A method for improving the oil yield of a slurry oil filtration system

Abstract

The application discloses a method for improving the oil yield of a slurry filtering system, and adopts the slurry filtering system which comprises a filtering unit and a regeneration unit; the filtering unit is provided with a filter; the regeneration unit is provided with a back-blowing gas tank and a pressure material gas tank; the back-blowing gas tank is connected with an outlet pipeline of filtered oil through a pipeline; and the pressure material gas tank is connected with the top inlet of the filter through a pipeline. The filtering mode, the forward pressure material mode, the slag discharge mode, the blowing mode and the next round of filtering mode, forward pressure material mode, slag discharge mode and blowing mode are alternately operated, so that the oil yield of filtered oil is improved.

Description

Technical Field

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

[0002] Catalytic cracking is a crucial technology for producing gasoline and diesel from heavy oil, and it is one of the most important and widely used technologies in the refining industry. However, catalytic cracking produces slurry oil as a byproduct. Currently, catalytic cracking often uses hydrotreated residue oil or wax oil blended with residue oil as feedstock, resulting in a relatively high slurry oil yield, generally around 5%, with some yields reaching as high as 8%. This slurry oil is rich in polycyclic aromatic hydrocarbons (PAHs), which could potentially be used as feedstock for producing marine fuel, carbon black, or carbon fiber. However, due to the presence of approximately 1–6 g / L of catalytic cracking catalyst particles in the slurry oil, it fails to meet the feedstock requirements for producing marine fuel, carbon black, or carbon fiber, thus its current utilization value is low.

[0003] To improve the utilization value of oil slurry, it is essential to first remove solid particles from it. Various methods exist for particle removal, such as sedimentation, flocculation, and centrifugation, but these methods are inefficient. Filtration is a superior method for removing solid particles from oil slurry. Filtration processes are categorized into blind-end filtration and cross-flow filtration based on the fluid and separation direction. In blind-end filtration, individual filters typically operate intermittently. Once the filter pressure drop reaches a certain value or a certain time interval is reached, the oil slurry needs to be discharged to regenerate the filter media, restoring its original filtration area. The amount of sludge discharged directly affects the yield of the degraded product. With the same feed rate within the same time interval, a larger discharge volume results in a lower yield. Generally, once the filter equipment is determined, the yield of the degraded product is essentially fixed.

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

[0005] CN111592909A discloses an oil slurry filtration system and method, including a filtration unit and a filter aid buffer tank. The filtration unit includes at least one filter, and an oil slurry inlet pipeline, a filtered oil outlet pipeline, and a filter residue discharge pipeline connected to each filter. The outlet of the filter aid buffer tank is connected to the oil slurry inlet of the filter. Each filter contains a flexible, pinhole-free filter bag. In this oil slurry filtration method, the oil slurry enters the filter through the oil slurry inlet pipeline and is filtered. The filtered oil is extracted from the filtered oil outlet pipeline.

[0006] Existing technologies primarily 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 to improve the oil yield after filtration in an oil slurry filtration system is provided.

[0008] This invention provides a method for improving the yield of filtered oil in an oil slurry filtration system. The oil slurry filtration system includes a filtration unit and a regeneration unit. The filtration unit is equipped with a filter, which has at least one filter component. An oil slurry inlet is provided at the bottom of the filter, a filtered oil outlet is provided at the top of the filter, a filter residue outlet is provided at the bottom of the filter, and a pressurizing gas inlet is provided at the top of the filter. An oil slurry inlet pipeline, a filtered oil outlet pipeline, a filter residue discharge pipeline, and a pressurizing gas inlet pipeline are respectively connected to each filter.

[0009] The filter assembly consists of a central tube, a support tube, and a flexible filter material arranged sequentially from the inside out. The central tube has no holes in its wall, while the support tube has evenly spaced holes in its wall. A first tuning fork level switch and a second tuning fork level switch are respectively installed at the upper and lower ends of the support tube.

[0010] The regeneration unit is equipped with a backflush gas tank and a pressurizing gas tank. The outlet of the backflush gas tank is connected to the filtered oil outlet pipeline, and the outlet pipeline of the pressurizing gas tank is connected to the pressurizing gas inlet at the top of the filter.

[0011] Oil slurry filtration methods include:

[0012] Filtration mode: The oil slurry inlet and the filtered oil outlet of the filter are open, while the other inlets and outlets of the filter are closed. 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 central tube of the filter assembly, and the filtered oil is discharged from the top of the central tube. The filtered oil is then extracted from the filtered oil outlet of the filter.

[0013] Forward pressing mode: The pressurizing gas inlet and the filtered oil outlet of the filter are open, while the other inlets and outlets of the filter are closed. Pressurizing gas enters the filter through the pressurizing gas inlet, pressurizing the oil slurry stored in the filter out through the filtered oil outlet and mixing with the filtered oil.

[0014] Sludge discharge mode: The filter sludge outlet is open, while the other inlets and outlets of the filter are closed, so that the residual oil slurry in the filter is discharged.

[0015] Purging mode: The filter cake outlet of the filter is open. Backflush gas enters the filter from the filtered oil outlet pipeline for purging. The backflush gas flows from the top of the central tube of the filter assembly down to the bottom and is then discharged, purging the inner surface of its flexible filter media.

[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 end of the central tube and the bottom end 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%.

[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 end caps.

[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 flexible filter material composed of any two or more of 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 0.1–15 micrometers, preferably 0.1–10 micrometers, and more preferably 0.2–5 micrometers. The basis weight of the flexible filter material is 300–1000 g / m³. 2 The preferred value is 520–660 g / m³. 2 The longitudinal tensile strength is 850 N / 5 cm to 9000 N / 5 cm, and the latitudinal tensile strength is 1000 N / 5 cm to 11000 N / 5 cm. The thickness of the flexible filter material is 0.5 to 3.4 mm, preferably 0.5 to 3.0 mm, and more preferably 1.8 to 2.9 mm.

[0021] In one embodiment of the present invention, the flexible filter material in the filter can be a single layer (one) or multiple layers (two or more). When it is in the form of multiple layers, it is formed by stacking multiple layers of flexible filter material. At this time, there are no restrictions on the number of layers or the arrangement between the layers.

[0022] In one embodiment of the present invention, the flexible filter material includes a debonding layer and a base fabric layer, wherein the porosity of the debonding 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 debonding layer is made of polytetrafluoroethylene.

[0023] The base fabric layer is obtained by weaving the aforementioned raw materials suitable for making flexible filter materials using weaving techniques known in the art. There are no limitations on the weaving techniques, including but not limited to hydroentangling, heat treatment, wet weaving, spunbonding, meltblowing, needle punching, stitch weaving, and hot rolling. The release layer is formed on the base fabric layer using the aforementioned raw materials suitable for making flexible filter materials through methods known in the art, such as hot pressing, coating, and hot rolling. The release layer and base fabric layer of the present invention can be prepared independently and sequentially, or they can be prepared as a single unit. The flexible filter material of the present invention, comprising at least a release layer and a base fabric layer, can be prepared using methods known in the art or commercially available products.

[0024] In one embodiment of the present invention, the flexible filter material includes at least a debonding layer and a base fabric layer, but is not limited thereto, and variations and derivatives can be made based on this. For example, based on the debonding layer and base fabric layer of the present invention, other layers may be further included without adversely affecting the effect of the present invention.

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

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

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

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

[0029] Therefore, this invention employs a forward pressing mode: by introducing pressing gas at a certain pressure from the top of the filter, the oil slurry higher than the filter assembly is forced out through a path consistent with the normal filter material flow direction (forward direction of the filter material), and this portion of forward-pressed oil is mixed with the filtered oil. In this invention, the forward-pressed oil refers to the oil slurry in the filter that is forced out by the pressing gas in the forward pressing mode.

[0030] The positive pressing mode set up in this invention reduces the amount of oil slurry discharged to the filter residue outlet during regeneration, thereby improving the oil yield after filtration. Furthermore, this portion of the positively pressed oil is already filtered and does not need to be recycled to the oil slurry feed tank for repeated filtration, thus saving filtration costs.

[0031] In one embodiment of the present invention, in the filtration mode, when the differential pressure of the filter reaches or exceeds the differential pressure set value, or when the set time is reached, the filter is switched to positive pressure mode operation.

[0032] After the filtration mode ends, the forward pressurization mode begins. At this point, the oil slurry level inside the filter is higher than the first tuning fork level gauge switch. During forward pressurization, when the oil slurry level drops to the first tuning fork level gauge switch, the forward pressurization mode stops, and the system switches to slag discharge mode. This operation avoids the situation where pressurization gas directly enters the downstream filtered oil pipeline if the oil slurry level is lower than the top of the filter assembly, thus affecting the operation of the filtration system, and 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 30-250°C, preferably 60-180°C.

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

[0035] In one embodiment of the present invention, in the filtration mode, the filter is set to a filtration time of 24h to 96h.

[0036] In one embodiment of the present invention, when a filter is provided in the filtration unit, the operation is carried out in a manner that alternates between filtration mode, positive pressing mode, slag discharge mode, purging mode, and the next round of filtration mode, positive pressing mode, slag discharge mode, and purging mode.

[0037] In this invention, the filtering unit may include one filter or two or more filters. When multiple filters are used, this invention does not limit the connection method. Multiple filters can be connected in parallel, in series, or alternately in parallel and series configurations, or simultaneously in parallel and series configurations. When multiple filters are used, multiple filters with the same filtration accuracy can be used, or multiple filters with different filtration accuracy can be used.

[0038] In one embodiment of the present invention, when the filtration unit is equipped with multiple filters, when the differential pressure of a certain online filter reaches or exceeds the differential pressure set value or reaches the set time, the filter is cut out of the filtration system and regenerated in positive pressing mode, slag discharge mode and purging mode.

[0039] Compared with the prior art, the method for improving the oil yield after filtration in an oil slurry filtration system provided by the present invention can improve the oil yield after filtration and save filtration costs. Attached Figure Description

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

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

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

[0043] Figure 4 This is a schematic diagram of the material flow direction in the purging mode of the oil slurry filtration method provided by the present invention. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings, but this description is not intended to limit the scope of the invention.

[0045] Figure 1 This is a schematic diagram of one embodiment of the method for improving the oil yield after filtration in an oil slurry filtration system provided by the present invention, as shown below. Figure 1 As shown, the oil slurry filtration system includes a filtration unit and a regeneration unit. The filtration unit contains a filter 1, which in turn contains a filter assembly 2. The filter has an oil slurry inlet at its lower part, a filtered oil outlet at its upper part, a filter residue outlet at its bottom, and a pressurizing gas inlet at its top. It also includes an oil slurry inlet pipeline 3, a filtered oil outlet pipeline 4, a filter residue discharge pipeline 5, and a pressurizing gas inlet pipeline 9, all connected to the filter 1. The filter assembly 2, from the inside out, consists of a central tube, a support tube, and flexible filter media. The central tube has no holes in its wall, while the support tube has evenly spaced holes. A first tuning fork level switch 6 and a second tuning fork level switch 7 are installed at the upper and lower ends of the support tube. The regeneration unit includes a backflush gas tank 10 and a pressurizing gas tank 8. The outlet of the backflush gas tank 10 is connected to the filtered oil outlet pipeline 4 via a pipeline 11, and the outlet of the pressurizing gas tank 8 is connected to the pressurizing gas inlet at the top of the filter via the pressurizing gas inlet pipeline 9.

[0046] Figure 2 This is a schematic diagram of one embodiment of the method for improving the oil yield after filtration in an oil slurry filtration system provided by the present invention, as shown below. Figure 2As shown, the oil slurry filtration system includes a filtration unit and a regeneration unit. The filtration unit includes filters 1 and 3. Oil slurry inlets are located at the lower parts of filters 1 and 3, filtered oil outlets are located at the upper parts of filters 1 and 3, pressurizing gas inlets are located at the top of filters 1 and 3, and filter residue outlets are located at the bottom of filters 1 and 3. Oil slurry inlet pipeline 5, filtered oil outlet pipeline 6, filter residue discharge pipeline 7, and pressurizing gas inlet pipeline 9 are connected to filter 1. Oil slurry inlet pipeline 14, filtered oil outlet pipeline 15, filter residue discharge pipeline 16, and pressurizing gas inlet pipeline 17 are connected to filter 3. Filter 1 includes a filtration assembly 2, and filter 3 includes a filtration assembly 4. Both filter components 2 and 4 are arranged from the inside out as a central tube, a support tube, and a flexible filter material. The central tube has no holes in its wall, while the support tube has evenly spaced holes in its wall. A first tuning fork level switch 12 and a second tuning fork level switch 13 are respectively installed at the upper and lower ends of the support tube of filter component 2. A first tuning fork level switch 19 and a second tuning fork level switch 20 are respectively installed at the upper and lower ends of the support tube of filter component 4.

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

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

[0049] Figure 3 This is a schematic diagram illustrating the material flow direction in both the filtration mode and the forward pressing mode of the oil slurry filtration method provided by this invention. (See diagram for example.) Figure 3As shown, the filter assembly includes a central tube 22 and a support tube 21 covered with flexible filter media. In filtration mode, after the slurry enters the filter from the slurry inlet line, the slurry outside the filter assembly enters the support tube 21 covered with flexible filter media in the direction indicated by flow streams 23 and 24. The filtered oil then flows from the bottom of the central tube 22 upwards to the top and is discharged from the top of the central tube as filtered oil 25, which is then extracted from the filtered oil outlet of the filter. In forward pressurization mode, pressurizing gas enters the filter from the pressurizing gas inlet, forcing the slurry stored in the filter into the support tube 21 covered with flexible filter media in the direction indicated by flow streams 23 and 24. The filtered oil then flows from the bottom of the central tube 22 upwards to the top and is discharged from the top of the central tube as forward pressurized oil 25, which is then extracted from the filtered oil outlet of the filter.

[0050] Figure 4 This is a schematic diagram of the material flow direction in the purging mode of the oil slurry filtration method provided by this invention. For example... Figure 4 As shown, the filter assembly includes a central tube 22 and a support tube 21 covered by flexible filter media. In the purging mode, backflushing gas enters the filter from the filtered oil outlet pipeline for purging. Backflushing gas 26 enters from the top of the central tube 22 of the filter assembly, flows from top to bottom and is discharged, and then purifies the inner surface of the flexible filter media covered by the support tube, blowing the filter cake on the outer surface of the flexible filter media off in the direction of the flow 27 and flow 28.

[0051] The present invention will be further described below with reference to embodiments, but this does not limit the present invention in any way.

[0052] Studies have shown that the solid particles in catalytic cracking slurry are mainly composed of catalytic cracking catalyst, with Al2O3 and SiO2 as the main components. During the implementation process, the desolidification effect of catalytic cracking slurry can be examined by analyzing the Al and Si content in the feedstock and desolidification products. The properties of the slurry feedstock used in the examples are listed in Table 1.

[0053] Table 1

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

[0055] Example 1

[0056] This embodiment adopts Figure 1The oil slurry filtration system shown has a single filter in its filtration unit, and a filtration assembly in the filter. The filtration assembly consists of a central tube, a support tube, and a flexible filter material arranged sequentially from the inside out. The central tube has no holes in its wall, while the support tube has uniformly perforated walls. A first tuning fork level switch 6 and a second tuning fork level switch 7 are respectively installed at the upper and lower ends of the support tube. The diameter ratio of the central tube to the support tube is 1:2.5, the distance between the bottom ends of the central tube and the support tube is 0.23m, and the perforation rate of the support tube wall is 57%. The flexible filter material has a deconsolidation layer and a base fabric layer. The specific properties are shown in Table 2.

[0057] Table 2

[0058]

[0059]

[0060] Oil slurry A was used to conduct oil slurry filtration tests:

[0061] Filtration mode: feed flow rate 1.2 kg / h, filtration temperature 120℃. The differential pressure for starting the filter in positive pressure mode is set to 0.26 MPa. At the start of filtration mode, the slurry inlet of the filter is opened, filling filter 1 with slurry. The slurry volume above the first tuning fork level switch 6 is 1.5 L, the slurry volume between the first tuning fork level switch 6 and the second tuning fork level switch 7 is 4 L, and the slurry volume below the second tuning fork level switch 7 is 2 L. In filtration mode, except for the slurry inlet pipeline 3 and the filtered oil outlet pipeline 4 connected to filter 1, all other pipelines are closed. After 30 hours of operation, the pressure drop reaches 0.26 MPa, at which point the positive pressure mode is initiated.

[0062] Forward pressurization mode: The slurry inlet line 3 is closed. The pressurization gas inlet line 9 and the filtered oil outlet line 4 are unobstructed. All other inlets and outlets of the filter are closed. Pressurization gas (nitrogen) enters the filter through the pressurization gas inlet line 9, forcing the slurry stored inside the filter out through the filtered oil outlet. During forward pressurization mode, the slurry expelled from the filter by the pressurization gas is the forward pressurized oil.

[0063] Sludge discharge mode: When the filter level drops to the tuning fork level gauge 6 and shows "off", close the pressurizing gas inlet line 9 and the filtered oil outlet line 4, start the sludge discharge mode, the filter sludge discharge line 5 is unobstructed, and the remaining liquid in the filter is discharged. After the remaining liquid is discharged, start the purging mode.

[0064] Purging mode: Purging nitrogen is introduced from the backflushing gas tank 10 and pipeline 11 for backflushing. The backflushing gas enters the filter from the filtered oil outlet pipeline for purging. The material obtained from purging is discharged from the filter residue discharge pipeline 5.

[0065] After the purging mode ends, the next filtration mode is started. Filter 1 goes through 7 filtration modes, positive pressure mode, slag discharge mode and purging mode. The filtration time, Al and Si content of the filtered oil and the yield of the filtered oil for each filtration are listed in Table 3.

[0066] In each round of filtration, the oil yield after filtration is calculated as follows: (feed flow rate * time + positive pressure oil volume * slurry density) / (feed flow rate * time + slurry volume in filter 1 during filtration mode * slurry density) * 100%.

[0067] Table 3

[0068]

[0069] Example 2

[0070] This embodiment adopts Figure 1 The oil slurry filtration system shown has a single filter in its filtration unit, and a filtration assembly in the filter. The filtration assembly consists of a central tube, a support tube, and a flexible filter material arranged sequentially from the inside out. The central tube has no holes in its wall, while the support tube has uniformly perforated walls. A first tuning fork level switch 6 and a second tuning fork level switch 7 are respectively installed at the upper and lower ends of the support tube. The diameter ratio of the central tube to the support tube is 1:5.8, the distance between the bottom ends of the central tube and the support tube is 0.78m, and the perforation rate of the support tube wall is 83%. The flexible filter material has a deconsolidation layer and a base fabric layer. The specific properties are shown in Table 4.

[0071] Table 4

[0072]

[0073]

[0074] Oil slurry filtration test was conducted using raw material B:

[0075] Filtration mode: feed flow rate 2.0 kg / h, filtration temperature 160℃. The differential pressure for starting the filter in positive pressure mode is set to 0.40 MPa. At the start of filtration mode, the slurry inlet of the filter is opened, filling filter 1 with slurry. The slurry volume above the first tuning fork level switch 6 is 1.5 L, the slurry volume between the first tuning fork level switch 6 and the second tuning fork level switch 7 is 4 L, and the slurry volume below the second tuning fork level switch 7 is 2 L. In filtration mode, except for the slurry inlet pipeline 3 and the filtered oil outlet pipeline 4 connected to filter 1, all other pipelines are closed. After 39 hours of operation, the pressure drop of filter 1 reaches 0.40 MPa, at which point the positive pressure mode is initiated.

[0076] Forward pressurization mode: The slurry inlet line 3 is closed. The pressurization gas inlet line 9 and the filtered oil outlet line 4 are unobstructed. All other inlets and outlets of the filter are closed. Pressurization gas (nitrogen) enters the filter through the pressurization gas inlet line 9, forcing the slurry stored inside the filter out through the filtered oil outlet. During forward pressurization mode, the slurry expelled from the filter by the pressurization gas is the forward pressurized oil.

[0077] Sludge discharge mode: When the filter level drops to the tuning fork level gauge 6 and shows "off", close the pressurizing gas inlet line 9 and the filtered oil outlet line 4, start the sludge discharge mode, and the filter sludge discharge line 5 of the filter is unobstructed, and the remaining liquid in the filter is discharged.

[0078] Purging mode: After the remaining liquid is drained, purging nitrogen is introduced from the backflush gas tank 10 and pipeline 11 for backflushing. The backflush gas enters the filter from the filtered oil outlet pipeline for purging. The material obtained from purging is discharged from the filter residue discharge pipeline 5.

[0079] After the purging mode ends, the next filtration mode is started. Filter 1 goes through 8 filtration modes, positive pressure mode, slag discharge mode and purging mode. The filtration time, Al and Si content of the filtered oil and the yield of the filtered oil for each filtration are listed in Table 5.

[0080] In each round of filtration, the oil yield after filtration is calculated as follows: (feed flow rate * time + positive pressure oil volume * slurry density) / (feed flow rate * time + slurry volume in filter 1 during filtration mode * slurry density) * 100%.

[0081] Table 5

[0082]

[0083] Comparative Example 1

[0084] The same slurry filtration system as in Example 1 was used, and slurry A was used to conduct the slurry filtration test. The filtration mode was exactly the same as that in Example 1. The difference was that there was no positive pressing mode, and the filtration mode was directly switched to the slag discharge mode and the purging mode.

[0085] Filtration mode: feed flow rate 1.2 kg / h, filtration temperature 120℃. The differential pressure for starting the filter in slag discharge mode is set to 0.26 MPa. At the start of filtration mode, the slurry inlet of the filter is opened, filling filter 1 with slurry. The slurry volume above the first tuning fork level switch 6 is 1.5 L, the slurry volume between the first tuning fork level switch 6 and the second tuning fork level switch 7 is 4 L, and the slurry volume below the second tuning fork level switch 7 is 2 L. In filtration mode, except for the slurry inlet pipeline 3 and the filtered oil outlet pipeline 4 connected to filter 1, all other pipelines are closed. After 30 hours of operation, the pressure drop reaches 0.26 MPa, at which point the slag discharge mode is initiated.

[0086] Sludge discharge mode: Close the slurry inlet pipeline 3 and the filtered oil outlet pipeline 4, and unblock the filter sludge discharge pipeline 5 to discharge the remaining liquid in the filter.

[0087] Purging mode: After the remaining liquid is drained, purging nitrogen is introduced from the backflush gas tank 10 and pipeline 11 for backflushing. The backflush gas enters the filter from the filtered oil outlet pipeline for purging. The material obtained from purging is discharged from the filter residue discharge pipeline 5.

[0088] After the purging mode ends, the next filtration mode is started. Filter 1 goes through 7 filtration modes, slag discharge mode and purging mode. The filtration time, Al and Si content of the filtered oil and the yield of the filtered oil for each filtration are listed in Table 6.

[0089] In each round of filtration, the oil yield after filtration is calculated as follows: (feed flow rate * time) / (feed flow rate * time + oil slurry volume in filter 1 during filtration mode * oil slurry density) * 100%.

[0090] Table 6

[0091] Filtering rounds 1 2 3 4 5 6 7 Filtering time, h 30.0 29.5 30.2 30.1 30.0 29.8 30.1 Al content of filtered oil, pg / g <5 <5 <5 <5 <5 <5 <5 Si content of filtered oil, pg / g <5 <5 <5 <5 <5 <5 <5 Yield of filtered oil, % 80.92 80.66 81.02 80.97 80.92 80.82 80.97

[0092] Comparative Example 2

[0093] The same slurry filtration system as in Example 2 was used, and slurry B was used to conduct the slurry filtration test. The filtration mode was exactly the same as that in Example 2. The difference was that there was no positive pressing mode. The filtration mode was directly switched to the slag discharge mode and the purging mode.

[0094] Filtration mode: feed flow rate 2.0 kg / h, filtration temperature 160℃. The differential pressure for starting the filter in slag discharge mode is set to 0.40 MPa. At the start of filtration mode, the slurry inlet of the filter is opened, filling filter 1 with slurry. The slurry volume above the first tuning fork level switch 6 is 1.5 L, the slurry volume between the first tuning fork level switch 6 and the second tuning fork level switch 7 is 4 L, and the slurry volume below the second tuning fork level switch 7 is 2 L. In filtration mode, except for the slurry inlet pipeline 3 and the filtered oil outlet pipeline 4 connected to filter 1, all other pipelines are closed. After 39 hours of operation, the pressure drop of filter 1 reaches 0.40 MPa, at which point the slag discharge mode is initiated.

[0095] Sludge discharge mode: Close the slurry inlet pipeline 3 and the filtered oil outlet pipeline 4, and unblock the filter sludge discharge pipeline 5 to discharge the remaining liquid in the filter.

[0096] Purging mode: After the remaining liquid is drained, purging nitrogen is introduced from the backflush gas tank 10 and pipeline 11 for backflushing. The backflush gas enters the filter from the filtered oil outlet pipeline for purging. The material obtained from purging is discharged from the filter residue discharge pipeline 5.

[0097] After the purging mode ends, the next filtration mode is started. Filter 1 goes through 8 filtration modes, slag discharge mode and purging mode. The filtration time, Al and Si content of the filtered oil and the yield of the filtered oil for each filtration are listed in Table 7.

[0098] In each round of filtration, the oil yield after filtration is calculated as follows: (feed flow rate * time) / (feed flow rate * time + oil slurry volume in filter 1 during filtration mode * oil slurry density) * 100%.

[0099] Table 7

[0100]

[0101] Example 3

[0102] This embodiment adopts Figure 2The oil slurry filtration system shown includes filters 1 and 3 in its filtration unit. Each filter contains a filter assembly of the same size. From the inside out, each filter assembly consists of a central tube, a support tube, and a flexible filter material. The central tube has no holes in its wall, while the support tube has uniformly perforated walls. A first tuning fork level switch 12 and a second tuning fork level switch 13 are installed at the upper and lower ends of the support tube of filter assembly 2, respectively. A first tuning fork level switch 19 and a second tuning fork level switch 20 are installed at the upper and lower ends of the support tube of filter assembly 4, respectively. The diameter ratio of the central tube to the support tube is 1:3.5, the distance between the bottom ends of the central tube and the support tube is 0.5m, and the perforation rate of the support tube wall is 70%. The flexible filter material consists of a deconsolidation layer and a base fabric layer. The specific properties are shown in Table 8.

[0103] Table 8

[0104]

[0105] Oil slurry filtration tests were conducted using coal tar. Two filters, Filter 1 and Filter 3, operated in parallel. Filter 1 was put into operation first. After Filter 1 ran in filtration mode for 24 hours, Filter 3 was put into operation. At this time, both Filter 1 and Filter 3 were in filtration mode. Each filter's filtration process consisted of the following steps in sequence: filtration mode, positive pressure mode, slag discharge mode, and purging mode. The filtration mode time for each filter was set to 35 hours.

[0106] The filtration mode of filter 1 is as follows: feed flow rate 1.5 kg / h, filtration temperature 110℃. The start-up time for the filter in the forward pressing mode is set to 35 hours. At the start of the filtration mode, the oil slurry inlet of the filter is opened, and filter 1 is filled with coal tar. The volume of coal tar above the first tuning fork level switch 12 is 1.5L, the volume between the first tuning fork level switch 12 and the second tuning fork level switch 13 is 4L, and the volume below the second tuning fork level switch 13 is 2L. The coal tar enters filter 1 through the oil slurry inlet pipeline 5 connected to filter 1 for filtration. The filtered oil is discharged through the filtered oil outlet pipeline 6. After 35 hours of operation, the forward pressing mode of filter 1 is started.

[0107] In the forward pressurization mode of filter 1: the slurry inlet pipeline 5 is closed, the pressurization gas inlet pipeline 9 and the filtered oil outlet pipeline 6 of filter 1 are unobstructed, and the other inlets and outlets of filter 1 are closed. Pressurization gas (nitrogen) enters filter 1 through the pressurization gas inlet pipeline 9, forcing the coal tar stored in filter 1 out through the filtered oil outlet. During the forward pressurization mode, the coal tar in filter 1 that is forced out by the pressurization gas is the forward pressurization oil.

[0108] Sludge discharge mode of filter 1: When the liquid level in filter 1 drops to the level indicated by the first tuning fork level gauge 12 (closed), the pressure gas inlet line 9 and the filtered oil outlet line 6 are closed, and the sludge discharge mode is initiated. The filter sludge discharge line 7 of filter 1 is unobstructed, discharging the remaining liquid in filter 1.

[0109] Purging mode of filter 1: After the remaining liquid is drained, purging nitrogen is introduced from the backflushing gas tank 10 and pipeline 11 for backflushing. The backflushing gas enters the filter 1 from the filtered oil outlet pipeline for purging. The material obtained from purging is discharged from the filter residue discharge pipeline 7.

[0110] After the purging mode ends, the next filtration mode is started. Filter 1 goes through two filtration modes, positive pressure mode, slag discharge mode and purging mode. The filtration time, ash content of the filtered oil and oil yield of each filtration mode are listed in Table 9.

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

[0112] The filtration mode of filter 3 is as follows: feed flow rate 1.5 kg / h, filtration temperature 110℃. The start-up time for the filter in the forward pressing mode is set to 35 hours. At the start of the filtration mode, the oil slurry inlet of the filter is opened, and filter 3 is filled with coal tar. The volume of coal tar above the first tuning fork level switch 19 is 1.5L, the volume of coal tar between the first tuning fork level switch 19 and the second tuning fork level switch 20 is 4L, and the volume of coal tar below the second tuning fork level switch 20 is 2L. The 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 35 hours of operation, filter 3 starts the forward pressing mode.

[0113] In the forward pressurization mode of filter 3: the slurry inlet pipeline 14 is closed, the pressurization gas inlet pipeline 17 of filter 3 and the filtered oil outlet pipeline 15 of filter 1 are unobstructed, and the other inlets and outlets of filter 3 are closed. Pressurization gas (nitrogen) enters filter 3 through the pressurization gas inlet pipeline 17, forcing the coal tar stored in filter 3 out through the filtered oil outlet of filter 3. During the forward pressurization mode, the coal tar in filter 3 that is forced out by the pressurization gas is the forward pressurization oil.

[0114] Sludge discharge mode of filter 3: When the liquid level in filter 3 drops to the level indicated by the first tuning fork level gauge 19 (closed), the pressure gas inlet line 17 and the filtered oil outlet line 15 are closed, and the sludge discharge mode is initiated. The filter sludge discharge line 16 of filter 3 is unobstructed, allowing the remaining liquid in filter 3 to be discharged.

[0115] Purging mode of filter 3: After the remaining liquid is drained, purging nitrogen is introduced from the backflushing gas tank 10 and pipeline 18 for backflushing. The backflushing gas enters the filter 3 from the filtered oil outlet pipeline for purging. The material obtained from purging is discharged from the filter residue discharge pipeline 16.

[0116] After the purging mode ends, the next filtration mode is started. Filter 3 goes through two filtration modes, positive pressure mode, slag discharge mode and purging mode. The filtration time, ash content of the filtered oil and oil yield of each filtration mode are listed in Table 9.

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

[0118] Table 9

[0119]

Claims

1. A method for improving the yield of filtered oil in an oil slurry filtration system, the oil slurry filtration system comprising a filtration unit and a regeneration unit, wherein the filtration unit is provided with a filter, the filter having at least one filter component, 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 pressurizing gas inlet is 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 pressurizing gas inlet pipeline are respectively connected to each filter; The filter assembly consists of a central tube, a support tube, and a flexible filter material arranged sequentially from the inside out. The central tube has no holes in its wall, while the support tube has uniformly spaced holes in its wall. A first tuning fork level switch and a second tuning fork level switch are respectively installed at the upper and lower ends of the support tube. In the filter assembly, the diameter ratio of the central tube to the support tube ranges from 1:2 to 1:6, the distance between the bottom ends of the central tube and the support tube is 0.2m to 0.8m, and the perforation rate of the support tube wall is 55% to 85%. The regeneration unit is equipped with a backflush gas tank and a pressurizing gas tank. The outlet of the backflush gas tank is connected to the filtered oil outlet pipeline, and the outlet pipeline of the pressurizing gas tank is connected to the pressurizing gas inlet at the top of the filter. Oil slurry filtration methods include: Filtration mode: The oil slurry inlet and the filtered oil outlet of the filter are open, while the other inlets and outlets of the filter are closed. 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 central tube of the filter assembly, and the filtered oil is discharged from the top of the central tube. The filtered oil is then extracted from the filtered oil outlet of the filter. Forward pressing mode: The pressurizing gas inlet and the filtered oil outlet of the filter are open, while the other inlets and outlets of the filter are closed. Pressurizing gas enters the filter through the pressurizing gas inlet, pressurizing the oil slurry stored in the filter out through the filtered oil outlet and mixing with the filtered oil. Sludge discharge mode: The filter sludge outlet is open, while the other inlets and outlets of the filter are closed, so that the residual oil slurry in the filter is discharged. Purging mode: The filter cake outlet of the filter is open. Backflush gas enters the filter from the filtered oil outlet pipeline for purging. The backflush gas flows from the top of the central tube of the filter assembly down to the bottom and is then discharged, purging the inner surface of its flexible filter media. In filtration mode, when the differential pressure of the filter reaches or exceeds the differential pressure set value, or when the set time is reached, the filter is switched to positive 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 drops to the first tuning fork level gauge switch, the forward pressing mode stops and switches to the slag discharge mode.

2. The method according to claim 1, characterized in that, The flexible filter media is selected from one or more of polyethylene, nylon, polyphenylene sulfide, polyimide, polytetrafluoroethylene, aramid, polyurethane, and glass fiber.

3. The method according to claim 1, characterized in that, The filtration precision of flexible filter media is 0.1~15 microns, and the basis weight of flexible filter media is 300~1000g / m³. 2 The longitudinal fracture strength is 850N / 5cm~9000N / 5cm, the latitudinal fracture strength is 1000N / 5cm~11000N / 5cm, and the thickness is 0.5~3.4mm.

4. The method according to claim 1, characterized in that, The flexible filter material includes a debonding layer and a base fabric layer. The porosity of the debonding layer is 25% to 98%, and 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 debonding layer is made of polytetrafluoroethylene.

5. The method according to claim 1, characterized in that, The backflush gas in the backflush gas tank is nitrogen and / or fuel gas; the pressurizing gas in the pressurizing gas tank is nitrogen and / or fuel gas.

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

7. The method according to claim 1, characterized in that, In filtration mode, the filtration temperature in the filter is 30~250℃; The pressure differential during filter use is 0.01~0.5MPa.

8. The method according to claim 1, characterized in that, In filtration mode, the filtration temperature in the filter is 60~180℃.

9. The method according to claim 1, characterized in that, In filtration mode, the filter is set to a filtration time of 24h~96h.

10. The method according to claim 1, characterized in that, When a filter is installed in the filtration unit, the operation is carried out in an alternating manner, using filtration mode, positive pressing mode, slag discharge mode, purging mode, and the next round of filtration mode, positive pressing mode, slag discharge mode, and purging mode.

11. The method according to claim 1, characterized in that, When a filtration unit is equipped with multiple filters, when the differential pressure of a certain online filter reaches or exceeds the differential pressure set value or reaches the set time, the filter is disconnected from the filtration system and regenerated in positive pressing mode, slag discharge mode and purging mode.

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