:

[0078] The hydrogen content is 20%, the carbon monoxide content is 400 ppmv, the methane content is 22%, the ethane content is 12.54%, the ethylene content is 45% and the acetylene content is 0.42%.

[0079] Comparative Example 2:

[0080] The hydrogenation feedstock including hydrogen, carbon monoxide, acetylene, ethylene and ethane is contacted with the acetylene selective hydrogenation BC-H-21 catalyst (composed of Pd-promoter / alumina) in a fixed bed reactor at a gas phase volume space velocity of 10000h -1, the reaction pressure is 3.3MPa. The volume composition of key components hydrogen, carbon monoxide, acetylene and ethylene is shown in Table 1, wherein the inlet acetylene content is 4200ppmv and the inlet ethylene volume content is 45%. When the hydrogen content is 10% higher than that of Comparative Example 1 and the contents of other key components are substantially unchanged, in order to prevent the rapid increase of hydrogen and the violent reaction of ethylene leading to the temperature rise of the reactor, the reaction temperature is lowered to 46 degrees, and the catalyst performance of Comparative Example 1 is substantially maintained.

[0081] Embodiment 1:

[0082] The hydrogenation feedstock including hydrogen, carbon monoxide, acetylene, ethylene and ethane is contacted with the acetylene selective hydrogenation BC-H-21 catalyst (composed of Pd-promoter / alumina) in a fixed bed reactor at a gas phase volume space velocity of 10000h -1 , the reaction pressure is 3.3MPa. The volume composition of key components hydrogen, carbon monoxide, acetylene and ethylene is shown in Table 1, wherein the inlet acetylene content is 4200ppmv and the inlet ethylene volume content is 45%. When the hydrogen content in the hydrogenation inlet material increases by 10%, the content of other key components does not change substantially. In order to avoid temperature runaway of the reactor and maintain good catalytic performance, the inlet temperature is reduced by a small amount, and the flow rate of crude hydrogen in the crude hydrogen 20 is increased. The carbon monoxide volume content in the crude hydrogen 20 used is 3000ppmv, and the flow rate of carbon monoxide 40 is increased. By adopting this operation, temperature runaway can be avoided, while improving ethylene selectivity and maintaining complete conversion of acetylene.

[0083] Embodiment 2:

[0084] The hydrogenation feedstock including hydrogen, carbon monoxide, acetylene, ethylene and ethane is contacted with the acetylene selective hydrogenation BC-H-21 catalyst (composed of Pd-promoter / alumina) in a fixed bed reactor at a gas phase volume space velocity of 10000h -1 , the reaction pressure is 3.3MPa. The volume composition of key components hydrogen, carbon monoxide, acetylene and ethylene is shown in Table 1, wherein the inlet acetylene content is 4200ppmv and the inlet ethylene volume content is 45%. When the hydrogen content in the hydrogenation inlet material is reduced by 10%, the content of other key components does not change substantially. In order to avoid acetylene leakage in the reactor, the feed inlet temperature is increased slightly, and the hydrogen flow in the dry hydrogen 30 is increased. The volume content of hydrogen in the dry hydrogen is 95%, and the volume content of methane is 5%. By adopting this operation, the complete conversion of acetylene can be maintained, the temperature runaway can be avoided, and the ethylene selectivity is slightly increased.

[0085] Comparative Example 3:

[0086] The hydrogenation feedstock including hydrogen, carbon monoxide, acetylene, ethylene and ethane is contacted with the acetylene selective hydrogenation BC-H-21 catalyst (composed of Pd-promoter / alumina) in a fixed bed reactor at a gas phase volume space velocity of 10000h -1 , the reaction pressure is 3.3MPa. The volume composition of key components hydrogen, carbon monoxide, acetylene and ethylene is shown in Table 1, wherein the inlet acetylene content is 4200ppmv and the inlet ethylene volume content is 45%. The carbon monoxide content is 400ppmv higher than that of Comparative Example 1, and the contents of other key components are basically unchanged. In order to prevent the reactor from leaking acetylene, the catalyst performance under Comparative Example 1 is basically maintained by increasing the reaction temperature to 61 degrees.

[0087] Embodiment 3:

[0088] The hydrogenation feedstock including hydrogen, carbon monoxide, acetylene, ethylene and ethane is contacted with the acetylene selective hydrogenation BC-H-21 catalyst (composed of Pd-promoter / alumina) in a fixed bed reactor at a gas phase volume space velocity of 10000h -1 , the reaction pressure is 3.3MPa. The volume composition of key components hydrogen, carbon monoxide, acetylene and ethylene is shown in Table 1, wherein the inlet acetylene content is 4200ppmv and the inlet ethylene volume content is 45%. When the carbon monoxide content in the hydrogenation inlet material increases by 400ppmv, the contents of other key components do not change substantially. In order to prevent the reactor from leaking acetylene, the reaction temperature is increased to 58 degrees by a small amount, and the hydrogen flow in the dry hydrogen 30 is increased. The volume content of hydrogen in the dry hydrogen is 95%, and the volume content of methane is 5%. This operation can ensure that acetylene is fully converted while improving ethylene selectivity.

[0089] Embodiment 4:

[0090] The hydrogenation feedstock including hydrogen, carbon monoxide, acetylene, ethylene and ethane is contacted with the acetylene selective hydrogenation BC-H-21 catalyst (composed of Pd-promoter / alumina) in a fixed bed reactor at a gas phase volume space velocity of 10000h -1 , the reaction pressure is 3.3MPa. The volume composition of key components hydrogen, carbon monoxide, acetylene and ethylene is as shown in Table 1, wherein the inlet acetylene content is 4200ppmv, and the inlet ethylene volume content is 45%. When the carbon monoxide content in the hydrogenation inlet material is reduced by 300ppmv, the content of other key components does not change substantially. In order to avoid the reactor temperature runaway and maintain good catalytic performance, the inlet temperature is reduced in a small amount, and the crude hydrogen flow in the crude hydrogen 20 is increased, the carbon monoxide volume content in the crude hydrogen 20 used is 3000ppmv, and the flow of carbon monoxide 40 is increased simultaneously. Adopting this operation, it is possible to avoid temperature runaway, improve ethylene selectivity, and maintain complete conversion of acetylene.

[0091] Example 5

[0092] The hydrogenation feedstock including hydrogen, carbon monoxide, acetylene, ethylene and ethane is contacted with the acetylene selective hydrogenation BC-H-21 catalyst (composed of Pd-promoter / alumina) in a fixed bed reactor at a gas phase volume space velocity of 10000h -1 , the reaction pressure is 3.3MPa. The volume composition of key components hydrogen, carbon monoxide, acetylene and ethylene is shown in Table 1, wherein the inlet acetylene content is 4200ppmv and the inlet ethylene volume content is 45%. When the carbon monoxide content in the hydrogenation inlet material increases by 200ppmv and the hydrogen content decreases by 5%, the contents of other key components remain essentially unchanged. In order to prevent the reactor from leaking acetylene, the hydrogen flow in the dry hydrogen 30 needs to be increased, and the reaction temperature is increased to 58 degrees by a small amount. The volume content of hydrogen in the dry hydrogen is 95%, and the volume content of methane is 5%. This operation can ensure the complete conversion of acetylene, avoid temperature runaway, and improve the selectivity of ethylene at the same time.

[0093] Example 6

[0094] The hydrogenation feedstock including hydrogen, carbon monoxide, acetylene, ethylene and ethane is contacted with the acetylene selective hydrogenation BC-H-21 catalyst (composed of Pd-promoter / alumina) in a fixed bed reactor at a gas phase volume space velocity of 10000h -1 , the reaction pressure is 3.3MPa. The volume composition of key components hydrogen, carbon monoxide, acetylene and ethylene is shown in Table 1, wherein the inlet acetylene content is 4200ppmv and the inlet ethylene volume content is 45%. When the carbon monoxide content in the hydrogenation inlet material is reduced by 200ppmv and the hydrogen content is increased by 5%, the content of other key components does not change substantially. In order to avoid temperature runaway of the reactor and maintain good catalytic performance, the inlet temperature is reduced by a small amount, and the flow rate of crude hydrogen in crude hydrogen 20 is increased. The carbon monoxide volume content in the crude hydrogen 20 used is 3000ppmv, and the flow rate of carbon monoxide 40 is increased. By adopting this operation, the selectivity of ethylene can be improved, temperature runaway can be avoided, the conversion rate of propyne and propadiene can be improved, and the complete conversion of acetylene can be maintained.

[0095] Table 1: Comparative Examples and Examples

[0096]

[0097] Table 2

[0098]

[0099]

[0100] As can be seen from Tables 1 and 2, by adopting the technical solution of the present invention, the ethylene selectivity can be improved by adjusting the controllable amount of crude hydrogen and / or dry hydrogen, as well as the optional means of regulating the input of carbon monoxide, ensuring that the outlet acetylene hydrogenation is qualified and avoiding the occurrence of temperature runaway.

[0101] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0102] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0103] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

[0104] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

[0105] All publications, patent applications, patents and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings conventionally understood by those skilled in the art. In the event of a conflict, the definition in this specification shall prevail.

[0106] When this specification uses the prefix "well-known to those skilled in the art", "prior art" or similar terms to introduce materials, substances, methods, steps, devices or components, etc., the objects introduced by the prefix cover those commonly used in the art when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as being suitable for similar purposes.

[0107] The endpoints and any values ​​of the scope disclosed in the present application document are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, between the endpoint values ​​of each scope, between the endpoint values ​​of each scope and a separate point value, and between separate point values, one or more new numerical ranges can be combined with each other, and these numerical ranges should be considered as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be considered as specifically disclosed in this article.

[0108] In the context of the present specification, any matters or items not mentioned are directly applicable to those known in the art without any changes except those explicitly stated.

[0109] Moreover, any embodiment described in this document may be freely combined with one or more other embodiments described in this document, and the technical solutions or technical ideas formed thereby are deemed to be part of the original disclosure or original record of the present invention, and should not be regarded as new content that has not been disclosed or anticipated in this document, unless a person skilled in the art considers that the combination is obviously unreasonable.

Claims

1. A method for controllable pre-hydrogenation of acetylene, the method comprising: Using the carbon distillate extracted from the top of the deethanizer as a hydrogenation material raw material, according to the change of the hydrogen and / or carbon monoxide content in the carbon distillate, before entering the hydrogenation reactor, inputting crude hydrogen and / or dry hydrogen, and optionally inputting carbon monoxide, into the carbon distillate to obtain a hydrogenation material with hydrogen and / or carbon monoxide content within a target range; The hydrogenated material is contacted with a catalytic hydrogenation catalyst to perform a hydrogenation reaction, and the acetylene in the hydrogenated material is subjected to a hydrogenation reaction to produce a hydrogenation effluent; The crude hydrogen contains 80% to 100% by volume of hydrogen, 500 to 20,000 ppmv of carbon monoxide, and a balance gas; The dry hydrogen contains 80% to 100% by volume of hydrogen and a balance of gas.

2. The method for pre-hydrogenation of acetylene according to claim 1, characterized in that: The carbon distillate contains at least hydrogen, carbon monoxide, acetylene, ethylene and ethane; preferably, The volume content of acetylene in the carbon distillate is 200-10000 ppmv, the volume content of hydrogen is 15%-50%, and the volume content of carbon monoxide is 100-3000 ppmv.

3. The method for pre-hydrogenation of acetylene according to claim 1, characterized in that: The input of crude hydrogen and / or dry hydrogen, and selectively the input of carbon monoxide, is adjusted according to the following changes in the hydrogen and / or carbon monoxide content in the carbon second fraction: (1) for every 5% increase in the volume content of hydrogen in the carbon dioxide fraction, crude hydrogen or crude hydrogen and carbon monoxide are introduced into the carbon dioxide fraction, so that the volume content of carbon monoxide in the hydrogenated material increases by 0 to 500 ppmv, preferably by 50 to 300 ppmv, compared with the volume content of carbon monoxide in the carbon dioxide fraction; (2) for every 500 ppmv increase in the carbon monoxide content in the carbon distillate, dry hydrogen is introduced into the carbon distillate so that the hydrogen content of the hydrogenated material increases by 0 to 5% by volume, preferably by 1 to 3% by volume, compared with the hydrogen content in the carbon distillate; (3) When the hydrogen content in the carbon distillation fraction is reduced, dry hydrogen is introduced into the carbon distillation fraction to make up 50% to 120% of the reduced amount of hydrogen in the hydrogenation material; (4) when the carbon monoxide content in the carbon dioxide fraction is reduced, by inputting crude hydrogen or crude hydrogen and carbon monoxide into the carbon dioxide fraction, 50% to 150% of the reduced amount of carbon monoxide is supplemented in the hydrogenated material; (5) When the content of one of carbon monoxide and hydrogen in the carbon distillation fraction increases and the content of the other decreases, firstly make adjustment according to (1) or (2) based on the increased content, then calculate the decrease in the decreased content and make adjustment according to (3) or (4).

4. The method for pre-hydrogenation of acetylene according to claim 1, characterized in that: The volume content of hydrogen in the hydrogenation material is 15% to 50%, and the volume content of carbon monoxide is 100 to 3000 ppmv.

5. The method for pre-hydrogenation of acetylene according to claim 1, characterized in that: Determining the change in the content of hydrogen and / or carbon monoxide in the carbon distillation fraction by monitoring the content of hydrogen and / or carbon monoxide in the carbon distillation fraction; and / or, The change in the content of hydrogen and / or carbon monoxide in the hydrogenated material is determined by monitoring the content of hydrogen and / or carbon monoxide in the hydrogenated material, preferably monitoring the content of hydrogen and / or carbon monoxide at the inlet of the reactor.

6. The method for pre-hydrogenation of acetylene according to claim 1, characterized in that: The temperature of the hydrogenated material is adjusted according to the content of hydrogen and / or carbon monoxide in the hydrogenated material; preferably, the temperature of the hydrogenated material is adjusted by heat exchange.

7. The method for pre-hydrogenation of acetylene according to claim 6, characterized in that: For every 5% increase in the volume content of hydrogen in the hydrogenated material, the temperature of the hydrogenated material is reduced by 0 to 5°C, preferably 1 to 4°C; For every 5% volumetric decrease in the hydrogen content in the hydrogenated material, the temperature of the hydrogenated material increases by 0-5°C, preferably 1-4°C.

8. The method for pre-hydrogenation of acetylene according to claim 6, characterized in that: For every 200 ppmv increase in the carbon monoxide content in the hydrogenated material, the temperature of the hydrogenated material increases by 0 to 2°C, preferably 0.5 to 1.5°C; For every 200 ppmv decrease in the carbon monoxide content in the hydrogenated material, the temperature of the hydrogenated material is reduced by 0-2°C, preferably 0.5-1.5°C.

9. The method for pre-hydrogenation of acetylene according to any one of claims 1 to 8, characterized in that: When the acetylene content in the carbon two fraction is less than 0.3% by volume, one-stage hydrogenation is adopted; When the acetylene content in the carbon distillate is higher than 0.3% by volume, a first stage hydrogenation and at least one stage hydrogenation downstream of the first stage hydrogenation are included, wherein the acetylene conversion rate after the first stage hydrogenation reaction is 50% to 100%, preferably 60% to 90%.

10. The method for pre-hydrogenation of acetylene according to any one of claims 1 to 8, characterized in that: The conditions of the hydrogenation reaction include: a hydrogenation reaction temperature of 20 to 120° C., and / or a reaction pressure of 1 to 4 MPa, and / or a catalyst gas phase volume space velocity of 2000 to 20000 h -1 and / or, The acetylene content in the hydrogenation effluent is less than or equal to 5 ppmv, preferably less than or equal to 2 ppmv, more preferably less than or equal to 0.5 ppmv, most preferably less than or equal to 0.1 ppmv.

11. The method for pre-hydrogenation of acetylene according to any one of claims 1 to 8, characterized in that: The catalytic hydrogenation catalyst comprises an active component, a co-active agent and a carrier, wherein the active component is a metal element of Group VIIIB, preferably at least one of Pd, Ru and Rh, and / or the active component, calculated by weight of the metal element, is 0.003% to 0.3% of the total weight of the carrier; the co-active component is one or more of Ag, Bi, Ga, K, La, F, In, Ni, Pt, Pb, Zn, Fe, Si, Ce and Sn; and / or the carrier is an inorganic carrier, preferably at least one of alumina, silicon oxide and activated carbon.

12. A method for producing ethylene from hydrocarbon raw materials through a cracking and separation process, comprising: The hydrocarbon cracking raw material is cracked to produce cracking gas, the cracking gas is subjected to a pre-processing step, the pre-processing step includes cooling, compression, alkali washing, and drying, and then enters a deethanizer to separate light and heavy components; the light component is extracted from the top of the deethanizer to obtain a carbon distillation fraction, and the carbon distillation fraction is subjected to a hydrogenation reaction using the acetylene pre-hydrogenation method according to any one of claims 1 to 11 to obtain a hydrogenation effluent; Preferably, the hydrocarbon cracking feedstock comprises at least one hydrocarbon or a mixture of ethane, propane, C4 light hydrocarbons, and naphtha; and / or, At least one of the following changes: Changes in the composition of the hydrocarbon cracking feedstock, changes in the cracking conditions, and changes in the pre-treatment conditions cause changes in the hydrogen and / or carbon monoxide content in the carbon II fraction.

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