阅读说明：本技术 一种利用甲醇制烯烃副产的乙烷产品增产乙烯的方法 (Method for increasing ethylene yield by using byproduct ethane product of methanol-to-olefin ) 是由 宫万福 刘佳涛 杨维慎 吕建宁 王红心 闫兵海 刘学线 丁干红 侯宁 吴笛 于 2021-10-28 设计创作，主要内容包括：本发明涉及一种利用甲醇制烯烃副产的乙烷产品增产乙烯的方法,具体为：(a)将MTO副产的乙烷产品与稀释气、氧化剂混合,后送入ODHE反应器中,生成富含乙烯的ODHE反应气；(b)ODHE反应气被送入ODHE气液分离器中,得到气相产品,送入ODHE产品分离塔,得到ODHE产品气和液相产品Ⅱ；(c)将ODHE产品气送入ODHE除氧装置,得到ODHE脱氧产品气；(d)将ODHE脱氧产品气送入ODHE脱CO-(2)装置,得到ODHE脱二氧化碳产品气和液相产品Ⅲ；(e)将ODHE脱二氧化碳产品气经压缩、混合后依次进行含氧化合物分离、碱洗脱CO-(2)、干燥和烯烃分离,最终得到乙烯产品、乙烷产品及其他,乙烷产品返回ODHE反应器的入口。本发明工艺流程简单,设备投资少,并且能够有效提高乙烯产品的产率。(The invention relates to a method for increasing the yield of ethylene by using a byproduct ethane product of methanol-to-olefin, which comprises the following steps: (a) mixing an ethane product of a byproduct of MTO with diluent gas and an oxidant, and then sending the mixture into an ODHE reactor to generate an ODHE reaction gas rich in ethylene; (b) feeding the ODHE reaction gas into an ODHE gas-liquid separator to obtain a gas-phase product, and feeding the gas-phase product into an ODHE product separation tower to obtain an ODHE product gas and a liquid-phase product II; (c) sending the ODHE product gas into an ODHE deoxygenation device to obtain an ODHE deoxygenation product gas; (d) feeding ODHE deoxygenation product gas into ODHE to remove CO 2 Device for obtaining ODHE decarbonated productGas and liquid phase product III; (e) compressing and mixing ODHE decarbonated product gas, and then sequentially carrying out oxygen-containing compound separation and alkali washing to remove CO 2 Drying and olefin separation, and finally obtaining ethylene products, ethane products and the like, wherein the ethane products return to the inlet of the ODHE reactor. The invention has simple process flow and less equipment investment and can effectively improve the yield of ethylene products.)

1. A method for increasing the yield of ethylene by using a byproduct ethane product produced by preparing olefin from methanol is characterized by comprising the following steps:

(a) mixing an ethane product of a byproduct of MTO with diluent gas and an oxidant, preheating, and then sending into an ODHE reactor to generate an ODHE reaction gas rich in ethylene under the action of a catalyst;

(b) recovering heat of the ODHE reaction gas obtained in the step (a), and then sending the ODHE reaction gas into an ODHE gas-liquid separator to obtain a gas-phase product and a liquid-phase product I, wherein the gas-phase product is sent into the bottom of an ODHE product separation tower and is in countercurrent contact with a coolant I and/or an absorbent introduced from the middle upper part of the ODHE product separation tower, the ODHE product gas is obtained at the top of the tower, and the liquid-phase product II is obtained at the bottom of the tower;

(c) preheating the ODHE product gas obtained in the step (b), and then sending the gas into an ODHE deoxygenation device to react with deoxygenated gas to obtain ODHE deoxygenation product gas;

(d) cooling the ODHE deoxygenation product gas obtained in the step (c), and sending the cooled ODHE deoxygenation product gas into an ODHE to remove CO₂In the device, the gas and the liquid phase products III of ODHE decarbonized products are obtained by physical absorption and/or chemical reaction with a decarbonizing agent;

(e) sending the ODHE decarbonated product gas obtained in the step (d) into an MTO product gas compressor of an MTO system, mixing the ODHE decarbonated product gas with the MTO product gas, and then sequentially enteringMTO oxygen-containing compound separation device and MTO alkaline washing CO removal₂The device, the MTO product gas drying device and the MTO olefin separation device finally obtain an ethylene product, a propylene product, an ethane product and other products, wherein the ethane product returns to the inlet of the ODHE reactor.

2. The method for increasing the yield of ethylene by using the byproduct ethane product from the preparation of olefin from methanol according to claim 1, wherein in the step (a), the diluent gas is selected from methanol or a mixture of methanol and one or more of nitrogen, water vapor and carbon dioxide;

in step (a), the oxidant is selected from pure oxygen or a mixture of one or more of air.

3. The method for increasing the yield of ethylene by using the byproduct ethane product from methanol to olefin according to claim 1, wherein the molar ratio of the ethane product to the diluent gas and the oxidant in the step (a) is 1: (0.6-4.65): (0.27-0.55).

4. The method for increasing the yield of ethylene by using the byproduct ethane product from methanol to olefin according to claim 1, wherein in the step (a), the active component of the catalyst is a transition metal oxide.

5. The method for increasing the yield of ethylene by using the byproduct ethane product from methanol to olefin according to claim 1, wherein in the step (a), the ethane product is uniformly mixed with the diluent gas and the oxidant, and then the preheating temperature is increased to 150-340 ℃;

in the step (a), the reaction temperature in the ODHE reactor is 350-450 ℃, and the reaction pressure is 0.20-1.00 MPaG.

6. The method for increasing the yield of ethylene by using the byproduct ethane product from the methanol-to-olefin production according to claim 1, wherein in the step (b), the ODHE reaction gas is cooled to 40-300 ℃ and then is sent into an ODHE gas-liquid separator.

7. The method for increasing the yield of ethylene by using the byproduct ethane product from the production of olefins from methanol as claimed in claim 1, wherein in the step (b), the coolant I is water or water containing methanol;

in step (b), the absorbent is water or water containing methanol.

8. The method for increasing the yield of ethylene by using the ethane product by-produced from methanol to olefin according to claim 1, wherein in the step (b), the liquid phase product I obtained from the ODHE gas-liquid separator and the liquid phase product II obtained from the ODHE product separation tower are mixed to obtain a mixed liquid, and at least a part of the mixed liquid is fed into an MTO feed vaporizer of an MTO system and fed into the MTO reactor as a raw material.

9. The method for increasing the yield of ethylene by using the byproduct ethane product from methanol to olefin according to claim 1, wherein in the step (c), the ODHE product gas is heated to 100-230 ℃ and then is sent into an ODHE deoxygenation device;

in step (c), the oxygen-scavenging gas reacted with the ODHE product gas is partially derived from carbon monoxide, ethylene or ethane in the ODHE product gas, and partially derived from the additional auxiliary oxygen-scavenging gas;

the auxiliary oxygen-removing gas is one or more selected from carbon monoxide, hydrogen, methane, ethylene or ethane.

10. The method for increasing the yield of ethylene by using the byproduct ethane product from methanol to olefin according to claim 1, wherein in the step (d), the ODHE deoxygenation product gas is cooled to 40-50 ℃, and then is sent to ODHE for CO removal₂In the device;

the decarbonizer is selected from one or more of sodium hydroxide aqueous solution, organic amine solvent, potassium carbonate aqueous solution, sulfolane and alcohol amine aqueous solution, propylene carbonate, polyethylene glycol dimethyl ether and methanol.

Technical Field

The invention belongs to the technical field of ethane resource utilization, and particularly relates to a method for increasing the yield of ethylene by using an ethane product as a byproduct in the process of preparing olefin from methanol.

Background

A typical MTO process product distribution is shown in FIG. 1, with ethylene and propylene as the major products and ethane, propane and mixed C as the major by-products₄+. Patent CN109651038A proposes a method for coupling MTO process and propane dehydrogenation process, which utilizes byproduct propane of MTO to increase the yield of propylene by PDH process; patent CN102190539B proposes a method for improving the yield of propylene, namely, a mixed C separated by an MTO device₄+ increasing the propylene yield through a catalytic cracking system and an olefin disproportionation system; patent CN101092322A proposes a process for converting by-products of the MTO reaction into alkanes, using MTO to chargeThe separated C-containing fraction₄+ is converted into alkane by reaction with hydrogen in the presence of hydrogenation catalyst. None of the above patents relate to the utilization of by-product ethane from MTO.

The by-product ethane product of the MTO process accounts for about 3% of the ethylene product, and the current by-product ethane of the MTO process is mainly used as a fuel or directly sold as an ethane product, so that the generated value is relatively low. In order to excavate higher profit margins, a suitable process may be employed to convert this portion of ethane to ethylene, increasing revenue for the business.

The invention patents CN104193574B, CN104151121B, CN107417481A, CN107056568A, CN104193570B and CN104230617B all relate to the coupling process of an MTO device and a device for preparing ethylene by steam cracking. The steam cracking method is a method for producing ethylene by ethane, which is widely applied in industry at present, gas raw materials are subjected to high-temperature cracking through a cracking furnace to produce olefin, but the process is a strong heat absorption process, the temperature is required to be high (generally higher than 850 ℃), the process is also carried out under the condition of negative pressure (dilution by increased amount of superheated steam), the energy consumption is extremely high, the investment of the cracking furnace is high, the operation is complex, and carbon deposition needs to be removed regularly. The conversion rate of ethane in the cracking furnace is 65%, while the selectivity of ethylene is low, about 80% -84%, and the composition of cracking gas is complex, mainly comprising ethane, ethylene, propylene, hydrogen, methane, mixed C4+, and the like. The adoption of the steam cracking method can cause the problems of high operation cost, very complex subsequent separation system, higher equipment investment, large occupied area and the like. There is therefore a need for a more economical and simple process for converting ethane by-produced from MTO to ethylene.

In recent years, attention has been paid to the production of ethylene (ODHE) by oxidative dehydrogenation of lower hydrocarbons, particularly ethane. Research on catalytic oxidative dehydrogenation of ethane began in the 70's of the 20 th century, and Gaspar et al, as early as the research report in 1971, were proposed in H₂The catalytic oxydehydrogenation of ethane to ethylene under the catalytic action of S, and the oxydehydrogenation process using Mo, Si and mixed oxides of Mo and V as catalysts was published in turn by Ward and Thorsteins in 1977 and 1978. Chinese patent CN105849069A discloses use of a catalyst with MoVTe (Nb) O as an active component in a range of 2 to EThe alkane with 6 carbon atoms is subjected to oxidative dehydrogenation, and the airspeed of the raw material gas is 7500-15000 h^-1The reaction temperature is 320-420 ℃, the conversion rate of ethane can reach 44%, and the corresponding ethylene selectivity is 92.2%. Chinese patent CN105080575B discloses that when a catalyst with an active component of MoVTeNbO is used for ethane catalytic oxidative dehydrogenation, the conversion rate of ethane and the selectivity of ethylene at 350 ℃ can respectively reach 70.5 percent and 95 percent.

How to reduce the separation equipment after ethane is converted into ethylene, simplify the process flow, and reduce the energy consumption of ethylene production through process coupling is the main problem to be solved by the invention.

Disclosure of Invention

The invention aims to provide a method for increasing the yield of ethylene by using a byproduct ethane product produced by preparing olefin from methanol.

The purpose of the invention is realized by the following technical scheme:

a method for increasing the yield of ethylene by using a byproduct ethane product produced by preparing olefin from methanol specifically comprises the following steps:

(a) mixing an ethane product which is a byproduct of MTO (specifically methanol to olefin) with diluent gas and an oxidant, preheating, and then sending into an ODHE (specifically ethane catalytic oxidation dehydrogenation) reactor to generate an ODHE reaction gas rich in ethylene under the action of a catalyst;

(b) recovering heat of the ODHE reaction gas obtained in the step (a), sending the ODHE reaction gas into an ODHE gas-liquid separator to obtain a gas-phase product and a liquid-phase product I, sending the gas-phase product into the bottom of an ODHE product separation tower, and carrying out countercurrent contact with a coolant I and/or an absorbent introduced from the middle upper part of the ODHE product separation tower to obtain an ODHE product gas at the top of the tower and obtain a liquid-phase product II at the bottom of the tower;

(c) preheating the ODHE product gas obtained in the step (b), and then sending the ODHE product gas into an ODHE deoxygenation device, wherein oxygen in the ODHE product gas reacts with deoxygenation gas, and removing the oxygen from a gas phase to obtain ODHE deoxygenation product gas;

(d) cooling the ODHE deoxygenation product gas obtained in the step (c), and sending the cooled ODHE deoxygenation product gas into an ODHE to remove CO₂The device is used for carrying out physical absorption and/or chemical reaction on carbon dioxide in the ODHE deoxygenation product gas and a decarbonizing agent, and removing the carbon dioxide from a gas phase to obtain an ODHE decarbonization product gas and a liquid phase product III;

(e) sending the ODHE decarbonized product gas obtained in the step (d) into an MTO product gas compressor, mixing the ODHE decarbonized product gas with the pretreated MTO product gas, and then sequentially sending the mixture into an MTO oxygen-containing compound separation device (used for separating oxygen-containing compounds) and MTO alkaline washing to remove CO₂Device (for alkali elution of CO₂) An MTO product gas drying unit (for product gas drying) and an MTO olefin separation unit (for olefin separation) to ultimately produce an ethylene product, a propylene product, an ethane product, and other products, the ethane product being returned to the inlet of the ODHE reactor.

In step (a), the diluent gas is selected from methanol or a mixture of methanol and one or more of nitrogen, water vapor and carbon dioxide, preferably methanol, and can be used as a raw material in an MTO system. The diluent gas does not participate or participates in small amount in ODHE reaction.

In step (a), the oxidant is selected from pure oxygen or a mixture of one or more of air.

In step (a), the molar ratio of the ethane product to the diluent gas to the oxidant is 1: (0.6-4.65): (0.27-0.55), the amount of the diluent gas is adjusted according to the siloxane ratio in actual operation and the pressure of working conditions, and when the siloxane ratio is high and the pressure of the working conditions is high, the amount of the diluent gas needs to be increased, so that the explosion risk is avoided.

In the step (a), the active component of the catalyst is a transition metal oxide.

The transition metal oxide comprises one or more of Mo, V, Te or Nb, and MoVTeNbO catalyst can be adopted.

In the step (a), after an ethane product is uniformly mixed with diluent gas and an oxidant, the preheating temperature is increased to 150-340 ℃.

In step (a), the ODHE reaction gas comprises ethylene, unreacted ethane, acetic acid, oxygen, methanol, acetic acid, carbon monoxide, carbon dioxide and water.

In the step (a), the reaction temperature in the ODHE reactor is 350-450 ℃, preferably 380-410 ℃, and the reaction pressure in the ODHE reactor is 0.20-1.00 MPaG, preferably 0.20-0.80 MPaG.

In the step (b), the ODHE reaction gas is cooled to 40-300 ℃, preferably 50-125 ℃, and more preferably 80-95 ℃, and then is sent into an ODHE gas-liquid separator.

In the step (b), the coolant I is introduced from the middle part or the top part of the ODHE product separation tower, and the absorbent is introduced from the top part of the ODHE product separation tower.

In step (b), the coolant I is selected from water or water containing methanol.

In step (b), the absorbent is selected from water or water containing methanol.

In the step (b), the liquid phase product II contains water and acetic acid.

In the step (b), mixing the liquid-phase product I obtained by the ODHE gas-liquid separator and the liquid-phase product II obtained by the ODHE product separation tower to obtain a mixed liquid, wherein the mass fraction range of methanol in the mixed liquid is 0-90% but not 0, preferably 50-90%, and further preferably 70.6-88.0%;

the mixed liquid is at least partially fed to an MTO feed vaporizer located before the MTO reactor as part of the feed to the MTO reactor. The reaction temperature in the MTO reactor may be 456 ℃ and the reaction pressure may be 0.28 MPaG.

In the step (c), the ODHE product gas is heated to 100-230 ℃, and then is sent into an ODHE deoxygenation device.

In the step (c), the oxygen content in the ODHE deoxidation product gas ranges from 1 to 1000ppmv, and preferably from 10 to 200 ppmv.

In step (c), the oxygen-scavenging gas that reacts with oxygen in the ODHE product gas is derived in part from the carbon monoxide, ethylene or ethane in the ODHE reaction product and in part from the added supplemental oxygen-scavenging gas.

The auxiliary oxygen-scavenging gas comprises one or more of carbon monoxide, hydrogen, methane, ethylene or ethane.

In step (d), the ODHE deoxygenated product gas is cooled to 40 deg.CAbout 50 ℃ before being sent to ODHE for CO removal₂In the device.

In the step (d), the decarbonizing agent is selected from one or more of aqueous sodium hydroxide solution, organic amine solvent, aqueous potassium carbonate solution, aqueous sulfolane and alcohol amine solution, propylene carbonate, polyethylene glycol dimethyl ether and methanol.

In step (d), CO is removed from the ODHE decarbonated product gas₂The content of (B) is in the range of 1ppm to 2 mol%.

In the step (e), an MTO oxygen-containing compound separation device and MTO alkali washing CO removal₂The operating parameters used in the operation of the device and the MTO olefin separation device can be set according to the existing process. According to the invention, the research shows that the ethane catalytic Oxidative Dehydrogenation (ODHE) is an exothermic reaction with lower Gibbs free energy by introducing an oxidant in the reaction, so that higher equilibrium conversion rate is obtained at lower temperature. Taking oxygen as an example of the oxidant, the reaction equation of the oxidative dehydrogenation reaction of ethane is as follows: c₂H₆+0.5O₂＝C₂H₄+H₂O, Gibbs free energy of the reaction at 400 ℃ is-193.2 kJ/mol, exothermic heat is 104.2kJ/mol, O₂The introduction of (A) leads to an equilibrium conversion of ethane far higher than that of the pure dehydrogenation reaction (C)₂H₆＝C₂H₄+H₂) Equilibrium conversion of time. The reaction involved in this process is exothermic and favours the production of ethylene over the ethane steam cracking reaction, which is endothermic. Under the condition of adopting proper catalyst, the ethane has high conversion rate even at lower temperature, the reaction by-products are only acetic acid, carbon monoxide and carbon dioxide, and the products are easy to separate. Compared with ethane steam thermal cracking process, the ethane catalytic Oxidative Dehydrogenation (ODHE) reactor adopts a tubular fixed bed reactor, the reaction condition is mild, the ethylene selectivity is high, the product is simple, the existing MTO process equipment can be used, the separation of all components is realized, and therefore the investment and the operation cost of a separation device can be obviously reduced. The process is well suited for converting ethane, which is a byproduct of the MTO process, to ethylene.

For ethane catalytic Oxidative Dehydrogenation (ODHE) reactionIn other words, because the system is oxygen-containing flammable and explosive mixed gas and the reaction is strongly exothermic, the diluent gas must be introduced to dilute the reaction heat, so that the reaction heat transfer efficiency is improved, and meanwhile, the introduction of the diluent gas enables the mixed gas to be out of the explosion limit range, so that the operation is safer. The introduction of a large amount of diluent gas is important for the influence of the reaction and the subsequent separation of the diluent gas, and patents such as CN105080575B, CN110963880A, CN110963879A, CN106660901B and CN105727975B mention methods using inert gases such as water vapor, nitrogen and carbon dioxide as diluents. The addition of these diluents presents challenges to the isolation and industrial application of this technology. The water vapor is used as the diluent gas, the advantages of realizing the separation of the diluent gas and the product gas by cooling, having low separation energy consumption, and having the defect that the raw material gas contains the water vapor, which can greatly improve the selectivity of the byproduct acetic acid product, thereby reducing the effective utilization rate of the raw material; using CO₂As a diluent gas, a large amount of CO is generated₂The carbon dioxide is absorbed, desorbed and then recycled to the reactor, the energy consumption of the decarburization unit is high, and the desorbed CO₂The energy consumption and the equipment investment of compressing and recycling the gas to the reactor are high for normal pressure gas, and a large amount of CO needs to be introduced during the driving₂Its material source is limited; the nitrogen is used as the diluent gas, the influence on the selectivity of the reaction is small, but a large amount of nitrogen is mixed with ethane and ethylene in the product gas, if a cryogenic separation mode is adopted, the pressure needs to be increased to more than 30atm and cooled to below-100 ℃, the pressure ratio of a compressor is large, the grade of required cold energy is high, the equipment investment is high, and the energy consumption of subsequent nitrogen separation is high.

Aiming at the problem, the invention proposes to adopt part of methanol as diluent gas of the ODHE reaction according to the characteristics of the ODHE and MTO reaction, the methanol does not participate in the reaction or the micro-reaction in the ODHE reactor, and the oxygen concentration of the reactor is controlled within the safe oxygen concentration by adjusting the feeding amount of the methanol, thereby ensuring the thermal stability of the reactor and avoiding the explosion risk. And separating the diluent gas methanol, water and trace acetic acid from other reaction products by cooling and washing the reacted gas. The liquid phase mixture can be separated from water and trace acetic acid by a feeding vaporizer before the MTO reactor, and the methanol is used as a raw material to enter the MTO reactor again.

Compared with the prior art, the invention has the following advantages:

(1) the ODHE method for preparing ethylene is exothermic reaction and has mild reaction conditions, the risk of high-temperature coking in the reactor is low, the service life of the catalyst is longer, and the reactor can avoid adopting high-temperature resistant materials. Compared with the ethane steam thermal cracking ethylene preparation method, the cracking furnace has large investment, complex product composition, low ethylene yield, higher energy consumption and larger occupied area of the device.

(2) The invention fully utilizes the characteristics of mild reaction conditions, high ethylene selectivity, simple product and the like of the ODHE process, provides a method for increasing the yield of ethylene by using an ethane product as a byproduct in the process of preparing olefin from methanol, greatly simplifies the process flow, reduces the equipment investment and increases the yield of the ethylene product.

(3) The invention provides the method for separating the methanol from the ODHE product gas by taking the methanol as the diluent gas of the ODHE process, and considering the characteristics of higher boiling point and mutual solubility with water of the methanol, the methanol can be separated from the ODHE product gas by cooling and washing, thereby greatly reducing the energy consumption for separating the diluent gas from the product gas and saving the corresponding equipment investment. In the process of separating the methanol, water and trace acetic acid in the ODHE product gas are simultaneously separated from the gas phase, so that the separation equipment is reduced. The separated methanol and water can be separated from water and trace acetic acid by the MTO feeding vaporizer, and the methanol is used as the raw material to enter the MTO reactor again, so that the waste of the methanol in the dilution gas is avoided.

Drawings

FIG. 1 is a typical MTO process product profile;

FIG. 2 is a process flow diagram for examples 1 and 2;

in the figure:

device label description: 2 is an MTO feed vaporizer; 6 is a heat exchanger A; 8 is an MTO reactor; 10 is a heat exchanger B; 12 is an MTO quenching tower; 16 is an MTO product separation tower; 20 is a heat exchanger C; 22 is an MTO product gas compressor; 24 is a heat exchanger H; 26 is an MTO oxygenate separation unit; 28 is MTO alkali washing CO removal₂A device; 31 is an MTO product air drying device; 33 is an MTO olefin separation unit; 41 is a heat exchanger D; 43 is an ODHE reactor; 46 is an ODHE gas-liquid separator; 49 is an ODHE product separation column; 53 is a heat exchanger E; 56 is a heat exchanger F; 58 is an ODHE deoxygenation device; 60 is a heat exchanger G; 62 is ODHE CO removal₂A device;

material flow label description: 1 is fresh methanol raw material; 3 is a vaporized methanol raw material; 4. 5, 7 is water containing methanol; 9. 11, 15, 18, 23, 25, 27, 29 and 32 are MTO product gas; 13 is fresh alkali liquor II; 14 is waste water containing sodium acetate; 17 is MTO product gas condensate; 19. 21 is a coolant II; 30 is waste alkali liquor II; 34 is an ethylene product; 35 is a propylene product; 36 is other products; 37 is an ethane product; 38 is a diluent gas; 39 is an oxidizing agent; 40. 42 is an ODHE feed gas; 44. 45 is ODHE reaction gas; 47 is a gas phase product; 48 is a liquid phase product I; 50 is an absorbent; 51 is a liquid-phase product II; 52. 54 is coolant I; 55. 57 is ODHE product gas; 59. 61 is ODHE deoxygenated product gas; 63 is a decarbonizer; 64 is ODHE CO removal₂Producing gas; 65 is a liquid phase product III; 66. 70, 71 are mixed liquid; 68 is carbon dioxide; and 72 is an auxiliary oxygen-removing gas.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

The invention provides a method for increasing the yield of ethylene by using a byproduct ethane product produced by preparing olefin from methanol, which specifically comprises the following steps:

(a) mixing an ethane product of a byproduct of MTO with diluent gas and an oxidant, raising the temperature to 150-340 ℃ through preheating, and then sending the mixture into an ODHE reactor, and generating an ODHE reaction gas rich in ethylene under the action of a catalyst, wherein the ODHE reaction gas contains ethylene, unreacted ethane, acetic acid, carbon monoxide, carbon dioxide and water, the diluent gas is selected from methanol or the mixture of methanol and one or more of nitrogen, water vapor and carbon dioxide, the oxidant is selected from the mixture of pure oxygen or one or more of air, and the molar ratio of the ethane product to the diluent gas to the oxidant is 1: (0.6-4.65): (0.27-0.55), the active component of the catalyst is transition metal oxide containing Mo, V, Te or Nb, the reaction temperature in the ODHE reactor is 350-450 ℃, and the reaction pressure in the ODHE reactor is 0.20-1.00 MPaG;

(b) the ODHE reaction gas obtained in the step (a) is cooled to 40-300 ℃ after heat recovery, and then is sent into an ODHE gas-liquid separator to obtain a gas-phase product and a liquid-phase product I, the gas-phase product is sent into the bottom of an ODHE product separation tower and is in countercurrent contact with a coolant I and/or an absorbent which are/is fed from the middle upper part of the ODHE product separation tower, ODHE product gas is obtained at the tower top, and a liquid-phase product II is obtained at the tower bottom, wherein the coolant is fed from the middle part or the top of the ODHE product separation tower, the absorbent is fed from the tower top of the ODHE product separation tower, the coolant I is selected from water or water containing methanol, and the absorbent is selected from water or water containing methanol; and mixing the liquid-phase product I obtained by the ODHE gas-liquid separator with the liquid-phase product II obtained by the ODHE product separation tower to obtain a mixed liquid, and at least partially sending the mixed liquid into an MTO feeding vaporizer positioned in front of the MTO reactor to be used as a part of raw materials of the MTO reactor.

(c) Preheating the ODHE product gas obtained in the step (b) to 100-230 ℃, and then sending the ODHE product gas into an ODHE deoxygenation device, wherein oxygen in the ODHE product gas reacts with deoxygenation gas, and removing the oxygen from a gas phase to obtain the ODHE deoxygenation product gas, the oxygen content in the ODHE deoxygenation product gas ranges from 1-1000 ppmv, wherein part of the deoxygenation gas reacted with the oxygen in the ODHE product gas is derived from carbon monoxide, ethylene or ethane in the ODHE reaction product, and part of the deoxygenation gas is derived from additional auxiliary deoxygenation gas;

(d) cooling the ODHE deoxygenation product gas obtained in the step (c) to 40-50 ℃, and then sending the cooled ODHE deoxygenation product gas into the ODHE to remove CO₂In the device, the carbon dioxide in the ODHE deoxygenation product gas and a decarbonizing agent are subjected to physical absorption and/or chemical reaction and removed from a gas phase to obtain an ODHE decarbonization product gas and a liquid phase product III, and CO in the ODHE decarbonization product gas₂The content range of (B) is 1 ppm-2 mol%;

(e) sending the ODHE decarbonation product gas obtained in the step (d) into an MTO product gas compressor, mixing the ODHE decarbonation product gas with the pretreated MTO product gas, and then sequentially sending the mixture into an MTO oxygen-containing compound separation device and MTO alkaline washing to remove CO₂The device, the MTO product gas drying device and the MTO olefin separation device finally obtain an ethylene product, a propylene product, an ethane product and other products, wherein the ethane product returns to the inlet of the ODHE reactor.

The above embodiments will be further described with reference to specific examples.

In the following embodiments, unless otherwise specified, functional components or structures are all conventional components or structures adopted in the art to achieve the corresponding functions.

Example 1

In this example, an MTO system of 60 ten thousand ton/year scale and producing 8500 ton/year of ethane as a by-product was used in combination with an ODHE system in which ethane feed was 2.86t/h (1.00t/h MTO by-product fresh ethane +1.86t/h recycled ethane) and oxygen was used as an oxidant and methanol was used as a diluent gas to convert ethane to ethylene. Product gas after conversion of ethane to ethylene product separation was achieved by the process of this example. The process flow is shown in FIG. 2, and comprises the following steps:

fresh ethane and recycle ethane, which are byproducts of the MTO, are mixed together to form an ethane product 37, which is mixed with methanol (as diluent gas 38), oxygen (as oxidant 39) in a molar ratio of 1: 0.6: after mixing at a ratio of 0.27 (low oxygen ratio and low oxygen ratio in this example, less diluent gas is needed to avoid the risk of explosion of ODHE feed gas) an ODHE feed gas 40 is obtained. The ODHE raw material gas 40 is preheated to 150 ℃ by a heat exchanger D41 and then is changed into ODHE raw material gas 42 which is sent into an ODHE reactor 43, and ethane and an oxidant undergo oxidative dehydrogenation reaction under the action of a catalyst (adopting MoVTeNbO catalyst) to generate ODHE reaction gas 44 rich in ethylene. The temperature in the ODHE reactor 43 was 350 ℃, the pressure was 0.20MPaG, the conversion of ethane was 35.0%, and the selectivities for ethylene, acetic acid, carbon monoxide, and carbon dioxide were 95.0%, 0.7%, 2.9%, and 1.4%, respectively. The ODHE reaction gas 44 has a molar flow of 191.9kmol/h and a composition (mol%): c₂H₄：16.5％；C₂H₆：32.2％；O₂：2.4％；CH₃OH：28.2％；H₂O：18.8％；CO：1.0％；CO₂：0.5％；CH₃COOH: 0.1 percent; and others: 0.3 percent.

The ODHE reaction gas 44 is cooled to 40 ℃ by a heat exchanger D41 to become ODHE reaction gas 45, and the ODHE reaction gas 45 is sent into an ODHE gas-liquid separator 46 for gas-liquid separation, so that a gas-phase product 47 and a liquid-phase product I48 are respectively obtained. The gas phase product 47 is sent to an ODHE product separation tower 49, and is in countercurrent contact with water (used as an absorbent 50) introduced from the top of the tower and a coolant I54 (water is adopted, in actual work, the coolant I52 can be recovered from the bottom of the tower, and then the coolant I54 is obtained through a heat exchanger E53) (the specific dosage of the absorbent and the coolant is not required, and is determined according to the absorption effect and the cooling effect), an ODHE product gas 55 is obtained from the top of the tower, and a liquid phase product II 51 containing methanol, water and trace acetic acid is obtained from the bottom of the tower. The liquid phase product II 51 of the ODHE product separation tower 49 is mixed with the liquid phase product I48 flowing out of the ODHE gas-liquid separator 46 to obtain a mixed liquid 66, and then the mixed liquid 66 is sent into the MTO feed vaporizer 2 (the mixed liquid 66 can be completely sent into the MTO feed vaporizer 2, and can also be divided into the mixed liquid 70 and the mixed liquid 71, wherein the mixed liquid 70 is sent into the MTO feed vaporizer 2, and the mixed liquid 71 leaves a boundary zone, and the latter is adopted in the embodiment), and then the mixed liquid is used as a part of the raw material of the MTO reactor 8, wherein the mass flow rate of the mixed liquid 66 is 2.6t/h, and the composition is (mass%): CH (CH)₃OH：66.0％、H₂O：33.0％、CH₃COOH: 0.5%, others: 0.5 percent. The mixed liquid 70 is separated into methanol, water and trace acetic acid in an MTO feeding vaporizer 2, wherein the methanol and a fresh methanol raw material 1 are vaporized to obtain a vaporized methanol raw material 3 (methanol-containing water flows out of the bottom of the MTO feeding vaporizer 2 and is divided into two streams of methanol-containing water 4 and methanol-containing water 5, then the methanol-containing water 4 flows out of a boundary region, the methanol-containing water 5 is heated by a heat exchanger A6 to obtain methanol-containing water 7, and then the methanol-containing water enters the MTO feeding vaporizer 2), and then enters an MTO reactor 8, wherein the temperature of the reactor is 456 ℃, and the pressure of the reactor is 0.28 MPaG. Methanol is converted into MTO product gas 9 containing ethylene, propylene, methane, ethane, propane, carbon monoxide, carbon dioxide, acetic acid, water vapor and other oxygenates in an MTO reactor 8, the temperature is reduced to 267 ℃ by a heat exchanger B10 to form MTO product gas 11, the MTO product gas 11 enters an MTO quench tower 12, fresh alkali liquor II 13 is introduced into the middle part of the MTO quench tower 12, MTO product gas 15 is obtained at the tower top, and the MTO product gas 15 is obtained at the tower topObtaining sodium acetate-containing wastewater 14 at the bottom, feeding MTO product gas 15 into an MTO product separation tower 16, obtaining MTO product gas 18 at the tower top, obtaining MTO product gas condensate 17 at the tower bottom, feeding a coolant II 21 into the upper part of the MTO product separation tower 16 (in actual work, the coolant II 19 can be recovered from the tower bottom, and then the coolant II 21 is obtained through a heat exchanger C20), and feeding the MTO product gas 18 into an MTO product gas compressor 22.

The obtained ODHE product gas 55 is heated to 100 ℃ by a heat exchanger F56 and then becomes ODHE product gas 57, the ODHE product gas 57 is sent to an ODHE deoxygenation device 58, the deoxygenation gas comprises carbon monoxide and auxiliary deoxygenation gas 72 contained in the ODHE product gas 57, and the auxiliary deoxygenation gas 72 is hydrogen. The oxygen content of the ODHE product gas 57 was reduced to 10ppmv by reaction of carbon monoxide and hydrogen with oxygen to produce the resultant ODHE deoxygenated product gas 59.

The obtained ODHE deoxygenation product gas 59 is cooled to 40 ℃ by a heat exchanger G60 to become ODHE deoxygenation product gas 61, and the ODHE deoxygenation product gas 61 is sent to ODHE for CO removal₂The device 62, the ODHE of the ODHE system removes CO because the ODHE product gas is mixed with the MTO product gas 18 after entering the MTO system and then needs to be subjected to alkaline washing once₂The device 62 only needs to remove CO in the ODHE deoxygenation product gas 61₂Most of the decarbonizing agent 63 is sodium hydroxide aqueous solution (hereinafter referred to as "alkali solution"), and in order to reduce the consumption of fresh alkali solution, the long tail Caoda method with low alkali consumption is used to remove CO₂When the ODHE deoxygenation device works, fresh alkali liquor I63 is introduced from the upper part of the ODHE alkaline washing tower 62, carbon dioxide in ODHE deoxygenation product gas 61 reacts with the alkali liquor under the action of the fresh alkali liquor I63, and is removed from a gas phase to obtain ODHE CO removal₂The product gas 64 and the liquid-phase product III 65, the liquid-phase product III 65 mainly comprises NaHCO₃And Na₂CO₃. ODHE CO removal in this example₂The molar flow of the product gas 64 is 96.1kmol/h, and the composition (mol%): c₂H₄：32.8％、C₂H₆：64.3％、H₂O: 2.3%, others: 0.6% of CO₂The content was 100 ppm.

The obtained ODHE is CO-removed₂The product gas 64 is sent to the existing MTO system, ODHE removes CO₂Product gas 64 in MTO productThe first section of the gas compressor 22 is mixed with the pretreated MTO product gas 18, the mixed MTO product gas 23 is cooled to 43 ℃ by a heat exchanger H24 to become MTO product gas 25, the MTO product gas 25 enters an MTO oxygen-containing compound separation device 26 to remove the oxygen-containing compound therein, the obtained MTO product gas 27 enters MTO alkali washing to remove CO₂A device 28 for removing CO therefrom₂Until the concentration is 1ppm, discharging MTO alkali from waste alkali liquor I30 to elute CO₂The obtained MTO product gas 29 enters an MTO product gas drying device 31 to remove water in the MTO product gas 28, the obtained MTO product gas 32 finally enters an MTO olefin separation device 33 to be separated to obtain an ethylene product 34, a propylene product 35, other products 36 and an ethane product 37, and the ethane product 37 is a mixture of ethane which is a byproduct of an MTO system and unreacted recycle ethane of an ODHE system and returns to an ODHE reactor 43.

For an MTO device with the scale of 60 ten thousand tons per year, by adopting the method of the embodiment, 7090 tons of ethylene can be increased for enterprises every year.

Example 2

In this example, the flow shown in fig. 2 is adopted, and the method for increasing the ethylene yield by using the byproduct ethane product from methanol to olefin (methanol) is adopted except that:

(1) the ethane feed to ODHE reactor 43 was 1.54t/h (1.00t/h fresh ethane +0.54t/h recycled ethane).

(2) An ethane product 37 formed by mixing fresh ethane and recycle ethane which are byproducts of the MTO is mixed with methanol (as a diluent gas 38) and oxygen (as an oxidant 39) in a molar ratio of 1: 4.65: after mixing at a ratio of 0.55 (the siloxane is relatively high in this example and is a high pressure condition, so a large amount of diluent gas is required to make the oxygen concentration below 10% to avoid explosion risk, in this example the oxygen concentration is 8.9%), an ODHE feed gas 40 is obtained. The ODHE raw material gas 40 is preheated to 340 ℃ by a heat exchanger D41 and then becomes ODHE raw material gas 42 which is sent into an ODHE reactor 43, and ethane and an oxidant undergo oxidative dehydrogenation reaction under the action of a catalyst (adopting MoVTeNbO catalyst) to generate ODHE reaction gas 44 rich in ethylene.

(3) The temperature in the ODHE reactor 43 is 450 ℃, the pressure is 0.80MPaG, the conversion rate of ethane is 65.0 percent, the selectivity of ethylene, acetic acid, carbon monoxide and carbon dioxide is 89.0 percent, 0.8 percent and 2.7 percent respectively,7.5 percent. The ODHE reaction gas 44 has a molar flow of 334.1kmol/h and a composition (mol%): c₂H₄：8.9％、C₂H₆：5.4％、O₂：0.5％、CH₃OH：70.6％、H₂O：12.0％、CO：0.5％、CO₂：1.5％、CH₃COOH: 0.1%, others: 0.4 percent.

(4) Cooling the ODHE reaction gas 44 to 150 ℃, sending the ODHE reaction gas into an ODHE gas-liquid separator 46 for gas-liquid separation, sending a gas-phase product 47 into an ODHE product separation tower 49, carrying out countercurrent contact with water 50 introduced from the top of the tower and a coolant I54 (adopting water) introduced from the middle part of the tower, obtaining ODHE water product gas 55 at the top of the tower, and obtaining a liquid-phase product II 51 containing methanol, water and trace acetic acid at the bottom of the tower. The liquid phase product II 51 of the ODHE product separation tower 49 is mixed with the liquid phase product I48 of the gas-liquid separator 46 to obtain a mixed liquid 66, and the mixed liquid is completely sent to an MTO feeding vaporizer 2 positioned in front of an MTO reactor 8 and is used as a part of raw materials of the MTO reactor 8, wherein the mass flow rate of the mixed liquid 66 is 8.68t/h and the composition (mass%): CH (CH)₃OH：88.0％、H₂O：11.3％、CH₃COOH: 0.2%, others: 0.5 percent.

(5) The ODHE product gas 55 is heated to 230 ℃ by a heat exchanger F56 and then becomes ODHE product gas 57, the ODHE product gas 57 is sent to an ODHE oxygen removal device 58, the oxygen removal gas comprises carbon monoxide contained in the ODHE product gas 57 and auxiliary oxygen removal gas 72, and the auxiliary oxygen removal gas 72 is carbon monoxide. The oxygen content of the ODHE product gas 57 was reduced to 200ppmv by reaction of carbon monoxide with oxygen to yield an ODHE deoxygenated product gas 59.

(6) The ODHE deoxygenation product gas 59 is cooled to 50 ℃ by a heat exchanger G60 to become ODHE deoxygenation product gas 61, and the ODHE deoxygenation product gas 61 is sent to ODHE for CO removal₂And a device 62. The decarbonizing agent 63 adopts an organic amine MDEA solution to remove CO from ODHE₂CO in the product gas 64₂The content is reduced to 2 mol%. The liquid-phase product III 65 mainly contains MDEA, water and CO₂. ODHE CO removal₂The molar flow of the product gas 64 was 49.6kmol/h, with the composition (mol%): c₂H₄：59.6％、C₂H₆：36.1％、CO₂：2.0％、H₂O: 2.2%, others: 0.1 percent.

Otherwise, the rest was the same as example 1.

For the MTO system with the scale of 60 ten thousand tons per year, the method of the embodiment can increase the yield of 6630 tons of ethylene for enterprises each year.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.