Two-stage backwashing catalytic slurry oil filtering system

Abstract

A two-stage backwashing catalytic slurry oil filtering system comprises a filter, a backwashing gas pipeline and a deslagging pipeline, the deslagging pipeline is provided with a first-stage deslagging circulating pipeline and a second-stage deslagging pipeline, the filter is provided with an upper shell, a lower shell and a metal filter element, the upper shell is communicated with the backwashing gas pipeline, the metal filter element is arranged in the lower shell, and the backwashing gas pipeline is communicated with the metal filter element. A baffle is longitudinally separated in the lower shell, an isolation groove for storing clean slurry oil is defined between the baffle and the lower shell, the isolation groove is communicated with a first-stage deslagging circulating pipeline, the first-stage deslagging circulating pipeline is connected back to the filter and is used for washing a filter cake and / or a component, and the bottom of the lower shell is communicated with a second-stage deslagging pipeline. The first-stage backwashing deslagging liquid returns to the filter for recovery, and the second-stage backwashing deslagging liquid generates a filter volume deslagging liquid, so that the loss amount of the two-stage backwashing backwashing liquid is 50% lower than the filter volume, and compared with a conventional backwashing mode, the oil slurry loss amount and the backwashing liquid deslagging amount are reduced by more than 50%.

Description

Technical Field

[0001] The utility model belongs to the technical field of liquid-solid filtration and separation, in particular to a double-stage backwashing catalytic oil slurry filtration system. Background Art

[0002] Catalytic oil slurry is a by-product of the catalytic cracking (FCC) process. It contains a large amount of polycyclic aromatic hydrocarbons and has a high utilization value. It can be used as a raw material for the production of high value-added products such as needle coke, carbon black, and carbon fiber. However, the catalyst solid particles contained in the catalytic oil slurry will cause many problems such as coking, wear, and clogging during the processing process. Therefore, the premise of high-value comprehensive utilization of catalytic oil slurry is to remove the solids from the catalytic oil slurry. At present, the filtration method represented by metal filter element filtration is the main method for the application of catalytic oil slurry industrial equipment. It has the characteristics of high filtration efficiency and long operation cycle. The automatic backwashing filter used in the filtration method is backwashed according to the set pressure difference or time. During backwashing, gas is used to pressurize the top of the filter, and then the slag discharge valve at the bottom of the filter is opened. The gas-assisted liquid backwashes the metal filter element to empty the catalyst and oil slurry intercepted in the filter. Therefore, each backwashing will consume about one filter volume of oil slurry, and the oil slurry loss is large. At the same time, the oil slurry produced by this part of backwashing contains more catalysts, which are sent to coking or refining as filter residues, with poor economic benefits. Utility Model Content

[0003] In view of the above technical problems, the purpose of the utility model is to provide a two-stage backwash catalytic oil slurry filtration system, in which the first-stage backwash slag liquid is returned to the filter for recovery, and the second-stage backwash slag liquid produces a filter volume of slag liquid, so that the loss of the two-stage backwash backwash liquid is less than 50% of the filter volume. Compared with the conventional backwashing method, the oil slurry loss and the backwash liquid slag volume are reduced by more than 50%.

[0004] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0005] A two-stage backwashing catalytic oil slurry filtration system comprises a filter, a backwashing gas pipeline and a slag discharge pipeline, wherein the slag discharge pipeline is provided with a primary slag discharge circulation pipeline and a secondary slag discharge pipeline.

[0006] The filter is provided with an upper shell, a lower shell and a metal filter element. The upper shell is connected with the backwash gas pipeline and is used for releasing the filter pressure and then inflating and pressurizing for slag removal. The metal filter element is arranged in the lower shell. The interior of the lower shell is longitudinally divided by a baffle. An isolation tank for storing clean oil slurry is enclosed between the baffle and the lower shell. The isolation tank is connected with the primary slag removal circulation pipeline. The primary slag removal circulation pipeline is back-connected to the filter and is used for flushing filter cakes and / or components. The bottom of the lower shell is connected with the secondary slag removal pipeline.

[0007] In some technical solutions, a tube sheet is installed between the upper shell and the lower shell, the tube sheet is provided with a plurality of through-hole connection ports, and the shells on both sides of the tube sheet are provided with diaphragm differential pressure gauges;

[0008] The bottom ends of the plurality of metal filter elements are closed, and the top ends are provided with connectors adapted to the through hole connection ports, and the connectors are configured to communicate with both sides of the tube sheet and be sealed with the tube sheet.

[0009] In some technical solutions, the isolation groove is constructed as an annular wall surface, and a gap for the clean oil slurry to flow is formed between the top side of the annular wall surface and the tube sheet.

[0010] In some technical solutions, the lower shell includes a straight section and a conical section, the isolation trough is arranged in the straight section, and a primary slag discharge port is provided at the bottom of the isolation trough; the conical section is equipped with a level meter for monitoring the filter cake material level, and a secondary slag discharge port is provided at the bottom of the conical section.

[0011] In some technical solutions, the cone section is respectively provided with a cleaning port and a purge port. The cleaning port is adjacent to the level meter and arranged toward the level meter, and the purge port is adjacent to the secondary slag discharge port and arranged toward the secondary slag discharge pipeline. The cleaning port and the purge port are both connected to the primary slag discharge circulation pipeline.

[0012] In some technical solutions, the first-level slag discharge circulation pipeline is provided with two routes, one route is connected in series between the first-level slag discharge port and the cleaning port, and the other route is connected in series between the first-level slag discharge port and the purge port. The first-level slag discharge circulation pipeline is sequentially connected with a first-level slag discharge valve, a first-level slag discharge tank, an oil slurry return pump and an oil slurry return valve.

[0013] In some technical solutions, the secondary slag discharge pipeline is sequentially connected with a secondary slag discharge valve, a secondary slag discharge tank and a slag discharge pump;

[0014] And / or, the lower shell is connected to an oil slurry inlet pipe, the oil slurry inlet pipe is provided with a feed valve, the upper shell is connected to a purified oil slurry outlet pipe, the purified oil slurry outlet pipe is provided with a discharge valve, and the upper shell is also provided with a liquid level meter;

[0015] And / or, the backwash gas pipeline comprises a backwash gas inlet pipe and a backwash gas outlet pipe, the backwash gas inlet pipe is provided with an air inlet valve, and the backwash gas outlet pipe is provided with an exhaust valve.

[0016] In some technical solutions, the system includes at least two filters connected in series for alternately performing filtration and double-stage backwashing.

[0017] The utility model adopts the above technical solution to have at least the following beneficial effects:

[0018] 1. The present application proposes a two-stage backwashing catalytic oil slurry filtration system, which uses an isolation groove designed in the filter to block the filter cake while collecting the clean oil slurry on the upper part and reuse it in the filter, so that the first-stage backwashing can be repeated when there is enough volume in the lower part of the filter, and the filter cake peeled off from the outside of the metal filter element can be collected at the bottom of the filter to achieve the regeneration of the metal filter element. No slag liquid is discharged externally during this first-stage backwashing process;

[0019] 2. The present application proposes a two-stage backwashing catalytic oil slurry filtration system. When the first-stage backwashing mode runs for a set number of times or the filter cake level in the lower shell reaches a set position, a second-stage backwashing is performed. During the process, when the clean oil slurry level in the upper shell drops to the height of the level gauge, the first-stage slag discharge valve is closed, and the second-stage slag discharge valve is closed after the oil slurry in the filter is emptied, thereby clearing the accumulated filter cake in the filter, restoring the volume of the filter, and maintaining the long-term stable operation of the filter;

[0020] 3. The double-stage backwashing catalytic oil slurry filtration system proposed in the present application uses the primary slag discharge liquid to wash the filter cake accumulated in the cone section of the filter to prevent the filter cake from accumulating at the secondary slag discharge port. At the same time, the primary slag discharge liquid is also used to clean the material level meter and the secondary slag discharge valve to wash off the filter cake attached thereto, which significantly improves the slag discharge efficiency and effect of the filter;

[0021] 4. The present application proposes a double-stage backwash catalytic oil slurry filtration system, in which the first-stage backwash slag liquid is returned to the filter for recycling, and the second-stage backwash slag liquid produces a filter volume of slag liquid, so that the loss of the double-stage backwash backwash liquid is less than 50% of the filter volume. Compared with the conventional backwashing method, the oil slurry loss and the backwash liquid slag volume are reduced by more than 50%;

[0022] 5. The double-stage backwash catalytic oil slurry filtration system proposed in the present application can realize alternating double-stage backwash processes between multiple filters by connecting multiple groups of filters in series, thereby realizing continuous and stable operation of the filtration system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings and their marks required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 This is a schematic structural diagram of a double-stage backwashing catalytic oil slurry filtration system according to an embodiment of the utility model;

[0025] Figure 2It is a structural schematic diagram of the filter according to the embodiment of the utility model when it is in the primary slag discharge state;

[0026] Figure 3 It is a structural schematic diagram of the filter described in an embodiment of the utility model when it is in a secondary slag discharge state.

[0027] The meanings of the symbols in the figure are as follows:

[0028] 11—feed valve, 12—discharge valve, 21—intake valve, 22—exhaust valve, 31—first-stage slag discharge valve, 32—first-stage slag discharge tank, 33—oil slurry return pump, 34—purge valve, 35—cleaning valve, 41—second-stage slag discharge valve, 42—second-stage slag discharge tank, 43—slag discharge pump;

[0029] 51—upper shell, 52—liquid level gauge, 53—tube sheet, 54—diaphragm differential pressure gauge;

[0030] 55—lower shell, 551—cleaning port, 552—purge port, 553—secondary slag discharge port, 56—metal filter element, 57—isolation tank, 58—level meter. DETAILED DESCRIPTION

[0031] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the specific implementation methods of the utility model will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0032] In order to simplify the drawings, only the parts related to the utility model are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0033] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0034] In this article, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

[0035] In one embodiment, see Figure 1 , showing a two-stage backwashing catalytic oil slurry filtration system, including a filter, a backwashing gas pipeline and a slag discharge pipeline, the slag discharge pipeline is provided with a primary slag discharge circulation pipeline and a secondary slag discharge pipeline, the filter is provided with an upper shell 51, a lower shell 55 and a metal filter element 56, the upper shell 51 is connected with the backwashing gas pipeline, and is used to discharge the filter pressure and then inflate and pressurize for slag discharge, the metal filter element 56 is arranged in the lower shell 55, the interior of the lower shell 55 is longitudinally divided by a baffle, and an isolation tank 57 for storing clean oil slurry is enclosed between the baffle and the lower shell 55, the isolation tank 57 is connected with the primary slag discharge circulation pipeline, the primary slag discharge circulation pipeline is back-connected to the filter and is used for washing filter cakes and / or components, and the bottom of the lower shell 55 is connected with the secondary slag discharge pipeline.

[0036] The present application is designed with a double-stage backwashing. During the long-cycle operation of the filter, the filter is preferentially backwashed at the first stage. The filter cake peeled off from the surface of the metal filter element 56 settles to the bottom of the filter for collection, and the clean oil slurry on the upper part enters the isolation tank 57 and is returned to the filter inlet for recovery through the first-stage slag discharge circulation pipeline. This process does not produce slag discharge liquid for external discharge. When the first-stage backwashing is repeated many times or the filter cake material level of the lower shell reaches the set position, the second-stage backwashing is selected to empty the oil slurry in the filter together with the filter cake, restore the filter volume, and then complete a filtration cycle. During a filtration cycle, the loss of the double-stage backwashing backwashing liquid is less than 50% of the filter volume. Compared with the conventional backwashing method, the oil slurry loss and the backwashing liquid slag discharge amount are reduced by more than 50%.

[0037] In the above embodiment, a tube sheet 53 is installed between the upper shell 51 and the lower shell 55, and a plurality of through-hole connection ports are provided on the tube sheet 53. The shells on both sides of the tube sheet are provided with diaphragm differential pressure gauges 54. The bottom ends of the plurality of metal filter elements 56 are closed, and the top ends are provided with connectors adapted to the through-hole connection ports, and the connectors are configured to communicate with both sides of the tube sheet and be sealed with the tube sheet 53. Preferably, the filter medium in the metal filter element 56 is sintered metal powder, and the filtering accuracy is 0.5 to 1 micron.

[0038] In this embodiment, the diaphragm differential pressure gauge 54 is used to monitor the pressure difference on both sides of the tube sheet in real time. When the filter cake thickness on the surface of the metal filter element 56 increases, the filter resistance increases, and the filter reaches the set pressure difference or the set time, the filter is controlled to perform a primary backwash, and the filter is put back on line for filtration after backwashing. After the filter reaches the set pressure difference or the set time again, the filter is backwashed for a secondary backwash to complete a filtration cycle. Of course, it is also possible to perform a secondary backwash after multiple primary backwashes, which can be set as needed or implemented with reference to the accumulated amount of filter cake at the bottom of the filter.

[0039] In the above embodiment, the backwash gas pipeline includes a backwash gas inlet pipe and a backwash gas outlet pipe, the backwash gas inlet pipe is provided with an inlet valve 21, and the backwash gas outlet pipe is provided with an exhaust valve 22. When the diaphragm differential pressure gauge 54 detects that the filter resistance is too large, the exhaust valve 22 is opened to release the pressure inside the filter, and then the inlet valve 21 is opened to inflate and pressurize the filter to discharge slag.

[0040] In the above embodiment, the lower shell 55 accounts for about 70% of the volume of the filter, and includes a straight section and a conical section. The isolation groove 57 is provided in the straight section, and a primary slag discharge port is provided at the bottom of the isolation groove 57; the conical section is equipped with a level meter 58 for monitoring the filter cake level, and a secondary slag discharge port 553 is provided at the bottom of the conical section.

[0041] In this embodiment, the level meter 58 is used to monitor the filter cake level in the filter in real time, and the volume of the filter cone section should accommodate at least the filter cake buffer volume for two backwashing cycles.

[0042] In some preferred embodiments, the isolation groove 57 is constructed as an annular wall, and a gap for clean oil slurry to flow is formed between the top side of the annular wall and the tube plate 53, and the gap distance is preferably 100-200 mm. The selection of this specific value can not only allow the clean oil slurry of the upper shell 51 to flow into the isolation groove 57, but also block the filter cake peeled off by the metal filter element 56 from entering the isolation groove 57, and then recover the clean oil slurry without filter cake in the isolation groove 57, thereby significantly reducing the oil slurry loss and backwash liquid slag discharge during the filtration cycle.

[0043] In some specific embodiments, the cone section of the lower shell 55 is connected to an oil slurry inlet pipe, on which a feed valve 11 is provided, and the upper shell 51 is connected to a purified oil slurry outlet pipe, on which a discharge valve 12 is provided, and the upper shell 51 is also provided with a liquid level gauge 52. The catalytic oil slurry enters the interior of the filter from the feed port of the cone section of the filter, passes through the metal filter element 56, obtains clean oil slurry on the upper part of the tube plate, and is discharged from the purified oil slurry outlet of the upper shell 51, and the catalyst is trapped on the outer surface of the metal filter element 56 to form a filter cake. During the backwashing process, the clean oil slurry of the upper shell 51 passes through the metal filter element 56 in the reverse direction, so that the filter cake on the surface of the metal filter element 56 can fall off and settle to the bottom of the filter. When the clean oil slurry level of the upper shell 51 drops to the measured height of the liquid level gauge 52, the primary slag discharge circulation pipeline is disconnected.

[0044] In the above embodiment, the conical section is provided with a cleaning port 551 and a purge port 552 respectively. The cleaning port 551 is arranged adjacent to the material level meter 58 and is arranged toward the material level meter. The purge port 552 is arranged adjacent to the secondary slag discharge port 553 and is arranged toward the secondary slag discharge pipeline. The cleaning port 551 and the purge port 552 are both connected to the primary slag discharge circulation pipeline. Preferably, the cone angle of the conical section is 30-45°, and the cleaning port 551 is inclined upward at 45° to wash the filter cake accumulated in the conical section to prevent the filter cake from accumulating at the slag discharge port, or to clean the filter cake attached to the material level meter; the purge port 552 is inclined downward at 45° to wash the filter cake attached to the secondary slag discharge valve 41 to prevent the filter cake from adhering to the secondary slag discharge valve 41 and causing poor sealing. The secondary slag discharge valve 41 is arranged on the secondary slag discharge pipeline. This embodiment can significantly improve the slag discharge efficiency and effect of the filter.

[0045] Specifically, two primary slag discharge circulation pipelines are provided, one of which is connected in series between the primary slag discharge port and the cleaning port 551, including a primary slag discharge valve 31, a primary slag discharge tank 32, an oil slurry return pump 33 and a cleaning valve 35 connected by pipelines as required; the other is connected in series between the primary slag discharge port and the purge port 552, including a primary slag discharge valve 31, a primary slag discharge tank 32, an oil slurry return pump 33 and a purge valve 34 connected by pipelines as required, wherein the primary slag discharge valve 31, the primary slag discharge tank 32 and the oil slurry return pump 33 are provided on the primary slag discharge circulation main line, and the cleaning valve 35 and the purge valve 34 are respectively provided on two primary slag discharge circulation branch lines; the secondary slag discharge pipeline is sequentially connected with a secondary slag discharge valve 41, a secondary slag discharge tank 42 and a slag discharge pump 43.

[0046] In this embodiment, the primary slag tank 32 and the secondary slag tank 42 are used to collect the oil slurry output by the filter, wherein the primary slag tank 32 collects the oil slurry without filter cake, which can be returned to the filter for reuse, and the secondary slag tank 42 collects the slag liquid enriched with filter cake, which is discharged externally.

[0047] It should be noted that the filters in the present application are preferably designed in series with at least two groups, and then alternately perform filtering and double-stage backwashing steps to achieve continuous long-term operation of the filtration system and improve the treatment efficiency of the catalytic oil slurry. In a specific filtration system, including a first filter and a second filter arranged in series, the upper shells 51 of the first filter and the second filter are both connected to the backwash gas pipeline, and the lower shells 55 are both connected to the slag discharge pipeline.

[0048] The following is a detailed description of the use of the above two-stage backwash catalytic oil slurry filtration system. Please refer to Figure 2-3 , including the following steps:

[0049] First-stage backwashing: First, cut off the filter inlet and outlet, release the filter pressure through the exhaust valve 22, and then fill the gas from the air inlet of the upper shell to pressurize the filter to a pressure higher than the back pressure of the slag discharge pipeline by 0.4-0.8MPa. Then open the first-stage slag discharge valve 31, and the clean oil slurry above the tube sheet is used as a cleaning liquid to reversely penetrate the filter element, wash the filter cake off the filter element, and regenerate the filter element. During the backwashing process, the filter cake falls to the bottom of the filter, and the oil slurry enters the isolation tank 57 and is discharged to the first-stage slag discharge tank 32 through the first-stage slag discharge valve 31. When the liquid level of the upper head drops to the height of the liquid level gauge 52, close the first-stage slag discharge valve 31, let it stand for 5-10 minutes to let the filter cake settle to the bottom of the filter, and then the filter is put back on line for filtration. During the backwashing process, the filter cake on the surface of the filter element falls from the filter element to the bottom of the filter, and the raw oil slurry is discharged from the first-stage slag discharge valve 31 to the first-stage slag discharge tank 32, and returns to the filter inlet for recovery through the oil slurry return pump 33 and the oil slurry return valve.

[0050] Double-stage backwashing: When the first-stage backwashing mode runs for a set number of times or the temporary filter cake in the cone section triggers the level meter switch, the second-stage slag discharge backwashing is started. First, the filter inlet and outlet are cut off, and the filter is depressurized through the exhaust valve 22. Then, gas is filled into the air inlet of the upper shell to pressurize the filter to a pressure higher than the back pressure of the slag discharge pipeline by 0.4-0.8MPa. Then, the first-stage slag discharge valve 31 and the second-stage slag discharge valve 41 are opened at the same time, and the clean oil slurry above the tube sheet reversely penetrates the filter element. When the liquid level of the upper head drops to the height of the liquid level meter 52, the first-stage slag discharge valve 31 is closed. When the oil slurry in the filter is emptied, the second-stage slag discharge valve 41 is closed. After the slag discharge is completed, the cleaning valve 35 is opened, and the level meter 58 is cleaned with cleaning oil to flush the attached filter cake. The cleaning oil uses the oil slurry of the primary slag discharge tank 32, and the filter cake is blown to prevent the filter cake from accumulating at the slag discharge port. The purge valve 34 is opened, and the secondary slag discharge valve 41 is cleaned with cleaning oil. The cleaning oil uses the oil slurry of the primary slag discharge tank 32 to flush the filter cake attached to the secondary slag discharge valve 41. After the filter backwashing is completed, it is put back on line for filtration. The loss of backwashing liquid is about one filter volume.

[0051] The present application proposes a two-stage backwashing catalytic oil slurry filtration system. When the first-stage backwashing mode runs for a set number of times or the filter cake level in the lower shell reaches a set position, a second-stage backwashing is performed. During the process, when the clean oil slurry level in the upper shell 51 drops to the height of the level gauge 52, the first-stage slag discharge valve 31 is closed, and the second-stage slag discharge valve 41 is closed after the oil slurry in the filter is emptied, thereby clearing the filter cake accumulated and settled in the filter, restoring the volume of the filter, and maintaining the long-term stable operation of the filter;

[0052] The present application proposes a double-stage backwash catalytic oil slurry filtration system, which utilizes the primary slag discharge liquid to flush the filter cake accumulated in the cone section of the filter to prevent the filter cake from accumulating at the secondary slag discharge port 553. At the same time, the primary slag discharge liquid is also used to clean the level meter 58 and the secondary slag discharge valve 41 to flush the filter cake attached thereto, thereby significantly improving the slag discharge efficiency and effect of the filter.

[0053] The above-mentioned embodiments only express several implementation methods of the utility model, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent of the utility model. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, and these all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model shall be based on the attached claims.

Claims

1. A two-stage backwash catalytic oil slurry filtration system, It is characterized in that It includes a filter, a backwash gas pipeline and a slag discharge pipeline. The slag discharge pipeline is provided with a primary slag discharge circulation pipeline and a secondary slag discharge pipeline. The filter is provided with an upper shell, a lower shell and a metal filter element. The upper shell is connected with the backwash gas pipeline and is used for releasing the filter pressure and then inflating and pressurizing for slag removal. The metal filter element is arranged in the lower shell. The interior of the lower shell is longitudinally divided by a baffle. An isolation tank for storing clean oil slurry is enclosed between the baffle and the lower shell. The isolation tank is connected with the primary slag removal circulation pipeline. The primary slag removal circulation pipeline is back-connected to the filter and is used for flushing filter cakes and / or components. The bottom of the lower shell is connected with the secondary slag removal pipeline.

2. The double-stage backwash catalytic oil slurry filtration system according to claim 1, It is characterized in that A tube sheet is installed between the upper shell and the lower shell, and a plurality of through-hole connection ports are provided on the tube sheet. The shells on both sides of the tube sheet are provided with diaphragm differential pressure gauges; The bottom ends of the plurality of metal filter elements are closed, and the top ends are provided with connectors adapted to the through hole connection ports, and the connectors are configured to communicate with both sides of the tube sheet and be sealed with the tube sheet.

3. The double-stage backwash catalytic oil slurry filtration system according to claim 2, It is characterized in that The isolation groove is constructed as an annular wall surface, and a gap is formed between the top side of the annular wall surface and the tube plate for the clean oil slurry to flow.

4. The double-stage backwash catalytic oil slurry filtration system according to claim 1, It is characterized in that The lower shell includes a straight section and a conical section. The isolation trough is arranged in the straight section. A primary slag discharge port is arranged at the bottom of the isolation trough. A level meter for monitoring the filter cake level is installed in the conical section. A secondary slag discharge port is arranged at the bottom of the conical section.

5. The double-stage backwash catalytic oil slurry filtration system according to claim 4, It is characterized in that The cone section is respectively provided with a cleaning port and a purge port. The cleaning port is adjacent to the level meter and arranged toward the level meter. The purge port is adjacent to the secondary slag discharge port and arranged toward the secondary slag discharge pipeline. The cleaning port and the purge port are both connected with the primary slag discharge circulation pipeline.

6. The double-stage backwash catalytic oil slurry filtration system according to claim 5, It is characterized in that The first-level slag discharge circulation pipeline is provided with two routes, one route is connected in series between the first-level slag discharge port and the cleaning port, and the other route is connected in series between the first-level slag discharge port and the purge port. The first-level slag discharge circulation pipeline is sequentially connected with a first-level slag discharge valve, a first-level slag discharge tank, an oil slurry return pump and an oil slurry return valve.

7. The double-stage backwash catalytic oil slurry filtration system according to claim 1, It is characterized in that The secondary slag discharge pipeline is connected in sequence with a secondary slag discharge valve, a secondary slag discharge tank and a slag discharge pump; And / or, the lower shell is connected to an oil slurry inlet pipe, the oil slurry inlet pipe is provided with a feed valve, the upper shell is connected to a purified oil slurry outlet pipe, the purified oil slurry outlet pipe is provided with a discharge valve, and the upper shell is also provided with a liquid level meter; And / or, the backwash gas pipeline comprises a backwash gas inlet pipe and a backwash gas outlet pipe, the backwash gas inlet pipe is provided with an air inlet valve, and the backwash gas outlet pipe is provided with an exhaust valve.

8. The double-stage backwashing catalytic oil slurry filtration system according to any one of claims 1 to 7, It is characterized in that The system comprises at least two filters connected in series for alternately performing filtering and double-stage backwashing.

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