Method for improving filtered oil yield of slurry oil filtering system

Abstract

According to the method for improving the filtered oil yield of the oil slurry filtering system, the oil slurry filtering system comprises a filtering unit and a regeneration unit, a filter is arranged in the filtering unit, the regeneration unit is provided with a back flushing gas tank and a material pressing gas tank, the back flushing gas tank is communicated with a filtered oil outlet pipeline through a pipeline, and the material pressing gas tank is communicated with a material pressing gas tank through a pipeline. And the material pressing gas tank is communicated with the top inlet of the filter through a pipeline. The filtering mode, the forward pressing mode, the deslagging mode, the purging mode and the filtering mode of the next round are adopted, the forward pressing mode, the deslagging mode and the purging mode are alternately carried out for operation, and the yield of filtered oil is increased.

Description

Technical Field

[0001] The invention relates to the field of oil slurry filtration, in particular to a method for improving the oil yield after filtration in an oil slurry filtration system. Background Art

[0002] Catalytic cracking is an important process technology for the production of gasoline and diesel from heavy oil. It is one of the most important and widely used technologies in the current oil refining field. However, catalytic cracking will produce slurry oil as a by-product. In particular, catalytic cracking currently uses hydrogenated residual oil or wax oil blended with residual oil as raw materials. The yield of slurry oil is relatively high, generally around 5%, and the highest yield can even reach 8%. Slurry oil is rich in polycyclic aromatic hydrocarbons, which can be used as raw materials for the production of marine fuel, carbon black, carbon fiber, etc. However, since the slurry oil contains about 1 to 6 g / L of catalytic cracking catalyst particles, it cannot meet the raw material index requirements for the production of marine fuel, carbon black, carbon fiber, etc., so its current utilization value is relatively low.

[0003] In order to improve the utilization value of oil slurry, solid particles in the oil slurry must be removed first. There are many ways to remove solid particles, such as sedimentation, flocculation, centrifugation and other methods, but these methods have too low removal efficiency. Filtration is a better way to remove solid particles in oil slurry. The filtration process is divided into blind-end filtration and cross-flow filtration according to the different fluids and separation directions. In the blind-end filtration process, a single filter is generally operated intermittently. After the filter pressure drop reaches a certain value or reaches a certain time, the oil slurry in the filter needs to be discharged and the filter material is regenerated so that the filtration area of ​​the filter material can be restored to the original amount. The amount of slag liquid discharged from the filter directly affects the yield of the desolidified product in the filtration process. Under the same feed amount in the same time, the larger the amount of slag liquid discharged, the lower the yield of the desolidified product. Generally, after the filter equipment is determined, the yield of the desolidified product is basically fixed.

[0004] CN111592908A discloses an oil slurry filtration system and an oil slurry filtration method, wherein at least one filter is arranged in a filtration unit, and the used filter is back-purged with a purge medium, the purge medium is an inert gas and / or flushing oil, the flushing oil is filtered oil, and a pinhole-free filter bag made of a flexible filter material is arranged in the filter.

[0005] CN111592909A discloses an oil slurry filtering system and an oil slurry filtering method, comprising a filtering unit and a filter aid buffer tank, wherein at least one filter is provided in the filtering unit, and an oil slurry inlet pipeline, a filtered oil outlet pipeline, and a filter residue discharge pipeline are respectively connected to each filter, the outlet of the filter aid buffer tank is connected to the oil slurry inlet of the filter, and a pinhole-free filter bag of a flexible filtering material is provided in the filter. In the oil slurry filtering method, the oil slurry enters the filter through the oil slurry inlet pipeline connected to the filter for filtering, and the filtered oil is extracted from the filtered oil outlet pipeline.

[0006] Existing technologies mostly focus on the effectiveness of filtration systems and the stability of filtration products. Summary of the invention

[0007] The technical problem to be solved by the present invention is the low oil yield after filtration in the prior art, and a method for improving the oil yield after filtration of an oil slurry filtration system is provided.

[0008] The present invention provides a method for improving the oil recovery rate after filtering of an oil slurry filtering system. The oil slurry filtering system comprises a filtering unit and a regeneration unit. A filter is arranged in the filtering unit. The filter has at least one filtering component. An oil slurry inlet is arranged at the lower part of the filter. A filtered oil outlet is arranged at the upper part of the filter. A filter residue outlet is arranged at the bottom of the filter. A pressurized gas inlet is arranged at the top of the filter. An oil slurry inlet pipeline, a filtered oil outlet pipeline, a filter residue discharge pipeline and a pressurized gas inlet pipeline are respectively connected to each filter.

[0009] The filter assembly is provided with a central tube, a support tube, and a flexible filter material in sequence from the inside to the outside. The central tube has no holes on its wall, and the support tube has holes evenly on its wall. The upper end and the lower end of the support tube are provided with a first tuning fork level gauge switch and a second tuning fork level gauge switch, respectively.

[0010] The regeneration unit is provided with a back-blowing gas tank and a pressurizing gas tank, the outlet of the back-blowing gas tank is connected to the outlet pipeline of the filtered oil, and the outlet pipeline of the pressurizing gas tank is connected to the pressurizing gas inlet at the top of the filter;

[0011] Slurry filtration methods include:

[0012] Filtering mode: The oil slurry inlet and filtered oil outlet of the filter are in the open state, and the other inlets and outlets of the filter are in the closed state. After the oil slurry enters the filter from the oil slurry inlet pipeline, the oil slurry flows from the bottom to the top of the center tube of the filter assembly, and the filtered oil is discharged from the top of the center tube. The filtered oil is extracted from the filtered oil outlet of the filter;

[0013] Forward pressure mode: the pressure gas inlet of the filter and the filtered oil outlet of the filter are open, and the other inlets and outlets of the filter are closed. The pressure gas enters the filter from the pressure gas inlet, presses the oil slurry stored in the filter out from the filtered oil outlet of the filter, and mixes with the filtered oil;

[0014] Slag discharge mode: The filter residue outlet is open, and the other inlets and outlets of the filter are closed, so that the residual oil slurry in the filter is discharged;

[0015] Purge mode: The filter residue outlet is open, and the back-blowing gas enters the filter from the oil outlet pipeline after filtration for purging. The back-blowing gas flows from the top of the center tube of the filter assembly from top to bottom and is discharged from the bottom, and then purged to the inner surface of its flexible filter material.

[0016] In one embodiment of the present invention, in the filter assembly, the diameter ratio of the central tube to the support tube is in the range of 1:2 to 1:6, the distance between the bottom of the central tube end and the bottom of the support tube end is 0.2m to 0.8m, and the porosity on the support tube wall is 55% to 85%.

[0017] In one embodiment of the present invention, the flexible filter material is fixed to the outer surface of the support tube by upper and lower heads.

[0018] In one embodiment of the present invention, the flexible filter material is selected from one or more of polyethylene, nylon, polyphenylene sulfide, polyimide, polytetrafluoroethylene, aramid, polyurethane, and glass fiber.

[0019] In one embodiment of the present invention, the flexible filter material is a composite of any two or more selected from polyethylene, nylon, polyphenylene sulfide, polyimide, polytetrafluoroethylene, aramid, polyurethane, and glass fiber.

[0020] In one embodiment of the present invention, the filtration accuracy of the flexible filter material is 0.1 to 15 microns, preferably 0.1 to 10 microns, more preferably 0.2 to 5 microns. The gram weight of the flexible filter material is 300 to 1000 g / m 2 , preferably 520~660g / m 2 The warp breaking strength is 850N / 5cm~9000N / 5cm, and the weft breaking strength is 1000N / 5cm~11000N / 5cm; the thickness of the flexible filter material is 0.5~3.4mm, preferably 0.5~3.0mm, and more preferably 1.8~2.9mm.

[0021] In one embodiment of the present invention, the flexible filter material in the filter of the present invention can be a single layer (single) or a multi-layer (more than two). When it is a multi-layer form, the multi-layer flexible filter material is stacked, and at this time, there is no restriction on the number of stacked layers and the arrangement of the layers.

[0022] In one embodiment of the present invention, the flexible filter material includes a desolidification layer and a base fabric layer, the porosity of the desolidification layer is 25% to 98%, the porosity of the base fabric layer is 30% to 40%, the base fabric layer is made of polytetrafluoroethylene and / or polyphenylene sulfide, and the desolidification layer is made of polytetrafluoroethylene.

[0023] The base fabric layer is obtained by weaving the raw materials that can be made into flexible filter materials using weaving technology known in the art. There is no limitation on the weaving technology, including but not limited to hydroentanglement, thermal weaving, wet weaving, spunbonding, meltblowing, needle punching, stitching, hot rolling, etc. The desolidification layer is formed on the base fabric layer by methods known in the art such as hot pressing, laminating, hot rolling, etc., using the raw materials that can be made into flexible filter materials. The desolidification layer and the base fabric layer of the present invention can be prepared independently and successively, or they can be prepared in an integrated manner. The flexible filter material of the present invention, which at least includes a desolidification layer and a base fabric layer, can be prepared by methods known in the art, or commercial products can be used.

[0024] In one embodiment of the present invention, the flexible filter material includes at least a desolidification layer and a base fabric layer, but is not limited thereto and may be modified and derived therefrom. For example, based on the desolidification layer and the base fabric layer of the present invention, other layers may be further included without adversely affecting the effects of the present invention.

[0025] In one embodiment of the present invention, the backwash gas in the backwash gas tank is nitrogen and / or fuel gas.

[0026] In one embodiment of the present invention, the pressurized gas in the pressurized gas tank is nitrogen and / or fuel gas.

[0027] In one embodiment of the present invention, the slurry oil is catalytic cracking slurry oil and / or coal tar.

[0028] The inventors of the present invention have discovered through extensive research that when the filter pressure drop or filtration time reaches a certain value, the filter material (flexible filter material) still has a certain flux. At this time, the oil slurry level in the filter is higher than the filter assembly. If the slag discharge regeneration mode is directly adopted, this part of the oil slurry in the filter will be lost.

[0029] Therefore, the present invention sets a forward pressing mode: by introducing a certain pressure of pressing gas from the top of the filter, the oil slurry above the filter assembly is pressed out through a path consistent with the normal filtering flow direction (the forward direction of the filtering material), and this part of the forward pressing oil is mixed with the filtered oil. In the present invention, the forward pressing oil refers to: the oil slurry in the filter pressed out by the pressing gas in the forward pressing mode.

[0030] The forward pressing mode provided in the present invention, on the one hand, reduces the amount of oil slurry discharged to the filter residue outlet during regeneration, thereby increasing the oil yield after filtration. On the other hand, this part of the forward pressing oil is filtered oil, and does not need to be circulated to the oil slurry raw material tank for repeated filtration, thereby saving filtration costs.

[0031] In one embodiment of the present invention, in the filtration mode, when the pressure difference of the filter reaches or exceeds the pressure difference setting value, or reaches the set time, the filter is converted to the forward pressure mode operation;

[0032] The filtering mode ends and the forward pressing mode begins. At this time, the oil slurry level stored in the filter is higher than the first tuning fork level gauge switch. In the forward pressing mode, when the oil slurry level stored in the filter drops to the first tuning fork level gauge switch, the forward pressing mode is stopped and switched to the slag discharge mode. This operation not only avoids the situation where the pressing gas directly enters the rear filtered oil pipeline when the oil slurry level is lower than the top of the filter assembly, affecting the operation of the filtering system, but also improves the yield of filtered oil.

[0033] In one embodiment of the present invention, in the filtration mode, the filtration temperature in the filter is 30 to 250°C, preferably 60 to 180°C.

[0034] In one embodiment of the present invention, in the filtration mode, the pressure difference during use of the filter is 0.01-0.5 MPa.

[0035] In one embodiment of the present invention, in the filtering mode, the filter sets the filtering time to 24 hours to 96 hours.

[0036] In one embodiment of the present invention, when a filter is set in the filtration unit, the operation is performed in an alternating manner of filtration mode, forward pressure mode, slag discharge mode, purge mode and the next round of filtration mode, forward pressure mode, slag discharge mode, purge mode.

[0037] In the present invention, one filter or more than two filters may be provided in the filter unit. When multiple filters are provided, the present invention does not limit any connection mode. Multiple filters may be provided in parallel or in series, or in parallel and in series, or in parallel and in series at the same time. When multiple filters are provided, multiple filters with the same filtering accuracy may be used, or multiple filters with inconsistent filtering accuracy may be used.

[0038] In one embodiment of the present invention, when a plurality of filters are arranged in the filtration unit, when the pressure difference of a certain online filter reaches or exceeds the pressure difference setting value or reaches the set time, the filter is cut out of the filtration system and regenerated in the forward pressing mode, slag discharge mode and purge mode.

[0039] Compared with the prior art, the method for improving the oil yield after filtration of the oil slurry filtration system provided by the present invention can improve the oil yield after filtration and save filtration costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1It is a schematic diagram of one embodiment of the method for improving the oil yield after filtration of an oil slurry filtration system provided by the present invention.

[0041] Figure 2 It is a schematic diagram of another embodiment of the method for improving the oil yield after filtration of the oil slurry filtration system provided by the present invention.

[0042] Figure 3 It is a schematic diagram of the material flow direction in the filtration mode and the forward pressing mode in the oil slurry filtration method provided by the present invention.

[0043] Figure 4 It is a schematic diagram of the material flow direction in the purge mode in the oil slurry filtration method provided by the present invention. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited thereby.

[0045] Figure 1 FIG. 1 is a schematic diagram of one embodiment of the method for improving the oil recovery rate after filtration of the oil slurry filtration system provided by the present invention, as shown in FIG. Figure 1 As shown, the oil slurry filtration system includes a filtration unit and a regeneration unit, wherein a filter 1 is provided in the filtration unit, a filter assembly 2 is provided in the filter 1, an oil slurry inlet is provided at the lower part of the filter, a filtered oil outlet is provided at the upper part of the filter, a filter residue outlet is provided at the bottom of the filter, a pressurized gas inlet is provided at the top of the filter, and an oil slurry inlet pipeline 3, a filtered oil outlet pipeline 4, a filter residue discharge pipeline 5 and a pressurized gas inlet pipeline 9 are connected to the filter 1. From the inside to the outside, the filtration assembly 2 is provided with a central tube, a support tube and a flexible filter material in sequence, the central tube has no holes on the tube wall, the support tube has holes evenly on the tube wall, and a first tuning fork level gauge switch 6 and a second tuning fork level gauge switch 7 are provided at the upper and lower ends of the support tube. The regeneration unit is provided with a back-blowing gas tank 10 and a pressurized gas tank 8, the outlet of the back-blowing gas tank 10 is connected to the filtered oil outlet pipeline 4 via a pipeline 11, and the outlet of the pressurized gas tank 8 is connected to the pressurized gas inlet at the top of the filter via a pressurized gas inlet pipeline 9.

[0046] Figure 2 FIG. 1 is a schematic diagram of one embodiment of the method for improving the oil recovery rate after filtration of the oil slurry filtration system provided by the present invention, as shown in FIG. Figure 2As shown, the oil slurry filtering system includes a filtering unit and a regeneration unit. The filtering unit is provided with a filter 1 and a filter 3, an oil slurry inlet is provided at the lower part of the filter 1 and the filter 3, a filtered oil outlet is provided at the upper part of the filter 1 and the filter 3, a pressurized gas inlet is provided at the top of the filter 1 and the filter 3, and a filter residue outlet is provided at the bottom of the filter 1 and the filter 3. The oil slurry inlet pipeline 5, the filtered oil outlet pipeline 6, the filter residue discharge pipeline 7, and the pressurized gas inlet pipeline 9 are connected to the filter 1, and the oil slurry inlet pipeline 14, the filtered oil outlet pipeline 15, the filter residue discharge pipeline 16, and the pressurized gas inlet pipeline 17 are connected to the filter 3. The filter 1 is provided with a filtering component 2, and the filter 3 is provided with a filtering component 4. The filter components 2 and 4 are respectively provided with a central tube, a support tube, and a flexible filter material from the inside to the outside. The tube wall of the central tube is not perforated, and the tube wall of the support tube is evenly perforated. A first tuning fork level gauge switch 12 and a second tuning fork level gauge switch 13 are respectively provided at the upper end and the lower end of the support tube of the filter component 2, and a first tuning fork level gauge switch 19 and a second tuning fork level gauge switch 20 are respectively provided at the upper end and the lower end of the support tube of the filter component 4.

[0047] The regeneration unit is provided with a pressurized gas tank 8 and a back-blowing gas tank 10. The outlet of the pressurized gas tank 8 is connected to the pressurized gas inlet at the top of the filter 1 via a pressurized gas inlet pipeline 9, and the outlet of the pressurized gas tank 8 is connected to the pressurized gas inlet at the top of the filter 3 via a pressurized gas inlet pipeline 17. The outlet of the back-blowing gas tank 10 is connected to the filtered oil outlet pipeline 6 of the filter 1 via a pipeline 11, and the back-blowing gas tank 10 is connected to the filtered oil outlet pipeline 15 of the filter 3 via a pipeline 18.

[0048] Use Figure 2 When the filtration system shown is filtering, filter 1 and filter 3 can be used in parallel or switched. When switched, filter 1 is filtering online while filter 3 is regenerating or in standby mode; or filter 3 is filtering online while filter 1 is regenerating or in standby mode.

[0049] Figure 3 Schematic diagram of the material flow direction in the filtration mode and the forward pressing mode in the oil slurry filtration method provided by the present invention. Figure 3As shown, the filter assembly includes a central tube 22 and a support tube 21 covered by a flexible filter material; in the filtering mode, after the oil slurry enters the filter from the oil slurry inlet pipeline, the oil slurry outside the filter assembly enters the support tube 21 covered by a flexible filter material in the filter assembly from the direction shown by the logistics 23 and logistics 24, and the filtered oil then flows from the bottom of the central tube 22 from bottom to top, and the filtered oil 25 is discharged from the top of the central tube, and the filtered oil is extracted from the filtered oil outlet of the filter. In the forward pressing mode, the pressing gas enters the filter from the pressing gas inlet, and the oil slurry stored in the filter is pressed into the support tube 21 covered by a flexible filter material in the filter assembly from the direction shown by the logistics 23 and logistics 24, and the filtered oil then flows from the bottom of the central tube 22 from bottom to top, and the forward pressing oil 25 is discharged from the top of the central tube, and the forward pressing oil is extracted from the filtered oil outlet of the filter.

[0050] Figure 4 Schematic diagram of the material flow direction in the purge mode in the oil slurry filtration method provided by the present invention. Figure 4 As shown, the filter assembly includes a central tube 22 and a support tube 21 covered with a flexible filter material; in the purge mode, the back-blowing gas enters the filter from the oil outlet pipeline after the filter for purge, and the back-blowing gas 26 enters from the top of the central tube 22 of the filter assembly, flows from top to bottom and is discharged from the bottom, and then is purged to the inner surface of the flexible filter material covered on the outside of the support tube, and the filter cake on the outer surface of the flexible filter material is blown off along the direction of logistics 27 and logistics 28.

[0051] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited thereto.

[0052] Studies have shown that the solid particles in the catalytic cracking oil slurry are mainly catalytic cracking catalysts, and their main components are Al 2 O 3 and SiO 2 During the implementation process, the desolidification effect of the catalytic cracking slurry can be investigated by analyzing the Al and Si contents in the raw materials and the desolidified products. The properties of the slurry raw materials used in the embodiment are listed in Table 1.

[0053] Table 1

[0054] Oil Slurry A Oil slurry B Coal tar <![CDATA[Density (g / cm 3 )]]> 1.1318 1.1151 1.06 <![CDATA[Viscosity at 100 °C (mm 2 / s)]]> 29.28 15.51 2.5 Al content (μg / g) 644 931 / Si content (μg / g) 428 594 / Ash content (μg / g) / / 3200

[0055] Example 1

[0056] This embodiment adopts Figure 1The oil slurry filtration system shown in the figure has a single filter arranged in its filtration unit, and a filtration assembly is arranged in the filter. The filtration assembly is sequentially arranged with a central tube, a support tube, and a flexible filter material from the inside to the outside. The tube wall of the central tube has no holes, and the tube wall of the support tube has holes uniformly. The upper end and the lower end of the support tube are respectively provided with a first tuning fork level gauge switch 6 and a second tuning fork level gauge switch 7. The diameter ratio of the central tube to the support tube is 1:2.5, the distance between the bottom of the central tube end and the bottom of the support tube end is 0.23m, the porosity on the tube wall of the support tube is 57%, and the flexible filter material is provided with a desolidification layer and a base fabric layer. The specific property parameters are shown in Table 2.

[0057] Table 2

[0058]

[0059]

[0060] The oil slurry filtration test was carried out using oil slurry A:

[0061] Filtration mode: feed flow rate 1.2kg / h, filtration temperature 120℃. Set the pressure difference for starting the filter in the forward pressure mode to 0.26MPa. At the beginning of the filtration mode, open the oil slurry inlet of the filter, fill the filter 1 with oil slurry, the volume of oil slurry above the first tuning fork level gauge switch 6 in the filter is 1.5L, the volume of oil slurry between the first tuning fork level gauge switch 6 and the second tuning fork level gauge switch 7 is 4L, and the volume of oil slurry below the second tuning fork level gauge switch 7 is 2L. In the filtration mode, except for the oil slurry inlet pipeline 3 and the filtered oil outlet pipeline 4 connected to the filter 1, the other pipelines are closed. After the filter 1 runs for 30 hours, the pressure drop reaches 0.26MPa, and the forward pressure mode is started.

[0062] Forward pressing mode: the oil slurry inlet pipeline 3 is closed, the filter's pressing gas inlet pipeline 9 and the filter's filtered oil outlet pipeline 4 are unblocked, the filter's other inlets and outlets are closed, and the pressing gas (nitrogen) enters the filter from the pressing gas inlet pipeline 9 to press the oil slurry stored in the filter out from the filter's filtered oil outlet. During the forward pressing mode, the oil slurry in the filter pressed out by the pressing gas is the forward pressing oil.

[0063] Slag discharge mode: When the filter liquid level drops to the level gauge 6 indicating closed, close the pressurized gas inlet pipeline 9 and the filtered oil outlet pipeline 4, start the slag discharge mode, unblock the filter residue discharge pipeline 5, and discharge the remaining liquid in the filter. After the remaining liquid is emptied, start the purge mode.

[0064] Purge mode: purge nitrogen is introduced from the back-blowing gas tank 10 and pipeline 11 for back-blowing, and the back-blowing gas enters the filter from the oil outlet pipeline after filtration for purge, and the material obtained by purge is discharged from the filter residue discharge pipeline 5.

[0065] After the purge mode is finished, the next round of filtration mode is started. Filter 1 undergoes 7 rounds of filtration mode, forward pressure mode, slag discharge mode and purge mode. The filtration time, Al and Si contents of filtered oil and the yield of filtered oil of each round of filtration are listed in Table 3.

[0066] Among them, in each round of filtration, the oil yield after filtration = (feed flow rate*time+forward pressure oil volume*oil slurry density) / (feed flow rate*time+oil slurry volume in filter 1 in filtration mode*oil slurry density)*100%.

[0067] Table 3

[0068]

[0069] Example 2

[0070] This embodiment adopts Figure 1 The oil slurry filtration system shown in the figure has a single filter arranged in its filtration unit, and a filtration assembly is arranged in the filter. The filtration assembly is sequentially arranged with a central tube, a support tube, and a flexible filter material from the inside to the outside. The tube wall of the central tube has no holes, and the tube wall of the support tube has holes uniformly. The upper end and the lower end of the support tube are respectively provided with a first tuning fork level gauge switch 6 and a second tuning fork level gauge switch 7. The diameter ratio of the central tube to the support tube is 1:5.8, the distance between the bottom of the central tube end and the bottom of the support tube end is 0.78m, the porosity on the tube wall of the support tube is 83%, and the flexible filter material is provided with a desolidification layer and a base fabric layer. The specific property parameters are shown in Table 4.

[0071] Table 4

[0072]

[0073]

[0074] The oil slurry filtration test was carried out using raw material B:

[0075] Filtration mode: feed flow rate 2.0kg / h, filtration temperature 160℃. Set the pressure difference for starting the filter in the forward pressure mode to 0.40MPa. At the beginning of the filtration mode, open the oil slurry inlet of the filter, fill the filter 1 with oil slurry, the volume of oil slurry above the first tuning fork level gauge switch 6 in the filter is 1.5L, the volume of oil slurry between the first tuning fork level gauge switch 6 and the second tuning fork level gauge switch 7 is 4L, and the volume of oil slurry below the second tuning fork level gauge switch 7 is 2L. In the filtration mode, except for the oil slurry inlet pipeline 3 and the filtered oil outlet pipeline 4 connected to the filter 1, the other pipelines are closed. After the filter 1 runs for 39h, the pressure drop reaches 0.40MPa, and the forward pressure mode is started.

[0076] Forward pressing mode: the oil slurry inlet pipeline 3 is closed, the filter's pressing gas inlet pipeline 9 and the filter's filtered oil outlet pipeline 4 are unblocked, the filter's other inlets and outlets are closed, and the pressing gas (nitrogen) enters the filter from the pressing gas inlet pipeline 9 to press the oil slurry stored in the filter out from the filter's filtered oil outlet. During the forward pressing mode, the oil slurry in the filter pressed out by the pressing gas is the forward pressing oil.

[0077] Slag discharge mode: When the filter liquid level drops to the level gauge 6 indicating closed, close the pressurized gas inlet pipeline 9 and the filtered oil outlet pipeline 4, start the slag discharge mode, unblock the filter residue discharge pipeline 5, and discharge the remaining liquid in the filter.

[0078] Purge mode: After the remaining liquid is drained, purge nitrogen is introduced from the back-blowing gas tank 10 and pipeline 11 for back-blowing. The back-blowing gas enters the filter from the oil outlet pipeline after filtration for purge, and the material obtained by purging is discharged from the filter residue discharge pipeline 5.

[0079] After the purge mode is finished, the next round of filtration mode is started. Filter 1 undergoes 8 rounds of filtration mode, forward pressure mode, slag discharge mode and purge mode. The filtration time, Al and Si contents of filtered oil and the yield of filtered oil of each round of filtration are listed in Table 5.

[0080] Among them, in each round of filtration, the oil yield after filtration = (feed flow rate*time+forward pressure oil volume*oil slurry density) / (feed flow rate*time+oil slurry volume in filter 1 in filtration mode*oil slurry density)*100%.

[0081] Table 5

[0082]

[0083] Comparative Example 1

[0084] The same oil slurry filtration system as in Example 1 was used, and oil slurry A was used to carry out the oil slurry filtration test. The filtration mode was exactly the same as the filtration mode in Example 1, except that there was no forward pressing mode, and the filtration mode was directly switched to the slag discharge mode and the purge mode.

[0085] Filtration mode: feed flow rate 1.2kg / h, filtration temperature 120℃. Set the pressure difference of the filter to start the slag discharge mode to 0.26MPa. At the beginning of the filtration mode, open the oil slurry inlet of the filter, fill the filter 1 with oil slurry, the volume of oil slurry above the first tuning fork level gauge switch 6 in the filter is 1.5L, the volume of oil slurry between the first tuning fork level gauge switch 6 and the second tuning fork level gauge switch 7 is 4L, and the volume of oil slurry below the second tuning fork level gauge switch 7 is 2L. In the filtration mode, except for the oil slurry inlet pipeline 3 and the filtered oil outlet pipeline 4 connected to the filter 1, the other pipelines are closed. After the filter 1 runs for 30 hours, the pressure drop reaches 0.26MPa, and the slag discharge mode is started.

[0086] Slag discharge mode: close the oil slurry inlet pipeline 3 and the filtered oil outlet pipeline 4, open the filter residue discharge pipeline 5, and discharge the remaining liquid in the filter.

[0087] Purge mode: After the remaining liquid is drained, purge nitrogen is introduced from the back-blowing gas tank 10 and pipeline 11 for back-blowing. The back-blowing gas enters the filter from the oil outlet pipeline after filtration for purge, and the material obtained by purging is discharged from the filter residue discharge pipeline 5.

[0088] After the purge mode is finished, the next round of filtration mode is started. Filter 1 undergoes 7 rounds of filtration mode, slag discharge mode and purge mode. The filtration time, Al and Si contents of filtered oil and the yield of filtered oil of each round of filtration are listed in Table 6.

[0089] Among them, in each round of filtration, the oil yield after filtration = (feed flow rate*time) / (feed flow rate*time+oil slurry volume in filter 1 in filtration mode*oil slurry density)*100%.

[0090] Table 6

[0091] Filter rounds 1 2 3 4 5 6 7 Filter time, h 30.0 29.5 30.2 30.1 30.0 29.8 30.1 Al content of filtered oil, μg / g <5 <5 <5 <5 <5 <5 <5 Si content of filtered oil, μg / g <5 <5 <5 <5 <5 <5 <5 Oil yield after filtration, % 80.92 80.66 81.02 80.97 80.92 80.82 80.97

[0092] Comparative Example 2

[0093] The same oil slurry filtration system as in Example 2 was used, and the oil slurry B was used to carry out the oil slurry filtration test. The filtration mode was exactly the same as the filtration mode in Example 2, except that there was no forward pressing mode, and the filtration mode was directly switched to the slag discharge mode and the purge mode.

[0094] Filtration mode: feed flow rate 2.0kg / h, filtration temperature 160℃. Set the pressure difference of the filter to start the slag discharge mode to 0.40MPa. At the beginning of the filtration mode, open the oil slurry inlet of the filter, fill the filter 1 with oil slurry, the volume of oil slurry above the first tuning fork level gauge switch 6 in the filter is 1.5L, the volume of oil slurry between the first tuning fork level gauge switch 6 and the second tuning fork level gauge switch 7 is 4L, and the volume of oil slurry below the second tuning fork level gauge switch 7 is 2L. In the filtration mode, except for the oil slurry inlet pipeline 3 and the filtered oil outlet pipeline 4 connected to the filter 1, the other pipelines are closed. After the filter 1 runs for 39h, the pressure drop reaches 0.40MPa, and the slag discharge mode is started.

[0095] Slag discharge mode: close the oil slurry inlet pipeline 3 and the filtered oil outlet pipeline 4, open the filter residue discharge pipeline 5, and discharge the remaining liquid in the filter.

[0096] Purge mode: After the remaining liquid is drained, purge nitrogen is introduced from the back-blowing gas tank 10 and pipeline 11 for back-blowing. The back-blowing gas enters the filter from the oil outlet pipeline after filtration for purge, and the material obtained by purging is discharged from the filter residue discharge pipeline 5.

[0097] After the purge mode is finished, the next round of filtration mode is started. Filter 1 undergoes 8 rounds of filtration mode, slag discharge mode and purge mode. The filtration time, Al and Si contents of filtered oil and the oil yield after filtration of each round of filtration are listed in Table 7.

[0098] Among them, in each round of filtration, the oil yield after filtration = (feed flow rate*time) / (feed flow rate*time+oil slurry volume in filter 1 in filtration mode*oil slurry density)*100%.

[0099] Table 7

[0100]

[0101] Example 3

[0102] This embodiment adopts Figure 2In the oil slurry filtration system shown, a filter 1 and a filter 3 are arranged in the filtration unit, and a filter assembly of the same size is arranged in each filter. The filter assembly is sequentially provided with a central tube, a support tube, and a flexible filter material from the inside to the outside. The tube wall of the central tube is not perforated, and the tube wall of the support tube is uniformly perforated. A first tuning fork level gauge switch 12 and a second tuning fork level gauge switch 13 are respectively arranged at the upper end and the lower end of the support tube of the filter assembly 2, and a first tuning fork level gauge switch 19 and a second tuning fork level gauge switch 20 are respectively arranged at the upper end and the lower end of the support tube of the filter assembly 4. The diameter ratio of the central tube to the support tube is 1:3.5, the distance between the bottom of the central tube end and the bottom of the support tube end is 0.5 m, the porosity on the tube wall of the support tube is 70%, and the flexible filter material is provided with a desolidification layer and a base cloth layer. The specific property parameters are shown in Table 8.

[0103] Table 8

[0104]

[0105] The oil slurry filtration test was carried out using coal tar. Two filters 1 and 3 were operated in parallel. Filter 1 was put into use first. After filter 1 was operated in the filtration mode for 24 hours, filter 3 was put into use. At this time, both filter 1 and filter 3 were in the filtration mode. Each filter performed each round of filtration in sequence: filtration mode, forward pressure mode, slag discharge mode and purge mode, and the filtration mode time of each filter was set to 35 hours.

[0106] Filter mode of filter 1: feed flow rate 1.5kg / h, filtration temperature 110℃. Set the time for the filter to start the forward pressure mode to 35h. At the beginning of the filtration mode, open the oil slurry inlet of the filter, fill the filter 1 with coal tar, the volume of coal tar above the first tuning fork level gauge switch 12 in the filter is 1.5L, the volume of coal tar between the first tuning fork level gauge switch 12 and the second tuning fork level gauge switch 13 is 4L, and the volume of coal tar below the second tuning fork level gauge switch 13 is 2L. Coal tar enters filter 1 through the oil slurry inlet pipeline 5 connected to filter 1 for filtration, and the filtered oil is discharged through the filtered oil outlet pipeline 6. After filter 1 runs for 35h, the forward pressure mode is started.

[0107] Forward pressing mode of filter 1: close the oil slurry inlet pipeline 5, the pressing gas inlet pipeline 9 of filter 1 and the filtered oil outlet pipeline 6 of filter 1 are unblocked, the other inlets and outlets of filter 1 are closed, the pressing gas (nitrogen) enters filter 1 from the pressing gas inlet pipeline 9, and presses the coal tar stored in filter 1 out from the filtered oil outlet of filter 1. In the forward pressing mode, the coal tar in filter 1 pressed out by the pressing gas is the forward pressing oil.

[0108] Slag discharge mode of filter 1: When the liquid level of filter 1 drops to the level indicator 12 indicating shutdown, the pressurized gas inlet pipeline 9 and the filtered oil outlet pipeline 6 are closed, and the slag discharge mode is started. The filter residue discharge pipeline 7 of filter 1 is unblocked, and the remaining liquid in filter 1 is discharged.

[0109] Purge mode of filter 1: after the remaining liquid is emptied, purge nitrogen is introduced from the back-blowing gas tank 10 and pipeline 11 for back-blowing, and the back-blowing gas enters the filter 1 from the rear oil outlet pipeline for purge, and the purged material is discharged from the filter residue discharge pipeline 7.

[0110] After the purge mode is finished, the next round of filtration mode is started. Filter 1 undergoes two rounds of filtration mode, forward pressure mode, slag discharge mode and purge mode. The filtration time, ash content after filtration and oil yield after filtration of each round of filtration are listed in Table 9.

[0111] Among them, in each round of filtration, the oil yield after filtration = (feed flow rate*time+forward pressure oil volume*coal tar density) / (feed flow rate*time+coal tar volume in filter 1 in filtration mode*coal tar density)*100%.

[0112] The filtering mode of filter 3: feed flow rate 1.5kg / h, filtering temperature 110℃. The time for the filter to start the forward pressure mode is set to 35h. At the beginning of the filtering mode, the oil slurry inlet of the filter is opened, and the filter 3 is filled with coal tar. The volume of coal tar above the first tuning fork level gauge switch 19 in the filter is 1.5L, the volume of coal tar between the first tuning fork level gauge switch 19 and the second tuning fork level gauge switch 20 is 4L, and the volume of coal tar below the second tuning fork level gauge switch 20 is 2L. Coal tar enters filter 3 through the oil slurry inlet pipeline 14 connected to filter 3 for filtration, and the filtered oil is discharged through the filtered oil outlet pipeline 15. After filter 3 runs for 35h, the forward pressure mode is started.

[0113] Forward pressing mode of filter 3: close the oil slurry inlet pipeline 14, the pressing gas inlet pipeline 17 of filter 3 and the filtered oil outlet pipeline 15 of filter 1 are unblocked, the other inlets and outlets of filter 3 are closed, and the pressing gas (nitrogen) enters filter 3 from the pressing gas inlet pipeline 17, and presses the coal tar stored in filter 3 out from the filtered oil outlet of filter 3. In the forward pressing mode, the coal tar in filter 3 pressed out by the pressing gas is the forward pressing oil.

[0114] Slag discharge mode of filter 3: When the liquid level of filter 3 drops to the level indicator 19 indicating shutdown, the pressurized gas inlet pipeline 17 and the filtered oil outlet pipeline 15 are closed, and the slag discharge mode is started. The filter residue discharge pipeline 16 of filter 3 is unblocked, and the remaining liquid in filter 3 is discharged.

[0115] Purge mode of filter 3: after the remaining liquid is drained, purge nitrogen is introduced from the back-blowing gas tank 10 and pipeline 18 for back-blowing, and the back-blowing gas enters the filter 3 from the oil outlet pipeline after filtration for purge, and the material obtained by purge is discharged from the filter residue discharge pipeline 16.

[0116] After the purge mode is finished, the next round of filtration mode is started. Filter 3 undergoes two rounds of filtration mode, forward pressure mode, slag discharge mode and purge mode. The filtration time, ash content after filtration and oil yield after filtration of each round of filtration are listed in Table 9.

[0117] Among them, in each round of filtration, the oil yield after filtration = (feed flow rate*time+forward pressure oil volume*coal tar density) / (feed flow rate*time+coal tar volume in filter 3 in filtration mode*coal tar density)*100%.

[0118] Table 9

[0119]

Claims

1. A method for improving the oil recovery rate of a slurry filtration system, the slurry filtration system comprising a filtration unit and a regeneration unit, the filtration unit being provided with a filter, the filter having at least one filter assembly, an oil slurry inlet being provided at the lower part of the filter, a filtered oil outlet being provided at the upper part of the filter, a filter residue outlet being provided at the bottom of the filter, a pressurized gas inlet being provided at the top of the filter, and an oil slurry inlet pipeline, a filtered oil outlet pipeline, a filter residue discharge pipeline and a pressurized gas inlet pipeline respectively connected to each filter; The filter assembly is provided with a central tube, a support tube, and a flexible filter material in sequence from the inside to the outside. The central tube has no holes on its wall, and the support tube has holes evenly on its wall. The upper end and the lower end of the support tube are provided with a first tuning fork level gauge switch and a second tuning fork level gauge switch, respectively. The regeneration unit is provided with a back-blowing gas tank and a pressurizing gas tank, the outlet of the back-blowing gas tank is connected to the outlet pipeline of the filtered oil, and the outlet pipeline of the pressurizing gas tank is connected to the pressurizing gas inlet at the top of the filter; Slurry filtration methods include: Filtering mode: The oil slurry inlet and filtered oil outlet of the filter are in the open state, and the other inlets and outlets of the filter are in the closed state. After the oil slurry enters the filter from the oil slurry inlet pipeline, the oil slurry flows from the bottom to the top of the center tube of the filter assembly, and the filtered oil is discharged from the top of the center tube. The filtered oil is extracted from the filtered oil outlet of the filter; Forward pressure mode: the pressure gas inlet of the filter and the filtered oil outlet of the filter are open, and the other inlets and outlets of the filter are closed. The pressure gas enters the filter from the pressure gas inlet, presses the oil slurry stored in the filter out from the filtered oil outlet of the filter, and mixes with the filtered oil; Slag discharge mode: The filter residue outlet is open, and the other inlets and outlets of the filter are closed, so that the residual oil slurry in the filter is discharged; Purge mode: The filter residue outlet is open, and the back-blowing gas enters the filter from the oil outlet pipeline after filtration for purging. The back-blowing gas flows from the top of the center tube of the filter assembly from top to bottom and is discharged from the bottom, and then purged to the inner surface of its flexible filter material.

2. The method according to claim 1, characterized in that In the filter assembly, the diameter ratio of the central tube to the support tube is in the range of 1:2 to 1:6, the distance between the end bottom of the central tube and the end bottom of the support tube is 0.2m to 0.8m, and the opening rate on the wall of the support tube is 55% to 85%.

3. The method according to claim 1, characterized in that The flexible filter material is selected from one or more of polyethylene, nylon, polyphenylene sulfide, polyimide, polytetrafluoroethylene, aramid, polyurethane, and glass fiber; or, the flexible filter material is a flexible filter material composited from any two or more of polyethylene, nylon, polyphenylene sulfide, polyimide, polytetrafluoroethylene, aramid, polyurethane, and glass fiber.

4. The method according to claim 1, characterized in that The filtration accuracy of the flexible filter material is 0.1 to 15 microns, and the weight of the flexible filter material is 300 to 1000 g / m 2 The warp breaking strength is 850N / 5cm~9000N / 5cm, the weft breaking strength is 1000N / 5cm~11000N / 5cm, and the thickness is 0.5~3.4mm.

5. The method according to claim 1, characterized in that The flexible filter material comprises a desolidification layer and a base fabric layer, wherein the porosity of the desolidification layer is 25% to 98%, the porosity of the base fabric layer is 30% to 40%, the base fabric layer is made of polytetrafluoroethylene and / or polyphenylene sulfide, and the desolidification layer is made of polytetrafluoroethylene.

6. The method according to claim 1, characterized in that The back-blowing gas in the back-blowing gas tank is nitrogen and / or fuel gas; the pressing gas in the pressing gas tank is nitrogen and / or fuel gas.

7. The method according to claim 1, characterized in that The slurry oil is catalytic cracking slurry oil and / or coal tar.

8. The method according to claim 1, characterized in that In the filtering mode, the filtering temperature in the filter is 30 to 250°C, preferably 60 to 180°C; The pressure difference during filter use is 0.01~0.5MPa.

9. The method according to claim 1, characterized in that In the filtering mode, the filter sets the filtering time to 24h~96h.

10. The method according to claim 1, characterized in that In the filtration mode, when the pressure difference of the filter reaches or exceeds the pressure difference setting value, or when the setting time is reached, the filter is converted to the forward pressure mode operation; The filtration mode ends and the forward pressing mode begins. At this time, the oil slurry level stored in the filter is higher than the first tuning fork level gauge switch. In the forward pressing mode, when the oil slurry level stored in the filter is lower than the first tuning fork level gauge switch, the forward pressing mode is stopped and switched to the slag discharge mode.

11. The method according to claim 1, characterized in that When a filter is set in the filtration unit, the operation is performed in a manner of alternating the filtration mode, the forward pressure mode, the slag discharge mode, the purge mode and the next round of filtration mode, the forward pressure mode, the slag discharge mode and the purge mode.

12. The method according to claim 1, characterized in that When the filtration unit is provided with multiple filters, when the differential pressure of a certain online filter reaches or exceeds the differential pressure setting value or reaches the set time, the filter is cut out of the filtration system and regenerated in the forward pressing mode, slag discharge mode and purge mode.

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