CN113896608B - Device and method for improving ethylene yield and income by using ethane as byproduct of methanol-to-olefin - Google Patents
Device and method for improving ethylene yield and income by using ethane as byproduct of methanol-to-olefin Download PDFInfo
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Abstract
The invention relates to a device and a method for improving the yield and the income of ethylene by utilizing ethane as a byproduct in the preparation of olefin from methanol, wherein the process comprises the following steps: (a) Mixing the ethane of the MTO byproduct with an oxidant and a diluent gas, and then sending the mixture into an ODHE reactor to generate an ODHE crude product gas rich in ethylene; (b) Sending the ODHE crude product gas into a deacidification tower to obtain deacidification product gas and absorption liquid; (c) Feeding the deacidified product gas into an deoxidizing device to obtain deoxidized product gas; (d) Compressed deoxidized product gas is fed into CO 2 An absorption tower for removing CO 2 Product gas; (e) Will remove CO 2 Mixing the product gas with MTO crude product gas, compressing, separating oxygen-containing compound, and eluting CO with alkali 2 Drying and olefin separation to finally obtain ethylene, ethane and other products, wherein the ethane is returned to the inlet of the ODHE reactor. The invention can improve the yield and benefit of ethylene products of the MTO system.
Description
Technical Field
The invention belongs to the technical field of ethane recycling, and relates to a device and a method for improving ethylene yield and income by utilizing ethane as a byproduct in the preparation of olefins from methanol.
Background
The steam cracking method is a method for producing ethylene by using ethane, which is widely applied in industry at present, and the gas raw material is 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 required to be carried out under the condition of negative pressure (greatly diluting superheated steam), the energy consumption is extremely high, the investment of the cracking furnace is high, the operation is complex, the carbon deposition is required to be removed periodically, and the scale limitation of the minimum treatment capacity of a single cracking furnace exists. The conversion rate of ethane in the cracking furnace is 65%, the selectivity of ethylene is lower and is about 80% -84%, and the composition of cracking gas is complex and mainly contains ethylene, ethane, propylene, hydrogen, methane and mixed C 4 ++, pyrolysis gasoline, etc.
Patent CN104193574B discloses a coupling method of MTO process and ethylene preparation process by naphtha steam cracking; patent CN104151121B discloses a method for coupling an MTO process with a pre-naphtha cracking depropanization process; patent CN107056575a discloses a method for coupling an MTO process with a deethanizer process prior to naphtha and propane pyrolysis; patent CN107417481a discloses a method for coupling MTO process with deethanization process before light hydrocarbon cracking; patent CN107056568A discloses a method for coupling an MTO process with a pre-naphtha and propane splitting process; patent CN104193570B discloses a method of coupling an MTO process with a naphtha cracking sequential separation process. The above patents are all coupling of MTO system and ethylene preparing device by steam cracking, but the steam cracking method is a strong endothermic process, and has the problems of harsh reaction conditions, long subsequent separation flow, high equipment investment and operation cost, large occupied area and the like.
In recent years, research into the production of ethylene (ODHE) by catalytic oxidative dehydrogenation of lower hydrocarbons, particularly ethane, has been receiving increasing attention. Related toThe catalytic oxidative dehydrogenation of ethane was studied in the 70 s of the 20 th century, and Gaspar et al, as early as in the 1971 study report, was proposed in H 2 Under the catalysis of S, ethane is catalyzed and oxidatively dehydrogenated to prepare ethylene, and then in 1977 and 1978 Ward and Thorsteinson, the oxidative dehydrogenation process using Mo, si and mixed oxides of Mo and V as catalysts is also sequentially disclosed. Chinese patent CN105849069a discloses the use of a catalyst with active component MoVTe (Nb) O for oxidative dehydrogenation of alkanes of 2 to 6 carbon atoms, feed gas space velocity 7500 to 15000h -1 The reaction temperature is 320-420 ℃, the conversion rate of ethane can reach 44%, and the selectivity of the corresponding ethylene is 92.2%. Chinese patent CN105080575B discloses the use of a catalyst with MoVTeNbO as active component for catalytic oxidative dehydrogenation of ethane, the conversion of ethane and the ethylene selectivity at 350 ℃ can reach 70.5% and 95%, respectively.
The method is a country rich in coal, takes coal to prepare methanol as a raw material, adopts an MTO process to produce ethylene and propylene, and is one of the important chemical core technologies at present. The product distribution of a typical MTO process is shown in fig. 1 (60 ten thousand ton scale), with the main products ethylene and propylene and the main by-products ethane, propane and mixed C 4 +. The byproduct ethane of the MTO process accounts for about 3% of the ethylene product, and the byproduct ethane of the MTO process is mainly used as fuel or is directly sold as ethane product, so that the value is relatively low. In order to dig higher profit margins, the ODHE process can be adopted to convert part of ethane into ethylene, and the increased ethylene can bring considerable economic benefit to enterprises.
How to fully utilize the ethane of MTO byproduct to increase ethylene yield and how to fully utilize the separation system of an MTO system, simplify the process flow, reduce the equipment quantity and investment and reduce the process energy consumption is an important problem.
Disclosure of Invention
The invention aims to provide a device and a method for improving the yield and the income of ethylene by utilizing ethane which is a byproduct of preparing olefin from methanol. The invention has simple whole process flow, can be well matched with the MTO process to achieve the purpose of improving the yield and the income of ethylene products of the MTO system, and has the advantages of investment saving, quick response, high income, short investment recovery period and the like.
The aim of the invention can be achieved by the following technical scheme:
one of the technical proposal of the invention provides a device for improving the yield and the income of ethylene by utilizing the byproduct ethane of the methanol to olefin, which comprises an ODHE reactor, a deacidification tower and CO which are sequentially connected with an ethane product outlet of an MTO system along the direction of main material flow 2 Absorption tower, the CO 2 CO is also arranged behind the absorption tower 2 A resolving tower for resolving CO 2 The gas phase outlet at the top of the absorption tower is also connected with an MTO system in a return way and is subjected to subsequent treatment together with the crude product gas of the MTO.
Further, the MTO system comprises an MTO reaction and pretreatment unit, an MTO product gas compressor, an MTO oxide-containing separation unit, an MTO alkaline washing unit, an MTO drying unit and an MTO olefin separation unit which are sequentially connected, wherein an ethylene product outlet, a propylene product outlet and an ethane product outlet are arranged on the MTO olefin separation unit, and the CO is formed by the steps of 2 The top gas phase outlet of the absorption tower is connected with the inlet of the MTO product gas compressor in a return way.
Further, a heat exchanger is further arranged between the ODHE reactor and the deacidification tower, and the ethane discharged from the outlet of the ethane product, the newly introduced oxidant and the diluent gas are subjected to heat exchange through the heat exchanger and then are sent into the ODHE reactor.
Further, the deacidification tower and CO 2 A deacidification product gas pipeline is also arranged between the absorption towers, and a deaerator and a deacidification product gas compressor are also arranged on the deacidification product gas pipeline.
Furthermore, a deaerator bypass pipeline connected with the deaerator in parallel is arranged between the deacidification tower and the deacidification product gas compressor. ( The purpose of arranging the bypass line here is: in specific cases, the deaerator can be not operated, and the deacidified product gas can be directly connected to the deacidified product gas compressor through the bypass pipeline )
The second technical scheme of the invention provides a method for improving the yield and income of ethylene by utilizing the byproduct ethane in the preparation of olefin from methanol, which is implemented by adopting the device as described in any one of the above, and comprises the following steps:
(1) After the ethane product of the MTO byproduct is mixed with oxidant and diluent gas, heat exchange is carried out to form preheated raw material gas, the preheated raw material gas enters an ODHE reactor, and ODHE crude product gas rich in ethylene is generated under the action of a catalyst;
(2) The ODHE crude product gas is sent to the bottom of a deacidification tower after heat exchange, and is in countercurrent contact with an absorbent introduced from the upper part of the deacidification tower, so as to obtain an absorption liquid at the bottom of the tower, and the deacidification product gas is obtained at the top of the tower;
(3) Mixing and preheating deacidified product gas and auxiliary deoxidizing gas, and then entering a deoxidizer to obtain deoxidized product gas;
(4) Cooling and pressurizing the deoxidized product gas (the pressure can be 1.7-3.5 MPaG) and then feeding the deoxidized product gas into CO 2 The bottom of the absorption tower is connected with CO 2 CO introduced from the upper part of the absorption tower 2 Countercurrent contact of the absorbent to obtain CO-eliminating product at the top of the tower 2 The product gas is returned to the MTO system, and CO-containing gas is obtained at the bottom of the tower 2 A rich liquid;
(5) Containing CO 2 Preheating the rich liquid and feeding into CO 2 The gas phase at the top of the tower is cooled and then sent into a gas-liquid separation tank, and CO is obtained at the top of the tank 2 Desorbing gas, obtaining reflux liquid at the bottom of the tank and returning CO 2 Upper part of the analysis tower, CO 2 The liquid at the bottom of the analysis tower is pressurized and cooled to be used as CO 2 Absorbent return CO 2 The upper part of the absorption tower.
Further, in step (1), the oxidizing agent is selected from the group consisting of air, oxygen-enriched or pure oxygen; the diluent gas is selected from one or a mixture of a plurality of nitrogen, water vapor or carbon dioxide.
Further, in the step (1), the molar ratio of the ethane product to the oxidant and the diluent gas is 1: (0.27-0.55): (0.6-3.5).
Further, in the step (1), the active component of the catalyst is a transition metal oxide, and the transition metal element in the transition metal oxide includes one or more of Mo, V, te or Nb, and specifically, a MoVTeNbO catalyst may be used.
Further, in the step (1), the temperature of the preheated raw material gas is 150-350 ℃.
Further, in the step (1), the reaction temperature in the ODHE reactor is 350-450 ℃, and the reaction pressure is 0.2-1.0 MPa.
Further, in step (2), the absorbent used is water and/or an aqueous alkaline solution, preferably water.
Further, in the step (3), the temperature after the deacidification product gas and the auxiliary deoxidizing gas are mixed and preheated is 60-230 ℃; the auxiliary deoxidizing gas is selected from one or more of carbon monoxide, hydrogen and methane.
Further, in step (4), the CO 2 The absorbent is selected from one or more of alcohol amine water solution, potassium carbonate water solution, sulfolane, propylene carbonate, polyethylene glycol dimethyl ether or methanol solution, and MDEA water solution.
The invention introduces oxidant (taking oxygen as an example) to mix raw material ethane and oxygen according to a certain proportion, then introduces the mixture into an oxidative dehydrogenation catalyst bed layer, and generates catalytic oxidative dehydrogenation reaction under the condition of relatively low temperature to generate ethylene (ODHE process). In the invention, the main chemical reaction equation of the ODHE process is as follows:
C 2 H 6 +0.5O 2 ＝C 2 H 4 +H 2 O (1)
C 2 H 6 +1.5O 2 ＝C 2 H 4 O 2 +H 2 O (2)
C 2 H 6 +2.5O 2 ＝2CO+3H 2 O (3)
C 2 H 6 +3.5O 2 ＝2CO 2 +3H 2 O (4)
in the invention, the crude product gas at the outlet of the ODHE reactor is firstly subjected to waste heat recovery and cooling by a heat exchanger, then enters the bottom of an absorption tower, and is used for removing acetic acid in the crude product gas under the action of an absorbent at the top of the absorption tower. The absorbent may be water and/or an aqueous alkaline solution, preferably water is used as the absorbent. The deacidified product gas at the top of the absorption tower is mixed with the auxiliary deoxidizing gas, preheated by a heat exchanger and then enters a deoxidizer for removing unreacted residual oxygen in the crude product gas.
The deoxidizer adopts the deoxidizing method, preferably adopts CO which is a byproduct of ODHE reaction and other auxiliary deoxidizing gases, and residual O which is not completely reacted in the crude product gas 2 Catalytic reaction takes place to generate H 2 O and CO 2 So as to achieve the purpose of removing residual oxygen in the discharge of the reactor. The auxiliary deoxidizing gas, preferably light component gas (containing H) obtained from a low-carbon hydrocarbon pretreatment device 2 And CH (CH) 4 ) Or from outside the boundary region. The preferred chemical reaction equation for removing residual oxygen of the present invention is as follows:
2H 2 +O 2 ＝2H 2 O (5)
CH 4 +2O 2 ＝CO 2 +2H 2 O (6)
2CH 4 +3O 2 ＝2CO+4H 2 O (7)
2CO+O 2 ＝2CO 2 (8)
deoxidization product gas is cooled by a heat exchanger and pressurized by a compressor and then is fed into CO 2 Absorption tower for removing CO in product gas by physical and/or chemical absorption mode 2 CO removal is obtained at the top of the tower 2 And (3) gas. CO 2 The absorbent is selected from one or more of alcohol amine water solution, potassium carbonate water solution, sulfolane, propylene carbonate, polyethylene glycol dimethyl ether or methanol solution; preferably, the CO 2 The absorbent adopts MDEA aqueous solution.
CO removal 2 The gas enters an MTO product gas compressor, is mixed with the pretreated MTO crude product gas, and then sequentially enters an MTO oxygen-containing compound separation device, an MTO alkaline washing device, an MTO drying device and an MTO olefin separation device to finally obtain ethylene products, propylene products, fuel gas and ethane. The ethane is sent to the inlet of the ODHE reactor.
The invention achieves the purpose of improving the yield and income of ethylene products of the MTO system through the method and the steps.
Compared with the prior art, the invention has the following advantages:
(1) The ODHE process has mild reaction condition, high ethylene selectivity and simple product, and by utilizing the characteristics, the process flow is greatly simplified, the equipment investment is reduced, and the yield of ethylene products is increased.
(2) The ODHE method provided by the invention has the advantages that the ethylene is prepared by an exothermic reaction, the reaction condition is mild, 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.
(3) The invention can be well matched with the separation flow of the MTO process to achieve the purpose of improving the yield and the income of ethylene products of an MTO system, and has the advantages of simple process flow, investment saving, quick response, high income and short investment recovery period.
Drawings
FIG. 1 is a product distribution diagram of a 60 ten thousand ton MTO process per year;
fig. 2 is a schematic flow chart of the present invention.
The figure indicates:
1 is ethane, 2 is oxidant, 3 is diluent gas, 4, 6, 12, 14, 19, 21, 22, 27 are heat exchangers, 5 is ODHE reactor, 5a is preheated raw material gas, 5b is ODHE crude product gas, 6a is cooling medium feeding pipeline, 6b is cooling medium discharging pipeline, 7 is deacidification tower, 8 is absorbent, 9 is absorption liquid, 10 is deacidification product gas, 11 is auxiliary deoxidization gas, 13 is deoxidizer, 13a is non-deoxidization mixed gas, 13b is deoxidization product gas, 15 is compressor, 16 is CO 2 Absorption tower, 17 is CO 2 The absorbent, 18 is a CO-containing 2 Rich liquid, 20 is CO 2 The analysis tower, 23 is a gas-liquid separator, 24 is CO 2 The desorption gas, 25 is a reflux pump, 26 is a lean solution pump, 28 is CO removal 2 Product gas, 29 is an MTO product gas compressor, 30 is fuel gas, 31 is propylene product, 32 is ethylene product, 33 is a deaerator bypass pipeline, 34-37 are valves, 38 is an MTO reaction and pretreatment unit, 39 is an MTO oxide separation unit, 40 is an MTO alkaline washing unit, 41 is an MTO drying unit, 42 is an MTO olefin separation unit, 43 is a pretreated MTO crude product gas, and 44, 45, 46 and 47 are MTO product gases.
Detailed Description
The invention will now be described in detail with reference to the drawings and specific examples. The present embodiment is implemented on the premise of the technical scheme of the present invention, and a detailed implementation manner and a specific operation process are given, but the protection scope of the present invention is not limited to the following examples.
In the following embodiments, unless otherwise specified, functional components or structures are indicated as conventional components or structures adopted in the art to achieve the corresponding functions.
Example 1:
in example 1, for an MTO system on a 60 ten thousand ton/year scale, the yield and benefits of ethylene products of the MTO system can be improved by converting its by-produced ethane to ethylene by the process of the present invention. The ODHE process has mild reaction conditions, high ethylene selectivity and simple products, and greatly simplifies the process flow by utilizing the characteristics; the invention can be well matched with the separation flow of the MTO process, and saves equipment investment.
An MTO system with a 60-kiloton/year scale, wherein fresh ethane is produced as a byproduct at about 1.0t/h, and recycled ethane at about 0.82t/h; the total flow of ethane 1 into the ODHE reactor 5 is about 1.82t/h. The oxidant 2 was air at a flow rate of about 3.54t/h. The dilution gas 3 was steam at a flow rate of about 0.37t/h. The temperature in the ODHE reactor 5 was about 405 c and the pressure was 0.30MPaG. The active component of the catalyst employed in the ODHE reaction is a transition metal oxide (which may be a MoVTeNbO catalyst). The conversion of ethane was 55.0%, and the selectivities of ethylene, acetic acid, carbon monoxide and carbon dioxide were 89.4%, 3.3%, 3.5% and 3.8%, respectively. The absorbent 8 at the top of the deacidification tower 7 adopts water. The auxiliary deoxidizing gas 11 adopts CO. The CO 2 CO at the top of the absorption column 16 2 The absorbent 17 is an aqueous MDEA solution.
As shown in fig. 2, the present embodiment provides a method for improving ethylene yield and income by using ethane as a byproduct of methanol to olefins, comprising the steps of:
(a) The mixed raw material gas total flow formed by mixing the ethane 1 of the MTO byproduct, the oxidant 2 (namely air) and the diluent gas 3 (namely water vapor) is about 5.73t/h, the temperature is 40 ℃, the pressure is 0.31Mpa G, the preheated raw material gas 5a is obtained after the preheating to 250 ℃ by a heat exchanger 4 and is fed into an ODHE reactor 5, and the ODHE raw product gas 5b rich in ethylene is generated under the action of a catalyst; the reaction temperature in the ODHE reactor 5 is about 405 ℃ and the pressure is about 0.30MPaG; the ODHE reactor 5 is provided with a cooling medium line with a heat exchanger 6, which is divided into a cooling medium feed line 6a and a cooling medium discharge line 6b.
(b) The temperature of the ODHE crude product gas 5b obtained in the step (a) is about 375 ℃, the temperature is reduced to 120 ℃ after heat is recovered by a heat exchanger 4, the temperature enters the bottom of a deacidification tower 7, the ODHE crude product gas is in countercurrent contact with an absorbent 8 (namely water) introduced into the upper part of the deacidification tower 7, an absorption liquid 9 obtained at the bottom of the tower is acetic acid aqueous solution, and deacidification product gas 10 is obtained at the top of the tower;
(c) The deacidified product gas 10 obtained in the step (b) is mixed with an auxiliary deoxidized gas 11 (CO here) sent after a valve 34 is opened, and then preheated to 180 ℃ by a heat exchanger 12 to obtain an unoxidized mixed gas 13a, and enters a deoxidizer 13, and an outlet of the deoxidized mixed gas is provided with deoxidized product gas 13b, wherein the oxygen content is reduced to below 10 ppmv; a deaerator by-pass line 33 (with valve 37) is connected between the deacidification product gas line (with valve 35) and the inlet line of the compressor 15;
(d) The deoxidized product gas 13b obtained in the step (c) is cooled to 40 ℃ through a heat exchanger 14 at 200 ℃, and is pressurized to 1.5mpa G through a compressor 15 and then is fed into CO (carbon monoxide) 2 The bottom of the absorption tower 16 is connected with CO 2 The MDEA aqueous solution (i.e. CO) introduced from the upper part of the absorption tower 16 2 The absorbent 17) is contacted countercurrently and CO-removed is obtained at the top of the column 2 Product gas 28, CO therein 2 The content is reduced to below 100 ppmv; CO-containing obtained at the bottom of the column 2 The rich liquid 18 enters CO after being preheated by a heat exchanger 19 2 The upper part of the analysis tower 20; the gas at the top of the tower is cooled by a heat exchanger 22 and then enters a gas-liquid separation tank 23, and CO is obtained at the top of the tank 2 Desorbing gas 24, obtaining reflux liquid at the bottom of the tank, pressurizing by a reflux pump 25, and delivering to CO 2 The upper part of the analysis tower 20; CO 2 The liquid at the bottom of the resolving tower 20 is pressurized by a lean liquid pump 26 and cooled by a heat exchanger 27 and then returned to CO 2 An upper portion of the absorption column 16;
(e) CO removal obtained in step (d) 2 The product gas 28 enters an MTO product gas compressor 29 and is mixed with the pretreated MTO crude product gas 43 to form an MTO product gas 44; then sequentially enters an MTO oxygen-containing compound separation device 39 to remove the oxygen-containing compound in the MTO oxygen-containing compound, and the obtained MTO product gas 45 enters an MTO alkaline washing device 40 to remove the CO in the MTO alkaline washing device 2 To below 1 ppm; the obtained MTO product gas 46 enters the MTO drying device 41, water therein is removed, the obtained MTO product gas 47 finally enters the MTO olefin separation device 42, the ethylene product 32, the propylene product 31, the fuel gas 30 and the ethane 1 are separated, the ethane 1 is a mixture of the ethane which is a byproduct of the MTO system and the circulating ethane which is unreacted by the ODHE system, and the mixture returns to the inlet of the ODHE reactor 5.
For a 60 ten thousand ton/year scale MTO system, 6670 tons of ethylene can be stimulated per year for an enterprise using the method of example 1 of the present invention. Assuming that the price difference of ethylene and ethane is 4000 yuan/ton, 6670 tons of ethylene which is increased by adopting the method can increase the income of about 2670 yuan per year for enterprises, and the economic benefit is quite considerable.
In example 1, valve 37 is closed, deaerator bypass line 33 is in a shut-off state, and valves 34, 35 and 36 are in an open state.
Example 2:
in example 2, for an MTO system of 30 ten thousand tons/year scale, the yield and the benefit of ethylene products of the MTO system can be improved by converting the ethane as a by-product into ethylene by the method of the present invention.
30 ten thousand tons/year scale MTO system, by-product fresh ethane about 0.6t/h, circulating ethane 0.6t/h; the total flow of ethane 1 into the ODHE reactor 5 is about 1.2t/h. The oxidant 2 is air at a flow rate of about 2.3t/h. The dilution gas 3 was steam at a flow rate of about 0.24t/h. The temperature in the ODHE reactor 5 was about 395 ℃ and the pressure was 0.34MPaG. The active component of the catalyst employed in the ODHE reaction is a transition metal oxide. The conversion of ethane was 50.0%, and the selectivities of ethylene, acetic acid, carbon monoxide and carbon dioxide were 89.6%, 3.6% and 3.2%, respectively. The top absorbent 8 of the deacidification tower 7 adopts water. The auxiliary deoxidizing gas 11 adopts CO and H 2 Is a mixed gas of (a) and (b). The CO 2 C at the top of absorption column 16O 2 The absorbent 17 is an aqueous MDEA solution.
As shown in fig. 2, the present embodiment provides a method for improving ethylene yield and income by using ethane as a byproduct of methanol to olefins, comprising the steps of:
(a) The total flow of mixed feed gas formed by mixing ethane 1, air 2 and water vapor 3 which are the MTO byproducts is about 3.74t/h, the temperature is 40 ℃, the pressure is 0.34MpaG, the mixed feed gas is preheated to 270 ℃ by a heat exchanger 4 and then enters an ODHE reactor 5, and an ODHE crude product gas 5b rich in ethylene is generated under the action of a catalyst; the reaction temperature in the ODHE reactor 5 is about 395 ℃ and the pressure is about 0.33MPaG;
(b) The temperature of the ODHE crude product gas 5b obtained in the step (a) is about 360 ℃, the temperature is reduced to 100 ℃ after heat is recovered by a heat exchanger 4, the gas enters the bottom of a deacidification tower 7, countercurrent contact is carried out on the gas and water 8 introduced into the upper part of the deacidification tower 7, an absorption liquid 9 obtained at the bottom of the tower is acetic acid aqueous solution, and deacidification product gas 10 is obtained at the top of the tower;
(c) The deacidified product gas 10 obtained in the step (b) is mixed with CO, preheated to 190 ℃ by a heat exchanger 12, enters a deaerator 13, and is discharged to obtain deoxidized product gas 13b, wherein the oxygen content is reduced to below 10 ppmv; a deaerator bypass line 33 is connected between the deacidification product gas 10 line and the compressor 15 inlet line;
(d) The deoxidization product gas 13b obtained in the step (c) is cooled to 40 ℃ through a heat exchanger 14 at 210 ℃, pressurized to 1.6mpa.G through a compressor 15 and then fed into CO 2 The bottom of the absorption tower 16 is connected with CO 2 The MDEA aqueous solution introduced from the upper part of the absorption tower 16 is countercurrently contacted, and CO is removed from the top of the tower 2 Product gas 28, CO therein 2 The content is reduced to below 100 ppmv; CO-containing obtained at the bottom of the column 2 The rich liquid 18 enters CO after being preheated by a heat exchanger 19 2 The upper part of the analysis tower 20; the gas at the top of the tower is cooled by a heat exchanger 22 and then enters a gas-liquid separation tank 23, and CO is obtained at the top of the tank 2 Desorbing gas, obtaining reflux liquid at the bottom of the tank, pressurizing by a reflux pump 25, and delivering to CO 2 The upper part of the analysis tower 20; CO 2 The liquid at the bottom of the resolving tower 20 is pressurized by a lean liquid pump 26 and cooled by a heat exchanger 27 and then sent to CO 2 An upper portion of the absorption column 16;
(e) Step (d) to obtainCO removal from the reactor 2 The product gas 28 enters an MTO product gas compressor 29 and is mixed with the pretreated MTO crude product gas 43 to form an MTO product gas 44; then sequentially enters an MTO (methyl thiazolyl tetrazolium) oxygen-containing compound separation device 39 to remove the oxygen-containing compound in the MTO oxygen-containing compound separation device; the obtained MTO product gas 45 enters the MTO alkaline washing device 40 again to remove CO therein 2 To below 1 ppm; the obtained MTO product gas 46 enters an MTO drying device 41 to remove water; the obtained MTO product gas 47 finally enters an MTO olefin separation device 42 to be separated to obtain an ethylene product 32, a propylene product 31, a fuel gas 30 and ethane 1; the ethane 1 is a mixture of the byproduct ethane of the MTO system and the unreacted circulating ethane of the ODHE system, and is returned to the inlet of the ODHE reactor 5.
For a 30 ten thousand ton/year scale MTO system, 4013 tons of ethylene can be increased per year for an enterprise using the method of example 2 of the present invention. Assuming that the price difference of ethylene and ethane is 4000 yuan/ton, 4013 tons of ethylene which is increased in production by adopting the method can increase the income of 1605 ten thousand yuan for enterprises each year, and the economic benefit is quite considerable.
In example 2, valve 37 was closed and deaerator bypass line 33 was shut off. Valves 34, 35 and 36 are in an open state.
Example 3:
in example 3, for an MTO system on a 60 ten thousand ton/year scale, the yield and benefits of ethylene products of the MTO system can be improved by converting its by-produced ethane to ethylene by the process of the present invention.
An MTO system with a scale of 60 ten thousand tons/year, wherein fresh ethane is produced as a byproduct at a rate of about 1.2t/h, and circulated ethane at a rate of 1.04t/h; the total flow of ethane 1 into ODHE reactor 5 is about 2.24t/h. The oxidant 2 adopts pure O 2 The flow rate was about 1.0t/h. The dilution gas 3 was steam at a flow rate of about 0.82t/h.
The conversion of ethane was 53.5%, and the selectivities of ethylene, acetic acid, carbon monoxide and carbon dioxide were 82.2%, 10.5%, 3.6% and 3.2%, respectively.
The process flow of example 3 is substantially the same as that of example 1, except that in example 3, valve 37 is closed and deaerator bypass line 33 is shut off. Valves 34, 35 and 36 are in an open state.
Example 4:
example 4 differs from examples 1 to 3 in that the CO content in the crude product gas at the outlet of the ODHE reactor 5 is relatively high, whereas O 2 Relatively low in content, residual O in the raw product gas in the subsequent deoxygenation reactor 13 2 Most of the reaction with CO is converted into CO 2 . In embodiment 4, the valve 34 is in the closed state, and the auxiliary oxygen-scavenging gas 11 is not consumed.
Example 5:
example 5 differs from examples 1 to 4 in that O in the ODHE reactor 5 2 Most of the O in the tail gas is consumed by ODHE reaction 2 The content is very low, and the O in the product gas can be satisfied in the subsequent separation process 2 The content is required. The valves 34, 35 and 36 are in the shut-off state and the deaerator 13 section is shut down. And valve 37 is opened, the deaerator bypass line 33 is in a vented condition, and the deacidified product gas 10 is directly fed to the compressor 15 inlet via the deaerator bypass line 33.
The previous description of the embodiments is provided to facilitate a person of ordinary skill in the art in order to make and use the present invention. It will be apparent to those skilled in the art that various modifications can be readily made to these embodiments 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-described embodiments, and those skilled in the art, based on the present disclosure, should make improvements and modifications without departing from the scope of the present invention.
Claims (10)
1. An apparatus for increasing the yield and income of ethylene by using the byproduct ethane generated in the preparation of olefin from methanol is characterized by comprising an ODHE reactor, a deacidification tower and CO which are sequentially connected with the outlet of the ethane product of an MTO system along the direction of the main material flow 2 Absorption tower, the CO 2 CO is also arranged behind the absorption tower 2 A resolving tower for resolving CO 2 The gas phase outlet at the top of the absorption tower is also connected with an MTO system in a return way, and is subjected to subsequent separation treatment together with the crude product gas of the MTO.
2. The apparatus for increasing ethylene yield and improvement of yield by using ethane as a byproduct in methanol-to-olefins process according to claim 1, wherein said MTO system comprises an MTO reaction and pretreatment unit, an MTO product gas compressor, an MTO oxygenate separation unit, an MTO alkaline washing unit, an MTO drying unit, and an MTO olefin separation unit, which are sequentially connected, an ethylene product outlet, a propylene product outlet, and said ethane product outlet are disposed on said MTO olefin separation unit, said CO 2 The top gas phase outlet of the absorption tower is connected with the inlet of the MTO product gas compressor in a return way.
3. The apparatus for increasing ethylene yield and improvement of yield by using ethane as a byproduct in the production of olefins from methanol according to claim 1, wherein a heat exchanger is further provided between the ODHE reactor and the deacidification tower, and the ethane discharged from the outlet of the ethane product is fed into the ODHE reactor after heat exchange with newly introduced oxidant and diluent gas by the heat exchanger.
4. The apparatus for increasing ethylene yield and improvement of yield using ethane as a byproduct in the production of olefins from methanol as claimed in claim 1, wherein said deacidification tower is connected with CO 2 A deacidification product gas pipeline is also arranged between the absorption towers, and a deaerator and a deacidification product gas compressor are also arranged on the deacidification product gas pipeline.
5. The apparatus for increasing ethylene yield and improvement of yield using ethane as a byproduct in the production of olefins from methanol as set forth in claim 4, wherein a deaerator bypass line connected in parallel with the deaerator is further provided between the deacidification tower and the deacidification product gas compressor.
6. A method for improving ethylene yield and recovery from methanol-to-olefin by-produced ethane, which is carried out using the apparatus according to any one of claims 1 to 5, comprising the steps of:
(1) After the ethane product of the MTO byproduct is mixed with oxidant and diluent gas, heat exchange is carried out to form preheated raw material gas, the preheated raw material gas enters an ODHE reactor, and ODHE crude product gas rich in ethylene is generated under the action of a catalyst;
(2) The ODHE crude product gas is sent to the bottom of a deacidification tower after heat exchange, and is in countercurrent contact with an absorbent introduced from the upper part of the deacidification tower, so as to obtain an absorption liquid at the bottom of the tower, and the deacidification product gas is obtained at the top of the tower;
(3) Mixing and preheating deacidified product gas and auxiliary deoxidizing gas, and then entering a deoxidizer to obtain deoxidized product gas;
(4) Cooling and pressurizing deoxidized product gas, and feeding into CO 2 The bottom of the absorption tower is connected with CO 2 CO introduced from the upper part of the absorption tower 2 Countercurrent contact of the absorbent to obtain CO-eliminating product at the top of the tower 2 The product gas is returned to the MTO system, and CO-containing gas is obtained at the bottom of the tower 2 A rich liquid;
(5) Containing CO 2 Preheating the rich liquid and feeding into CO 2 The gas phase at the top of the tower is cooled and then sent into a gas-liquid separation tank, and CO is obtained at the top of the tank 2 Desorbing gas, obtaining reflux liquid at the bottom of the tank and returning CO 2 Upper part of the analysis tower, CO 2 The liquid at the bottom of the analysis tower is pressurized and cooled to be used as CO 2 Absorbent return CO 2 The upper part of the absorption tower.
7. The method for increasing ethylene yield and recovery from methanol-to-olefins byproduct ethane of claim 6, wherein in step (1), the oxidant is selected from the group consisting of air, oxygen enrichment, and a mixture of one or more of pure oxygen; the diluent gas is selected from one or a mixture of a plurality of nitrogen, water vapor or carbon dioxide;
the molar ratio of ethane product to oxidant and diluent gas is 1: (0.27-0.55): (0.6-3.5).
8. The method for increasing ethylene yield and improvement in yield using ethane as a byproduct in the production of olefins from methanol according to claim 6, wherein in step (1), the active component of the catalyst is a transition metal oxide;
the temperature of the preheated raw material gas is 150-350 ℃;
the reaction temperature in the ODHE reactor is 350-450 ℃, and the reaction pressure is 0.2-1.0 MPa.
9. The method for improving ethylene yield and improvement of yield by using ethane as a byproduct in the production of olefins from methanol according to claim 6, wherein in the step (2), the absorbent is water and/or an alkaline aqueous solution;
in the step (3), the temperature after the deacidification product gas and the auxiliary deoxidizing gas are mixed and preheated is 60-230 ℃; the auxiliary deoxidizing gas is selected from one or more of carbon monoxide, hydrogen and methane.
10. The method for increasing ethylene yield and improvement in yield using ethane as a by-product in the production of olefins from methanol as claimed in claim 6, wherein in step (4), said CO 2 The absorbent is selected from one or more of alcohol amine water solution, potassium carbonate water solution, sulfolane, propylene carbonate, polyethylene glycol dimethyl ether or methanol solution.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103864556A (en) * | 2012-12-13 | 2014-06-18 | 中国科学院大连化学物理研究所 | Method for production of low carbon olefins from synthetic gas via low carbon alkanes |
| CN103965003A (en) * | 2013-01-30 | 2014-08-06 | 中国石油化工股份有限公司 | Production method of butadiene |
| CN104193574A (en) * | 2014-08-13 | 2014-12-10 | 中石化上海工程有限公司 | Method for coupling MTO (methanol to olefin) process with process of preparing ethylene by cracking naphtha steam |
| CN107417481A (en) * | 2017-05-10 | 2017-12-01 | 中石化上海工程有限公司 | The method that MTO techniques couple with light hydrocarbon cracking front-end deethanization technique |
| WO2021009307A1 (en) * | 2019-07-18 | 2021-01-21 | Linde Gmbh | Method and facility for producing a target compound |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103864556A (en) * | 2012-12-13 | 2014-06-18 | 中国科学院大连化学物理研究所 | Method for production of low carbon olefins from synthetic gas via low carbon alkanes |
| CN103965003A (en) * | 2013-01-30 | 2014-08-06 | 中国石油化工股份有限公司 | Production method of butadiene |
| CN104193574A (en) * | 2014-08-13 | 2014-12-10 | 中石化上海工程有限公司 | Method for coupling MTO (methanol to olefin) process with process of preparing ethylene by cracking naphtha steam |
| CN107417481A (en) * | 2017-05-10 | 2017-12-01 | 中石化上海工程有限公司 | The method that MTO techniques couple with light hydrocarbon cracking front-end deethanization technique |
| WO2021009307A1 (en) * | 2019-07-18 | 2021-01-21 | Linde Gmbh | Method and facility for producing a target compound |
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