Method for converting methanol to olefins

Abstract

The present invention relates to a process for converting methanol to olefins, which includes: Feeding a feedstock comprising methanol to a fluidized bed reactor for contacting catalysts to produce an olefin product, wherein the process at least partially deactivates the catalysts to form catalysts that are at least partially deactivated; feeding spent catalysts from the at least partially deactivated catalysts to a regenerator for regeneration, thereby forming regenerated catalysts, and returning activated catalysts from the regenerated catalysts to the reactor via a regenerated catalyst line; characterized in that In the regenerated catalyst line, the amount of oxygen by volume in the gas phase component at the outlet of the regenerated catalyst line is controlled to be less than 0.1 percent, preferably less than 0.05 percent, and more preferably less than 0.01 percent.

Description

Method for converting methanol to olefins Technical background The present invention relates to a process for converting methanol to olefins. History Lower olefins mainly include ethylene and propylene, which are two basic chemical raw materials, and the demand for lower olefins is constantly increasing. Ethylene is used to produce various types of polyethylene, vinyl chloride, ethylene oxide, ethylbenzene and ethanol plastics. Propylene is used to produce various types of polypropylene, acrylonitrile and propylene oxide plastics. In addition to cracking petroleum products to prepare lower olefins, one of the preferred conversion processes is the process of oxygenates to olefins. When methanol is used as the primary oxygenate, the process is known as the MTO process. In an MTO reactor, under specific conversion conditions, methanol or a mixture of methanol and a diluent is contacted with an MTO catalyst to be converted to lower olefins. One of the preferred MTO catalysts is a silicoaluminophosphate molecular sieve (SAPO) catalyst, in particular SAPO-34, due to its high selectivity towards ethylene and propylene. US4499327 documents detailed studies on the application of a silicoaluminophosphate molecular sieve catalyst in a process for preparing olefins by methanol conversion and proposes SAPO-34 as the preferred catalyst for the MTO process. The SAPO-34 catalyst has high selectivity and activity for lower olefins and can ensure that the reaction time for the conversion of methanol to lower olefins is less than 10 seconds, even up to the reaction time limit of a riser. Document US6166282 discloses a technology and reactor for converting methanol to lower olefins using a fast fluidized bed reactor, in which after the gas phase reaction in the dense phase reaction zone with a lower gas velocity, the gas phase is rapidly raised to the separation zone. Having a significantly reduced inner diameter, a special gas-solid separation device is used to further separate the bubbled catalysts. Since the product gas and the catalyst are rapidly separated after the reaction, the occurrence of secondary reaction is effectively prevented. Through simulation calculations, it can be seen that compared with the traditional bubbled fluidized bed reactor, the inner diameter of the fast fluidized bed reactor and the required catalyst inventory are greatly reduced. The lower olefin carbon-based yield in the process is generally about 77%. Document CN101357874B discloses a method for producing lower olefins from methanol or dimethyl ether, comprising the following steps: a, providing a fast fluidized bed reactor; b. feeding a feedstock containing methanol or dimethyl ether to the fast bed reaction zone of the reactor to contact the catalysts and convert the feedstock into a product stream containing ethylene and propylene under effective conditions; c. after separating the product stream, feeding most of the catalysts to a second dense phase stripping zone; d, contacting the catalysts entering the second dense phase stripping zone with a stripping medium to remove the bubbled product stream; and e. dividing the separated, hot catalysts into at least two portions, where at least the first portion is returned to the bottom of the fast bed reaction zone and at least the second portion is fed to a regenerator. Document CN1723262A discloses a multi-stage riser reactor equipped with a central catalyst ring for the process of converting oxides to lower olefins, which includes a plurality of riser reactors, a gas-solid separation zone, a plurality of displacement elements and the like, wherein each riser reactor has a port for injecting catalyst and separates the catalyst separation zone from the product gas. The yield of lower olefins, calculated as carbon, in this process is typically 75 to 80%. However, with the increasing demand for ethylene and propylene in the market, higher requirements have been raised for lower olefin production technology. Summary of the invention The inventors of the present invention found that in the reaction-regeneration process during the conversion of methanol to lower olefins, due to the different environments in the reaction process and the regeneration process, the existence of catalyst circulation and the porous nature of the solid catalyst, the transition from one environment to another is inevitable, thereby affecting the reaction process or the regeneration process. For example, an excessive amount of oxygen introduced into the reactor can cause an increase in the by-products of alkyne, dialkene, oxygenate and the like, and the excessive production of these impurities can seriously affect the separation process. An excessive amount of steam introduced into a high-temperature regenerator (the regeneration temperature is usually greater than 650 ° C) can lead to a sharp increase in the steam volume in the pore channel of the catalyst due to the excessive temperature difference, so that the catalyst is broken and the fine powder content increases, and the catalyst loss increases.The inventors of the invention have found through extensive research that the problems can be solved by arranging a catalyst flow rate control device on the spent catalyst line and the regenerated catalyst line connecting the reactor and the regenerator, and logically arranging a stripping or degassing device, a purification or loosening medium upstream of the inlet of the catalyst flow rate control device, enhancing the stripping and degassing effects, and precisely controlling the amount of oxygen entering the reactor and the amount of steam entering the regenerator. The present invention has been completed based on these discoveries. In general, for example, the invention provides a process for converting methanol to olefins, the process comprising: regenerating at least partially deactivated catalysts produced in the conversion process in a regenerator, and returning the regenerated catalysts thus formed to said reactor via a regenerated catalyst line; wherein a second catalyst flow rate control device is arranged on the regenerated catalyst line, and the second catalyst flow rate control device controls the oxygen volume content in the gas phase component at the outlet of the regenerated catalyst line to be less than 0.1 percent. Preferably, in the above process, the at least partially deactivated catalysts are fed to the regenerator for regeneration via a spent catalyst line, and the spent catalyst line is equipped with a first catalyst flow rate control device that controls the vapor volume content in the gas phase component at the outlet of the first catalyst flow rate control device to be less than 0.1%. Preferably, however, in the above process, a stripping branch line from the stripping medium is arranged on a line between the inlet of the spent catalyst line and the first catalyst flow rate control device; and a degassing branch line from the degassing medium is arranged on a line between the inlet of the regenerated catalyst line and the second catalyst flow rate control device. For the purposes of the present invention, "at least partially deactivated catalyst" includes catalysts that have been completely deactivated and is therefore used in place of the term "deactivated catalyst" in the present invention. In particular, the present invention provides examples such as the following: 1. A process for converting methanol to olefins, comprising: feeding a methanol feedstock to a fluidized bed reactor for contacting catalysts to produce an olefin product, wherein the process at least partially deactivates the catalysts to form at least deactivated catalysts; feeding spent catalysts from the at least partially deactivated catalysts to a regenerator for regeneration, thereby forming regenerated catalysts, and returning activated catalysts from the regenerated catalysts to the reactor via a regenerated catalyst line; characterized therein In the regenerated catalyst line, the oxygen content by volume in the gas phase component at the outlet of the regenerated catalyst line is controlled to be less than 0.1 percent, preferably less than 0.05 percent, and more preferably less than 0.01 percent. 2. The process of Example 1, wherein the spent catalysts are regenerated by feeding the spent catalysts through a spent catalyst line to a regenerator, wherein in the spent catalyst line, the amount of vapor by volume in the gas phase component at the outlet of the spent catalyst line is controlled to be less than 0.1 percent, preferably less than 0.05 percent, and more preferably less than 0.01 percent. 3. The process according to Example 2, wherein additional stripping is performed on the line between the inlet of the spent catalyst line and the first catalyst flow rate control device; and / or additional degassing is performed on the line between the inlet of the regenerated catalyst line and the second catalyst flow rate control device. 4. The process according to Example 3, it is determined that the average flow rate adjustments are made respectively on each of the stripping branch lines from the stripping medium and the degassing branch line from the degassing medium, preferably by means of a regulating valve or orifice plate. 5. The process according to each of the previous examples is determined as follows: Catalysts that have been at least partially deactivated are subjected to steam stripping by at least one stage of steam stripping media in a steam stripper apparatus to prepare spent catalysts; Spent catalysts are fed into the regenerator through the spent catalyst line for regeneration to provide regenerated catalysts; The regenerated catalysts are degassed in a degassing tank using at least one stage of degassing medium to provide activated catalyst; and the activated catalysts are returned to the reactor via a regenerated catalyst line; Where the stripping medium is steam and the degassing medium is steam or nitrogen. 6. The process according to Example 5, wherein the spent catalyst line is operated under the following conditions: temperature of 200 to 500°C, preferably 250 to 450°C; catalyst density of 50 to 500 kg / m3, preferably 150 to 400 kg / m3; and volumetric ratio of steam to spent catalysts of 0.001 to 0.5, preferably 0.01 to 0.1; and The regenerated catalyst line operates under the following conditions: a temperature of 300 to 700°C, preferably 400 to 650°C; a catalyst density of 50 to 500 kg / m3, preferably 150 to 400 kg / m3; a volume ratio of degassing medium to regenerated catalysts of 0.001 to 0.5, preferably 0.01 to 0.1. 7. Process according to Example 1, it is determined that the active component of the catalyst is a silicoaluminophosphate molecular sieve comprising SAPO-34. 8. An apparatus for carrying out the process of converting methanol to olefins according to any of the preceding examples, comprising: a fluidized bed reactor, for receiving methanol feedstock and contacting it with catalysts to produce an olefin product, wherein the process at least partially deactivates the catalysts to produce a minimum of deactivated catalysts; A regenerator, for regenerating spent catalysts from the fluidized bed reactor to provide regenerated catalysts; a regenerated catalyst line, for returning activated catalysts to the reactor therethrough; and A second catalyst flow rate control device located on the regenerated catalyst line, configured to control the oxygen content by volume in the gas phase component at the outlet of the regenerated catalyst line to less than 0.1 percent, preferably less than 0.05 percent, more preferably less than 0.01 percent. 9. The apparatus according to embodiment 8, further comprising a spent catalyst line for feeding deactivated catalysts to a regenerator for regeneration, wherein the spent catalyst line is provided with a first catalyst flow rate control device configured to control the vapor content by volume of the gas phase component at the outlet of the spent catalyst line to be less than 0.1 percent, preferably less than 0.05 percent, more preferably less than 0.01 percent. 10. The apparatus according to Example 9, characterized in that a stripping branch line from the stripping medium is arranged on a line between the inlet of the spent catalyst line and the first catalyst flow rate control device, for performing additional stripping; and a degassing branch line from the degassing medium is arranged on a line between the inlet of the regenerated catalyst line and the second catalyst flow rate control device for performing additional degassing. 11. Apparatus according to example 9, further comprising: a stripper for performing at least one stripping step by a stripping medium on the at least partially deactivated catalyst to provide spent catalysts; a degassing tank, for degassing the regenerated catalysts in the degassing tank by at least one stage of degassing medium, to provide active catalyst; It is noted that the stripper inlet is connected to the reactor separation zone and the stripper outlet is connected to the spent catalyst line inlet; the degassing tank inlet is connected to the dilute phase section of the regenerator and the degassing tank outlet is connected to the regenerated catalyst line inlet. In one exemplary embodiment of the invention, the stripper is arranged inside the reactor. In another exemplary embodiment of the invention, the stripper is arranged outside the reactor. In one exemplary embodiment of the invention, the degassing tank is arranged inside the regenerator device. In another exemplary embodiment of the invention, the degassing tank is arranged outside the regenerator. In a preferred embodiment of the invention, at least one baffle layer is provided in the stripper device and at least one baffle layer is provided in the degassing tank, where the degassing medium is fed to the degassing tank in portions. 12. The apparatus according to Example 11, characterized in that the top of the stripper is equipped with a gas phase outlet connected to the reactor separation zone, and the top of the degassing tank is equipped with a gas phase outlet connected to the reactor of the dilute phase part of the regenerator or the flue gas line of the regenerator outlet. 13. The apparatus according to Example 9 is characterized in that the first catalyst flow rate control device and the second catalyst flow rate control device are each independently a pneumatic or hydraulic one-way slide valve. 14. The apparatus according to Example 8 is determined to be a fluidized bed reactor in the dense phase form, turbulent form or fast fluid form. Technical effects Due to the inventive process, the product has fewer impurities. Due to the inventive process, catalyst losses are low. Description of maps Figure 1 is a schematic flow diagram of the process according to the present invention. In Figure 1, 1 The donor is a reactor raw material; 2 represents a reactor reaction zone; 3. The diffuser is a rapid gas-solid separation zone; 4 represents a stripper; 5 represents an inclined tube with external circulation of the reactor; 6 represents the distributor of raw materials; 7 indicates the regeneration area of ​​the regenerator; 8 represents the gas-solid cyclone separator of the reactor; 9 represents a reactor isolation zone; 10 represents a gas collection chamber; 11 represents a product gas outlet line; 12 represents a dilute phase portion of the regenerator; 13 represents an input line of the reconstruction environment; 14 indicates a spent catalyst line (or a spent slant line); 15 represents an external heat remover from the regenerator; 16 represents the gas-solid cyclone separator of the regenerator; 17 shows a reconstructed flue gas outlet line; 18 represents an external reactor heat remover; 19 represents a regenerated catalyst line (or a regenerated inclined pipe); 20 indicates a line for steam entry into the reactor; 21 represents a regenerator; 22 represents a reactor; 23 indicates the oil inlet line is burning; 24 indicates the charge / discharge line of the lower catalyst of the regenerator; 25 represents an auxiliary heating furnace; 26 represents a second catalyst flow rate control device (regeneration slant line slide valve); 27 represents the first catalyst flow rate control device (consumed oblique line slide valve); 28 represents a degassing tank; 29 indicates a branch line from the stripping environment; and 30 represents a degassing branch line from the degassing medium. Examples of inventions The present invention will be illustrated in more detail below, while it should be understood that the scope of the invention is not limited by the examples, but rather defined by the appended claims. All publications, patent applications, patents and other references cited in this specification are hereby incorporated by reference in their entirety. All technical and scientific terms used herein, unless specifically defined, have the same meaning as commonly understood by one skilled in the art to which this invention pertains. In the event of conflict, the present specification, including the definitions, shall control. When the present description refers to a material, object, method, step, means, or component, etc., with the words "known to those skilled in the art," "prior art," or the like, the term "derived" is intended to be used. The terms are commonly used in the context of the present disclosure, but also cover matters not currently known, while known in the art to be useful for similar purposes. In the context of this description, methods for preparing SAPO molecular sieves or SAPO molecular sieve catalysts are well known in the art. In the context of the present description, the term "at least partially deactivated catalyst" or "deactivated catalyst" is used to refer to catalysts whose activity is at least partially reduced after passing through a reaction zone. In the context of this description, the term "spent catalyst" is used to refer to catalyst that is delivered from the reactor (e.g., via a spent catalyst line) to the regenerator for regeneration. In the context of the present description, the term "regenerated catalyst" is used to refer to catalyst obtained after regeneration (e.g., by burning coke) in the regenerator zone. In the context of this description, the term "active catalyst" is used to refer to a catalyst that is sent (e.g., via a regenerated catalyst line) to the reactor for reaction after regeneration and optional further purification (e.g., completion of regeneration) in the regenerator. All percentages, parts, ratios, etc., involved in this description are expressed by weight and pressures are gauge pressures, unless expressly stated otherwise. They may be combined to form a sample, and the resulting sample is part of the main disclosure of this description and is within the scope of the invention. An exemplary embodiment A of the present invention is shown in Figure 1. Referring to Figure 1, a stream comprising a methanol feedstock is introduced via a feed line 1, and optionally via a feedstock distributor 6, into reaction zone 2 of reactor 22 and contacted with molecular sieve catalysts to react to produce a product comprising lower olefins, wherein the catalysts are at least partially deactivated. The at least partially deactivated catalysts are fed through the fast gas-solid separation zone 3 to the separation zone 9 of the reactor, where most of the at least partially deactivated catalysts separated by the fast solid-gas separation device 3 are fed to a stripper device 4, and the gas phase product separated by the fast gas-solid separation device 3 and a portion of the at least partially deactivated catalysts not separated by the fast gas-solid separation device are fed to the cyclone separator 8 for further separation. The at least partially deactivated catalysts separated by the cyclone 8 are also returned to the stripper 4 through the dipleg of the cyclone 8.The gas phase product separated by the rapid gas-solid separation device 3 and the gas phase product separated by the cyclone separator 8 are fed to the next separation working section through a gas collection chamber 10 and an outlet line 11. The at least partially deactivated catalysts separated by the rapid gas-solid separation zone 3 and by the cyclone separator 8 are separated to provide spent catalysts, which are divided into two parts, where one part is returned to the bottom of the reaction zone 2 via the inclined external circulation catalyst line 5; and another part is fed to the regenerator 21 via the spent catalyst line 14. The spent catalyst line 14 is equipped with a first catalyst flow rate control device 27 configured to control the vapor content by volume of the gas phase component at the outlet of the spent catalyst in the catalyst line to be less than 0.1 percent, preferably less than 0.05 percent, more preferably less than 0.01 percent. The spent catalysts are regenerated in the regeneration zone 7 of the regenerator 21, where the regeneration medium used may be those commonly used in the art, such as air, oxygen, etc. The regeneration is preferably carried out by burning coke to provide regenerated catalysts. The flue gas produced by the coke burning is passed through a cyclone separator 16 and then fed to a subsequent energy recovery system via a flue gas outlet line 17. The regenerated catalysts are fed to a degassing tank 28 connected to the dilute phase section 12 in the upper part of the regenerator 21 and in the degassing tank 28 are degassed by at least one stage of degassing medium to provide activated catalyst. The activated catalysts are returned to the reaction zone 2 of the reactor via a regenerated catalyst line 19. The regenerated catalyst line 19 is equipped with a second catalyst flow rate control device 26 configured to control the oxygen content by volume of the gas phase component at the outlet of the regenerated catalyst line to less than 0.1 percent, preferably less than 0.05 percent, preferably less than 0.01 percent. In the above example A, preferably the line 20 for introducing steam into the reactor is equipped with an auxiliary heating furnace 25, which line 20 is combined with the feed line 1 and then introduced into the reactor 22. According to the invention, for example, one of the functions of the steam fed through the steam line 20 is that it serves for start-up heating; accordingly, the auxiliary furnace 25 helps to reach the reaction start temperature during charging. In the above example A, preferably, the external catalyst circulation inclined line 5 of the reactor 22 is equipped with an external reactor heat remover 5 to remove the heat generated by the reaction in the reactor to achieve the purpose of controlling the required reaction temperature of the reaction zone. In the above example A, preferably, the lower part of the regenerator 21 is equipped with a catalyst charge / discharge line 24, for introducing catalyst into the regenerator during start-up or normal operation or for discharging catalyst from the regenerator during shutdown. In the above example A, preferably, regeneration medium is added to the regenerator 21 through regeneration medium inlet line 13; and a burning oil is added to the regenerator 21 through burning oil inlet line 23. In the above example A, preferably, the regenerator 21 is equipped with an external regenerator heat remover 15 for removing the heat generated by the reaction in the regenerator 21, to achieve the purpose of controlling the required regeneration temperature of the regenerator. In one embodiment of the present invention, optionally, a group of steam stripping branch lines are provided at intervals on the line between the inlet of the spent catalyst line and the catalyst flow rate control device, and each group of steam stripping branch lines is arranged radially around the line. In one embodiment of the invention, optionally, a group of degassing branch lines from the degassing medium are provided at intervals on the line between the inlet of the regenerated catalyst line and the catalyst flow rate control device, and each group of degassing branch lines of the degassing medium are arranged radially around the line. In one embodiment of the invention, optionally, both the steam stripping branch line and the degassing medium branch line are equipped with orifice plates. The dimensions of the orifice plates are selected according to the design. The average flow of each branch is fixed without manual adjustment. Each branch line is equipped with a switch valve. In one embodiment of the invention, the stripping branch line of the stripping medium and the degassing branch line of the degassing medium optionally have not only a loosening function, but also an additional stripping or degassing function. The present invention is illustrated below by examples which do not indicate a limitation on the scope of the present invention. Example 1 Referring to Figure 1, Exemplary Example A of the present invention was used. The active catalyst component was a silicoaluminophosphate molecular sieve containing SAPO-34 and the fluidized bed reactor was of the fast fluidization type. The catalyst flow rate control device was a pneumatic one-way slide valve. The at least partially deactivated catalysts in the reactor were separated by a single-stage stripping medium. The spent catalysts for regeneration were fed to the regenerator via the spent catalyst line. The regenerated catalysts were degassed via a degassing medium. The regenerated activated catalysts were returned to the reactor via the regenerated catalyst line. The stripping medium was steam and the degassing medium was steam. The steam stripping process was carried out in a steam stripper apparatus, in which the inlet of the steam stripper was connected to the reactor and the outlet of the steam stripper was connected to the inlet of the spent catalyst line. The degassing process was carried out in a degassing tank located inside the regenerator. The inlet of the degassing tank was connected to the regenerator and the outlet of the degassing tank was connected to the inlet of the regenerated catalyst line.A steam stripping branch line was set on the line between the inlet of the spent catalyst line and the catalyst flow rate control device, and the steam stripping branch line was placed radially around the line. A degassing branch line from the degassing medium was set on the line between the inlet of the regenerated catalyst line and the catalyst flow rate control device, and the degassing medium degassing branch line was placed radially around the line. Both the steam stripping branch line and the degassing medium degassing branch line were equipped with orifice plates, and each branch line was equipped with a switch valve. The stripper was equipped with 5 baffle layers arranged in a staggered manner. The degassing tank was equipped with 2 baffle layers, and the degassing medium entered the degassing tank in two parts. The top of the device was connected to a gas phase outlet connected to the main body of the reactor, and the top of the degassing tank was equipped with a gas phase outlet connected to the dilute phase section of the regenerator. The spent catalyst line was operated under the following conditions: a temperature of 200°C, a catalyst density of 50 kg / m3, and a steam to spent catalyst volume ratio of 0.5. The regenerated catalyst line was operated under the following conditions: a temperature of 300°C, a catalyst density of 50 kg / m3, and a degassing medium to regenerated catalyst volume ratio of 0.5. The steam content by volume in the gas phase component at the outlet of the catalyst flow rate control device in the spent catalyst line was 0.05 percent, and the oxygen content by volume in the gas phase component at the outlet of the catalyst flow rate control device in the regenerated catalyst line was 0.005 percent. By analysis, the product gas at the reactor outlet contained, in weight fractions, less than 100ppm of oxygenates (sum of aldehydes, ketones, and acids) and less than 1ppm of acetylene, and catalyst loss was reduced by 4% over 3 months. Example 2 The conditions and procedures described in Example 1 were essentially followed, except as specifically indicated below. The fluidized bed reactor was in the condensed phase fluid mode. The catalyst flow rate control device was a hydraulic one-way slide valve. At least partially deactivated catalysts in the reactor were separated by two-stage stripping media. The degassing medium was nitrogen gas. The stripper was equipped with 2 baffle layers arranged in a staggered manner. The degassing tank was equipped with 4 baffle layers and the degassing medium was fed to the degassing tank in two parts. The top of the degassing tank was equipped with a gas phase outlet connected to the regenerator outlet flue gas line. The spent catalyst line was operated under the following conditions: a temperature of 490°C, a catalyst density of 480 kg / m3, and a steam to spent catalyst volume ratio of 0.002. The regenerated catalyst line was operated under the following conditions: a temperature of 680°C, a catalyst density of 460 kg / m3, and a degassing medium to regenerated catalyst volume ratio of 0.003. The volumetric steam content in the gas phase component at the outlet of the catalyst flow rate control device in the spent catalyst line was 0.03 percent, and the oxygen content by volume in the gas phase component at the outlet of the catalyst flow rate control device in the regenerated catalyst line was 0.008 percent. By analysis, the product gas at the reactor outlet contained, in weight fractions, less than 50 ppm oxygenates and less than 1 ppm acetylene, and catalyst loss was reduced by 6% over 3 months. Example 3 The conditions and methods described in Example 1 were followed. The spent catalyst line was operated under the following conditions: a temperature of 400°C, a catalyst density of 380 kg / m3, and a steam to spent catalyst volume ratio of 0.01. The regenerated catalyst line was operated under the following conditions: a temperature of 630°C, a catalyst density of 380 kg / m3, and a degassing medium to regenerated catalyst volume ratio of 0.01. The volumetric steam content in the gas phase component at the outlet of the catalyst flow rate control device in the spent catalyst line was 0.01 percent and the oxygen content by volume in the gas phase component at the outlet of the catalyst flow rate control device in the regenerated catalyst line was 0.01 percent. By analysis, the product gas at the reactor outlet contained, in weight fractions, less than 150ppm of oxygenates and less than 1ppm of acetylene, and catalyst loss was reduced by 10% within 3 months. Example 4 The conditions and methods described in Example 1 were followed. The spent catalyst line was operated under the following conditions: a temperature of 480°C, a catalyst density of 450 kg / m3, and a steam to spent catalyst volume ratio of 0.005. The regenerated catalyst line was operated under the following conditions: a temperature of 670°C, a catalyst density of 380 kg / m3, and a degassing medium to regenerated catalyst volume ratio of 0.005. The volumetric steam content in the gas phase component at the outlet of the catalyst flow rate control device in the spent catalyst line was 0.001 percent and the oxygen content by volume in the gas phase component at the outlet of the catalyst flow rate control device in the regenerated catalyst line was 0.0004 percent. By analysis, the product gas at the reactor outlet contained, in weight fractions, less than 40 ppm of oxygenates and less than 1 ppm of acetylene, and catalyst loss was reduced by 15% within 3 months. Comparative Example 1 The procedures described in Example 1 were followed. The vapor content by volume in the gas phase component at the outlet of the catalyst flow rate control device in the spent catalyst line was 0.21 percent and the oxygen content by volume in the gas phase component at the outlet of the catalyst flow rate control device in the regenerated catalyst line was 0.18 percent. The product gas at the reactor outlet contains weight fractions of 308 ppm oxygenates and 3 ppm acetylene. It is obvious that the process according to the present invention can achieve the objective of improving the performance of lower olefins and can therefore be used for the industrial production of lower olefins.

Claims

CLAIMS 1. A process of converting methanol to olefins, comprising: feeding a feedstock comprising methanol to a fluidized bed reactor to contact with catalysts to produce an olefin product, wherein the process at least partially deactivates the catalysts to form at least partially deactivated catalysts; feeding spent catalyst s from the at least partially deactivated catalyst s to a regenerator for regeneration , thereby forming regenerated catalysts , and returning the activated catalyst s from the regenerated catalysts to the reactor via a regenerated catalyst line; characterized in that o n the regenerated catalyst line, the oxygen content by volume in the gas phase component at the outlet of the regenerated catalyst line is controlled to be less than 0.1%, preferably less than 0.05%, and more preferably less than 0.01%.

2. The process according to claim 1, wherein the spent catalysts are regenerated by feeding the spent catalysts through a spent catalyst line to a regenerator, where in on the spent catalyst line, the steam content by volume in the gas phase component at the outlet of the spent catalyst line is controlled to be less than 0.1%, preferably less than 0.05%, and more preferably less than 0.01%.

3. The process according to claim 2, characterized in that additional stripping is performed on the line between the inlet of the spent catalyst line and the first catalyst flow rate control device; and / or additional degassing is performed on the line between the regenerated catalyst line inlet to the second catalyst flow rate control device.

4. The process according to claim 3, characterized in that regulations of the medium flow rates are respectively carried out on each of the stripping branch line of the stripping medium and the degassing branch line of the degassing medium, preferably by means of a regulating valve or orifice plate.

5. The process according to any one of the preceding claims, characterized in that t he at least partially deactivated catalysts are subjected to steam stripping by at least one stage of steam stripping medium in a steam stripper , to provide the spent catalysts; the spent catalysts are fed into the regenerator through t he spent catalyst line for regeneration to provide the regenerated catalysts; the regenerated catalysts are degassed in a degassing tank by using at least one stage of degassing medium, to provide the activated catalyst; and the activated catalysts are returned to the reactor through the regenerated catalyst line; w herein the stripping medium is steam and the degassing medium is steam or nitrogen.

6. The process according to claim 5, characterized in that the spent catalyst line is operated under conditions of: a temperature of 200-500 ℃ , preferably 250-450 ℃ ; a density of the catalyst of 50-500 kg / m3 , preferably 150-400 kg / m3 ; and a volume ratio of the steam to the spent catalysts of 0.001-0.5, preferably 0.01-0.1; and the regenerated catalyst line is operated under conditions of: a temperature of 300-700 ℃ , preferably 400-650 ℃ ; a density of the catalyst of 50-500 kg / m3 , preferably 150-400 kg / m3 ; a volume ratio of the degassing medium to the regenerated catalysts of 0.001 to 0.5, preferably 0.01 to 0.1.7 . A device for carrying out the process of converting methanol to olefins according to any one of the preceding claims, comprising: a fluidized bed reactor , for receiving a methanol feedstock and contacting it with catalysts to produce an olefin product, wherein the process at least partially deactivates the catalyst s to produce at least partially deactivated catalysts; a regenerator , for regenerating the spent catalysts from the fluidized bed reactor to provide regenerated catalysts; a regenerated catalyst line , for returning the activated catalysts to the reactor therethrough; and a second catalyst flow rate control device disposed o n the regenerated catalyst line , which is configured to control the oxygen content by volume in the gas phase component at the outlet of the regenerated catalyst line to be less than 0.1%, preferably less than 0.05%, more preferably less than 0.01%.8 . The device according to claim 7 , further comprising a spent catalyst line for feeding the deactivated catalysts into the regenerator for regeneration, wherein the spent catalyst line is provided with a first catalyst flow rate control device , which is configured to control the steam content by volume of the gas phase component at the outlet of the spent catalyst line to be less than 0.1%, preferably less than 0.05%, more preferably less than 0.01%.

9. The device according to claim 8, characterized in that a stripping branch line of the stripping medium is arranged on a line between the inlet of the spent catalyst line and the first catalyst flow rate control device, for performing additional stripping; and a degassing branch line of the degassing medium is arranged on a line between the inlet of the regenerated catalyst line and the second catalyst flow rate control device, for carrying out additional degassing. 1 0 . The device according to claim 8 , further comprising: a stripper , for carrying out at least one stage of stripping by a medium stripping on the at least partially deactivated catalyst , to provide the spent catalysts; a degassing tank , for degassing the regenerated catalysts in the degassing tank by at least one stage of degassing medium , to provide the activated catalyst; characterized in that the inlet of the stripper is connected with the separation zone of the reactor, and the outlet of the stripper is connected with the inlet of the spent catalyst line; the inlet of the degassing tank is connected with the dilute phase section of the regenerator, and the outlet of the degassing tank is connected with the inlet of the regenerated catalyst line.

11. The device according to claim 10, characterized in that the top of the stripper is equipped with a gas phase outlet connected to the separation zone of the reactor, and the top of the degassing tank is equipped with a gas phase outlet connected to the dilute phase section of the regenerator or a flue gas line of the regenerator outlet.

12. The device according to claim 8, characterized in that the first catalyst flow rate control device and the second catalyst flow rate control device are each independently a pneumatic or hydraulic one-way slide valve.

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