Settling separation method and settling separator of crude methanol raw material, and method and system for preparing olefin by methanol conversion

Abstract

The invention discloses a settling separation method and a settling separator of a crude methanol raw material, and a method and a system for preparing olefin through methanol conversion. The settling separator for the crude methanol raw material comprises a separator main body, and the separator main body comprises a separation area, a settling area and an accumulation area which are sequentially communicated from top to bottom along the gravity height direction; the separation area comprises a first separation area and a second separation area which are formed by separation through a separator arranged along the gravity direction, and the first separation area and the second separation area are respectively communicated with the settlement area; the first separation area comprises a first mixing area I and a first speed increasing area I from high to low in the gravity direction, and the second separation area comprises a second mixing area II and a second speed increasing area II from high to low in the gravity direction; a hot crude methanol raw material inlet I and a cold crude methanol raw material inlet I are formed in the top of the first separation area. By adopting the method provided by the invention, the content of high-carbon hydrocarbon in the methanol raw material can be reduced to 30 ppm or below.

Description

Technical Field

[0001] The present invention relates to a method and system for sedimentation separation of crude methanol raw materials and a method and system for methanol conversion to olefins. Background Art

[0002] Light olefins, defined here as ethylene and propylene, are two important basic chemical raw materials, and their demand is increasing continuously. In recent years, people have begun to vigorously develop alternative energy conversion technologies, such as the process of converting oxygenates to olefins (OTO), and oxygenates include methanol, ethanol, dimethyl ether, methyl ethyl ether, etc. There are many technologies available for producing oxygenates, and the raw materials include coal, natural gas, biomass, etc. For example, methanol can be produced from coal or natural gas, and the process is very mature, and a production scale of millions of tons can be achieved. Due to the wide range of sources of oxygenates and the economy of the process of converting to light olefins, the process of converting oxygenates to olefins (OTO), especially the process of converting methanol to olefins (MTO), has received more and more attention.

[0003] CN201873629 discloses a novel methanol dewaxing device, which uses a combination of multi-stage cyclone and wire mesh demisting to remove the wax generated in methanol synthesis, and the removal efficiency reaches 99.9%.

[0004] CN109758821 discloses a methanol filtration system for dewaxing in a methanol system, which uses a sintered stainless steel wire felt or a sintered stainless steel wire mesh as a filter element, and uses multiple filtration devices to continuously separate paraffin in methanol by filtration, and uses hot water to clean the solid paraffin blocked on the filter element to restore the filtration capacity of the filter element. Summary of the Invention

[0005] 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. The present invention provides a method for quickly removing high-carbon hydrocarbons from MTO raw materials. This method is used in the production of light olefins, and has the advantages of effectively removing high-carbon hydrocarbons in the methanol raw material and recovering them, and greatly reducing the adverse effects of high-carbon hydrocarbons on the MTO reaction.

[0006] According to the first aspect of the present invention, the present invention provides a sedimentation separator for crude methanol raw materials, and the sedimentation separator includes: a separator main body, and the separator main body includes a separation zone, a sedimentation zone and an aggregation zone that are sequentially communicated from top to bottom along the gravity height direction;

[0007] The separation zone includes a first separation zone and a second separation zone formed by being isolated by an isolation member arranged along the gravity direction, and the first separation zone and the second separation zone are respectively communicated with the sedimentation zone;

[0008] The first separation zone includes a first mixing zone I and a first acceleration zone I from high to low in the gravity direction, and the second separation zone includes a second mixing zone II and a second acceleration zone II from high to low in the gravity direction;

[0009] A hot crude methanol raw material inlet I and a cold crude methanol raw material inlet I are arranged at the top of the first separation zone, and are respectively communicated with a hot crude methanol raw material conveying pipeline and a cold crude methanol raw material conveying pipeline, and valves are arranged on each communication pipeline;

[0010] A hot crude methanol raw material inlet II and a cold crude methanol raw material inlet II are arranged at the top of the second separation zone, and are respectively communicated with a hot crude methanol raw material conveying pipeline and a cold crude methanol raw material conveying pipeline, and valves are arranged on each communication pipeline;

[0011] The hot crude methanol raw material inlet I and the hot crude methanol raw material inlet II are communicated with a discharge pipeline, and valves are arranged on each communication pipeline.

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

[0013] A methanol buffer tank, the settling separator described in the present invention, and a methanol flash tank;

[0014] The cold crude methanol raw material inlet of the settling separator is communicated with the methanol buffer tank, and the hot crude methanol raw material inlet of the settling separator is communicated with the bottom of the methanol flash tank; the discharge pipeline of the settling separator is communicated with the inlet of the methanol flash tank;

[0015] Preferably, the side line extraction outlet of the settling tank of the settling separator is communicated with the methanol buffer tank.

[0016] According to the third aspect of the present invention, the present invention provides a method for settling and separating a crude methanol raw material, and the method is carried out in the settling separator described in the present invention, and the method includes:

[0017] The crude methanol raw material contains methanol and high-carbon hydrocarbons, including a hot crude methanol raw material and a cold crude methanol raw material;

[0018] (a) The hot crude methanol raw material stream refluxed from the bottom of the methanol flash tank enters the first separation zone through the hot crude methanol raw material inlet I; the cold crude methanol raw material stream enters the first separation zone through the cold crude methanol raw material inlet I, contacts and mixes in the first mixing zone I, and high-carbon hydrocarbons are precipitated and suspended in the methanol stream after mixing;

[0019] (b) The methanol stream entrained with high-carbon hydrocarbons enters the settling zone after accelerating in the first acceleration zone I, the high-carbon hydrocarbons aggregate and settle in the settling zone and enter the aggregation zone, and the methanol stream enters the second mixing zone II of the second separation zone and then flows out of the settling separator through the hot crude methanol raw material inlet II to the methanol flash tank;

[0020] (c) Switch the feeding and discharging directions of the first separation zone and the second separation zone. The hot crude methanol raw material stream refluxed from the bottom of the methanol flash tank enters the second mixing zone II through the hot crude methanol raw material inlet II and contacts and mixes with the cold crude methanol raw material entering through the cold crude methanol raw material inlet II. After the mixing contact, the high-carbon hydrocarbons precipitate and suspend in the methanol stream.

[0021] (d) The methanol stream entrained with high-carbon hydrocarbons enters the sedimentation zone after being accelerated in the second acceleration zone II. The high-carbon hydrocarbons aggregate and settle in the sedimentation zone and enter the aggregation zone. The methanol stream enters the first mixing zone I from the first acceleration zone I of the first separation zone and then flows out of the separator through the hot crude methanol raw material inlet I to the methanol flash tank.

[0022] (e) Continue to switch the feeding and discharging directions of the first separation zone and the second separation zone, and cycle steps (a)-(d) until the sedimentation separation ends.

[0023] (f) After the sedimentation separation ends, stop feeding the hot crude methanol raw material and the cold crude methanol raw material, open the drain valve at the outlet of the aggregation zone, and discharge the methanol and high-carbon hydrocarbons in the separator into the static tank. After natural sedimentation and stratification, the high-carbon hydrocarbon crude product is obtained in the lower layer, and the upper-layer methanol clear liquid is returned to the methanol buffer tank.

[0024] According to the fourth aspect of the present invention, the present invention provides a method for methanol conversion to olefins, which includes:

[0025] Section A: Methanol synthesis process, used for synthesizing methanol and obtaining cold crude methanol raw material in the raw material buffer tank.

[0026] Section C: Methanol conversion to olefins process. The cold crude methanol raw material from the raw material buffer tank of Section A enters the flash tank to flash and form hot crude methanol raw material.

[0027] Section B: The cold crude methanol raw material of Section A and the hot crude methanol raw material of Section C enter the sedimentation separator, and sedimentation separation is carried out according to the method described in the present invention. After separation, it enters the flash tank of Section C as the raw material for the methanol-to-olefins MTO process through the discharge pipeline, and the methanol clear liquid obtained from the static tank is returned to the raw material buffer tank of Section A.

[0028] Analyzing the MTO crude methanol raw material of the industrial device, its long-chain saturated alkanes and paraffins are mainly high-carbon hydrocarbons with carbon numbers of C9-C40. The total content of these high-carbon hydrocarbons in the crude methanol is generally about 100 ppm. At the bottom of the methanol flash tank, the content of high-carbon hydrocarbons in methanol can reach more than 3000 ppm. This methanol rich in high-carbon hydrocarbons is extremely easy to precipitate paraffin-like solid substances when cooled, and it is easy to cause pipeline blockage.

[0029] The temperature inside the methanol flash tank is relatively high. As methanol continuously vaporizes, the high-boiling high-carbon hydrocarbons are relatively difficult to vaporize and accumulate in the liquid-phase methanol with an increasing content, which is also significantly higher than that in the methanol buffer tank. In particular, the higher the carbon number and molecular weight of these alkanes, the higher their content. When the temperature of this high-temperature methanol stream rich in high-carbon hydrocarbons decreases, the high-carbon hydrocarbons rapidly precipitate from the methanol solution due to the decreased solubility. Taking advantage of this characteristic, the present invention uses the cold methanol stream from the methanol buffer tank to quench this high-temperature methanol stream rich in high-carbon hydrocarbons, so that the high-carbon hydrocarbons rapidly precipitate and aggregate into solid particles in the mixing zone. The methanol entraining the high-carbon hydrocarbon particles enters the settling zone after accelerating in the acceleration zone. The outlet direction of the acceleration zone is consistent with the conical surface direction of the variable diameter in the settling zone, enabling the methanol and solid particles entering the settling zone to be preliminarily separated in the settling zone by inertia. Then, combined with the natural settling of the solid particles, the solid high-carbon hydrocarbons accumulate at the lower part of the settling zone, and the methanol flows out of the settling separator through another acceleration zone and mixing zone.

[0030] By using the method of the present invention, the high-carbon hydrocarbons enriched in the methanol flash tank can be removed and recovered, and the content of high-carbon hydrocarbons in the methanol raw material entering the methanol flash tank can be reduced to below 30 ppm, reducing the carbon accumulation caused by the heavy carbon deposited on the MTO catalyst during the catalytic cracking process of high-carbon hydrocarbons and alleviating the adverse effects of high-carbon hydrocarbons on the performance of the MTO catalyst. At the same time, it also alleviates the fouling problem of high-carbon hydrocarbons on the trays, heat exchangers, and inner walls of air coolers in the water system, avoiding the instability of the device caused by the blockage of high-carbon hydrocarbons. In addition, even if the content of high-carbon hydrocarbons in the crude methanol sent from the upstream methanol synthesis unit to the MTO unit increases, the high-carbon hydrocarbons in the crude methanol can be effectively removed by adopting this technical solution, thus ensuring the stable operation of the MTO unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a process flow diagram according to an embodiment of the present invention.

[0032] DESCRIPTION OF THE REFERENCE NUMERALS

[0033] 1 - hot methanol stream, 2 - cold methanol stream, 3 - to flash tank, 4 - hot methanol stream inlet I, 5 - first mixing zone I, 6 - first acceleration zone I, 7 - hot methanol stream inlet II, 8 - second mixing zone II, 9 - second acceleration zone II, 10 - settling zone, 11 - aggregation zone, 12 - drain valve, 13 - static tank, 14 - hot methanol stream inlet valve I, 15 - hot methanol stream inlet valve II, 16 - outlet valve I, 17 - outlet valve II, 18 - cold methanol stream inlet valve I, 19 - cold methanol stream inlet valve II, 20 - to raw material buffer tank, 21 - high-carbon hydrocarbon detection point. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] 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, 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 considered to be specifically disclosed in this document.

[0035] 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 as shown in the reference drawings; "inner, outer" refer to the inner and outer relative to the contour of each component itself.

[0036] In the present invention, unless otherwise specified, the orientation terms such as "upper, lower, top, bottom" are generally used to describe the relative positional relationship of each component with respect to the direction shown in the drawings or with respect to the vertical, perpendicular, or gravitational direction.

[0037] The "vertical direction" refers to the up and down direction of the paper surface shown in the figure, and the "lateral direction" refers to the left and right direction of the generally horizontal paper surface shown in the figure; "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.

[0038] The present invention provides a sedimentation separator for raw methanol. The sedimentation separator includes: a separator main body, and the separator main body includes a separation zone, a sedimentation zone, and an aggregation zone that are connected in sequence from top to bottom along the gravity height direction.

[0039] The separation zone includes a first separation zone and a second separation zone formed by being isolated by an isolation member arranged along the gravity direction. The first separation zone and the second separation zone are each connected to the sedimentation zone.

[0040] The first separation zone includes a first mixing zone I and a first acceleration zone I from high to low in the gravity direction. The second separation zone includes a second mixing zone II and a second acceleration zone II from high to low in the gravity direction.

[0041] A hot raw methanol feed inlet I and a cold raw methanol feed inlet I are provided at the top of the first separation zone, which are respectively connected to the hot raw methanol feed pipeline and the cold raw methanol feed pipeline, and valves are provided on each connecting pipeline.

[0042] A hot raw methanol feed inlet II and a cold raw methanol feed inlet II are provided at the top of the second separation zone, which are respectively connected to the hot raw methanol feed pipeline and the cold raw methanol feed pipeline, and valves are provided on each connecting pipeline.

[0043] The hot crude methanol raw material inlet I and the hot crude methanol raw material inlet II are communicated with the discharge pipeline, and valves are arranged on each communication pipeline. With the foregoing arrangement, it is possible to utilize the solubility difference of high-carbon hydrocarbons in methanol at different temperatures to efficiently remove and recover the high-carbon hydrocarbons enriched in the methanol flash tank. The temperature in the methanol flash tank is relatively high. As methanol continuously vaporizes, the high-boiling high-carbon hydrocarbons are relatively difficult to vaporize, and their content deposited in the liquid-phase methanol continuously increases, and their content is also significantly higher than that in the methanol buffer tank, especially those alkanes with a high carbon number and a large molecular weight have a higher content. When the temperature of this high-temperature methanol stream rich in high-carbon hydrocarbons decreases, the high-carbon hydrocarbons rapidly precipitate from the methanol solution due to the decrease in solubility. The present invention utilizes this characteristic and uses the cold methanol stream in the methanol buffer tank to quench this high-temperature methanol stream rich in high-carbon hydrocarbons, so that the high-carbon hydrocarbons rapidly precipitate and aggregate into solid particles in the mixing zone. The methanol entraining the high-carbon hydrocarbon particles enters the settling zone after accelerating in the acceleration zone. The outlet direction of the acceleration zone is consistent with the conical surface direction of the variable diameter of the settling zone, so that the methanol and solid particles entering the settling zone are initially separated in the settling zone by inertia, and then combined with the natural settling of the solid particles to make the solid high-carbon hydrocarbons aggregate at the lower part of the settling zone, and the methanol flows out of the settling separator through another acceleration zone and the mixing zone.

[0044] According to a preferred embodiment of the present invention, an exhaust valve is arranged at the outlet of the aggregation zone, and a high-carbon hydrocarbon detection point is arranged at the upper part of the aggregation zone; by arranging the exhaust valve, it is possible to discharge the methanol stream rich in solid high-carbon hydrocarbons, and by arranging the high-carbon hydrocarbon detection point, it is possible to monitor the aggregation degree of the solid high-carbon hydrocarbons in the aggregation zone. The high-carbon hydrocarbons in the settling zone are in a flocculent state in methanol, and at this time the light transmittance is lower than that of the clear methanol solution. As the flocculent high-carbon hydrocarbons gradually aggregate into a solid state, the light transmittance at this time is much lower than that in the flocculent state. Therefore, the detection method can be to calculate the content of the solid high-carbon hydrocarbons by measuring the light transmittance of the solid-liquid mixture at the upper part of the aggregation zone, or it can also be directly judged by visual observation of the aggregation degree of the high-carbon hydrocarbons. When the high-carbon hydrocarbon detection point detects the solid high-carbon hydrocarbons, it can be judged whether to stop the sedimentation separation. The high-carbon hydrocarbon detection point is provided with an upper detector and a lower detector. The lower detector is used to judge whether to stop the sedimentation separation operation, and the upper detector is used to forcibly stop the sedimentation separation operation.

[0045] According to a preferred embodiment of the present invention, preferably, the settling separator includes a static tank communicated with the aggregation zone, and the side-line extraction outlet of the static tank is communicated with the methanol buffer tank; by arranging the static tank, it is possible to further coalesce the solid high-carbon hydrocarbons into paraffin products.

[0046] According to a preferred embodiment of the present invention, the discharge pipeline is communicated with the flash tank inlet, so that it is possible to reduce the content of high-carbon hydrocarbons in the methanol entering the flash tank and enter the flash tank as the next synthesis raw material.

[0047] According to a preferred embodiment of the present invention, the ratio of the cross-sectional areas of the first mixing zone I and the first acceleration zone I is 1.5 to 20:1. In the present invention, the first mixing zone I and the first acceleration zone I achieve the reduction of the cross-sectional diameter through the setting of an eccentric conical diameter change, and thus achieve the ratio of the cross-sectional areas. The eccentric conical diameter change gradually expands from top to bottom, and the eccentric conical diameter change section is a transition section. Setting the ratio of the cross-sectional areas of the first mixing zone I and the first acceleration zone I to be 1.5 to 20:1, preferably, the ratio of the cross-sectional areas of the first mixing zone I and the first acceleration zone I is 4 to 10:1, which has the advantage of stable acceleration of solid high-carbon hydrocarbons.

[0048] According to a preferred embodiment of the present invention, the ratio of the cross-sectional areas of the second mixing zone II and the second acceleration zone II is 4 to 10:1. In the present invention, the first mixing zone II and the second acceleration zone II achieve the reduction of the cross-sectional diameter through the setting of an eccentric conical diameter change, and thus achieve the ratio of the cross-sectional areas. The eccentric conical diameter change gradually expands from top to bottom, and the eccentric conical diameter change section is a transition section. Setting the ratio of the cross-sectional areas of the first mixing zone II and the second acceleration zone II to be 1.5 to 20:1, preferably, the ratio of the cross-sectional areas of the second mixing zone II and the second acceleration zone II is 4 to 10:1, which has the advantage of stable acceleration of solid high-carbon hydrocarbons.

[0049] According to a preferred embodiment of the present invention, the settling zone gradually reduces in diameter and has a structure as shown in Figure 1 , for example, an inverted conical structure. Preferably, the ratio of the maximum inner diameter to the minimum inner diameter of the settling zone is 1.2 - 5, and the ratio of the height of the settling zone to the maximum inner diameter is 0.8 - 3. Thereby, it has the advantage of high separation efficiency of methanol and solid particles.

[0050] According to a preferred embodiment of the present invention, filters are provided at both the hot crude methanol raw material inlet I and the hot crude methanol raw material inlet II. By setting the filters, further separation of methanol and solid high-carbon hydrocarbons can be achieved. Due to the limited separation and settling effect of the settling zone, a small amount of solid high-carbon hydrocarbons inevitably flow out of the settling separator with methanol. Therefore, filters are provided at the outlet to further filter and remove the solid high-carbon hydrocarbons entrained by methanol. As the amount of solid high-carbon hydrocarbons attached to the filters increases, the filters will gradually be blocked, and these high-carbon hydrocarbons need to be removed in a timely manner. In the present invention, this outlet is also cleverly designed as the inlet of the hot methanol logistics. The temperature of the hot methanol logistics is used to heat the filters, thereby melting the solid high-carbon hydrocarbons and allowing them to enter the mixing zone with the methanol logistics. This not only has the effect of cleaning the filters but also does not introduce a third-party heat source medium, and the solid high-carbon hydrocarbons attached to the filters can also return to the mixing zone for re-separation and recovery. And when filtering, attention should be paid to the degree of solid high-carbon hydrocarbons attached to the filters to prevent the complete blockage of the filters, resulting in the inability of the hot methanol logistics to flow in and the failure to heat the filters.

[0051] According to a preferred embodiment of the present invention, the present invention provides a raw material system for methanol conversion to olefins, and the system includes:

[0052] a methanol buffer tank, the settling separator described in the present invention, and a methanol flash tank;

[0053] The cold crude methanol raw material inlet of the settling separator is communicated with the methanol buffer tank, and the hot crude methanol raw material inlet of the settling separator is communicated with the bottom of the methanol flash tank; the discharge pipeline of the settling separator is communicated with the inlet of the methanol flash tank;

[0054] Preferably, the side line extraction outlet of the settling tank of the settling separator is communicated with the methanol buffer tank. The methanol buffer tank directly receives the product crude methanol from the upstream methanol synthesis unit, and the gaseous methanol at the outlet of the methanol flash tank goes to the reaction system of MTO. Through the foregoing settings, the linkage between the methanol synthesis unit, the raw material system, and the methanol conversion to olefins reaction unit can be realized. Therefore, it has the advantage of efficiently connecting the methanol synthesis unit and the methanol reaction unit. Even if the process of the methanol synthesis unit fluctuates and the high-carbon hydrocarbons in methanol increase, the raw material system can efficiently remove these high-carbon hydrocarbons without affecting the normal operation of the methanol reaction unit.

[0055] The present invention provides a method for settling and separating crude methanol raw materials, and the method is carried out in the settling separator described in the present invention. The method includes:

[0056] The crude methanol raw material contains methanol and high-carbon hydrocarbons, including hot crude methanol raw material and cold crude methanol raw material;

[0057] (a) The hot crude methanol raw material stream refluxed from the bottom of the methanol flash tank enters the first separation zone through the hot crude methanol raw material inlet I; the cold crude methanol raw material stream enters the first separation zone through the cold crude methanol raw material inlet I, contacts and mixes in the first mixing zone I, and high-carbon hydrocarbons precipitate and suspend in the methanol stream after mixing and contacting;

[0058] (b) The methanol stream entraining high-carbon hydrocarbons enters the settling zone after accelerating in the first acceleration zone I. The high-carbon hydrocarbons aggregate and settle in the settling zone and enter the aggregation zone, and the methanol stream enters the second mixing zone II from the second acceleration zone II in the second separation zone and then flows out of the settling separator through the hot crude methanol raw material inlet II to the methanol flash tank;

[0059] (c) Switch the feeding and discharging directions of the first separation zone and the second separation zone. The hot crude methanol raw material stream refluxed from the bottom of the methanol flash tank enters the second mixing zone II through the hot crude methanol raw material inlet II and contacts and mixes with the cold crude methanol raw material entering from the cold crude methanol raw material inlet II. High-carbon hydrocarbons precipitate and suspend in the methanol stream after mixing and contacting;

[0060] (d) The methanol stream entraining high-carbon hydrocarbons enters the settling zone after being accelerated in the second acceleration zone II. The high-carbon hydrocarbons aggregate and settle in the settling zone and enter the aggregation zone. The methanol stream enters the first mixing zone I from the first acceleration zone I of the first separation zone and then flows out of the separator through the hot crude methanol raw material inlet I to the methanol flash tank;

[0061] (e) Continue to switch the feeding and discharging directions of the first separation zone and the second separation zone, and cycle steps (a)-(d) until the sedimentation separation ends;

[0062] (f) After the sedimentation separation ends, stop feeding the hot crude methanol raw material and the cold crude methanol raw material, open the vent valve at the outlet of the aggregation zone, and discharge the methanol and high-carbon hydrocarbons in the separator into the static tank. After natural sedimentation and stratification, the high-carbon hydrocarbon crude product is obtained in the lower layer, and the upper-layer methanol clear liquid is returned to the methanol buffer tank. The foregoing method can achieve efficient separation and recovery of high-carbon hydrocarbons and methanol.

[0063] According to a preferred embodiment of the present invention, the methanol buffer tank is used to buffer the crude methanol from the upstream methanol synthesis unit; thereby, an effective connection between the methanol system and the upstream methanol synthesis unit can be achieved.

[0064] According to a preferred embodiment of the present invention, the flash tank is used to flash methanol as the feed for the methanol-to-olefins reactor.

[0065] The present invention is suitable for the separation of various methanol raw materials. According to a preferred embodiment of the present invention, the composition of the hot crude methanol raw material includes: methanol, n-alkanes / isoparaffins with carbon numbers from C9 to C40, and the temperature is 90 - 140°C.

[0066] According to a preferred embodiment of the present invention, the composition of the cold crude methanol raw material includes: methanol, n-alkanes / isoparaffins with carbon numbers from C9 to C40, and the temperature is 0 - 50°C.

[0067] In the present invention, the high-carbon hydrocarbons refer to n-alkanes / isoparaffins with carbon numbers from C9 to C40. According to a preferred embodiment of the present invention, the high-carbon hydrocarbons are n-alkanes with carbon numbers from C16 to C40 and / or isoparaffins with carbon numbers from C16 to C40.

[0068] According to a preferred embodiment of the present invention, the inlet temperature of the hot crude methanol raw material at the hot crude methanol raw material inlet I and the hot crude methanol raw material inlet II is not lower than 90°C, preferably not lower than 110°C. Thereby, a relatively high high-carbon hydrocarbon content can be achieved in the hot methanol stream.

[0069] According to a preferred embodiment of the present invention, the temperature of the mixed methanol stream in the first mixing zone I and the second mixing zone II is adjusted by regulating the feed rates of the hot crude methanol feedstock and the cold crude methanol feedstock; preferably, the average temperature of the methanol streams in the first mixing zone I and the second mixing zone II is not higher than 60 °C, preferably not higher than 40 °C. Thus, as much high-carbon hydrocarbons as possible in the mixed methanol stream can be precipitated.

[0070] According to a preferred embodiment of the present invention, when the filter is used for outlet filtration, after the pressure difference of the filter is higher than 10 kPa, the feeding and discharging directions of the first separation zone and the second separation zone are switched.

[0071] According to a preferred embodiment of the present invention, after solid high-carbon hydrocarbons are detected at the high-carbon hydrocarbon detection point at the top of the aggregation zone, step (f) is entered, and the feeding of the hot crude methanol feedstock and the cold crude methanol feedstock is stopped.

[0072] As Figure 1 shown, a sedimentation separator for a crude methanol feedstock of the present invention includes: a separator main body, and the separator main body includes a separation zone, a sedimentation zone 10 and an aggregation zone 11 that are connected in sequence from top to bottom along the gravity height direction;

[0073] The separation zone includes a first separation zone and a second separation zone formed by being isolated by a separating member arranged along the gravity direction, and the first separation zone and the second separation zone are respectively communicated with the sedimentation zone;

[0074] The first separation zone includes a first mixing zone I 5 and a first acceleration zone I6 from high to low in the gravity direction, and the second separation zone includes a second mixing zone II 8 and a second acceleration zone II 9 from high to low in the gravity direction;

[0075] A hot crude methanol feedstock inlet I and a cold crude methanol feedstock inlet I are arranged at the top of the first separation zone, and are respectively communicated with the hot crude methanol feedstock conveying pipeline and the cold crude methanol feedstock conveying pipeline, and valves are arranged on each communication pipeline, a cold methanol stream inlet valve I 18 and a hot methanol stream inlet valve I 14;

[0076] A hot crude methanol feedstock inlet II and a cold crude methanol feedstock inlet II are arranged at the top of the second separation zone, and are respectively communicated with the hot crude methanol feedstock conveying pipeline and the cold crude methanol feedstock conveying pipeline, and valves are arranged on each communication pipeline, a hot methanol stream inlet valve II 15 and a cold methanol stream inlet valve II 19;

[0077] The hot crude methanol feedstock inlet I and the hot crude methanol feedstock inlet II are communicated with the discharge pipeline, and valves are arranged on each communication pipeline, an outlet valve I 16 and an outlet valve II 17;

[0078] The settling separator includes a static tank 13 communicated with the aggregation area, and a side line extraction port of the static tank is communicated with a raw material buffer tank;

[0079] An evacuation valve 12 is arranged at the outlet of the aggregation area, and a high-carbon hydrocarbon detection point 21 is arranged at the upper part of the aggregation area.

[0080] According to Figure 1 the shown process, the method of the present invention includes:

[0081] Step 1: The hot methanol logistics inlet valve I 14, the outlet valve I 16, and the cold methanol logistics inlet valve I 18 are opened, and the hot methanol logistics inlet valve II 15, the outlet valve II 17, and the cold methanol logistics inlet valve II 19 are closed. The hot methanol logistics 1 refluxed from the flash tank enters the first mixing area I 5 of the separator through the hot methanol logistics inlet valve I 14 from the hot methanol logistics inlet I 4 and contacts and mixes with the cold methanol logistics 2 coming from the raw material buffer tank through the cold methanol logistics inlet valve I 18. The high-carbon hydrocarbons in the methanol logistics quickly precipitate and suspend in the methanol logistics. The methanol logistics entrained with high-carbon hydrocarbons enters the settling area 10 after accelerating in the first acceleration area I 6. The high-carbon hydrocarbons aggregate and settle in the settling area and enter the aggregation area 11. The methanol logistics enters the second mixing area II 8 from the second acceleration area II 9 and then flows out of the separator through the hot methanol logistics inlet II 7 from the outlet valve I 16 to the flash tank 3.

[0082] Step 2: The hot methanol logistics inlet valve I 14, the outlet valve I 16, and the cold methanol logistics inlet valve I 18 are closed, and the hot methanol logistics inlet valve II 15, the outlet valve II 17, and the cold methanol logistics inlet valve II 19 are opened. The hot methanol logistics 1 refluxed from the flash tank enters the second mixing area II 8 of the separator through the hot methanol logistics inlet valve II 15 from the hot methanol logistics inlet II 7 and contacts and mixes with the cold methanol logistics 2 coming from the raw material buffer tank through the cold methanol logistics inlet valve II 19. The high-carbon hydrocarbons in the methanol logistics quickly precipitate and suspend in the methanol logistics. The methanol logistics entrained with high-carbon hydrocarbons enters the settling area 10 after accelerating in the second acceleration area II 9. The high-carbon hydrocarbons aggregate and settle in the settling area and enter the aggregation area 11. The methanol logistics enters the first mixing area I 5 from the first acceleration area I 6 and then flows out of the separator through the hot methanol logistics inlet I 4 from the outlet valve II 17 to the flash tank 3.

[0083] Step 1 and Step 2 are switched back and forth until solid-state high-carbon hydrocarbons are detected by the high-carbon hydrocarbon detection point 21 at the top of the aggregation area, and then Step 3 is entered.

[0084] Step 3: Close the hot methanol logistics inlet valve I 14, outlet valve I 16, and cold methanol logistics inlet valve I 18, as well as the hot methanol logistics inlet valve II 15, outlet valve II 17, and cold methanol logistics inlet valve II 19. Stop the feeding of cold and hot methanol logistics. Open the drain valve 12 at the bottom of the separator to discharge the methanol and high-carbon hydrocarbons in the sedimentation area 11 of the separator into the static tank 13. After natural sedimentation and stratification, the lower layer obtains the crude high-carbon hydrocarbon product, and the upper-layer methanol clear liquid goes to the raw material buffer tank 20.

[0085] The following examples are carried out according to the Figure 1 described process.

[0086] The present invention will be described in detail below through examples. In the following examples, parameters such as the high-carbon hydrocarbon content in the methanol logistics entering and leaving the separator are measured by gas chromatography-mass spectrometry analysis method.

[0087] Example 1

[0088] The ratio of the cross-sectional areas of the first mixing zone I and the first acceleration zone I is 20:1, and the ratio of the cross-sectional areas of the second mixing zone II and the second acceleration zone II is 20:1; the ratio of the maximum inner diameter to the minimum inner diameter of the sedimentation area is 1.2, and the ratio of the height of the sedimentation area to the maximum inner diameter is 3.0. The normal paraffins with carbon numbers C16 - C40 in the hot crude methanol raw material have a flow rate of 100 kg / h and a temperature of 140°C; the normal paraffins with carbon numbers C16 - C40 in the cold crude methanol raw material have a temperature of 0°C; the inlet temperature of the hot crude methanol raw material at the hot crude methanol raw material inlet I and the hot crude methanol raw material inlet II is 130°C, and the average temperature of the methanol logistics in the first mixing zone I and the second mixing zone II is 60°C; switch the feeding directions of the first separation zone and the second separation zone after the filter pressure difference is higher than 10 kPa; stop the feeding of the hot crude methanol raw material and the cold crude methanol raw material after the detector at the lower end of the high-carbon hydrocarbon detection point at the top of the aggregation zone detects solid-state high-carbon hydrocarbons. Use gas chromatography-mass spectrometry to analyze the high-carbon hydrocarbon content in the methanol logistics at the inlet and outlet of the sedimentation separator. The high-carbon hydrocarbons in the static tank are centrifuged, separated, dried, and then weighed to calculate the high-carbon hydrocarbon recovery rate. The analysis results are shown in Table 1.

[0089] Example 2

[0090] The ratio of the cross-sectional areas of the first mixing zone I and the first acceleration zone I is 1.5:1, and the ratio of the cross-sectional areas of the second mixing zone II and the second acceleration zone II is 1.5:1; the ratio of the maximum inner diameter to the minimum inner diameter of the settling zone is 5.0, and the ratio of the height of the settling zone to the maximum inner diameter is 0.8. The normal paraffins with carbon numbers C16 - C40 in the hot crude methanol feedstock have a flow rate of 100 kg / h and a temperature of 90 °C; the normal paraffins with carbon numbers C16 - C40 in the cold crude methanol feedstock have a temperature of 50 °C; the inlet temperature of the hot crude methanol feedstock at the hot crude methanol feedstock inlet I and the hot crude methanol feedstock inlet II is 90 °C, and the average temperature of the methanol logistics in the first mixing zone I and the second mixing zone II is 40 °C; after the filter differential pressure is higher than 10 kPa, the feeding and discharging directions of the first separation zone and the second separation zone are switched; after the detector at the lower end of the high-carbon hydrocarbon detection point at the top of the aggregation zone detects solid-state high-carbon hydrocarbons, the feeding of the hot crude methanol feedstock and the cold crude methanol feedstock is stopped. The high-carbon hydrocarbon content in the methanol logistics at the inlet and outlet of the settling separator is analyzed by gas chromatography-mass spectrometry. The high-carbon hydrocarbons in the static tank are centrifuged, dried, and then weighed to calculate the high-carbon hydrocarbon recovery rate. The analysis results are shown in Table 1.

[0091] Example 3

[0092] The ratio of the cross-sectional areas of the first mixing zone I and the first acceleration zone I is 8:1, and the ratio of the cross-sectional areas of the second mixing zone II and the second acceleration zone II is 8:1; the ratio of the maximum inner diameter to the minimum inner diameter of the settling zone is 3.0, and the ratio of the height of the settling zone to the maximum inner diameter is 2.0. The normal paraffins with carbon numbers C16 - C40 in the hot crude methanol feedstock have a flow rate of 100 kg / h and a temperature of 120 °C; the normal paraffins with carbon numbers C16 - C40 in the cold crude methanol feedstock have a temperature of 10 °C; the inlet temperature of the hot crude methanol feedstock at the hot crude methanol feedstock inlet I and the hot crude methanol feedstock inlet II is 115 °C, and the average temperature of the methanol logistics in the first mixing zone I and the second mixing zone II is 35 °C; after the filter differential pressure is higher than 10 kPa, the feeding and discharging directions of the first separation zone and the second separation zone are switched; after the detector at the lower end of the high-carbon hydrocarbon detection point at the top of the aggregation zone detects solid-state high-carbon hydrocarbons, the feeding of the hot crude methanol feedstock and the cold crude methanol feedstock is stopped. The high-carbon hydrocarbon content in the methanol logistics at the inlet and outlet of the settling separator is analyzed by gas chromatography-mass spectrometry. The high-carbon hydrocarbons in the static tank are centrifuged, dried, and then weighed to calculate the high-carbon hydrocarbon recovery rate. The analysis results are shown in Table 1.

[0093] Example 4

[0094] Settling separation is carried out according to the method of Example 3, except that the feeding and discharging directions of the first separation zone and the second separation zone are switched after the filter differential pressure is higher than 15 kPa. The high-carbon hydrocarbon content in the methanol logistics at the inlet and outlet of the settling separator is analyzed by gas chromatography-mass spectrometry. The high-carbon hydrocarbons in the static tank are centrifuged, dried, and then weighed to calculate the high-carbon hydrocarbon recovery rate. The results are shown in Table 1.

[0095] Example 5

[0096] Sedimentation separation was carried out according to the method of Example 3, except that after the upper detector at the high-carbon hydrocarbon detection point at the top of the aggregation zone detected solid-state high-carbon hydrocarbons, the feeding of the hot crude methanol raw material and the cold crude methanol raw material was stopped. The high-carbon hydrocarbon content in the methanol streams at the inlet and outlet of the sedimentation separator was analyzed by gas chromatography-mass spectrometry. The high-carbon hydrocarbons in the static tank were centrifuged, dried and then weighed, and the high-carbon hydrocarbon recovery rate was calculated. The results are shown in Table 1.

[0097] Example 6

[0098] Sedimentation separation was carried out according to the method of Example 3, except that the content of n-alkanes with carbon numbers C16 - C40 in the hot crude methanol raw material was 1000 ppm. The high-carbon hydrocarbon content in the methanol streams at the inlet and outlet of the sedimentation separator was analyzed by gas chromatography-mass spectrometry. The high-carbon hydrocarbons in the static tank were centrifuged, dried and then weighed, and the high-carbon hydrocarbon recovery rate was calculated. The results are shown in Table 1.

[0099] Example 7

[0100] Sedimentation separation was carried out according to the method of Example 3, except that no filters were installed at both the hot crude methanol raw material inlet I and the hot crude methanol raw material inlet II. The high-carbon hydrocarbon content in the methanol streams at the inlet and outlet of the sedimentation separator was analyzed by gas chromatography-mass spectrometry. The high-carbon hydrocarbons in the static tank were centrifuged, dried and then weighed, and the high-carbon hydrocarbon recovery rate was calculated. The results are shown in Table 1.

[0101] Comparative Example 1

[0102] Sedimentation separation was carried out according to the method of Example 3, except that there was no separation zone in the sedimentation separator, only a natural sedimentation zone, and the cold crude methanol stream was not used for quenching. A heat exchanger was used to cool the methanol stream to 80 °C. The high-carbon hydrocarbon content in the methanol streams at the inlet and outlet of the sedimentation separator was analyzed by gas chromatography-mass spectrometry. The high-carbon hydrocarbons in the static tank were centrifuged, dried and then weighed, and the high-carbon hydrocarbon recovery rate was calculated. The results are shown in Table 1.

[0103] Comparative Example 2

[0104] Sedimentation separation was carried out according to the method of Comparative Example 1, except that a heat exchanger was used to cool the methanol stream to 35 °C. The heat exchanger became blocked after operating for 6 hours. The high-carbon hydrocarbon content in the methanol streams at the inlet and outlet of the sedimentation separator was analyzed by gas chromatography-mass spectrometry. The high-carbon hydrocarbons in the static tank were centrifuged, dried and then weighed, and the high-carbon hydrocarbon recovery rate was calculated. The results are shown in Table 1.

[0105] Table 1

[0106]

[0107] High-carbon hydrocarbon recovery rate = mass of high-carbon hydrocarbons after drying / feed amount of high-carbon hydrocarbons in hot crude methanol

[0108] High-carbon hydrocarbon feed rate in hot crude methanol = hot crude methanol flow rate * high-carbon hydrocarbon content * feed time

[0109] As can be seen from the results in Table 1, in the examples of using the high-efficient settling separator of the present invention to remove high-carbon hydrocarbons in the methanol at the bottom of the methanol flash tank, the content of high-carbon hydrocarbons in methanol can be reduced to below 30 ppm at the lowest, and the recovery rate of high-carbon hydrocarbons can reach over 98% at the highest. It has significantly better effects such as good high-carbon hydrocarbon removal effect and high recovery efficiency.

[0110] 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 solution 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 sedimentation separator for raw crude methanol, characterized in that, the sedimentation separator comprises: a separator main body, and the separator main body comprises a separation zone, a sedimentation zone and an aggregation zone which are sequentially communicated from top to bottom along the gravity height direction; the separation zone comprises a first separation zone and a second separation zone formed by being isolated by an isolation member arranged along the gravity direction, and the first separation zone and the second separation zone are respectively communicated with the sedimentation zone; the first separation zone comprises a first mixing zone I and a first acceleration zone I from high to low in the gravity direction, and the second separation zone comprises a second mixing zone II and a second acceleration zone II from high to low in the gravity direction; a hot raw crude methanol inlet I and a cold raw crude methanol inlet I are arranged at the top of the first separation zone, and are respectively communicated with a hot raw crude methanol conveying pipeline and a cold raw crude methanol conveying pipeline, and valves are arranged on each communication pipeline; a hot raw crude methanol inlet II and a cold raw crude methanol inlet II are arranged at the top of the second separation zone, and are respectively communicated with a hot raw crude methanol conveying pipeline and a cold raw crude methanol conveying pipeline, and valves are arranged on each communication pipeline; the hot raw crude methanol inlet I and the hot raw crude methanol inlet II are communicated with a discharge pipeline, and valves are arranged on each communication pipeline.

2. The sedimentation separator according to claim 1, a vent valve is arranged at the outlet of the aggregation zone, and a high-carbon hydrocarbon detection point is arranged at the upper part of the aggregation zone; preferably, the sedimentation separator comprises a static tank communicated with the aggregation zone, and a side-line extraction outlet of the static tank is communicated with a methanol buffer tank; the discharge pipeline is communicated with a flash tank.

3. The sedimentation separator according to claim 1 or 2, wherein, the ratio of the cross-sectional areas of the first mixing zone I and the first acceleration zone I is 1.5-20:1; and / or the ratio of the cross-sectional areas of the second mixing zone II and the second acceleration zone II is 1.5-20:1; and / or preferably, the ratio of the cross-sectional areas of the first mixing zone I and the first acceleration zone I is 4-10:1; and / or the ratio of the cross-sectional areas of the second mixing zone II and the second acceleration zone II is 4-10:1; the sedimentation zone gradually reduces in diameter, preferably the ratio of the maximum inner diameter to the minimum inner diameter of the sedimentation zone is 1.2-5, and the ratio of the height of the sedimentation zone to the maximum inner diameter is 0.8-3.

4. The sedimentation separator according to any one of claims 1-3, wherein, filters are arranged on both the hot raw crude methanol inlet I and the hot raw crude methanol inlet II.

5. A system for methanol conversion to olefins, characterized in that, the system comprises: a methanol buffer tank, the sedimentation separator according to any one of claims 1-4, and a methanol flash tank; the cold raw crude methanol inlet of the sedimentation separator is communicated with the methanol buffer tank, and the hot raw crude methanol inlet of the sedimentation separator is communicated with the bottom of the methanol flash tank; the discharge pipeline of the sedimentation separator is communicated with the inlet of the methanol flash tank; preferably, the side-line extraction outlet of the static tank of the sedimentation separator is communicated with the methanol buffer tank.

6. A method for sedimentation separation of raw crude methanol, characterized in that, the method is carried out in the sedimentation separator according to any one of claims 1-4, and the method comprises: The raw crude methanol contains methanol and higher carbon hydrocarbons, including hot raw crude methanol and cold raw crude methanol; (a) The hot raw crude methanol feed stream refluxed from the bottom of the methanol flash tank enters the first separation zone through the hot raw crude methanol inlet I; the cold raw crude methanol feed stream enters the first separation zone through the cold raw crude methanol inlet I, contacts and mixes in the first mixing zone I, and after the mixing contact, higher carbon hydrocarbons precipitate and suspend in the methanol stream; (b) The methanol stream entraining higher carbon hydrocarbons enters the settling zone after accelerating in the first acceleration zone I. The higher carbon hydrocarbons aggregate and settle in the settling zone and enter the aggregation zone. The methanol stream enters the second mixing zone II from the second acceleration zone II of the second separation zone and then flows out of the settling separator through the hot raw crude methanol inlet II to the methanol flash tank; (c) Switch the feeding and discharging directions of the first separation zone and the second separation zone. The hot raw crude methanol feed stream refluxed from the bottom of the methanol flash tank enters the second mixing zone II from the hot raw crude methanol inlet II and contacts and mixes with the cold raw crude methanol entering from the cold raw crude methanol inlet II. After the mixing contact, higher carbon hydrocarbons precipitate and suspend in the methanol stream; (d) The methanol stream entraining higher carbon hydrocarbons enters the settling zone after accelerating in the second acceleration zone II. The higher carbon hydrocarbons aggregate and settle in the settling zone and enter the aggregation zone. The methanol stream enters the first mixing zone I from the first acceleration zone I of the first separation zone and then flows out of the separator through the hot raw crude methanol inlet I to the methanol flash tank; (e) Continue to switch the feeding and discharging directions of the first separation zone and the second separation zone, and cycle steps (a)-(d) until the settling separation ends; (f) After the settling separation ends, stop feeding the hot raw crude methanol and the cold raw crude methanol, open the drain valve at the outlet of the aggregation zone, discharge the methanol and higher carbon hydrocarbons in the separator into the static tank. After natural sedimentation and stratification, the higher carbon hydrocarbon crude product is obtained in the lower layer, and the upper layer of methanol clear liquid is returned to the methanol buffer tank.

7. The method according to claim 6, wherein, the higher carbon hydrocarbons are normal paraffins and / or isoparaffins with C16-C40; and / or the methanol buffer tank is used to buffer the raw crude methanol from the upstream methanol synthesis unit; and / or the methanol flash tank is used to flash methanol as the feed for the methanol-to-olefins reactor; and / or the composition of the hot raw crude methanol includes: methanol, normal paraffins and / or isoparaffins with carbon numbers of C9-C40; the temperature is 90-140°C; and / or the composition of the cold raw crude methanol includes: methanol, normal paraffins and / or isoparaffins with carbon numbers of C9-C40; the temperature is 0-50°C.

8. The method according to claim 6 or 7, wherein, the inlet temperature of the hot raw crude methanol at the hot raw crude methanol inlet I and the hot raw crude methanol inlet II is not lower than 90°C, preferably not lower than 110°C; the temperature of the mixed methanol stream in the first mixing zone I and the second mixing zone II is adjusted by adjusting the feeding amounts of the hot raw crude methanol and the cold raw crude methanol; preferably, the average temperature of the methanol stream in the first mixing zone I and the second mixing zone II is not higher than 60°C, preferably not higher than 40°C.

9. The method according to any one of claims 6-8, wherein, When the filter is used for outlet filtration, after the differential pressure of the filter is higher than 10 kPa, the feeding directions of the first separation zone and the second separation zone are switched. After the solid high-carbon hydrocarbons are detected by the high-carbon hydrocarbon detection point at the top of the aggregation zone, step (f) is entered, and the feeding of the hot crude methanol raw material and the cold crude methanol raw material is stopped.

10. A method for methanol conversion to olefins characterized in that the method comprises: Section A: Methanol synthesis process, used for synthesizing methanol and obtaining cold crude methanol raw material in the raw material buffer tank; Section C: Methanol conversion to olefins process, the cold crude methanol raw material from the raw material buffer tank in Section A enters the flash tank to be flashed to form hot crude methanol raw material; Section B: The cold crude methanol raw material in Section A and the hot crude methanol raw material in Section C enter the sedimentation separator, and sedimentation separation is carried out according to the method described in any one of claims 6-9. After separation, it enters the flash tank in Section C as the raw material for the methanol conversion to olefins process through the discharge pipeline, and the methanol clear liquid obtained from the static tank returns to the raw material buffer tank in Section A.

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