System and method for separating Fischer-Tropsch synthesis heavy wax and catalyst

Abstract

The present invention relates to the field of Fischer-Tropsch synthesis heavy wax processing, and discloses a system and method for separating Fischer-Tropsch synthesis heavy wax and catalyst. The system comprises: a heavy wax raw material tank, a high gradient magnetic separation device, a heavy wax product tank, a concentrated liquid tank, a second separation device, a flushing liquid tank, a waste catalyst receiving tank and a flushing pipeline; wherein the high gradient magnetic separation device is used to perform a first separation on the heavy wax, and the obtained qualified wax is stored in the heavy wax product tank; the flushing pipeline is used to flush the catalyst adsorbed in the high gradient magnetic separation device, and the obtained concentrated liquid containing the waste catalyst is sent to the concentrated liquid tank; the second separation device is used to perform a second separation on the concentrated liquid, and the obtained clear liquid with the catalyst separated enters the flushing liquid tank as a flushing liquid raw material, and the obtained waste catalyst enters the waste catalyst receiving tank. The separation efficiency of heavy wax and catalyst can be improved, and the flushing effect of the high gradient magnetic separation device can be improved at the same time.

Description

Technical Field

[0001] The invention relates to the field of Fischer-Tropsch synthesis heavy wax processing, and in particular to a system and method for separating Fischer-Tropsch synthesis heavy wax from a catalyst. Background Art

[0002] The Fischer-Tropsch reaction is the main reaction of indirect coal liquefaction. Its process mainly uses coal-based synthesis gas as raw material to synthesize light hydrocarbons and heavy wax products in a slurry bed reactor in the presence of iron-based or cobalt-based catalysts. Among them, a considerable amount of catalyst (solid content of about 100-300μg / g) is entrained in the heavy wax, and these catalysts need to be separated to obtain qualified wax that meets product standards.

[0003] The separation of heavy wax and catalyst in Fischer-Tropsch synthesis usually adopts the pre-coating filtration method, which requires the use of a large amount of white clay and diatomaceous earth as filter aids. On the one hand, the mixing of filter aids will increase the difficulty and cost of catalyst treatment. On the other hand, the pre-coating filtration process requires a large number of supporting equipment, with low efficiency and high cost. Some researchers have proposed a method of using magnetic separation to simplify the process, reduce the amount of filter aids, and increase the yield of heavy wax, but there is still a problem of low actual separation efficiency.

[0004] CN111187636A discloses a system and method for separating catalysts from heavy wax of Fischer-Tropsch synthesis, the device includes: a raw material tank, a high gradient magnetic separation device, a flushing pipeline, a heavy wax intermediate tank, a pre-coated raw material tank, a pre-coated filter, a pre-coated waste residue receiving tank, a concentrated liquid tank, a rotary drum magnetic separation device, a waste catalyst receiving tank and an incinerator; wherein the rotary drum magnetic separation device is connected to the concentrated liquid tank, the raw material tank and the waste catalyst receiving tank, and is used to perform secondary magnetic separation on the concentrated liquid obtained by flushing the high gradient magnetic separation device, and the obtained clear liquid separated from the catalyst is returned to the raw material tank; the rotary drum magnetic separation device includes the following parts: a closed box body provided with a concentrated liquid inlet, a clear liquid outlet, a waste catalyst outlet and a heating and heat preservation structure, a rotatable sealed rotary drum arranged in the box body, a second magnet fixed in the rotary drum, and a scraper arranged at the waste catalyst outlet and in contact with the surface of the rotary drum. The system and method can better realize the recovery of qualified wax in heavy wax of Fischer-Tropsch synthesis.

[0005] In the above technical solution, since the clear liquid obtained by the drum magnetic separation still contains a certain amount of catalyst, when the clear liquid returns to the raw material tank, it means that this part of the catalyst also returns to the raw material tank. The lower the efficiency of the drum magnetic separation, the more catalyst is returned, and the lower the actual separation efficiency. Since the flushing effect of high-gradient magnetic separation is generally positively correlated with the amount of flushing liquid used, the greater the amount of flushing liquid used, the more clear liquid of the secondary magnetic separation product and the amount of entrained catalyst returned to the raw material tank, and the lower the actual separation efficiency, which in turn limits the amount of flushing liquid used. The problem of low actual separation efficiency still needs to be solved. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems of low separation efficiency and unsatisfactory flushing effect of magnetic separation device in the prior art of separating heavy wax obtained by slurry bed Fischer-Tropsch synthesis, and to provide a system and method for separating Fischer-Tropsch synthesis heavy wax and catalyst.

[0007] In order to achieve the above-mentioned object, the first aspect of the present invention provides a system for separating Fischer-Tropsch synthesis heavy wax and catalyst, comprising: a heavy wax raw material tank, a high gradient magnetic separation device, a heavy wax product tank, a concentrated liquid tank, a second separation device, a waste catalyst receiving tank, a flushing liquid tank, and a flushing pipeline; wherein,

[0008] The heavy wax raw material tank stores heavy wax produced from a Fischer-Tropsch synthesis unit;

[0009] The high-gradient magnetic separation device is connected to the heavy wax raw material tank, the heavy wax product tank, the concentrated liquid tank and the flushing pipeline, and is used to perform a first separation on the heavy wax, and the obtained qualified wax is stored in the heavy wax product tank;

[0010] The flushing pipeline conveys the flushing liquid from the flushing liquid tank to flush the catalyst adsorbed in the high gradient magnetic separation device, and the obtained concentrated liquid containing the spent catalyst is sent to the concentrated liquid tank;

[0011] The second separation device is connected to the concentrate tank, the flushing liquid tank and the waste catalyst receiving tank, and is used to perform a second separation on the concentrate. The clear liquid from which the catalyst is separated enters the flushing liquid tank as a flushing liquid raw material, and the waste catalyst enters the waste catalyst receiving tank.

[0012] A second aspect of the present invention provides a method for separating Fischer-Tropsch synthesis heavy wax and a catalyst, comprising:

[0013] (1) pretreating the Fischer-Tropsch synthesis product to obtain a Fischer-Tropsch synthesis heavy wax;

[0014] (2) introducing the heavy wax into the system described in the first aspect, and performing a first separation in a high gradient magnetic separation device of the system to obtain qualified wax;

[0015] (3) introducing the flushing liquid into the high gradient magnetic separation device through the flushing pipeline of the system for flushing to obtain a concentrated solution containing the spent catalyst;

[0016] (4) introducing the concentrated solution into the second separation device of the system for second separation to obtain waste catalyst and a clear solution from which the catalyst is separated, and the clear solution is returned to step (3) and added to the flushing solution; wherein:

[0017] The content of the catalyst in the Fischer-Tropsch synthesis heavy wax is 20-500 mg / kg, and the content of the catalyst in the clear liquid is 500-2000 mg / kg.

[0018] Through the above-mentioned technical scheme, the present invention adopts multi-stage separation, utilizes the magnetic field of high magnetic induction intensity provided by the high gradient magnetic separation device to separate the Fischer-Tropsch synthesis heavy wax and the catalyst, performs a second separation on the concentrated liquid containing the waste catalyst produced after flushing the high gradient magnetic separation device, and recycles the product liquid produced by the second separation (which has a higher catalyst concentration than the Fischer-Tropsch synthesis heavy wax raw material) as a flushing liquid for the high gradient magnetic separation device, which can significantly improve the actual separation efficiency of the Fischer-Tropsch synthesis heavy wax and the catalyst, and at the same time obtain a better flushing effect of the high gradient magnetic separation device. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic flow diagram of a system and method for separating Fischer-Tropsch synthesis heavy wax and catalyst provided by the present invention;

[0020] Description of Reference Numerals

[0021] E1 Heavy wax raw material tank E2 High gradient magnetic separation device E3 Heavy wax product tank

[0022] E4 Concentrate tank E5 Second separation device E6 Flushing liquid tank

[0023] E7 Waste Catalyst Receiving Tank DETAILED DESCRIPTION

[0024] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and 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, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0025] The first aspect of the present invention provides a system for separating Fischer-Tropsch synthesis heavy wax and catalyst, such as Figure 1 As shown, including:

[0026] Heavy wax raw material tank E1, high gradient magnetic separation device E2, heavy wax product tank E3, concentrated liquid tank E4, second separation device E5, flushing liquid tank E6, waste catalyst receiving tank E7 and flushing pipeline; wherein,

[0027] The heavy wax raw material tank E1 stores heavy wax produced from a Fischer-Tropsch synthesis unit;

[0028] The high-gradient magnetic separation device E2 is connected to the heavy wax raw material tank E1, the heavy wax product tank E3, the concentrated liquid tank E4 and the flushing pipeline, and is used to perform a first separation on the heavy wax, and the obtained qualified wax is stored in the heavy wax product tank E3;

[0029] The flushing pipeline conveys the flushing liquid from the flushing liquid tank E6 for flushing the catalyst adsorbed in the high gradient magnetic separation device E2, and the obtained concentrated liquid containing the spent catalyst is sent to the concentrated liquid tank E4;

[0030] The second separation device E5 is connected to the concentrated liquid tank E4, the flushing liquid tank E6 and the waste catalyst receiving tank E7, and is used to perform a second separation on the concentrated liquid. The obtained clear liquid with the catalyst separated enters the flushing liquid tank E6 as a flushing liquid raw material, and the obtained waste catalyst enters the waste catalyst receiving tank E7.

[0031] According to the present invention, in the system for separating the Fischer-Tropsch synthesis heavy wax and the catalyst, the high gradient magnetic separation device E2 is used to perform a first separation on the heavy wax to obtain qualified wax. The content of the catalyst in the heavy wax is 20-500 mg / kg, and the content of the catalyst in the qualified wax is less than 10 mg / kg. The high gradient magnetic separation device E2 can be a conventional high gradient magnetic separator in the art, including: a cylinder, a magnetic medium filled in the cylinder, and a magnet surrounding the outside of the cylinder. The outside of the cylinder is surrounded and provided with a magnet, and the inside of the cylinder is provided with a magnetic medium, an internal component for fixing and supporting the magnetic medium, an upper / lower magnetic pole head for preventing magnetic leakage and making the magnetic field more uniform, and a separation chamber surrounded by the above components.

[0032] In the present invention, in the high gradient magnetic separation device E2, the magnetic medium is preferably made of magnetically conductive stainless steel wool, more preferably stainless steel wool with a diameter of 0.01-0.3 mm. Preferably, the filling rate of the magnetic medium in the cylinder is 1-8% by volume, more preferably 2-4% by volume.

[0033] According to the present invention, in the high gradient magnetic separation device E2, the magnet is preferably an electromagnet. Under the condition of power on, the magnet produces a magnetic field. When the heavy wax passes into the high gradient magnetic separation device E2 from bottom to top, under the action of the magnetic field, the catalyst in the heavy wax is adsorbed and deposited on the magnetic medium, that is, the first separation is performed, and the qualified wax obtained is drawn out from the upper outlet of the high gradient magnetic separation device E2 and stored in the heavy wax product tank E3. During the process of the magnet of the high gradient magnetic separation device E2 being powered on to perform the separation operation, the valve on the flushing pipeline is closed, that is, the flushing pipeline is in a closed state.

[0034] According to the present invention, when the high gradient magnetic separation device E2 absorbs and accumulates too much catalyst, causing the internal and external pressure difference to exceed the specified threshold or the catalyst content in the heavy wax product exiting the high gradient magnetic separation device E2 is higher than the index requirement of qualified wax, the heavy wax inlet and outlet pipeline valves of the high gradient magnetic separation device E2 are closed, the feeding of heavy wax is stopped, and the magnet is powered off to not generate a magnetic field, while the flushing pipeline is open, and the catalyst adsorbed and deposited by the high gradient magnetic separation device E2 in the first separation process is flushed from top to bottom with a flushing liquid, and a concentrated solution containing waste catalyst is obtained and sent to the concentrated solution tank E4. After the flushing is completed, the flushing pipeline is closed, the magnet is powered on again, and the heavy wax inlet and outlet pipeline valves of the high gradient magnetic separation device E2 are opened to start a new round of the first separation process.

[0035] According to the present invention, in the system for separating the Fischer-Tropsch synthesis heavy wax and the catalyst, the high gradient magnetic separation device E2 can be one or more, preferably more than one. When there are more than one high gradient magnetic separation devices E2, they can be connected in parallel to meet the requirement that when the magnetic medium is flushed with a flushing liquid, the multiple high gradient magnetic separation devices E2 can be switched to operate, so that the first separation can be carried out continuously and the utilization efficiency of the equipment is improved.

[0036] According to the present invention, the flushing liquid comes from the flushing liquid tank E6, and is intermittently flushed through the flushing liquid pipeline to the catalyst adsorbed by the high gradient magnetic separation device E2 during the first separation process. In the initial startup operation of the system for separating the Fischer-Tropsch synthesis heavy wax and catalyst of the present invention, the flushing liquid can be selected from at least one of unseparated heavy wax, qualified wax after separation, paraffin and heavy diesel, preferably unseparated heavy wax; in the process of the system gradually turning from the initial operation to the stable operation, no new flushing liquid is introduced from outside the boundary, and the clear liquid separated from the catalyst obtained by the second separation continuously enters the flushing liquid tank E6, and the proportion of the clear liquid in the flushing liquid is gradually increased until the clear liquid is completely used as the flushing liquid to flush the high gradient magnetic separation device E2.

[0037] According to the present invention, the concentrated solution is a mixture containing waste catalyst and flushing liquid obtained by flushing the high gradient magnetic separation device E2 with the flushing liquid. In the initial stage of startup operation of the system for separating Fischer-Tropsch synthesis heavy wax and catalyst according to the present invention, the waste catalyst in the concentrated solution mainly comes from the catalyst adsorbed by the high gradient magnetic separation device E2 in the first separation process; after the system gradually stabilizes, the waste catalyst in the concentrated solution mainly includes the catalyst adsorbed by the high gradient magnetic separation device E2 in the first separation process, and the catalyst carried in the clear liquid obtained from the second separation.

[0038] According to the present invention, the second separation device E5 is used to perform a second separation on the concentrated solution to obtain a clear solution from which the catalyst is separated and a waste catalyst. The catalyst content in the clear solution is 500-2000 mg / kg. Preferably, the second separation device E5 can be at least one of a cylindrical magnetic separator, a centrifugal separator, a hydrocyclone separator and a sedimentation separation tank, and is more preferably a cylindrical magnetic separator, so as to further separate the catalyst in the concentrated solution and enable the system to have better operation continuity.

[0039] In the present invention, the structure, working process and operating parameters of the cylindrical magnetic separator can refer to the rotary drum magnetic separation device disclosed in CN111187636A, and the present invention will not be repeated here.

[0040] In the present invention, preferably, the high gradient magnetic separation device E2 and the second separation device E5 have steam or electric heating externally so that the heavy wax flowing through the high gradient magnetic separation device E2 and the concentrated liquid flowing through the second separation device E5 have good fluidity to ensure the separation effect.

[0041] According to the present invention, the second separation device E5 is connected to the flushing liquid tank E6, and the clear liquid from the second separation device E5 with the catalyst separated enters and is stored in the flushing liquid tank E6 as a flushing liquid raw material, and then is used as a flushing liquid to flush the high gradient magnetic separation device E2.

[0042] According to the present invention, the system for separating heavy wax and catalyst from Fischer-Tropsch synthesis further comprises an unqualified product line, which is connected to the high gradient magnetic separation device E2 and the concentrated liquid tank E4, and is used to send the unqualified wax produced by the high gradient magnetic separation device E2 in the initial stage of separation into the concentrated liquid tank E4. After the high gradient magnetic separation device E2 is flushed with a flushing liquid, a small amount of catalyst remains in the separation chamber of the high gradient magnetic separation device E2 and the pipeline connected thereto, which makes it possible that the catalyst content in the heavy wax product of the high gradient magnetic separation device E2 is higher than 10 mg / kg in the initial stage of the first separation in a new round after flushing, that is, an unqualified product is obtained. This part of the unqualified product is sent to the concentrated liquid tank E4 through the unqualified product line and incorporated into the concentrated liquid, and the second separation is continued, so that the heavy wax raw material can be fully utilized and more waste catalyst can be separated.

[0043] According to the present invention, the system for separating the heavy wax and the catalyst in the Fischer-Tropsch synthesis further comprises a flushing liquid discharge pipeline connected to the flushing liquid tank E6, which is used to discharge the excess flushing liquid accumulated in the flushing liquid tank E6. After each round of the first separation, a certain amount of heavy wax will remain in the high-gradient magnetic separation device E2. This part of the heavy wax will be incorporated into the concentrated solution through flushing with the flushing liquid. After the subsequent second separation, a part of the residual heavy wax will enter the flushing liquid tank E6, which makes the flushing liquid accumulated in the flushing liquid tank E6 more and more. When the liquid level exceeds the threshold, it needs to be discharged through the flushing liquid discharge pipeline.

[0044] The second aspect of the present invention provides a method for separating Fischer-Tropsch synthesis heavy wax and catalyst, such as Figure 1 As shown, including:

[0045] (1) pretreating the Fischer-Tropsch synthesis product to obtain a Fischer-Tropsch synthesis heavy wax;

[0046] (2) introducing the heavy wax into the system described in the first aspect, and performing a first separation in a high gradient magnetic separation device of the system to obtain qualified wax;

[0047] (3) introducing the flushing liquid into the high gradient magnetic separation device through the flushing pipeline of the system for flushing to obtain a concentrated solution containing the spent catalyst;

[0048] (4) introducing the concentrated solution into the second separation device of the system for second separation to obtain waste catalyst and a clear solution from which the catalyst is separated, and the clear solution is returned to step (3) and added to the flushing solution; wherein:

[0049] The content of the catalyst in the Fischer-Tropsch synthesis heavy wax is 20-500 mg / kg, and the content of the catalyst in the clear liquid is 500-2000 mg / kg.

[0050] The system provided in the first aspect of the present invention is used for separating Fischer-Tropsch synthesis heavy wax and catalyst.

[0051] According to the present invention, in step (1), the Fischer-Tropsch synthesis product may be a slurry containing heavy wax and catalyst obtained by reacting synthesis gas in a slurry bed reactor under the action of a Fischer-Tropsch synthesis catalyst (usually an iron-based or cobalt-based catalyst).

[0052] According to the present invention, in step (1), the pretreatment includes flash evaporation and cooling in sequence. The synthesis gas and low-carbon hydrocarbons dissolved in the Fischer-Tropsch synthesis product can be removed by flash evaporation to obtain Fischer-Tropsch synthesis heavy wax. Preferably, the pressure of the flash evaporation is 0.1-0.8MP. In addition, the obtained Fischer-Tropsch synthesis heavy wax needs to be cooled during the flash evaporation process. Preferably, the temperature reached by the cooling is 130-250°C, and more preferably 150-190°C.

[0053] In the present invention, the content of the catalyst in the Fischer-Tropsch synthesis heavy wax is 20-500 mg / kg.

[0054] According to the present invention, in step (2), preferably, the first separation is performed under heating and inert atmosphere. Steam or electric heating outside the high gradient magnetic separation device E2 can be used, and an inert gas (such as nitrogen) is introduced into the high gradient magnetic separation device E2 to avoid oxidation and combustion of the catalyst, thereby ensuring the safety of the separation process.

[0055] Preferably, the heating temperature is 130-250°C, more preferably 150-190°C.

[0056] Preferably, the working pressure of the high gradient magnetic separation device E2 is 0.01-0.6 MPa, and more preferably 0.03-0.4 MPa.

[0057] According to the present invention, in step (2), the magnet in the high gradient magnetic separation device E2 is preferably an electromagnet. When the magnet is powered on, it can generate a magnetic field in the magnetic medium filled in the cylinder of the high gradient magnetic separation device E2. When the heavy wax passes into the high gradient magnetic separation device E2 from bottom to top, under the action of the magnetic field, the catalyst in the heavy wax is adsorbed and deposited on the magnetic medium, that is, the first separation is performed. The qualified wax obtained after separation is drawn out from the upper outlet of the high gradient magnetic separation device E2 and stored in the heavy wax product tank E3. During the first separation, the flushing pipeline of the system is closed.

[0058] In the present invention, in step (2), the magnetic field generated by the magnet disposed outside the cylinder of the high gradient magnetic separation device E2 in the magnetic medium filled in the cylinder should have sufficient magnetic induction intensity to achieve effective separation of the heavy wax and the catalyst. Preferably, in the high gradient magnetic separation device E2, the magnetic induction intensity of the first separation is 2000-20000 Gauss, more preferably 2000-10000 Gauss.

[0059] According to the present invention, in step (2), in order to obtain a better separation effect, preferably, the cross-sectional flow rate of the heavy wax flowing through the high gradient magnetic separation device is 0.001-0.05 m / s, and more preferably 0.002-0.03 m / s.

[0060] According to the present invention, in step (2), the catalyst content in the qualified wax obtained by the first separation is less than 10 mg / kg.

[0061] According to the present invention, in step (3), when the internal and external pressure difference of the high gradient magnetic separation device E2 exceeds the defined threshold value or the catalyst content in the heavy wax product exiting the high gradient magnetic separation device E2 is higher than the index requirement of qualified wax, the valves of the heavy wax inlet and outlet pipelines of the high gradient magnetic separation device E2 are closed, and the power is turned off to not generate a magnetic field, and at the same time, the flushing pipeline is opened, and the catalyst adsorbed and deposited on the magnetic medium of the high gradient magnetic separation device E2 is flushed from top to bottom with a flushing liquid to obtain a concentrated solution containing waste catalyst and send it to the concentrated solution tank E4. After the flushing is completed, the flushing pipeline is closed, the magnet is powered on again, and the valves of the heavy wax inlet and outlet pipelines of the high gradient magnetic separation device E2 are opened to start a new round of the first separation process. Preferably, the flushing conditions include: the flushing liquid flow rate is 0.1-1m / s, the single flushing time is 5-60s, and the number of flushing times is 1-5 times.

[0062] In the present invention, it is preferred to use a plurality of high gradient magnetic separation devices E2 connected in parallel. When one or more of the high gradient magnetic separation devices E2 need to be flushed, the separation operation can be switched to other devices that have completed flushing to continue, so as to improve the continuity of the first separation process.

[0063] According to the present invention, in step (3), at the initial stage of the startup operation of the system, at least one of unseparated heavy wax, separated qualified wax, paraffin and heavy diesel can be used as the flushing liquid, preferably unseparated heavy wax; then the clear liquid from which the catalyst is separated obtained by the second separation in the subsequent step (4) is incorporated into the flushing liquid as the flushing liquid raw material, and no new flushing liquid is added from outside the boundary. As the system continues to operate, the proportion of the clear liquid in the flushing liquid gradually increases until the clear liquid is completely used as the flushing liquid.

[0064] According to the present invention, in step (3), when the system operates stably, the catalyst content in the concentrated solution containing the spent catalyst is 1000-50000 mg / kg.

[0065] According to the present invention, in step (4), the concentrated solution containing the waste catalyst is further separated and treated by the second separation, the waste catalyst obtained is collected, and the clear solution from which the catalyst is separated is returned to step (3) and incorporated into the cleaning solution. Preferably, the second separation is carried out under heating and an inert atmosphere, so that the concentrated solution maintains good fluidity during the separation process and ensures the safety of the separation process. The heating can be carried out by steam or electric heating outside the separation device, and the inert atmosphere can preferably be provided by introducing nitrogen.

[0066] Preferably, in step (4), the heating temperature is 130-250°C, more preferably 150-190°C;

[0067] Preferably, in step (4), the introduction of the inert gas makes the working pressure of the second separation device E5 0.001-0.3 MPa, more preferably 0.001-0.1 MPa.

[0068] According to the present invention, in step (4), preferably, the conditions of the second separation are such that the content of the catalyst in the clear liquid is 500-2000 mg / kg.

[0069] In the present invention, the clear liquid obtained after the second separation has a higher catalyst concentration, and the catalyst content in the clear liquid can be higher than the catalyst content in the Fischer-Tropsch synthesis heavy wax. The present invention recycles the second separation product liquid with a higher catalyst concentration as a flushing liquid for the high-gradient magnetic separation device in the first separation, which can improve the actual separation efficiency of the Fischer-Tropsch synthesis heavy wax and the catalyst, and at the same time obtain a better flushing effect of the high-gradient magnetic separation device.

[0070] According to the present invention, the method further includes incorporating the unqualified wax generated in the initial stage of the first separation into the concentrated solution containing the waste catalyst through the unqualified product line in the system. After each round of flushing, a small amount of catalyst remains in the separation chamber of the high gradient magnetic separation device E2 and the pipeline connected thereto, which makes it possible to obtain unqualified products with excessive catalyst content in the initial stage of the next new round of the first separation process. Introducing this part of the unqualified product into the concentrated solution and continuing the second separation is more conducive to the full utilization of the heavy wax raw material and can separate more waste catalyst.

[0071] According to the present invention, the method further includes discharging the excess flushing liquid generated by continuous accumulation through the flushing liquid external discharge line of the system. After each round of magnetic separation, a certain amount of heavy wax will remain in the high gradient magnetic separation device E2. After flushing and the second separation, part of this heavy wax will be incorporated into the flushing liquid. As the system runs longer, the amount of flushing liquid accumulates more and more. When the liquid level exceeds the threshold of the flushing liquid tank E6, it needs to be discharged through the flushing liquid external discharge line.

[0072] The following combination Figure 1 , the system for separating the Fischer-Tropsch synthesis heavy wax and the catalyst and the method for separating the Fischer-Tropsch synthesis heavy wax and the catalyst using the system according to the present invention are further described in detail.

[0073] like Figure 1 As shown, the product slurry containing the catalyst and the heavy wax product exiting the slurry bed Fischer-Tropsch synthesis reactor is introduced into a flash tank, and the synthesis gas and low-carbon hydrocarbons dissolved in the product slurry are removed under a flash pressure of 0.1-0.8 MPa, and the temperature is reduced to 130-250° C. to obtain Fischer-Tropsch synthesis heavy wax (wherein the catalyst content is 20-500 mg / kg) which is stored in the heavy wax raw material tank E1;

[0074] The heavy wax in the heavy wax raw material tank E1 is introduced into the high gradient magnetic separation device E2 for the first separation. The unqualified wax obtained in the initial stage of separation is sent to the concentrated liquid tank E4 through the unqualified product line. After a short transition, the qualified wax obtained by separation (wherein the catalyst content is less than 10 mg / kg) is drawn out and stored in the heavy wax product tank E3. During the first separation, the flushing pipeline is closed.

[0075] When the magnetic medium in the high gradient magnetic separation device E2 absorbs and deposits a sufficient amount of catalyst, the internal pressure difference of the high gradient magnetic separation device E2 will exceed the specified threshold or the catalyst content in the heavy wax product leaving the high gradient magnetic separation device E2 will be higher than the index requirement of qualified wax. At this time, it is necessary to close the heavy wax inlet and outlet pipeline valves of the high gradient magnetic separation device E2, and cut off the power to prevent the magnetic field from being generated. Use a flushing liquid (which can be at least one of unseparated heavy wax, separated qualified wax, paraffin and heavy diesel) to flush the high gradient magnetic separation device E2. The device E2 is flushed multiple times to obtain a concentrated solution containing the spent catalyst (wherein the catalyst content is 1000-50000 mg / kg), and is sent to the concentrated solution tank E4; after the flushing is completed, the flushing pipeline is closed, the magnet of the high gradient magnetic separation device E2 is powered on again, and the heavy wax inlet and outlet pipeline valves of the high gradient magnetic separation device E2 are opened to start a new round of the first separation process; multiple high gradient magnetic separation devices E2 can be connected in parallel to meet the switching of the first separation during flushing;

[0076] The concentrate in the concentrate tank E4 is introduced into the second separation device E5 for second separation, and the obtained waste catalyst is sent to the waste catalyst receiving tank E7, and the obtained clear liquid with the catalyst separated (wherein the catalyst content is 500-2000 mg / kg) is sent to the flushing liquid tank E6 to be incorporated into the flushing liquid, and circulated for flushing the high gradient magnetic separation device E2; as the system continues to operate, when the liquid level of the flushing liquid tank E6 exceeds the threshold value, the excess flushing liquid is discharged through the flushing liquid discharge pipeline.

[0077] The present invention will be described in detail below by way of examples. In the following examples and comparative examples,

[0078] High gradient magnetic separation device: the separation chamber has a diameter of 100 mm and a height of 120 mm; it is filled with 2.1% by volume of magnetically conductive stainless steel wool (material: SUS430, diameter: 0.01 mm);

[0079] Cylindrical magnetic separator: Refer to the structure of the rotary drum magnetic separation device disclosed in CN111187636A, wherein the diameter of the rotary drum is 600 mm and the length is 400 mm; the magnet adopts permanent magnetic poles, arranged in a fan shape, and the central angle of the fan is 180°.

[0080] Example 1

[0081] like Figure 1 As shown, the product slurry containing the catalyst and the heavy wax product exiting the slurry bed Fischer-Tropsch synthesis reactor is introduced into a flash tank, and under the conditions of a pressure of 0.2 MPa and a temperature of 170° C. in the flash tank, the synthesis gas and low-carbon hydrocarbons dissolved in the product slurry are removed to obtain Fischer-Tropsch synthesis heavy wax (wherein the catalyst content is 500 mg / kg) and stored in the heavy wax feed tank E1;

[0082] The heavy wax in the heavy wax raw material tank E1 is introduced from bottom to top into the high gradient magnetic separator E2 for the first separation (the feed rate is 163 kg / h, the magnetic induction intensity is 3000 Gauss, the cross-sectional flow rate of the heavy wax flowing through the high gradient magnetic separator E2 is 0.002 m / s, and the separation time is 92 min). The unqualified wax obtained in the initial stage of separation is sent to the concentrated liquid tank E4 through the unqualified product line. After a short transition, the qualified wax obtained by separation (the catalyst content thereof is 8 mg / kg) is drawn out from the upper end outlet of the high gradient magnetic separator E2 and stored in the heavy wax product tank E3; the shell of the high gradient magnetic separator E2 is heated with steam at a temperature of 170° C., and nitrogen is introduced so that the pressure in the separation chamber of the high gradient magnetic separator E2 is 0.1 MPa; during the first separation, the flushing pipeline is kept closed;

[0083] When the outlet product concentration of the high gradient magnetic separator E2 exceeds 10 mg / kg, the heavy wax inlet and outlet pipeline valves of the high gradient magnetic separator E2 are closed, and the power is turned off so that the magnet does not generate a magnetic field. At the same time, the flushing pipeline is opened, and the unseparated raw material heavy wax is used as a flushing liquid to flush the high gradient magnetic separator E2 from top to bottom (the flushing liquid flow rate is 0.18 m / s, the single flushing time is 10 s, and the number of flushings is 2 times), and a concentrated solution containing waste catalyst (wherein the catalyst content is 1500 mg / kg) is obtained, and sent to the concentrated solution tank E4; after the flushing is completed, the flushing pipeline is closed, the magnet of the high gradient magnetic separator E2 is powered on again, and the heavy wax inlet and outlet pipeline valves of the high gradient magnetic separator E2 are opened to start a new round of the first separation process;

[0084] The concentrate in the concentrate tank E4 is introduced into the cylindrical magnetic separator E5 for the second separation (the feed rate is 150 kg / h, the concentrate flows counterclockwise on the inner wall of the cylindrical magnetic separator E5, the drum rotates clockwise, the magnetic induction intensity on the drum surface is 2000 Gauss, and the surface linear velocity of the drum is 0.03 m / s), the shell of the cylindrical magnetic separator E5 is heated with steam so that the temperature inside the magnetic separator is 180° C., and nitrogen is introduced at the same time so that the working pressure of the magnetic separator is 0.02 MPa. After the second separation, the waste catalyst (wherein the mass fraction of solid catalyst is 60%) is sent to the waste catalyst receiving tank E7, and the clear liquid (wherein the content of catalyst is 500 mg / kg) separated from the catalyst is sent to the flushing liquid tank E6 and incorporated into the flushing liquid, and circulated for flushing the high gradient magnetic separator E2; the separation efficiency of the cylindrical magnetic separator E5 is 66%;

[0085] As the system continues to operate, when the liquid level in the flushing liquid tank E6 exceeds a threshold value, excess flushing liquid is discharged through the flushing liquid discharge pipeline.

[0086] As a result, in one adsorption and flushing cycle of the high gradient magnetic separation device, the actual separation efficiency of the heavy wax from the catalyst was 98.4%, and the flushing efficiency of the high gradient magnetic separator E2 was 98%.

[0087] Comparative Example 1

[0088] The method of Example 1 is the same as that of Example 1, except that the concentrate in the concentrate tank E4 is introduced into the cylindrical magnetic separator E5 for second separation, and the obtained clear liquid with the catalyst separated is returned to the heavy wax raw material tank E1 and combined with the heavy wax raw material. Other conditions are the same as those of Example 1.

[0089] As a result, in one adsorption and flushing cycle of the high gradient magnetic separator, the actual separation efficiency of the heavy wax from the catalyst was 65.3%, and the flushing efficiency of the high gradient magnetic separator E2 was 98%.

[0090] Comparative Example 2

[0091] The method of Example 1 is used, except that the single flushing time of the high gradient magnetic separator E2 is changed to 5s, the number of flushing times is changed to 1, and a concentrated solution containing waste catalyst (the catalyst content of which is 4200 mg / kg) is obtained; the concentrated solution is introduced into the cylindrical magnetic separator E5 for the second separation, the surface linear speed of the rotating drum is changed to 0.04 m / s, the catalyst content in the obtained clear solution from which the catalyst is separated is 2200 mg / kg, the mass fraction of solid catalyst in the obtained waste catalyst is 25%, and the separation efficiency of the cylindrical magnetic separator E5 is 48%. Other conditions are the same as those of Example 1.

[0092] The result is that in one adsorption and flushing cycle of the high gradient magnetic separation device, the actual separation efficiency of heavy wax and catalyst is 98.4%; the catalyst concentration in the clear liquid obtained by the second separation is too high, which in turn makes the catalyst concentration in the flushing liquid too high, and the flushing efficiency of the high gradient magnetic separator E2 is only 70%. The significantly reduced flushing efficiency will significantly reduce the adsorption amount of the catalyst of the high gradient magnetic separator E2 in a single adsorption and flushing cycle.

[0093] Example 2

[0094] like Figure 1 As shown, the product slurry containing the catalyst and the heavy wax product exiting the slurry bed Fischer-Tropsch synthesis reactor is introduced into a flash tank, and under the conditions of a pressure of 0.2 MPa and a temperature of 170° C. in the flash tank, the synthesis gas and low-carbon hydrocarbons dissolved in the product slurry are removed to obtain Fischer-Tropsch synthesis heavy wax (wherein the catalyst content is 200 mg / kg) and stored in the heavy wax raw material tank E1;

[0095] The heavy wax in the heavy wax raw material tank E1 is introduced from bottom to top into the high gradient magnetic separator E2 for the first separation (the feed rate is 163 kg / h, the magnetic induction intensity is 3000 Gauss, the cross-sectional flow rate of the heavy wax flowing through the high gradient magnetic separator E2 is 0.002 m / s, and the separation time is 237 min). The unqualified wax obtained in the initial stage of separation is sent to the concentrated liquid tank E4 through the unqualified product line. After a short transition, the qualified wax obtained by separation (the catalyst content thereof is 6 mg / kg) is drawn out from the upper end outlet of the high gradient magnetic separator E2 and stored in the heavy wax product tank E3; the shell of the high gradient magnetic separator E2 is heated with steam at a temperature of 170° C., and nitrogen is introduced so that the pressure in the separation chamber of the high gradient magnetic separator E2 is 0.1 MPa; during the first separation, the flushing pipeline is kept closed;

[0096] When the outlet product concentration of the high gradient magnetic separator E2 exceeds 10 mg / kg, the heavy wax inlet and outlet pipeline valves of the high gradient magnetic separator E2 are closed, and the power is turned off so that the magnet does not generate a magnetic field. At the same time, the flushing pipeline is opened, and the unseparated raw material heavy wax is used as a flushing liquid to flush the high gradient magnetic separator E2 from top to bottom (the flushing liquid flow rate is 0.18 m / s, the single flushing time is 5 s, and the number of flushings is 2 times), and a concentrated solution containing waste catalyst (wherein the catalyst content is 2700 mg / kg) is obtained, and sent to the concentrated solution tank E4; after the flushing is completed, the flushing pipeline is closed, the magnet of the high gradient magnetic separator E2 is powered on again, and the heavy wax inlet and outlet pipeline valves of the high gradient magnetic separator E2 are opened to start a new round of the first separation process;

[0097] The concentrate in the concentrate tank E4 is introduced into the cylindrical magnetic separator E5 for the second separation (the feed rate is 150 kg / h, the concentrate flows counterclockwise on the inner wall of the cylindrical magnetic separator E5, the drum rotates clockwise, the magnetic induction intensity on the drum surface is 2000 Gauss, and the surface linear velocity of the drum is 0.05 m / s), the shell of the cylindrical magnetic separator E5 is heated with steam so that the temperature inside the magnetic separator is 180° C., and nitrogen is introduced at the same time so that the working pressure of the magnetic separator is 0.02 MPa. After the second separation, the waste catalyst (wherein the mass fraction of solid catalyst is 45%) is sent to the waste catalyst receiving tank E7, and the clear liquid (wherein the content of catalyst is 2000 mg / kg) separated from the catalyst is sent to the flushing liquid tank E6 and incorporated into the flushing liquid, and circulated for flushing the high gradient magnetic separator E2; the separation efficiency of the cylindrical magnetic separator E5 is 27%;

[0098] As the system continues to operate, when the liquid level in the flushing liquid tank E6 exceeds a threshold value, excess flushing liquid is discharged through the flushing liquid discharge pipeline.

[0099] As a result, in one adsorption and flushing cycle of the high gradient magnetic separation device, the actual separation efficiency of the heavy wax from the catalyst was 97%, and the flushing efficiency of the high gradient magnetic separator E2 was 90%.

[0100] Example 3

[0101] like Figure 1 As shown, the product slurry containing the catalyst and the heavy wax product exiting the slurry bed Fischer-Tropsch synthesis reactor is introduced into a flash tank, and under the conditions of a pressure of 0.1 MPa and a temperature of 150° C. in the flash tank, the synthesis gas and low-carbon hydrocarbons dissolved in the product slurry are removed to obtain Fischer-Tropsch synthesis heavy wax (wherein the catalyst content is 20 mg / kg) and stored in a heavy wax feed tank E1;

[0102] The heavy wax in the heavy wax raw material tank E1 is introduced from bottom to top into the high gradient magnetic separator E2 for the first separation (the feed rate is 326 kg / h, the magnetic induction intensity is 5000 Gauss, the cross-sectional flow rate of the heavy wax flowing through the high gradient magnetic separator E2 is 0.004 m / s, and the separation time is 1264 min). The unqualified wax obtained in the initial stage of separation is sent to the concentrated liquid tank E4 through the unqualified product line. After a short transition, the qualified wax obtained by separation (the catalyst content thereof is 2 mg / kg) is drawn out from the upper end outlet of the high gradient magnetic separator E2 and stored in the heavy wax product tank E3; the shell of the high gradient magnetic separator E2 is heated with steam at a temperature of 150° C., and nitrogen is introduced so that the pressure in the separation chamber of the high gradient magnetic separator E2 is 0.1 MPa; during the first separation, the flushing pipeline is kept closed;

[0103] When the outlet product concentration of the high gradient magnetic separator E2 exceeds 10 mg / kg, the heavy wax inlet and outlet pipeline valves of the high gradient magnetic separator E2 are closed, and the power is turned off so that the magnet does not generate a magnetic field. At the same time, the flushing pipeline is opened, and the unseparated raw material heavy wax is used as a flushing liquid to flush the high gradient magnetic separator E2 from top to bottom (the flushing liquid flow rate is 0.15 m / s, the single flushing time is 10 s, and the number of flushings is 2 times), and a concentrated solution containing waste catalyst (wherein the catalyst content is 1800 mg / kg) is obtained, and sent to the concentrated solution tank E4; after the flushing is completed, the flushing pipeline is closed, the magnet of the high gradient magnetic separator E2 is powered on again, and the heavy wax inlet and outlet pipeline valves of the high gradient magnetic separator E2 are opened to start a new round of the first separation process;

[0104] The concentrate in the concentrate tank E4 is introduced into the cylindrical magnetic separator E5 for the second separation (the feed rate is 150 kg / h, the concentrate flows counterclockwise on the inner wall of the cylindrical magnetic separator E5, the drum rotates clockwise, the magnetic induction intensity on the drum surface is 2000 Gauss, and the surface linear velocity of the drum is 0.03 m / s), the shell of the cylindrical magnetic separator E5 is heated with steam so that the temperature inside the magnetic separator is 150° C., and nitrogen is introduced at the same time so that the working pressure of the magnetic separator is 0.01 MPa. After the second separation, the waste catalyst (wherein the mass fraction of solid catalyst is 62%) is sent to the waste catalyst receiving tank E7, and the clear liquid (wherein the content of catalyst is 500 mg / kg) separated from the catalyst is sent to the flushing liquid tank E6 and incorporated into the flushing liquid, and circulated for flushing the high gradient magnetic separator E2; the separation efficiency of the cylindrical magnetic separator E5 is 72%;

[0105] As the system continues to operate, when the liquid level in the flushing liquid tank E6 exceeds a threshold value, excess flushing liquid is discharged through the flushing liquid discharge pipeline.

[0106] As a result, in one adsorption and flushing cycle of the high gradient magnetic separation device, the actual separation efficiency of the heavy wax from the catalyst was 90%, and the flushing efficiency of the high gradient magnetic separator E2 was 98%.

[0107] Example 4

[0108] like Figure 1 As shown, the product slurry containing the catalyst and the heavy wax product exiting the slurry bed Fischer-Tropsch synthesis reactor is introduced into a flash tank, and under the conditions of a pressure of 0.3 MPa and a temperature of 190° C. in the flash tank, the synthesis gas and low-carbon hydrocarbons dissolved in the product slurry are removed to obtain Fischer-Tropsch synthesis heavy wax (wherein the catalyst content is 200 mg / kg) and stored in a heavy wax feed tank E1;

[0109] The heavy wax in the heavy wax raw material tank E1 is introduced from bottom to top into the high gradient magnetic separator E2 for the first separation (the feed rate is 244 kg / h, the magnetic induction intensity is 2000 Gauss, the cross-sectional flow rate of the heavy wax flowing through the high gradient magnetic separator E2 is 0.003 m / s, and the separation time is 159 min). The unqualified wax obtained in the initial stage of separation is sent to the concentrated liquid tank E4 through the unqualified product line. After a short transition, the qualified wax obtained by separation (the catalyst content thereof is 9 mg / kg) is drawn out from the upper end outlet of the high gradient magnetic separator E2 and stored in the heavy wax product tank E3; the shell of the high gradient magnetic separator E2 is heated with steam at a temperature of 190° C., and nitrogen is introduced so that the pressure in the separation chamber of the high gradient magnetic separator E2 is 0.2 MPa; during the first separation, the flushing pipeline is kept closed;

[0110] When the outlet product concentration of the high gradient magnetic separator E2 exceeds 10 mg / kg, the heavy wax inlet and outlet pipeline valves of the high gradient magnetic separator E2 are closed, and the power is turned off so that the magnet does not generate a magnetic field. At the same time, the flushing pipeline is opened, and the unseparated raw material heavy wax is used as a flushing liquid to flush the high gradient magnetic separator E2 from top to bottom (the flushing liquid flow rate is 0.3 m / s, the single flushing time is 5 s, and the number of flushings is 2 times), and a concentrated solution containing the waste catalyst (wherein the catalyst content is 1800 mg / kg) is obtained, and sent to the concentrated solution tank E4; after the flushing is completed, the flushing pipeline is closed, the magnet of the high gradient magnetic separator E2 is powered on again, and the heavy wax inlet and outlet pipeline valves of the high gradient magnetic separator E2 are opened to start a new round of the first separation process;

[0111] The concentrate in the concentrate tank E4 is introduced into the cylindrical magnetic separator E5 for the second separation (the feed rate is 150 kg / h, the concentrate flows counterclockwise on the inner wall of the cylindrical magnetic separator E5, the drum rotates clockwise, the magnetic induction intensity on the drum surface is 2000 Gauss, and the surface linear velocity of the drum is 0.04 m / s), the shell of the cylindrical magnetic separator E5 is heated with steam so that the temperature inside the magnetic separator is 190° C., and nitrogen is introduced at the same time so that the working pressure of the magnetic separator is 0.01 MPa. After the second separation, the waste catalyst (wherein the mass fraction of solid catalyst is 58%) is sent to the waste catalyst receiving tank E7, and the clear liquid (wherein the content of catalyst is 1000 mg / kg) separated from the catalyst is sent to the flushing liquid tank E6 and incorporated into the flushing liquid, and circulated for flushing the high gradient magnetic separator E2; the separation efficiency of the cylindrical magnetic separator E5 is 44%;

[0112] As the system continues to operate, when the liquid level in the flushing liquid tank E6 exceeds a threshold value, excess flushing liquid is discharged through the flushing liquid discharge pipeline.

[0113] As a result, in one adsorption and flushing cycle of the high gradient magnetic separation device, the actual separation efficiency of the heavy wax from the catalyst was 95.5%, and the flushing efficiency of the high gradient magnetic separator E2 was 98%.

[0114] Example 5

[0115] like Figure 1 As shown, the product slurry containing the catalyst and the heavy wax product exiting the slurry bed Fischer-Tropsch synthesis reactor is introduced into a flash tank, and under the conditions of a pressure of 0.5 MPa and a temperature of 210° C. in the flash tank, the synthesis gas and low-carbon hydrocarbons dissolved in the product slurry are removed to obtain Fischer-Tropsch synthesis heavy wax (wherein the catalyst content is 500 mg / kg) and stored in the heavy wax feed tank E1;

[0116] The heavy wax in the heavy wax raw material tank E1 is introduced from bottom to top into the high gradient magnetic separator E2 for the first separation (the feed rate is 407 kg / h, the magnetic induction intensity is 6000 Gauss, the cross-sectional flow rate of the heavy wax flowing through the high gradient magnetic separator E2 is 0.005 m / s, and the separation time is 37 min). The unqualified wax obtained in the initial stage of separation is sent to the concentrated liquid tank E4 through the unqualified product line. After a short transition, the qualified wax obtained by separation (the catalyst content thereof is 9 mg / kg) is drawn out from the upper end outlet of the high gradient magnetic separator E2 and stored in the heavy wax product tank E3; the shell of the high gradient magnetic separator E2 is heated with steam at a temperature of 190° C., and nitrogen is introduced so that the pressure in the separation chamber of the high gradient magnetic separator E2 is 0.3 MPa; during the first separation, the flushing pipeline is kept closed;

[0117] When the outlet product concentration of the high gradient magnetic separator E2 exceeds 10 mg / kg, the heavy wax inlet and outlet pipeline valves of the high gradient magnetic separator E2 are closed, and the power is turned off so that the magnet does not generate a magnetic field. At the same time, the flushing pipeline is opened, and the unseparated raw material heavy wax is used as a flushing liquid to flush the high gradient magnetic separator E2 from top to bottom (the flushing liquid flow rate is 0.1 m / s, the single flushing time is 10 s, and the number of flushings is 2 times), and a concentrated solution containing waste catalyst (wherein the catalyst content is 2500 mg / kg) is obtained, and sent to the concentrated solution tank E4; after the flushing is completed, the flushing pipeline is closed, the magnet of the high gradient magnetic separator E2 is powered on again, and the heavy wax inlet and outlet pipeline valves of the high gradient magnetic separator E2 are opened to start a new round of the first separation process;

[0118] The concentrate in the concentrate tank E4 is introduced into the cylindrical magnetic separator E5 for the second separation (the feed rate is 150 kg / h, the concentrate flows counterclockwise on the inner wall of the cylindrical magnetic separator E5, the drum rotates clockwise, the magnetic induction intensity on the drum surface is 2000 Gauss, and the surface linear velocity of the drum is 0.03 m / s), the shell of the cylindrical magnetic separator E5 is heated with steam so that the temperature inside the magnetic separator is 190° C., and nitrogen is introduced at the same time so that the working pressure of the magnetic separator is 0.1 MPa. After the second separation, the waste catalyst (wherein the mass fraction of solid catalyst is 45%) is sent to the waste catalyst receiving tank E7, and the clear liquid (wherein the content of catalyst is 1000 mg / kg) separated from the catalyst is sent to the flushing liquid tank E6 and incorporated into the flushing liquid, and circulated for flushing the high gradient magnetic separator E2; the separation efficiency of the cylindrical magnetic separator E5 is 59%;

[0119] As the system continues to operate, when the liquid level in the flushing liquid tank E6 exceeds a threshold value, excess flushing liquid is discharged through the flushing liquid discharge pipeline.

[0120] As a result, in one adsorption and flushing cycle of the high gradient magnetic separation device, the actual separation efficiency of the heavy wax from the catalyst was 98.2%, and the flushing efficiency of the high gradient magnetic separator E2 was 90%.

[0121] It can be seen from the above examples and comparative examples that in Examples 1-5, the second separation product liquid (catalyst content of 500-2000 mg / kg) with a higher catalyst concentration is circulated as a flushing liquid for the high gradient magnetic separation device for the first separation of the heavy wax raw material (catalyst content of 20-500 mg / kg), which can make the actual separation efficiency and flushing efficiency of the high gradient magnetic separation device reach more than 90%. However, Comparative Example 1 adopts the scheme of returning the clear liquid obtained from the second separation to the raw material tank, and the actual separation efficiency of the heavy wax and the catalyst is only 65.3%; the catalyst concentration of the second separation product liquid in Comparative Example 2 is too high, resulting in too low flushing efficiency of the high gradient magnetic separator E2.

[0122] By using the system and method provided by the present invention, the separation efficiency can be significantly improved and an ideal flushing effect can be obtained.

[0123] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for separating Fischer-Tropsch synthesis heavy wax and catalyst, characterized in that: include: (1) pretreating the Fischer-Tropsch synthesis product to obtain a Fischer-Tropsch synthesis heavy wax; (2) introducing the heavy wax into a system for separating Fischer-Tropsch synthesis heavy wax from a catalyst, and performing a first separation in a high-gradient magnetic separation device of the system to obtain qualified wax; (3) introducing the flushing liquid into the high gradient magnetic separation device through the flushing pipeline of the system for flushing to obtain a concentrated solution containing the spent catalyst; (4) introducing the concentrated solution into the second separation device of the system for second separation to obtain waste catalyst and a clear solution from which the catalyst is separated, and the clear solution is returned to step (3) and added to the flushing solution; wherein: The content of the catalyst in the Fischer-Tropsch synthesis heavy wax is 20-500 mg / kg, and the content of the catalyst in the clear liquid is 500-2000 mg / kg; The system for separating Fischer-Tropsch synthesis heavy wax and catalyst comprises: Heavy wax raw material tank, high gradient magnetic separation device, heavy wax product tank, concentrated liquid tank, second separation device, flushing liquid tank, spent catalyst receiving tank and flushing pipeline; wherein, The heavy wax raw material tank stores heavy wax produced from a Fischer-Tropsch synthesis unit; The high-gradient magnetic separation device is connected to the heavy wax raw material tank, the heavy wax product tank, the concentrated liquid tank and the flushing pipeline, and is used to perform a first separation on the heavy wax, and the obtained qualified wax is stored in the heavy wax product tank; The flushing pipeline conveys the flushing liquid from the flushing liquid tank to flush the catalyst adsorbed in the high gradient magnetic separation device, and the obtained concentrated liquid containing the spent catalyst is sent to the concentrated liquid tank; The second separation device is connected to the concentrate tank, the flushing liquid tank and the waste catalyst receiving tank, and is used to perform a second separation on the concentrate. The clear liquid from which the catalyst is separated enters the flushing liquid tank as a flushing liquid raw material, and the waste catalyst enters the waste catalyst receiving tank.

2. The method according to claim 1, wherein: The high gradient magnetic separation device comprises: a cylinder, a magnetic medium filled in the cylinder and a magnet surrounding the cylinder.

3. The method according to claim 1 or 2, wherein: The second separation device is at least one of a cylindrical magnetic separator, a centrifugal separator, a hydrocyclone separator and a sedimentation separation tank.

4. The method according to claim 3, wherein: The second separation device is a cartridge separator.

5. The method according to claim 1 or 2, wherein: The system further comprises a defective product line, which is connected to the high gradient magnetic separation device and the concentrated liquid tank and is used to send the defective wax produced by the high gradient magnetic separation device in the initial stage of separation into the concentrated liquid tank.

6. The method according to claim 1 or 2, wherein: The system also includes a flushing liquid discharge pipeline connected to the flushing liquid tank, which is used to discharge the excess flushing liquid accumulated in the flushing liquid tank.

7. The method according to claim 1 or 2, wherein: In step (1), the pretreatment includes flash evaporation and cooling in sequence.

8. The method according to claim 7, wherein: The flash evaporation pressure is 0.1-0.8 MPa; And / or, the temperature reached by the cooling is 130-250°C.

9. The method according to claim 8, wherein: The temperature reached by the cooling is 150-190°C.

10. The method according to claim 1 or 2, wherein: In step (2), the first separation is carried out under heating and an inert atmosphere; And / or, the working pressure of the high gradient magnetic separation device is 0.01-0.6 MPa.

11. The method according to claim 10, wherein: The working pressure of the high gradient magnetic separation device is 0.03-0.4 MPa.

12. The method according to claim 11, wherein: The heating temperature is 130-250°C.

13. The method according to claim 12, wherein: The heating temperature is 150-190°C.

14. The method according to claim 1 or 2, wherein: In step (2), in the high gradient magnetic separation device, the magnetic induction intensity of the first separation is 2000-20000 Gauss; And / or, the cross-sectional flow velocity of the heavy wax flowing through the high gradient magnetic separation device is 0.001-0.05 m / s.

15. The method according to claim 14, wherein: In step (2), in the high gradient magnetic separation device, the magnetic induction intensity of the first separation is 2000-10000 Gauss; And / or, the cross-sectional flow velocity of the heavy wax flowing through the high gradient magnetic separation device is 0.002-0.03 m / s.

16. The method according to claim 1 or 2, wherein: In step (3), the flushing conditions include: the flushing liquid flow rate is 0.1-1m / s, the single flushing time is 5-60s, and the flushing times are 1-5 times.

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