Method and system for purifying high-hydrocarbon-containing crude methanol raw material and method and device for preparing low-carbon olefin through methanol conversion

Abstract

The invention provides a method and a system for purifying a high-carbon hydrocarbon-containing crude methanol raw material and a method and a device for preparing low-carbon olefin by methanol conversion, the method comprises the following steps: (1) feeding the high-carbon hydrocarbon-containing crude methanol raw material into an adsorption-desorption unit for adsorption, and feeding the high-carbon hydrocarbon-removed raw material into a raw material buffer tank and / or a flash tank; (2) in the adsorption-desorption unit, switching to a desorption process after the adsorption process is finished, and switching the raw materials to a desorption medium for desorption; (3) after desorption, a desorption medium containing high-carbon hydrocarbon enters a separation tank, the high-carbon hydrocarbon is collected at the bottom of the separation tank, and the desorption medium enters a desorption medium buffer tank and is compressed and returned as the desorption medium; and (4) after the desorption is finished, switching the desorption medium back to the high-carbon hydrocarbon-containing crude methanol raw material, and carrying out adsorption in the step (1) again. By adopting the method disclosed by the invention, the content of the high-carbon hydrocarbon in the methanol raw material can be reduced to be below 10ppm, and carbon accumulation caused by the fact that heavy carbon generated in the catalytic cracking process of the high-carbon hydrocarbon is attached to the MTO catalyst is avoided.

Description

Technical Field

[0001] The present invention relates to a method and system for purifying a raw methanol feedstock containing high-carbon hydrocarbons, and a method and apparatus for converting methanol into light olefins. Background Art

[0002] With the maturity of the MTO process technology, the raw material of MTO has gradually been replaced from refined methanol in the initial stage to raw methanol. Especially after the large-scale MTO unit, industrially, the coal gasification unit, methanol synthesis unit, MTO unit, and polyolefin unit are integrated into a production line, and the crude product of the methanol synthesis unit directly goes to the MTO unit as a raw material. Due to the decline in the activity of the catalyst in the methanol synthesis unit and the inevitable influence of iron elements in pipeline equipment on the catalyst, long-chain saturated alkane substances and paraffin are found in the raw methanol. These long-chain saturated alkanes and paraffin are directly brought into the MTO unit with the raw methanol, which will have an adverse impact on the methanol raw material gasification system, MTO reaction system, and water system. Especially, paraffin scales on the trays, heat exchangers, and inner walls of air coolers in the water system, causing blockage and affecting the long-term stable operation of the unit. In severe cases, it is necessary to stop the production to remove the wax.

[0003] In the existing industrial synthesis of raw methanol, methanol dewaxing technology is often used to remove the paraffin in the synthesis unit and relieve the influence of paraffin substances on the methanol synthesis unit. Common technical solutions include: (1) Stopping the production to boil the wax. Using this method, the production is restricted, the treatment process takes at least more than 6 hours, and the wax removal is not thorough. (2) Online wax boiling. Using the synthesis gas of the system to heat the paraffin and the corresponding pipelines, the wax removal effect is good, but the paraffin will be brought into the separator, making the methanol separation effect worse, and there is wax deposition in the separator. (3) Methanol dewaxer.

[0004] CN109351211 discloses a methanol dewaxing membrane separator and a method for methanol dewaxing using the polar selective permeable membrane prepared from polyacrylic acid and 1,3-propanediol. The polar small molecules such as methanol can be selectively permeated to achieve the purpose of separating methanol and paraffin. Although the separation selectivity is high, the treatment capacity is limited and it is difficult to meet the requirements of industrial production.

[0005] Analyzing the MTO raw methanol feedstock of industrial plants, its long-chain saturated alkanes and paraffin are mainly high-carbon hydrocarbons with carbon numbers from C9 to C40. The total content of these high-carbon hydrocarbons in the raw methanol is about 200 ppm, indicating that it is difficult to completely remove the high-carbon hydrocarbons in the raw methanol by using the existing dewaxing technology solutions in the methanol synthesis unit. In order to prevent these high-carbon hydrocarbons from affecting the normal operation of the MTO unit and relieve the fouling problem on the equipment, it is necessary to further remove the high-carbon hydrocarbons in the raw methanol. Summary of the Invention

[0006] The technical problem to be solved by the present invention is the problems existing in the existing MTO technology, such as the relatively high content of high-carbon hydrocarbons in the methanol raw material and the adverse effects of high-carbon hydrocarbons on the MTO reaction and the water system. A method for purifying the raw material for methanol conversion to light olefins is provided. This method is used in the production of light olefins and can effectively remove high-carbon hydrocarbons in the methanol raw material and recover them, and greatly reduce the adverse effects of high-carbon hydrocarbons on the MTO reaction and the water system, etc.

[0007] According to the first aspect of the present invention, the present invention provides a method for purifying a crude methanol raw material containing high-carbon hydrocarbons, and the method includes:

[0008] (1) Feeding the crude methanol raw material containing high-carbon hydrocarbons into an adsorption-desorption unit for adsorption, wherein the raw material from which high-carbon hydrocarbons are adsorbed and removed goes to a raw material buffer tank and / or a flash tank;

[0009] (2) In the adsorption-desorption unit, when the adsorption process is completed, it is switched to the desorption process, and the raw material is switched to a desorption medium for desorption;

[0010] (3) After desorption, the desorption medium containing high-carbon hydrocarbons goes to a separation tank, the high-carbon hydrocarbons are collected at the bottom of the separation tank, and the desorption medium goes to a desorption medium buffer tank and is compressed and returned as the desorption medium;

[0011] (4) After the desorption is completed, the desorption medium is switched back to the crude methanol raw material containing high-carbon hydrocarbons, and the adsorption described in step (1) is carried out again.

[0012] According to the second aspect of the present invention, the present invention provides a method for methanol conversion to light olefins, and the method includes:

[0013] (1) Synthesizing methanol by using CO and H 2 to obtain a crude methanol raw material containing high-carbon hydrocarbons;

[0014] (2) Purifying the crude methanol raw material containing high-carbon hydrocarbons according to the method described in the present invention;

[0015] (3) Using the purified methanol as a raw material for conversion to light olefins.

[0016] According to the third aspect of the present invention, the present invention provides a purification system for a crude methanol raw material containing high-carbon hydrocarbons, and the system includes:

[0017] An adsorption-desorption unit, including at least 2 parallel towers, used for switching back and forth between the adsorption process and the desorption process. The crude methanol raw material containing high-carbon hydrocarbons enters the adsorption-desorption unit for adsorption. When the adsorption process is completed, it is switched to the desorption process, and the raw material is switched to a desorption medium for desorption;

[0018] A separation unit, including at least one separation tank, used for separating the desorption medium containing high-carbon hydrocarbons from the desorption process;

[0019] The pressurizing unit is used for pressurizing and transporting the desorption medium;

[0020] The desorption medium buffer tank is used for providing the desorption medium raw material or storing the desorption medium from the separation unit;

[0021] The raw material buffer tank and / or the flash tank. The raw material buffer tank is used for providing the crude methanol raw material containing high-carbon hydrocarbons or storing the purified methanol raw material from the adsorption-desorption unit. The flash tank is used for providing the crude methanol raw material containing high-carbon hydrocarbons or heating and gasifying the purified methanol for the MTO reaction.

[0022] According to the fourth aspect of the present invention, the present invention provides a device for methanol conversion to light olefins, which includes: a CO and H 2 synthesis methanol system connected in series along the material flow direction; the crude methanol raw material purification system described in the present invention, and the system for methanol conversion to light olefins.

[0023] By using the method of the present invention, the content of high-carbon hydrocarbons in the methanol raw material can be reduced to less than 10 ppm, avoiding the carbon accumulation caused by the attachment of heavy carbon produced during the catalytic cracking of high-carbon hydrocarbons on the MTO catalyst, effectively alleviating the adverse effects of high-carbon hydrocarbons on the performance of the MTO catalyst, and avoiding the decrease in the selectivity of light olefins in the MTO reaction. At the same time, it also effectively alleviates the fouling problem of high-carbon hydrocarbons on the trays, heat exchangers, and inner walls of air coolers in the water system, and avoids the instability of the device caused by the blockage of high-carbon hydrocarbons. In addition, even if the upstream methanol synthesis unit has an increase in high-carbon hydrocarbons due to a decrease in catalyst activity or other adverse factors, or the content of high-carbon hydrocarbons in the crude methanol sent to the MTO unit increases due to the poor effect of the methanol dewaxing technology, the technical solution of the present invention can effectively remove the high-carbon hydrocarbons in the crude methanol in a timely manner, and will not affect the stable operation of the downstream MTO unit due to the unstable operation of the upstream methanol synthesis unit. Description of the Drawings

[0024] Figure 1 is a schematic process flow diagram of the method according to the present invention;

[0025] Figure 2 is the radial cross-sectional view and axial cross-sectional view of the pipe network section;

[0026] Figure 3 is the radial cross-sectional view and axial cross-sectional view of each layer of filter screen in the filtration section.

[0027] Description of the Reference Numerals

[0028] 1 - from the raw material buffer tank, 2 - to the raw material buffer tank, 3 - to the flash tank, 4 - tower, 5 - separation tank, 6 - high-carbon hydrocarbon product, 7 - desorption medium buffer tank, 8 - booster pump, 9 - to the exhaust, 10 - desorption medium, 11 - heat exchanger. Detailed Embodiments

[0029] The endpoints and any values within the ranges disclosed in this document are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this document.

[0030] In the present invention, unless otherwise specified, the orientation terms such as "upper, lower, left, right" generally refer to the upper, lower, left, and right shown in the reference drawings; "inner, outer" refer to the inside and outside relative to the contour of each component itself.

[0031] In the present invention, unless otherwise specified, the orientation terms such as "upper, lower, top, bottom" generally refer to the directions shown in the drawings or the relative positional relationship of each component in the vertical, perpendicular, or gravitational directions.

[0032] The "vertical direction" refers to the up and down directions of the paper surface shown in the drawing, and the "horizontal direction" refers to the left and right directions of the generally horizontal paper surface shown in the drawing; "inner, outer" generally refer to the inside and outside of the chamber relative to the chamber or the radial inside and outside relative to the center of the circle.

[0033] The present invention provides a method for purifying a crude methanol raw material containing high-carbon hydrocarbons, and the method includes:

[0034] (1) Feeding the crude methanol raw material containing high-carbon hydrocarbons into an adsorption-desorption unit for adsorption. Among them, the raw material from which high-carbon hydrocarbons are adsorbed is sent to a raw material buffer tank and / or a flash tank;

[0035] (2) In the adsorption-desorption unit, when the adsorption process ends, it is switched to the desorption process, and the raw material is switched to a desorption medium for desorption;

[0036] (3) After desorption, the desorption medium containing high-carbon hydrocarbons goes to a separation tank, the high-carbon hydrocarbons are collected at the bottom of the separation tank, and the desorption medium goes to a desorption medium buffer tank and is returned as a desorption medium after compression;

[0037] (4) After the desorption ends, the desorption medium is switched back to the crude methanol raw material containing high-carbon hydrocarbons and the adsorption described in step (1) is carried out again.

[0038] The method of the present invention is suitable for purifying the compositions of various crude methanol raw materials containing high-carbon hydrocarbons, and is particularly suitable for MTO units using crude methanol as the feed. According to a preferred embodiment of the present invention, the composition of the crude methanol raw material containing high-carbon hydrocarbons includes: methanol, normal paraffins / isoparaffins with carbon numbers from C9 to C40.

[0039] According to a preferred embodiment of the present invention, in the crude methanol raw material containing high-carbon hydrocarbons, the content of normal paraffins / isoparaffins with carbon numbers from C9 to C40 is 10 - 300 ppm. In the prior art, the crude methanol raw material with such a content is directly subjected to the MTO reaction in the next process section. However, in the research of the present invention, it is found that high-carbon hydrocarbons have an adverse effect on the selectivity of low-carbon olefins in the MTO reaction. Especially, alkanes with higher carbon numbers undergo thermal cracking under the action of the catalyst, and at the same time, the generated coke deposits adhere to the surface of the catalyst and block the catalyst pores. The higher the content of high-carbon hydrocarbons, the easier it is to occur coke accumulation, resulting in a significant decrease in the selectivity of low-carbon olefins in the MTO reaction. By reducing the content of high-carbon hydrocarbons in the methanol raw material, the selectivity of low-carbon olefins in the MTO reaction can return to normal. Most existing large-scale MTO industrial plants use the crude methanol produced in the upstream methanol synthesis as the raw material, and the content of high-carbon hydrocarbons in these crude methanols is relatively high, which has an adverse effect on both the selectivity of low-carbon olefins in the MTO reaction and the stable operation of the subsequent separation system. If the content of high-carbon hydrocarbons in the crude methanol can be effectively reduced, the stable, safe, long-term, full-load, and high-quality operation of the MTO plant can be ensured. Therefore, for the first time, it is proposed to reduce the content of high-carbon hydrocarbons in the crude methanol raw material. The method of the present invention also has the advantages of simple process, high efficiency in removing high-carbon hydrocarbons, and recyclability of high-carbon hydrocarbons.

[0040] According to a preferred embodiment of the present invention, preferably, the crude methanol raw material containing high-carbon hydrocarbons is derived from the methanol synthesis unit, and more preferably from the crude methanol product tank in the process of synthesizing methanol from carbon monoxide and hydrogen. Thus, the method of the present invention can achieve efficient upstream and downstream connection in series with the methanol synthesis unit.

[0041] According to a preferred embodiment of the present invention, preferably, the raw material after adsorbing and removing high-carbon hydrocarbons goes to the raw material buffer tank as the purified methanol raw material for use as the methanol raw material in the methanol conversion to low-carbon olefins; the purpose of the raw material after adsorbing and removing high-carbon hydrocarbons going to the flash tank is for flash preheating and is used as the preheated methanol raw material in the methanol conversion to low-carbon olefins after preheating. Thus, it can effectively alleviate the adverse effects of high-carbon hydrocarbons on the regeneration system and water system of the MTO reaction.

[0042] The present invention has special requirements for the operating conditions of the adsorption process. The following is a demonstration but does not limit the scope of the present invention thereby. According to a preferred embodiment of the present invention, during the adsorption process, the temperature of the bed layer in the tower is 1 - 60 °C, and the working pressure is 0 - 2 MPa(G); preferably, during the adsorption process, the temperature of the bed layer in the tower is 10 - 30 °C, and the working pressure is 0.5 - 1.5 MPa(G).

[0043] In the present invention, the types of adsorbents have a relatively wide selection range, and common adsorbents can all be used in the present invention. The following is a demonstration, but it does not limit the scope of the present invention. The present invention proposes to use an adsorbent to adsorb high-carbon hydrocarbons in crude methanol. Such high-performance adsorbents are preferably non-polar adsorbents, and their adsorption performance for non-polar molecules such as high-carbon hydrocarbons is much higher than that for strongly polar molecules such as methanol. Therefore, methanol and high-carbon hydrocarbons can be effectively separated, and the content of high-carbon hydrocarbons in crude methanol can be reduced to less than 10 ppm. According to a preferred embodiment of the present invention, the adsorbent is at least one of activated carbon, graphite carbon black, and carbon molecular sieve, preferably graphite carbon black.

[0044] The present invention has special requirements for the operating conditions of the desorption process. The following is a demonstration, but it does not limit the scope of the present invention. According to a preferred embodiment of the present invention, during the desorption process, the temperature of the bed layer in the tower is 60-160°C, and the working pressure is -0.1-0.5 MPa (G); preferably, during the desorption process, the temperature of the bed layer in the tower is 80-120°C, and the working pressure is -0.08 MPa to 0.1 MPa (G).

[0045] In the present invention, the types of desorption media have a relatively wide selection range, and common desorption media can all be used in the present invention. The following is a demonstration, but it does not limit the scope of the present invention. The desorption medium is at least one of steam, nitrogen, air, and flue gas, preferably nitrogen.

[0046] Adopting the foregoing embodiment, using a vacuum negative pressure condition during desorption is beneficial to the desorption of high-carbon hydrocarbons from the adsorption medium, effectively reducing the desorption operation temperature, improving the desorption efficiency, prolonging the service life of the adsorbent, reducing energy waste, and saving operating costs. At the same time, the desorption medium is used to desorb and recycle the high-carbon hydrocarbons on the adsorbent.

[0047] Therefore, for the present invention, a vacuum pumping device is also included, and there are no special requirements for its installation method and model selection, as long as it can achieve vacuum pumping as needed.

[0048] According to a preferred embodiment of the present invention, along the flow direction of the desorption medium containing high-carbon hydrocarbons in the separation tank, a pipe network section and a filter screen section are provided from bottom to top. Liquid is concentrated at the bottom of the separation tank, and the desorption medium is discharged from the top of the separation tank; the pipe network section is used for preliminary gas-liquid separation; the filter screen section is used for in-depth gas-liquid separation.

[0049] In the present invention, through the above settings, the pipe network section and the filter screen section can be used to efficiently separate and recover high-carbon hydrocarbons in the desorption medium.

[0050] According to a preferred embodiment of the present invention, the temperatures of the pipe network section and the filter screen section are each not lower than 65°C, preferably 75-80°C. This can avoid the condensation and blockage of the pipe network and filter screen of the separation tank by high-carbon hydrocarbons.

[0051] According to a preferred embodiment of the present invention, the pipe network provided in the separation tank is honeycomb-shaped, and the aperture ratio of the pipe network is 30-80%. Thus, the best initial gas-liquid separation effect can be achieved. Figure 2 The radial cross-sectional view and the axial cross-sectional view of the pipe network section are shown.

[0052] According to a preferred embodiment of the present invention, the filter screen provided in the separation tank is corrugated, and the mesh number of the filter screen is 10-200 meshes; preferably, the number of layers of the filter screen is 2-10 layers. Thus, a better deep gas-liquid separation effect can be achieved. Figure 3 The radial cross-sectional view and the axial cross-sectional view of each layer of the filter screen in the filtering section are shown.

[0053] In the present invention, the pipe network and the filter screen are used in two stages in the separation tank to strengthen gas-liquid separation. Heat exchange medium inlets and outlets are arranged on the shell layer of the pipe network section to adjust and control the temperatures of the pipe network section and the filter screen section of the separation tank. When the large droplet entrained by the desorption medium passes through the pipe network designed to be a zigzag honeycomb shape, the collision probability between the large droplet and the pipe wall is increased, and the large droplet is effectively attached to the pipe wall and continuously aggregated, and then falls from the bottom of the pipe network into the bottom of the separation tank; the corrugated filter screen design can attach the small droplet entrained by the desorption medium to the filter screen, and the filter screen made of lipophilic material is more conducive to the aggregation of small droplet, and flows downward along the corrugation, and aggregates into large droplets at the lower edge of the filter screen corrugation and falls into the pipe network section, and then falls into the bottom of the separation tank through the pipe network.

[0054] According to a preferred embodiment of the present invention, the adsorption-desorption unit includes at least 2 towers in parallel, which are used to switch back and forth between the adsorption process and the desorption process.

[0055] The purification method of the present invention is the intermediate section connecting the methanol synthesis unit and the MTO process, and provides the technical effect of ensuring the quality of the raw material methanol for the effective series connection of the two.

[0056] Thus, the present invention provides a method for converting methanol to light olefins, which method includes:

[0057] (1) Using CO and H 2 to synthesize methanol to obtain a crude methanol raw material containing high-carbon hydrocarbons;

[0058] (2) Purifying the crude methanol raw material containing high-carbon hydrocarbons according to the method described in the present invention;

[0059] (3) Using the purified methanol as a raw material to convert to light olefins. Thus, using the purified methanol as a raw material to convert to light olefins can have the advantages of high MTO light olefin selectivity and stable operation of the MTO reaction regeneration system and the water system. The present invention has high selectivity for CO and H 2There are no special requirements for the method and steps of synthesizing methanol and converting the purified methanol as a raw material into light olefins, and they can be selected and implemented according to the processes of the existing technologies.

[0060] The present invention provides a purification system for a crude methanol raw material containing high-carbon hydrocarbons, and the system includes:

[0061] An adsorption-desorption unit, including at least 2 parallel towers, which are used for switching between the adsorption process and the desorption process. The crude methanol raw material containing high-carbon hydrocarbons enters the adsorption-desorption unit for adsorption. After the adsorption process ends, it is switched to the desorption process, and the raw material is switched to the desorption medium for desorption;

[0062] A separation unit, including at least one separation tank, which is used for separating the desorption medium containing high-carbon hydrocarbons from the desorption process;

[0063] A pressurization unit is used for pressurized transportation of the desorption medium;

[0064] A desorption medium buffer tank is used for providing desorption medium raw materials or storing the desorption medium from the separation unit;

[0065] A raw material buffer tank and / or a flash tank. The raw material buffer tank is used for providing the crude methanol raw material containing high-carbon hydrocarbons or storing the purified methanol raw material from the adsorption-desorption unit, and the flash tank is used for providing the crude methanol raw material containing high-carbon hydrocarbons or heating and gasifying the purified methanol for MTO reaction.

[0066] According to a preferred embodiment of the present invention, each tower of the adsorption-desorption unit includes a top purified methanol raw material discharge port, a bottom desorption medium discharge port containing high-carbon hydrocarbons, a lower crude methanol raw material inlet containing high-carbon hydrocarbons, and an upper desorption medium inlet.

[0067] According to a preferred embodiment of the present invention, preferably, a heat exchanger is provided between the pipelines for transporting the desorption medium to heat the desorption medium to the required process temperature.

[0068] According to a preferred embodiment of the present invention, preferably, inside the separation tank along the flow direction of the desorption medium containing high-carbon hydrocarbons, a pipe network section and a filter section are provided from bottom to top. Liquid is enriched at the bottom of the separation tank, and the desorption medium is discharged from the top of the separation tank.

[0069] According to a preferred embodiment of the present invention, the pipe network section is used for preliminary gas-liquid separation. Preferably, the linear velocity of the desorption medium in the pipe network section is 0.01 - 0.3 m / s.

[0070] According to a preferred embodiment of the present invention, the filter section is used for in-depth gas-liquid separation. Preferably, the linear velocity of the desorption medium in the filter section is 0.001 - 0.05 m / s.

[0071] According to a preferred embodiment of the present invention, the pipe network arranged in the separation tank is honeycomb-shaped, the aperture ratio of the pipe network is 30-80%, preferably, each pipe is in a continuous zigzag "W" shape, and preferably, the linear velocity of the desorption medium in the pipe network section is 0.01-0.3 m / s.

[0072] According to a preferred embodiment of the present invention, the filter screen arranged in the separation tank is in a folded shape, the mesh number of the filter screen is 10-200 meshes, the number of layers of the filter screen is 2-10 layers, preferably, the distance between each layer of the filter screen is 0.05-0.2 m; preferably, the linear velocity of the desorption medium in the filter screen section is 0.001-0.05 m / s.

[0073] According to a preferred embodiment of the present invention, the pipe network section and the filter screen section are 0.2-1 cm apart.

[0074] The present invention provides a device for methanol conversion to lower olefins, which includes: a CO and H connected in series along the material flow direction 2 synthesis methanol system; the crude methanol raw material purification system containing high-carbon hydrocarbons and the system for methanol conversion to lower olefins as described in the present invention. The present invention mainly adds a purification system, and there are no special requirements for the synthesis methanol system and the system for methanol conversion to lower olefins, and it can be carried out according to the existing process. By adding a purification system, efficient connection of the two systems can be achieved.

[0075] According to an embodiment of the present invention, as Figure 1 shown, the crude methanol raw material purification system containing high-carbon hydrocarbons of the present invention includes: an adsorption-desorption unit, at least including 2 parallel towers 4, which are used for switching between the adsorption process and the desorption process. The crude methanol raw material containing high-carbon hydrocarbons enters the adsorption-desorption unit for adsorption. When the adsorption process ends, it is switched to the desorption process, and the raw material is switched to the desorption medium for desorption;

[0076] a separation unit, including a separation tank 5, which is used for separating the desorption medium containing high-carbon hydrocarbons from the desorption process;

[0077] A booster pump 8 is used for pressurizing and transporting the desorption medium and is arranged on the desorption medium pipeline;

[0078] A desorption medium buffer tank 7 is used for providing desorption medium raw materials and storing the desorption medium from the separation unit;

[0079] A raw material buffer tank and / or a flash tank. The raw material buffer tank is used for providing the crude methanol raw material containing high-carbon hydrocarbons or storing the purified methanol raw material from the adsorption-desorption unit, and the flash tank is used for providing the crude methanol raw material containing high-carbon hydrocarbons or heating and gasifying the purified methanol for MTO reaction;

[0080] A pipe network section and a filter screen section are arranged in the separation tank. The pipe network is arranged in a honeycomb shape by a plurality of pipe bundles, and each pipe is in a continuous zigzag "W" shape.

[0081] The filter screen is in a "W" corrugated shape, with a distance of 0.1 m between each layer of the filter screen, and the pipe network section is 0.5 cm away from the filter screen section.

[0082] Such as Figure 1 shown, the purification method includes:

[0083] (1) The raw methanol raw material containing high-carbon hydrocarbons (from the raw material buffer tank 1) enters the adsorption-desorption unit for adsorption. Among them, the raw material from which high-carbon hydrocarbons are adsorbed and removed goes to the raw material buffer tank 2 and / or goes to the flash tank 3;

[0084] (2) In the adsorption-desorption unit, when the adsorption process ends, it is switched to the desorption process, and the raw material is switched to the desorption medium 10 (first heat-exchanged through the heat exchanger 11) for desorption;

[0085] (3) After desorption, the desorption medium containing high-carbon hydrocarbons goes to the separation tank 5, the high-carbon hydrocarbon product 6 is collected at the bottom of the separation tank, and the desorption medium goes to the desorption medium buffer tank 7, is compressed by the booster pump 8 and returned as the desorption medium. The desorption medium can also be partially discharged to the exhaust 9;

[0086] (4) After the desorption ends, the desorption medium is switched back to the raw methanol raw material containing high-carbon hydrocarbons and the adsorption described in step (1) is carried out again.

[0087] The following examples are carried out according to the foregoing Figure 1 described process.

[0088] The present invention will be described in detail below through examples. In the following examples, parameters such as the content of high-carbon hydrocarbons in methanol and the content of high-carbon hydrocarbons in the desorption medium are measured by a gas chromatography-mass spectrometry analysis method; nitrogen is a commercially available product with a purity of 99.999% from Shanghai Lingyi Company.

[0089] Example 1

[0090] During the adsorption process, the bed temperature in the tower is 20°C and the working pressure is 0.8 MPa (G); the adsorbent is graphite carbon black. The content of high-carbon hydrocarbons in the raw material crude methanol is 200 ppm, the material temperature is 20°C, and it is fed into the bottom of the adsorption tower at a flow rate of 22.5 kg / h. After adsorption, it flows out from the top of the adsorption tower. The content of high-carbon hydrocarbons in the methanol at the outlet of the top of the adsorption tower is analyzed by gas chromatography-mass spectrometry (GC-MS), and the analysis results are shown in Table 1. During the desorption process, the bed temperature in the tower is 105°C and the working pressure is -0.06 MPa (G); the desorption medium is nitrogen with a purity of 99.999%. The nitrogen enters the adsorption tower from the top after heat exchange, entraining high-carbon hydrocarbons and flowing out from the bottom of the adsorption tower and then into the separation tank. After gas-liquid separation, it flows out from the top of the separation tank. The temperature of the pipe network section and the filter screen section is 78°C, the opening rate of the pipe network is 60%, the linear velocity of the desorption medium in the pipe network is 0.1 m / s, the mesh number of the filter screen is 80 meshes, the number of filter screen layers is 6 layers, and the linear velocity of the desorption medium in the filter screen section is 0.005 m / s. The content of high-carbon hydrocarbons in the nitrogen at the top of the separation tank is analyzed by GC-MS, and the analysis results are shown in Table 1.

[0091] Example 2

[0092] During the adsorption process, the bed temperature in the tower is 60°C and the working pressure is 0.01 MPa (G); the adsorbent is graphite carbon black. The content of high-carbon hydrocarbons in the raw material crude methanol is 200 ppm, the material temperature is 60°C, and it is fed into the bottom of the adsorption tower at a flow rate of 22.5 kg / h. After adsorption, it flows out from the top of the adsorption tower. The content of high-carbon hydrocarbons in the methanol at the outlet of the top of the adsorption tower is analyzed by GC-MS, and the analysis results are shown in Table 1. During the desorption process, the bed temperature in the tower is 155°C and the working pressure is 0.01 MPa (G); the desorption medium is nitrogen with a purity of 99.999%. The nitrogen enters the adsorption tower from the top after heat exchange, entraining high-carbon hydrocarbons and flowing out from the bottom of the adsorption tower and then into the separation tank. After gas-liquid separation, it flows out from the top of the separation tank. The temperature of the pipe network section and the filter screen section is 95°C, the opening rate of the pipe network is 80%, the linear velocity of the desorption medium in the pipe network is 0.01 m / s, the mesh number of the filter screen is 20 meshes, the number of filter screen layers is 10 layers, and the linear velocity of the desorption medium in the filter screen section is 0.001 m / s. The content of high-carbon hydrocarbons in the nitrogen at the top of the separation tank is analyzed by GC-MS, and the analysis results are shown in Table 1.

[0093] Example 3

[0094] During the adsorption process, the temperature of the bed layer in the tower is 1°C, and the working pressure is 2.0 MPa (G); the adsorbent is activated carbon. The content of high-carbon hydrocarbons in the raw material crude methanol is 200 ppm, the material temperature is 1°C, and it is fed into the bottom of the adsorption tower at a flow rate of 22.5 kg / h. After adsorption, it flows out from the top of the adsorption tower. The content of high-carbon hydrocarbons in the methanol at the outlet of the top of the adsorption tower is analyzed by gas chromatography-mass spectrometry (GC-MS), and the analysis results are shown in Table 1. During the desorption process, the temperature of the bed layer in the tower is 60°C, and the working pressure is 0.5 MPa (G); the desorption medium is nitrogen with a purity of 99.999%. The nitrogen enters the adsorption tower from the top after heat exchange, entraining high-carbon hydrocarbons and flowing out from the bottom of the adsorption tower and then entering the separation tank. After gas-liquid separation, it flows out from the top of the separation tank. The temperature of the pipeline section and the filter section is 65°C, the opening rate of the pipeline network is 30%, the linear velocity of the desorption medium in the pipeline network is 0.3 m / s, the mesh number of the filter is 200 meshes, the number of filter layers is 2 layers, and the linear velocity of the desorption medium in the filter section is 0.05 m / s. The content of high-carbon hydrocarbons in the nitrogen at the top of the separation tank is analyzed by GC-MS, and the analysis results are shown in Table 1.

[0095] Example 4

[0096] The adsorption-desorption operation was carried out according to the method of Example 1, except that the pipeline section and the filter section were not provided in the separation tank. The results are shown in Table 1.

[0097] Comparative Example 1

[0098] The removal of high-carbon hydrocarbons from crude methanol was carried out according to the method of Example 1, except that the adsorbent was not filled in the adsorption tower, and the high-carbon hydrocarbons in the adsorption tower naturally settled in the methanol without a desorption process. The results are shown in Table 1.

[0099] Table 1

[0100]

[0101] It can be seen from the results in Table 1 that in the examples of using the technology of the present invention to remove high-carbon hydrocarbons from crude methanol by using an adsorbent, the content of high-carbon hydrocarbons in the methanol raw material can be reduced to less than 10 ppm, and the effect of high-carbon hydrocarbon removal is significantly better.

[0102] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A purification method for crude methanol raw materials containing high-carbon hydrocarbons, characterized in that, the method comprises: (1) Feeding the crude methanol raw materials containing high-carbon hydrocarbons into an adsorption-desorption unit for adsorption, wherein the raw materials from which high-carbon hydrocarbons are adsorbed and removed go to a raw material buffer tank and / or a flash tank; (2) In the adsorption-desorption unit, when the adsorption process ends, it is switched to the desorption process, and the raw materials are switched to a desorption medium for desorption; (3) After desorption, the desorption medium containing high-carbon hydrocarbons goes to a separation tank, the high-carbon hydrocarbons are collected at the bottom of the separation tank, and the desorption medium goes to a desorption medium buffer tank and is compressed and returned as the desorption medium; (4) After the desorption ends, the desorption medium is switched back to the crude methanol raw materials containing high-carbon hydrocarbons, and the adsorption described in step (1) is carried out again.

2. The purification method according to claim 1, wherein, the composition of the crude methanol raw materials containing high-carbon hydrocarbons includes: methanol, normal paraffins / isoparaffins with carbon numbers from C9 to C40, preferably, the content of normal paraffins / isoparaffins with carbon numbers from C9 to C40 is 10-300 ppm; Preferably, the crude methanol raw materials containing high-carbon hydrocarbons are derived from a methanol synthesis unit, and more preferably from the crude methanol product tank of the process of synthesizing methanol from carbon monoxide and hydrogen.

3. The purification method according to claim 1 or 2, wherein, the raw materials from which high-carbon hydrocarbons are adsorbed and removed go to a raw material buffer tank as purified methanol raw materials for use as methanol raw materials in the conversion of methanol to lower olefins; The purpose of feeding the raw materials from which high-carbon hydrocarbons are adsorbed and removed to a flash tank is for flash preheating, and after preheating, it is used as preheated methanol raw materials in the conversion of methanol to lower olefins.

4. The purification method according to any one of claims 1-3, wherein, during the adsorption process, the temperature of the bed layer in the tower is 1-60 °C, and the working pressure is 0-2 MPa (G); Preferably, during the adsorption process, the temperature of the bed layer in the tower is 10-30 °C, and the working pressure is 0.5-1.5 MPa (G); and / or The adsorbent is a non-polar adsorbent, preferably at least one of activated carbon, graphite carbon black, and carbon molecular sieve, preferably graphite carbon black.

5. The purification method according to any one of claims 1-4, wherein, during the desorption process, the temperature of the bed layer in the tower is 60-160 °C, and the working pressure is -0.1 MPa to 0.5 MPa (G); Preferably, during the desorption process, the temperature of the bed layer in the tower is 80-120 °C, and the working pressure is -0.08 MPa to 0.1 MPa (G); and / or The desorption medium is at least one of steam, nitrogen, air, and flue gas, preferably nitrogen.

6. The purification method according to any one of claims 1-5, wherein, in the separation tank, along the flow direction of the desorption medium containing high-carbon hydrocarbons, a pipe network section and a filter screen section are provided from bottom to top, liquid is enriched at the bottom of the separation tank, and the desorption medium is discharged from the top of the separation tank; The pipe network section is used for preliminary gas-liquid separation, and the linear velocity of the desorption medium in the pipe network section is 0.01-0.3 m / s; The filter screen section is used for in-depth gas-liquid separation, and the linear velocity of the desorption medium in the filter screen section is 0.001-0.05 m / s; Preferably, the temperatures of the pipe network section and the filter screen section are each not lower than 65 °C, preferably 75-80 °C.

7. The purification method according to claim 6, wherein, the pipe network disposed in the separation tank is honeycomb-shaped, and the aperture ratio of the pipe network is 30-80%; and / or the filter screen disposed in the separation tank is pleated, and the mesh number of the filter screen is 10-200 meshes; preferably, the number of layers of the filter screen is 2-10 layers; and / or the adsorption-desorption unit includes at least 2 parallel towers for switching between the adsorption process and the desorption process.

8. A method for converting methanol to light olefins, characterized in that, the method includes: (1) Use CO and H 2 to synthesize methanol and obtain a raw methanol feedstock containing high-carbon hydrocarbons; (2) Purifying the crude methanol raw material containing high-carbon hydrocarbons according to any one of claims 1-7; (3) Using the purified methanol as a raw material for conversion to light olefins.

9. A purification system for a crude methanol raw material containing high-carbon hydrocarbons, characterized in that, the system includes: an adsorption-desorption unit including at least 2 parallel towers for switching between the adsorption process and the desorption process. The crude methanol raw material containing high-carbon hydrocarbons enters the adsorption-desorption unit for adsorption. After the adsorption process ends, it is switched to the desorption process, and the raw material is switched to the desorption medium for desorption; a separation unit including at least one separation tank for separating the desorption medium containing high-carbon hydrocarbons from the desorption process; a pressurization unit for pressurizing and transporting the desorption medium; a desorption medium buffer tank for providing desorption medium raw materials or storing the desorption medium from the separation unit; a raw material buffer tank and / or a flash tank. The raw material buffer tank is used to provide the crude methanol raw material containing high-carbon hydrocarbons or store the purified methanol raw material from the adsorption-desorption unit, and the flash tank is used to provide the crude methanol raw material containing high-carbon hydrocarbons or heat and gasify the purified methanol for the MTO reaction; preferably, each tower of the adsorption-desorption unit includes a purified methanol raw material discharge port at the top, a desorption medium discharge port containing high-carbon hydrocarbons at the bottom, a crude methanol raw material inlet at the lower part, and a desorption medium inlet at the upper part; preferably, a heat exchanger is provided between the pipelines for transporting the desorption medium; preferably, along the flow direction of the desorption medium containing high-carbon hydrocarbons in the separation tank, a pipe network section and a filter screen section are provided from bottom to top. Liquid is enriched at the bottom of the separation tank, and the desorption medium is discharged from the top of the separation tank; the pipe network section is used for preliminary gas-liquid separation; the filter screen section is used for deep gas-liquid separation; more preferably, the pipe network disposed in the separation tank is honeycomb-shaped, the aperture ratio of the pipe network is 30-80%, and the linear velocity of the desorption medium in the pipe network is 0.01-0.3 m / s; and / or the filter screen disposed in the separation tank is pleated, the mesh number of the filter screen is 10-200 meshes; preferably, the number of layers of the filter screen is 2-10 layers, and the distance between each layer of the filter screen is 0.05-0.2 m; the linear velocity of the desorption medium in the filter screen section is 0.001-0.05 m / s; and / or the pipe network section and the filter screen section are 0.2-1 cm apart.

10. A device for converting methanol to light olefins, characterized in that, The device includes a CO and H connected in series along the material flow direction 2 synthesis methanol system; the crude methanol raw material purification system containing high-carbon hydrocarbons as described in claim 9, and a system for converting methanol into lower olefins.

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