Safe filtering and washing device and method for separating PTA oxidation products

Abstract

The embodiment of the invention provides a safe filtering and washing device for separating PTA oxidation products and a filtering and washing method, and belongs to the technical field of chemical separation equipment. The safe filtering and washing device comprises a main shaft; the driving rotating hub is arranged at one end of the spindle and used for driving the spindle; the driven rotating hub is arranged at the other end of the main shaft; when the main shaft rotates, the driven rotating hub is driven to rotate; the separation filter element is composed of filter cloth, and the filter cloth is arranged layer by layer in the circumferential direction of the main shaft and fixedly arranged on the inner wall of the driven rotating hub; the cover body is arranged on the outer side of the driven rotating hub and comprises a gas conveying part for providing countercurrent pressurized gas into the driven rotating hub and a washing part for providing countercurrent washing liquid; the filter cloth adsorbs oxidation products and rotates along with the driven rotating hub to sequentially form a filtering area, a grading washing area and a dewatering area, and recyclable filter cakes are obtained in the dewatering area. According to the safe filtering and washing device, the filtering and washing efficiency is improved through pneumatic filtering and countercurrent circulating washing, and the installation energy consumption and the production cost are reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical separation equipment, and in particular relates to a safe filtering and washing device and a filtering and washing method for separating PTA oxidation products. Background Art

[0002] Purified terephthalic acid (PTA) is one of the important industrial organic raw materials, widely used in chemical fiber production, electronic manufacturing, construction and other fields. Usually, PTA is used to produce polyethylene terephthalate, polyester fiber, bottle-grade polyester, film-grade polyester, etc. These products can be further used in the manufacture of packaging materials, textile materials, films and tapes, etc.

[0003] At present, the preparation method of industrial PTA is first to use para-xylene as raw material, acetic acid as solvent, cobalt acetate and manganese acetate as catalysts, and hydrobromic acid as a co-catalyst for oxidation. Among them, terephthalic acid has low solubility in acetic acid, and the oxidation product is in a slurry state. After filtration, separation and drying, crude terephthalic acid (CTA) can be obtained. Then CTA is dissolved in a high-temperature, high-pressure water medium for hydrogenation refining. Finally, the refined aqueous solution after hydrogenation refining is depressurized and cooled to precipitate the refined crystals, and the crystal slurry is subjected to solid-liquid separation and drying to obtain PTA.

[0004] Since the oxidation product CTA contains harmful impurities such as p-carboxybenzaldehyde, it is necessary to fully filter, wash and dry the CTA to recover the filter cake. The traditional filtering and washing device uses a hydraulic pressure filter, which has a small filtering area, low comprehensive filtering and washing processing capacity, and a complex structure, resulting in high investment costs, operating costs, and subsequent maintenance frequency and costs.

[0005] In view of this, a new type of safe filtering and washing device for a PTA oxidation unit and a filtering and washing method thereof are needed to solve the above problems in whole or in part. Summary of the invention

[0006] In order to solve at least one aspect of the above-mentioned problems and defects in the prior art, the embodiments of the present invention provide a safe filtering and washing device and a filtering and washing method for separating PTA oxidation products, which uses a continuous pneumatic pressure filtering method to allow the separation filter element inside the safe filtering and washing device to continuously adsorb the oxidation products generated by the PTA oxidation unit, and at the same time cooperates with the countercurrent circulation washing method to wash the filter cake on the separation filter element step by step, thereby improving the filtering and washing efficiency of the safe filtering and washing device and reducing the installed energy consumption. The technical solution is as follows:

[0007] According to one aspect of the present invention, a safety filtering and washing device is provided, which is used to separate oxidation products in a PTA oxidation unit by filtering and washing. The safety filtering and washing device comprises:

[0008] Spindle;

[0009] A driving hub is arranged at one end of the main shaft and is used to drive the main shaft to rotate;

[0010] A driven hub is arranged at the other end of the main shaft, and drives the driven hub to rotate when the main shaft rotates;

[0011] The separation filter element is composed of filter cloths which are arranged layer by layer along the circumferential direction of the main shaft and fixedly arranged on the inner wall of the driven rotating hub;

[0012] The cover body is arranged on the outside of the driven rotating hub, and the cover body includes a gas delivery part for providing countercurrent pressurized gas to the interior of the driven rotating hub and a washing part for providing countercurrent washing liquid;

[0013] The filter cloth absorbs the oxidation products and rotates with the driven hub to form a filtration zone, a graded washing zone and a dehydration zone in sequence, and a filter cake that can be recovered after separation is obtained in the dehydration zone.

[0014] In some embodiments, specifically, the washing section includes at least two groups of infusion tubes; the graded washing area includes at least two washing zones, and the number of partitions of the at least two washing zones is equal to the number of groups of the at least two groups of infusion tubes; the at least two groups of infusion tubes transport the washing liquid in the same filter washing cycle in the opposite direction of the rotation direction of the separation filter element to each washing zone of the at least two washing zones in sequence.

[0015] In some embodiments, alternatively, one end of each of the at least two groups of infusion tubes is fixed inside the washing unit, and the other end of each infusion tube is fixedly connected to a nozzle, and the nozzle sprays the washing liquid on the filter cloth located in the graded washing area. Alternatively, the at least two groups of infusion tubes include a first group of infusion tubes, a second group of infusion tubes, and a third group of infusion tubes.

[0016] In some embodiments, alternatively, the at least two washing zones include a first washing zone, a second washing zone and a third washing zone; when the main shaft drives the driven hub to rotate, the first group of infusion tubes is arranged corresponding to the third washing zone and sprays washing liquid to the third washing zone, the second group of infusion tubes is arranged corresponding to the second washing zone and sprays washing liquid to the second washing zone, and the third group of infusion tubes is arranged corresponding to the first washing zone and sprays washing liquid to the first washing zone.

[0017] In some embodiments, alternatively, the gas delivery section includes an air inlet, an air duct and an exhaust port. Specifically, the air duct along the inlet and outlet direction of the pressurized gas includes a dehydration section, a washing section and a filtering section corresponding to the dehydration area, the graded washing area and the filtering area respectively. The dehydration section, the washing section and the filtering section are all provided with air delivery channels for delivering the pressurized gas to the dehydration area, the graded washing area and the filtering area respectively.

[0018] In some embodiments, alternatively, a portion of the pressurized gas passes through the dehydration section, the washing section, and the filtering section in sequence through the air inlet and is delivered to the corresponding dehydration area, the graded washing area, and the filtering area. Another portion of the pressurized gas passes through the dehydration section, the washing section, and the filtering section in sequence through the air inlet and is discharged from the exhaust port.

[0019] In some embodiments, alternatively, the separation filter element further includes a filter cloth cleaning area, which is arranged behind the dehydration area along the rotation direction of the driven hub and is used to clean the filter cloth after the filter cake is removed.

[0020] In some embodiments, alternatively, the safety filtering and washing device further comprises a shell, wherein the main shaft, the driven hub and the cover are arranged inside the shell, and one end of the main shaft passes through the shell and is connected to the driving hub.

[0021] In some embodiments, alternatively, the safety filtering and washing device also includes a rotating sealing portion arranged between the shell and one end of the main shaft extending out of the shell, and the rotating sealing portion includes: a sealing column, which is a hollow structure and is sleeved on the outside of the main shaft, and the inner wall of the sealing column and the outer side surface of the main shaft form a sealing cavity; a rolling bearing, which is arranged at the end of the sealing column for positioning and supporting between the main shaft and the sealing column; a rotary pan-plug seal, which is used for rotating sealing between the main shaft and the sealing column; a sealing airway, which is arranged on the sealing column and the air outlet of the sealing airway is connected to the sealing cavity, and the sealed gas enters the sealing cavity through the sealing airway; a sealing waterway, which is arranged close to the rotary pan-plug seal to prevent the polluted gas in the shell from entering the interior of the rotating sealing portion.

[0022] In some embodiments, alternatively, the rotary flood seal comprises at least two rotary flood seals, which are arranged at one end of the sealing column inside the housing; the sealing lips of the rotary flood seals are arranged facing the polluted gas side inside the housing.

[0023] According to another aspect of the present invention, a filtering and washing method is provided, which is used for filtering and washing the oxidation product in the PTA oxidation unit in the safe filtering and washing device described in the above aspect. The filtering and washing method comprises:

[0024] By injecting low-pressure steam and / or heating tail gas into the safety filtering and washing device, the inside of the safety filtering and washing device reaches a preset working pressure and working temperature;

[0025] The oxidation product produced by the PTA oxidation unit is delivered to the feed section of the safety filtering and washing device by a delivery pump;

[0026] The safety filtering and washing device is started by driving the rotating hub, so that the separation filter element in the driven rotating hub continuously rotates in the first rotating direction;

[0027] The gas supply part of the cover body provides pressurized gas to the interior of the driven hub, and the washing liquid is provided to the interior of the driven hub through the washing part of the cover body, and the flow direction of the pressurized gas and the washing liquid is a second rotation direction, and the second rotation direction is opposite to the first rotation direction;

[0028] The washing liquid enters each washing zone of the graded washing zone in turn according to the second rotation direction to wash the filter cake in the separation filter element step by step;

[0029] The separation filter element adsorbs the oxidation product in the first rotating direction and sequentially passes through the filtering area, the graded washing area and the dehydration area, and obtains a filter cake that can be recovered after separation in the dehydration area.

[0030] The present invention also provides a plurality of embodiments according to the following aspects, which are specifically as follows:

[0031] Aspect 1: A countercurrent liquid supply device for safe filtration and washing of a PTA oxidation unit, the countercurrent liquid supply device comprising:

[0032] The cover body is arranged on the outside of the separation filter element of the safety filtering and washing device, and the cover body includes a gas delivery part for providing countercurrent pressurized gas to the separation filter element and a washing part for providing countercurrent washing liquid;

[0033] The washing part includes at least two groups of infusion tubes, each of which corresponds to a different washing area of ​​the separation filter element; the at least two groups of infusion tubes sequentially transport the washing liquid in the same filter washing cycle to different washing areas in the opposite direction of the rotation direction of the separation filter element;

[0034] The pressurized gas provides a portion of the pressurized gas to the separation filter element in the interior of the gas delivery portion along a direction opposite to the rotation direction of the separation filter element.

[0035] Aspect 2: According to the countercurrent liquid supply device according to Aspect 1, one end of each of the at least two groups of infusion tubes is fixed inside the washing part, and the other end of each infusion tube is fixedly connected to a nozzle, and the nozzle sprays the washing liquid on the filter cloth of the separation filter element located in the graded washing area; the at least two groups of infusion tubes include a first group of infusion tubes, a second group of infusion tubes and a third group of infusion tubes.

[0036] Aspect 3: According to the countercurrent liquid supply device described in Aspect 1, the gas delivery part includes an air inlet, an air duct and an exhaust port; the air duct along the inlet and outlet direction of the pressurized gas includes a dehydration section, a washing section and a filtration section corresponding to the dehydration area, the graded washing area and the filtration area of ​​the separation filter element respectively; the dehydration section, the washing section and the filtration section are all provided with air supply channels for delivering the pressurized gas into the dehydration area, the graded washing area and the filtration area respectively.

[0037] Aspect 4: A countercurrent liquid supply device according to Aspect 3, wherein a portion of the pressurized gas passes through the dehydration section, the washing section and the filtration section in sequence through the air inlet and is supplied to the corresponding dehydration area, the graded washing area and the filtration area; another portion of the pressurized gas passes through the dehydration section, the washing section and the filtration section in sequence through the air inlet and is discharged from the exhaust port.

[0038] Aspect 5: A safety filtering and washing device using the countercurrent liquid supply device according to any one of aspects 1 to 4, for filtering and washing oxidation products in a PTA oxidation unit, the safety filtering and washing device comprising:

[0039] Spindle;

[0040] A driving hub is arranged at one end of the main shaft and is used to drive the main shaft to rotate;

[0041] A driven hub is arranged at the other end of the main shaft, and drives the driven hub to rotate when the main shaft rotates;

[0042] The separation filter element is composed of filter cloths which are arranged layer by layer along the circumferential direction of the main shaft and fixedly arranged on the inner wall of the driven rotating hub;

[0043] The countercurrent liquid supply device is arranged on the outside of the driven rotating hub, and the countercurrent liquid supply device includes a gas supply part for supplying countercurrent pressurized gas to the inside of the driven rotating hub and a washing part for supplying countercurrent washing liquid;

[0044] The filter cloth absorbs the oxidation products and rotates with the driven hub to form a filtration zone, a graded washing zone and a dehydration zone in sequence, and a recyclable filter cake is obtained in the dehydration zone.

[0045] Aspect 6: A rotary sealing device, used in the safety filtering and washing device according to Aspect 5, the rotary sealing device comprising:

[0046] A sealing column, which is a hollow structure and is sleeved on the outside of the main shaft of the safety filtering and washing device, and the inner wall of the sealing column and the outer side surface of the main shaft form a sealing cavity;

[0047] A rolling bearing is arranged at the end of the sealing column to position and support the main shaft and the sealing column;

[0048] Rotary plug seal, used for rotary sealing between the main shaft and the sealing column;

[0049] A sealing air channel is arranged on the sealing column and the air outlet of the sealing air channel is communicated with the sealing cavity, and the gas used for sealing enters the sealing cavity through the sealing air channel;

[0050] A sealed water channel is arranged close to the rotary flood seal and is used to prevent polluted gas in the shell of the safety filtering and washing device from entering the interior of the rotary sealing part.

[0051] Aspect 7: A rotary sealing device according to Aspect 6, wherein the rotary pan-plug seal comprises at least two rotary pan-plug seals, and the at least two rotary pan-plug seals are arranged at one end of the sealing column inside the shell; and the sealing lip of the rotary pan-plug seal is arranged facing the contaminated gas side inside the shell.

[0052] Aspect 8: A rotary sealing device according to Aspect 6, wherein a sealing air duct is arranged on the sealing column and an air outlet of the sealing air duct is connected to the sealing cavity, and the gas used for sealing enters the sealing cavity through the sealing air duct; the sealing air duct is opened at one end of the rotary sealing device inside the shell of the safety filtering and washing device.

[0053] Aspect 9: A rotary sealing device according to Aspect 6, wherein the sealing water channel is arranged close to the rotary flood seal, and the sealing water channel is arranged at one end of the rotary sealing device inside the shell of the safety filtering and washing device.

[0054] Aspect 10: A rotary sealing device according to any one of Aspects 6-9, wherein the rotary sealing device further comprises a condensate collecting pipe; the condensate collecting pipe is arranged at a low point of the sealing cavity, and the condensate collecting pipe is also provided with a condensate discharge port on the surface of the rotary sealing device.

[0055] Aspect 11: A safety filtration and washing system, comprising the safety filtration and washing device according to Aspect 5, and a liquid supply unit, a gas-liquid separation unit and a condensation unit, wherein:

[0056] The liquid supply unit is used to provide the slurry of oxidation products to be filtered to the safety filtering and washing device;

[0057] The gas-liquid separation unit is used to recover the washing liquid in a filtering and washing cycle step by step and circulate it step by step to the washing part of the countercurrent liquid supply device;

[0058] The condensing unit is used to collect the gas from the gas-liquid separation unit and cool and liquefy it.

[0059] Aspect 12: According to the safety filtration and washing system of Aspect 11, the liquid supply unit includes an overflow tank, a filtrate gas-liquid separator and a filtrate recovery tank.

[0060] Aspect 13: According to the safety filtration washing system of Aspect 11, the gas-liquid separation unit includes at least one gas-liquid separator, and each of the at least one gas-liquid separator corresponds to each washing zone of the graded washing zone of the separation filter element in the safety filtration washing device.

[0061] Aspect 14: A safe filtration and washing system according to Aspect 11, wherein the condensation unit comprises at least one condenser; the gas from the gas-liquid separation unit is cooled and liquefied in each of the at least one condenser to form a condensate, and each condenser returns the collected condensate to the mother liquor of the oxidation product of the PTA oxidation unit for recycling.

[0062] The safe filtering and washing device and filtering and washing method for separating PTA oxidation products provided by the embodiments of the present invention have at least one or part of at least one of the following advantages:

[0063] (1) The separation filter element inside the safety filtration and washing device is continuously adsorbed by the oxidation products produced by the PTA oxidation unit through the method of continuous pneumatic pressure filtration. At the same time, the filter cake on the separation filter element is washed step by step in conjunction with the countercurrent circulation washing method, thereby improving the filtration and washing efficiency of the safety filtration and washing device and reducing the installed energy consumption;

[0064] (2) The filter cloth is used to form the separation filter element, which has a simple structure and low cost. The number and arrangement density of the filter cloth can be adjusted according to the impurity composition and content of the filter cake in the actual process flow, and has high adaptability;

[0065] (3) By providing a cover on the outside of the driven hub, it is possible to further prevent the filter cake on the separation filter element in the driven hub from being contaminated by the acidic gas generated by evaporation and sputtering of the slurry;

[0066] (4) By arranging a gas delivery section in the housing for countercurrent gas delivery, on the one hand, the different filtration pressure differences in different process areas of the separation filter element can be independently adjusted by controlling the gas delivery pressure; on the other hand, the backflow of polluted gas generated in the filtration area of ​​the separation filter element can be suppressed by a portion of the pressurized gas that always flows countercurrently in the gas delivery section;

[0067] (5) By arranging a washing section in the housing for countercurrent washing, the washing liquid in one filtering and washing cycle can be recycled to perform multi-stage washing on the filter cake on the separation filter element, thereby reducing the consumption of washing liquid and improving the washing effect, thereby effectively improving the washing efficiency of the filter cake;

[0068] (6) By using a rotary pan seal in the rotary seal part, the friction between the sealing component and the main shaft can be effectively reduced, thereby reducing the output torque of the drive hub and reducing power consumption;

[0069] (7) By using auxiliary pure gas seals and water seals in the rotating seal part, the polluted gas inside the housing of the safety filtration and washing device can be effectively prevented from entering the main shaft and the sealing structure, maintaining a good sealing environment, extending the service life of the main shaft, helping to improve the safety factor of the equipment and process flow, and effectively reducing the maintenance cost of the drive unit;

[0070] (8) The overall structure of the safety filtering and washing device forms a vertical pressure vessel with a compact internal structure, small footprint, and easy and quick installation;

[0071] (9) The filtration area of ​​a single safety filter and washing device is large, which is three times that of a traditional hydraulic pressure filter device, and the processing capacity of a single filter and washing device is twice that of a traditional device, effectively reducing the number of equipment configurations, thereby reducing equipment investment costs and reducing the overall production cost of PTA;

[0072] (10) The safety filtering and washing device has a simple internal mechanical structure and few vulnerable parts, which helps to extend its service life and improve the safety factor. In addition, the long life cycle of each component reduces the maintenance frequency and thus reduces maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] These and / or other aspects and advantages of the present invention will become apparent and readily understood from the following description of the preferred embodiments in conjunction with the accompanying drawings, in which:

[0074] Figure 1 Schematic diagram of the overall structure of a safety filtering and washing device according to Example 1 of the present invention;

[0075] Figure 2 for Figure 1 The schematic cross-sectional structure diagram of the safety filtering and washing device shown;

[0076] Figure 3 for Figure 1 The overall structural schematic diagram of the cover of the safety filtering and washing device shown;

[0077] Figure 4 for Figure 3 A schematic diagram of the working process of the gas delivery part and the washing part inside the cover body shown;

[0078] Figure 5 for Figure 1 The structural schematic diagram of the rotary sealing part of the safety filtering and washing device shown;

[0079] Figure 6 for Figure 5 A schematic diagram of the structure of the rotary seal portion at position A shown;

[0080] Figure 7 for Figure 5 A schematic diagram of the structure of the rotary seal portion at position B shown;

[0081] Figure 8 It is a schematic diagram of the operation process of the safety filtering and washing device according to Example 2 of the present invention. DETAILED DESCRIPTION

[0082] The technical solution of the present invention is further specifically described below by examples and in conjunction with the accompanying drawings. In the specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation of the present invention.

[0083] At the same time, it should be understood that although the terms "first", "second", "third", etc. may be used in the following embodiments of the present invention to describe that a component includes two or more components, these components should not be limited to these terms, and these terms are only used to distinguish each component from each other. And the descriptions of "up", "down", "left", "right", etc. indicating the direction, and the descriptions of "counterclockwise", "clockwise", etc. indicating the rotation direction of the rotating component are only for illustrative purposes to illustrate the relative position or relative movement of the components, and should not be understood as a limitation to the present invention.

[0084] According to the common preparation method of industrial purified terephthalic acid (PTA), acetic acid is used as solvent, cobalt acetate and manganese acetate are used as catalysts, and hydrobromic acid is used as a catalyst promoter, which makes the oxidation product obtained by the oxidation reaction contain a certain amount of acetic acid and metal catalyst. At the same time, the mixture of oxidation products also contains harmful impurities such as p-hydroxybenzaldehyde. Therefore, the subsequent process flow of recycling the oxidation product into the preparation of PTA must be separated by filtering and washing to remove substances that are harmful to the subsequent process flow.

[0085] The oxidation product after filtering and washing is the recyclable filter cake, which will enter the subsequent process of PTA preparation. Generally, the main index requirements for the recyclable filter cake in industrial applications include: acetic acid content ≤3% w / w, cobalt content ≤20ppm w / w, manganese content ≤20ppm w / w, etc. In order to ensure that the recyclable filter cake meets the index requirements, on the one hand, the filter washing equipment needs to have a high filter cake washing efficiency, and on the other hand, it is necessary to avoid the pollution of gas phase impurities inside the filter washing equipment to the greatest extent.

[0086] Therefore, the following embodiments of the present invention provide a safe filtering and washing device 100 and a safe filtering and washing method thereof, which adopts continuous pneumatic pressure filtration and combines graded countercurrent washing to achieve efficient filtration and washing of the oxidation products generated by the PTA oxidation unit, improve the filtration and washing efficiency of the safe filtering and washing device, and reduce the installed energy consumption and comprehensive operating costs. Among them, continuous pneumatic pressure filtration refers to the regulation of the pressure difference in the safe filtering and washing device 100 to meet the different pressure requirements for filtering and washing of the filter cake at different stages of filtration and washing and provide a clean atmosphere for the filtering and washing space. Graded countercurrent washing refers to the washing process in which the filter cake is washed step by step from more to less impurity content, and at the same time, the supply path of the washing liquid is cyclically supplied step by step from less to more impurity content of the filter cake.

[0087] See also Figure 1 , shows the overall structure of the safety filtering and washing device 100. The safety filtering and washing device 100 is composed of seven main parts, namely, a driving unit 10, a separation filter element 20, a cover body 30, a stirring device 40, a feeding part 50, a cake unloading part 60 and a housing 70.

[0088] See also Figure 2 , shows the cross-sectional structure of the safety filtering and washing device 100. Figure 1 and Figure 2 As shown, the drive unit 10 includes a main shaft 11, a driving hub 12 connected to one end of the main shaft 11, and a driven hub 13 connected to the other end of the main shaft 11. A separation filter element 20 composed of a plurality of filter cloths 201 is fixedly arranged inside the driven hub 13, and the plurality of filter cloths 201 are arranged layer by layer along the circumferential direction of the main shaft 11 and fixedly arranged on the inner wall of the driven hub 13 so that the separation filter element 20 rotates with the driven hub 13. A cover body 30 is arranged on the outside of the driven hub 13, and the cover body 30 includes a gas delivery part 31 for providing countercurrent pressurized gas to the inside of the driven hub 13 and a washing part 32 for providing countercurrent washing liquid.

[0089] When the driving hub 12 drives the main shaft 11 to rotate, and the main shaft 11 drives the driven hub 13 and the separation filter element 20 inside to rotate, the plurality of filter cloths 201 continue to absorb the oxidation products generated by the PTA oxidation unit from the feed part 50, and the plurality of filter cloths 201 carrying the oxidation products continue to rotate, filter and wash until the cake unloading part 60 unloads the filter cake to be recovered, thus completing a filtering and washing cycle ( Figure 2 The separation filter element 20 rotates clockwise from the feed portion 50 to the cake discharge portion 60 for one circle, after which the clean filter cloths 201 continue to adsorb the oxidation products from the feed portion 50 and enter the next filtering and washing cycle.

[0090] Furthermore, if Figure 2As shown, in one filtering and washing cycle, the separation filter element 20 sequentially forms a filtering zone 21, a graded washing zone 22 and a dehydration zone 23. Among them, the filter cloth 201 in a part of the filtering zone 21 adsorbs the oxidation product in the feed part 50 and filters the liquid to obtain an initial filter cake. Then the filter cloth 201 carrying the initial filter cake enters the graded washing zone 22, and the graded washing zone 22 includes a plurality of washing zones. At this time, the washing section 32 corresponding to the plurality of washing zones in the cover body 30 performs countercurrent washing on the filter cloth 201 carrying the initial filter cake by spraying washing liquid to obtain the washed filter cake. Finally, the filter cloth 201 carrying the washed filter cake is dehydrated and dried in the dehydration zone 23 to obtain a recyclable filter cake and the recyclable filter cake is unloaded from the filter cloth 201 through the cake unloading section 60. The clean filter cake is recycled and enters the subsequent PTA preparation process, and the clean filter cloth 201 enters the next filtering and washing cycle.

[0091] The following specifically describes the internal structure and working process of the safety filtering and washing device 100 through Example 1, and specifically describes the method (process flow) of safety filtering and washing through Example 2.

[0092] Example 1

[0093] Since the filtration zone 21 mainly filters the particles to obtain the initial filter cake of the oxidation product, it is necessary to perform repeated washing in the subsequent graded washing zone 22 to remove the ionic impurities in the filter cake, so that a highly clean and recyclable filter cake can be obtained in the dehydration zone 23. In order to obtain a washing process with higher efficiency and lower energy consumption in the graded washing zone 22, various embodiments of the present invention propose a structure and method for graded countercurrent washing.

[0094] Combination Figure 1 and Figure 2 As shown, in order to achieve graded countercurrent washing, the graded washing zone 22 of the separation filter element 20 is first divided into at least two washing zones (e.g. Figure 2 The first washing area 221, the second washing area 222 and the third washing area 223 are shown. Then, at least two groups of infusion tubes (for example, Figure 2 The at least two groups of liquid infusion pipes sequentially deliver the washing liquid in the same filter washing cycle to each of the at least two washing zones in the direction opposite to the rotation direction of the separation filter element 20.

[0095] At this time, the number of divisions of the graded washing area 22 is equal to the number of groups of the infusion pipes of the washing part 32, that is, if the graded washing area 22 is divided into two areas, then two groups of infusion pipes need to be set in the washing part 32 corresponding to the two areas, and so on. Of course, the specific number of pipes of each group of infusion pipes, the number of pipe-connected spray devices, and the pipe layout can be set according to the actual design requirements of the safety filtering and washing device 100.

[0096] For example, liquid or gas pipelines and common mechanical connection components, mechanical connection structures, etc. can be designed and optimized by those skilled in the art using common technical means according to the actual operating requirements of the safety filtering and washing device 100. For example, several branch pipelines can be arranged through three-way or multi-way pipe joints. The various embodiments of the present invention only provide some illustrative examples, which should not be understood by those skilled in the art as a limitation of the present invention. Common technical solutions for similar pipeline structures, joint valves, etc. will not be described in detail below.

[0097] In one example, specifically, Figure 2 As shown, the graded washing zone 22 of the separation filter element 20 is divided into three stages, namely a first washing zone 221 for first-stage washing, a second washing zone 222 for second-stage washing, and a third washing zone 223 for third-stage washing.

[0098] In one example, alternatively, a dehydration zone 23 and a filter cloth cleaning zone 24 are sequentially arranged behind the graded washing zone 22. The initial filter cake that has been washed is dehumidified and dried in the dehydration zone 23 to form a recyclable filter cake. The recyclable filter cake is then unloaded and recycled in the cake unloading section 60, and the filter cloth 201 continues to rotate clockwise to the filter cloth cleaning zone 24 to complete the cleaning.

[0099] In one example, alternatively, the filter cloth cleaning area 24 can also be divided into a filter cake backwashing area 241 and a filter cloth washing area 242. The filter cloth cleaning area 24 is close to the cake unloading part 60, and a flushing structure (not shown) can be provided on the cake unloading part 60, such as a washing pipe, etc., to clean the filter cloth 201 from which the filter cake has been unloaded to remove the particulate impurities attached thereto.

[0100] In one example, alternatively, the size and material of each filter cloth 201 constituting the separation filter element 20 remain consistent, and the specific number of filter cloths 201 can be designed according to the actual installation requirements of the safety filtering and washing device 100 .

[0101] In one example, alternatively, the size of each different process area (filtration area 21, graded washing area 22, dehydration area 23, filter cloth washing area 24, etc.) of the separation filter element 20 and the number of stages of the graded washing area 22 can be designed according to the actual installation requirements of the safety filtering and washing device 100. For example, in the actual filtering and washing process of the safety filtering and washing device 100, the impurity components and content of the filter cake on the separation filter element 20 are the main influencing parameters for determining the area size of the graded washing area 22 and the design of its number of stages.

[0102] See also Figure 3 , shows the overall structure of a cover body 30 according to Example 1. The cover body 30 is arranged on the outside of the driven hub 13, and usually the cover body 30 is in a stationary state relative to the driven hub 13 or the drive unit 10. The cover body 30 can effectively prevent the filter cake in the separation filter element 20 from contacting the acidic polluted gas (for example, the polluted gas evaporated or sputtered by the oxidation product in the feed part 50). According to the process area division of the separation filter element 20, preferably, the cover body 30 at least wraps the graded washing area 22 and the dehydration area 23 of the separation filter element 20. Further, a gas delivery part 31 and a washing part 32 are fixedly arranged inside the cover body 30, and clean pressurized gas is introduced into the gas delivery part 31 to start continuous pneumatic pressure filtration, and washing liquid is introduced into the washing part 32 to perform graded countercurrent washing on the filter cake in the separation filter element 20. At this time, the cover body 30 forms a countercurrent liquid supply device for graded washing of the filter cake in the graded washing area 22 of the separation filter element 20.

[0103] In one example, specifically, in conjunction with Figure 1-Figure 3 As shown, corresponding to the three-level graded washing area 22, the washing part 32 of the cover body 30 is provided with three groups of infusion tubes, each group of infusion tubes includes a plurality of infusion tubes, and one end of each infusion tube outputting washing liquid is connected to a spray device (such as a nozzle) for spraying washing liquid onto the filter cloth 201 in the separation filter element 20. Specifically, the three groups of infusion tubes are provided as a first group of infusion tubes 321 for washing the third washing area 223, a second group of infusion tubes 322 for washing the second washing area 222, and a third group of infusion tubes 323 for washing the first washing area 221.

[0104] In the same filter washing cycle, the washing liquid is only supplied to the safety filter washing device 100 once, and the washing liquid circulates in the three groups of infusion pipes in turn and sprays and cleans the corresponding three washing areas. Figure 2When the filter cloth 201 rotates clockwise, the first group of liquid infusion pipes 321 sprays washing liquid to the third washing area 223, and then the second group of liquid infusion pipes 322 sprays washing liquid to the second washing area 222 using the washing liquid from the first group of liquid infusion pipes 321. Finally, the third group of liquid infusion pipes 323 sprays washing liquid to the first washing area 221 using the washing liquid from the second group of liquid infusion pipes 322. At this point, the initial filter cake carried on the filter cloth 201 completes graded countercurrent washing, continues to rotate clockwise to enter the dehydration area 23 for dehydration and drying, unloads the filter cake, and enters the filter cloth cleaning area 24 to clean the filter cloth 201 before entering the next filtering and washing cycle.

[0105] See also Figure 4 , shows the flow process of the pressurized gas inside the gas delivery part 31 of the cover body 30. Figure 3 and Figure 4 As shown, the gas delivery unit 31 includes an air inlet 311, an air passage 312 and an exhaust port 313. Figure 4 The air passage 312 is divided into a dehydration section 312a, a washing section 312b and a filtering section 312c in sequence (in the direction of the white arrow in the middle). The dehydration section 312a, the washing section 312b and the filtering section 312c correspond to the dehydration area 23, the graded washing area 22 and the filtering area 21 of the separation filter element 20 in sequence.

[0106] In the filtration zone 21, the pressurized gas provides a filtration pressure difference so that a portion of the filter cloth 201 in the separation filter element 20 continuously adsorbs the liquid oxidation product from the feed section 50, and the solid matter in the oxidation product remains on this portion of the filter cloth 201 to form an initial filter cake. The liquid matter in the oxidation product can be recovered through a recovery pipe (not shown) in the safety filtration and washing device 100 and returned to the PTA preparation mother liquor to continue to participate in the oxidation reaction.

[0107] Before entering the graded washing area 22, when the filter cloth 201 carrying the initial filter cake leaves the surface of the oxidation product suspension in the feed section 50, the air pressure in the shell 70 is balanced with the air pressure in the cover body 30, and the polluted gas generated during the filtration process can be discharged from the cover body 30 through the exhaust port 313 through the pressurized gas output by the gas transmission section 31 in reverse flow, thereby preventing the polluted gas from flowing back into the cover body 30.

[0108] In the staged washing zone 22, the filter cake is efficiently cleaned in the staged washing zone 22 by controlling and adjusting the pressure of the pressurized gas in the staged washing zone 22. Alternatively, the pressures in different areas of the staged washing zone 22 may be adjusted individually or jointly.

[0109] In the dehydration zone 23, the pressure of the pressurized gas is higher than the pressure inside the shell 70. The pressurized gas applies pressure to the filter cloth 201 to remove the residual moisture on the filter cloth 201, and finally obtains a dry and highly clean recyclable filter cake.

[0110] The pressurized gas always flows from high pressure to low pressure in the gas transmission section 31, that is, its flow direction is opposite to the rotation direction of the separation filter element 20. While providing pneumatic filtration, washing and dehydration for the separation filter element 20, the countercurrent movement of the pressurized gas can also suppress the polluted gas in the filtration and washing process from entering the interior of the cover body 30 along the airway 312.

[0111] In one example, specifically, during the operation of the safety filtering and washing device 100, the pressurized gas is continuously supplied through the gas delivery section 31. A portion of the pressurized gas passes through the dehydration section 312a, the washing section 312b and the filtering section 312c in sequence through the air inlet 311 and is delivered to the corresponding dehydration area 23, the graded washing area 22 and the filtering area 21. Another portion of the pressurized gas passes through the dehydration section 312a, the washing section 312b and the filtering section 312c in sequence through the air inlet 311 and is discharged from the exhaust port 313.

[0112] In one example, alternatively, Figure 3 As shown, a number of gas supply channels 313 are provided on the dehydration section 312a, the washing section 312b and the filtering section 312c for supplying pressurized gas to the dehydration zone 23, the graded washing zone 22 and the filtering zone 21 respectively.

[0113] In one example, alternatively, a gas compression device (arranged outside the safety filtering and washing device 100 or integrated inside the housing 70 of the safety filtering and washing device 100) can be separately provided to provide pressurized gas at a specified pressure into the gas delivery part 31 of the cover body 30. Preferably, the maximum absolute pressure in the gas delivery part 31 of Example 1 can reach 3.5 barg.

[0114] In one example, alternatively, the specific pressure value of the pressurized gas can be specifically designed according to the structure, layout, process flow arrangement, etc. of the actual safety filtering and washing device 100. Alternatively, the filtering pressure of the filtering area 21, the washing pressure of the graded washing area 22, and the dehydration pressure of the dehydration area 23 can also be adjusted separately through a number of air supply channels 313 on the air supply part 31.

[0115] In one example, alternatively, Figure 4 As shown, a washing zone partition 33 may also be provided inside the housing 30, and the washing zone partition 33 is pre-set in the housing 30 in accordance with the process partition design of the separation filter element 20. The washing zone partition 33 can effectively provide installation position guidance and partitioning for the gas delivery pipeline and the washing liquid delivery pipeline in the housing 30. When the safety filtering and washing device 100 is maintained, the partition guidance of the washing zone partition 33 also helps to improve the maintenance efficiency.

[0116] In a filtering and washing cycle, when the filter cloth 201 carrying the initial filter cake enters the graded washing zone 22, since the initial filter cake carries a variety of impurities, the impurity amount is the largest when it enters the first washing zone 221, and then the impurity amount gradually decreases when it is washed in the second washing zone 222 and the third washing zone 223. If a new washing liquid is provided separately for each washing zone, the amount of washing liquid used will increase significantly, and the consumption of washing liquid will affect the overall installed energy consumption and production cost of the safety filtering and washing device 100. If the washing liquid is reused, it is necessary to consider the impact of impurities carried in the washing liquid on the washing efficiency. It can be seen that by using a countercurrent washing structure, the excessive consumption of washing liquid can be solved and the washing efficiency of the filter cake can be improved. At the same time, its compact structural design can further reduce the installed volume of the safety filtering and washing device 100 while ensuring the filtration area.

[0117] In one example, if Figure 1 As shown, the main shaft 11 and the driven hub 13 of the driving unit 10, the separation filter element 20, the cover 30, the stirring device 40, the feeding part 50 and the cake discharge part 60 are all arranged inside the housing 70. One end of the main shaft 11 connected to the driving hub 12 extends out of the housing 70 and is connected to the driving hub 12 outside the housing 70. In order to ensure the sealing inside the safety filtering and washing device 100, each embodiment of the present invention further provides a rotating sealing part 80 for sealing the main shaft 11 and the housing 70.

[0118] In one example, specifically, a rotating sealing portion 80 is provided at one end of the main shaft 11 extending out of the shell 70 to prevent polluted gas inside the shell 70 from entering the driving hub 12 through the main shaft 11, thereby protecting the main shaft 11 and helping to reduce the output torque of the driving hub 12 and reduce energy consumption.

[0119] Since the main shaft 11 of the safety filtering and washing device 100 is running at a low speed, a rotary seal is considered to be used for sealing. The rotary seal 80 is the only sealing structure between the driving unit 10 and the housing 70 to ensure the smooth operation of the safety filtering and washing device 100.

[0120] At the same time, the rotary seal portion 80 also plays the role of connecting the main shaft 11 and the driving hub 12. Alternatively, as Figure 1 As shown, by means of bolt connection, for example, fixing positions can be respectively set on the surface of the rotary seal portion 80 and the surface of the driving hub 12, and then fastened by screws.

[0121] See also Figure 5 , showing the overall structure of the rotary seal portion 80, see Figure 6 and Figure 7 They are shown respectively Figure 5The partial structure of the rotary seal portion 80 at A and B is shown. Figure 5-Figure 7 As shown, the rotary sealing portion 80 is composed of five main parts, namely, a sealing column 81, a rolling bearing 82, a rotary flood seal 83, a sealing air channel 84 and a sealing water channel 85.

[0122] In one example, specifically, the sealing column 81 is a hollow structure and is sleeved on the outside of the main shaft 11 , and the inner wall of the sealing column 81 and the outer side surface of the main shaft form a sealing cavity 801 .

[0123] In one example, specifically, the main shaft 11 rotates continuously, the sealing column 81 is stationary, and the rolling bearing 82 is disposed at the end of the sealing column 81 for positioning and supporting the main shaft 11 and the sealing column 81. Alternatively, as Figure 5 As shown, a group of rolling bearings 82 are respectively arranged at both ends of the sealing column 81.

[0124] In one example, specifically, the rotary pan seal 83 is used for rotary sealing between the main shaft 11 and the sealing column 81. Figure 5 As shown, the rotary flood seal 83 is disposed at one end of the sealing column 81 inside the housing 70. Alternatively, as Figure 6 and Figure 7 As shown, the rotary pan-plug seal 83 includes at least two rotary pan-plug seals; preferably, the number of the rotary pan-plug seals 83 is two, namely a first rotary pan-plug seal 83a and a second rotary pan-plug seal 83b.

[0125] In one example, alternatively, the components disposed on the sealing column 81 are in a relatively static state with the sealing column 81, so a common O-ring can be used for sealing at the position where sealing is required, such as when the rolling bearing 82 is installed in the sealing column 81, the screw seal used for assembly and fixing, etc.

[0126] In one example, further, the rotating pan-seal 83 (including the first rotating pan-seal 83a and the second rotating pan-seal 83b) is based on the working principle of the pan-seal and is a high-performance sealing component with a special spring inside a U-shaped Teflon. Under the combined action of appropriate spring force and system fluid pressure, the sealing lip of the pan-seal pushes out and presses the metal surface to be sealed to achieve a sealing effect. At the same time, the actuation effect of the spring can also overcome the slight eccentricity of the metal mating surface and the wear of the sealing lip, thereby extending the service life of the pan-seal.

[0127] In one example, specifically, the sealing lips of the rotary flood seal 83 (including the first rotary flood seal 83 a and the second rotary flood seal 83 b ) are arranged to face the polluted gas side in the housing 70 , that is, the sealing lips thereof are uniformly directed toward the interior of the housing 70 .

[0128] Since the air pressure in the sealing chamber 801 is higher than the air pressure in the housing 70, the sealing lip surface of the first rotary flood seal 83a is in an open state, which can effectively prevent the polluted gas in the housing 70 from entering the rolling bearing 82 and the sealing chamber 801. On the other hand, a small amount of sealing gas in the sealing chamber 801 can also carry out a part of the heat generated by wear through the sealing lip surface of the rotary flood seal 83, thereby reducing the wear of the rotary flood seal 83.

[0129] At the same time, the second rotary flood seal 83b can prevent the sealing gas in the sealing cavity 801 from leaking outward under a large pressure difference between the inside and the outside.

[0130] In one example, specifically, in conjunction with Figure 6 and Figure 7 As shown, considering the particularity of the PTA process (such as corrosion and pollution), the sealing effect of the pan-seal structure alone may be weakened and may affect its service life. Therefore, two auxiliary sealing structures are also involved in the rotary seal part 80, one is an air seal structure - sealing air channel 84, and the other is a water seal structure - sealing water channel 85.

[0131] In one example, alternatively, the sealing air channel 84 is disposed on the sealing column 81 and the gas outlet of the sealing air channel 84 is communicated with the sealing cavity 801, and the gas used for sealing enters the sealing cavity 801 through the sealing air channel 84. Figure 6 As shown, the sealing air passage 84 may be selectively opened at the end of the rotary sealing portion 80 inside the housing 70 .

[0132] In one example, alternatively, the sealing water channel 85 is disposed near the rotating flood seal 83, and the sealing water channel 85 is disposed at one end of the rotating seal portion 80 inside the housing 70, such as Figure 7 As shown, rolling bearing 82, first rotating flood seal 83a, second rotating flood seal 83b and sealing water channel 85 are sequentially arranged from left to right. The sealing water channel 85 can prevent polluted gas and gas containing oxidation product particles existing in the internal atmosphere of housing 70 from accumulating at rotating flood seal 83 and entering sealing cavity 801 through rotating flood seal 83, thereby maintaining the clean state inside sealing cavity 801 and preventing particle impurities from causing wear on the surface of rotating flood seal 83 and main shaft 11.

[0133] In one example, alternatively, a condensed water collection pipe 86 may be provided on the rotary seal portion 80. Figure 5 As shown, a condensate discharge port C is provided at a low point of the sealing cavity 801 (the inner wall of the sealing cavity 801 may be provided with a certain slope), and a drainage channel is further provided downward along the condensate discharge port C to lead the condensate out to the outside of the rotating sealing part 80.

[0134] The condensed water in the sealing chamber 801 can be discharged regularly according to the actual operation status of the safety filtering and washing device 100. At the same time, the status of the rotary sealing part 80 can be judged according to the status of the discharged condensed water (for example, whether it contains a lot of impurities), such as whether its sealing status is good or needs to be replaced.

[0135] In one example, alternatively, a coupling 14 and a support bearing 15 are also provided on the main shaft 11. Figure 1 In the direction from left to right), the coupling 14 is arranged behind the driving hub 12, and the support bearing 15 is arranged behind the coupling 14. Alternatively, a support bearing (not shown) on the non-driving side can also be arranged at the position where the driven hub 13 is connected to the main shaft 11.

[0136] In one example, alternatively, the main components of the safety filtering and washing device 100 are mostly made of metal materials, especially the main shaft 11, the driven hub 13, the coupling 14 and the housing 70 in the driving unit 10 all require high strength. Therefore, preferably, the metal material is made of duplex steel ASTM A240 UNS S32205.

[0137] Taking the safe filtering and washing device 100 of Example 1 as an example, its working process of filtering and washing the oxidation products from the upstream of the PTA manufacturing process and sending the recoverable filter cake to the downstream process is described as follows.

[0138] After a portion of the filter cloth 201 located in the filter area 21 of the separation filter element 20 is immersed in the liquid oxidation product (slurry) in the feed part 50, under the action of the filtration pressure difference provided by the air supply part 31 of the cover body 30, the solid mixed substance in the slurry is blocked by the filter cloth 201 and remains on the filter cloth 201 to form an initial filter cake, and the liquid in the slurry circulates back to the oxidation reaction mother liquor to continue to participate in the oxidation reaction.

[0139] The filter cloth 201 carrying the initial filter cake continues to rotate clockwise and enters the graded washing area 22. In the graded washing area 22, the initial filter cake is washed in a countercurrent manner in cooperation with the washing part 32 of the cover body 30, that is, the washing liquid supplied in the same washing cycle first cleans the last washing area (for example, the third washing area 223), and then the used washing liquid from the next level is circulated to the previous washing area (for example, the second washing area 222) until the first washing area (for example, the first washing area 221) is washed and discharged.

[0140] The washed filter cake enters the dehydration zone 23. Under the pressure of the pressurized gas provided by the gas delivery portion 31 of the housing 30, the pressurized gas replaces the liquid and moisture in the pores of the filter cloth 201 and the filter cake to complete the dehydration and drying of the filter cake. At this time, the filter cake on the filter cloth 201 is a clean and recyclable filter cake.

[0141] Finally, the recyclable filter cake reaches the inlet position of the cake unloading part 60 at the end of the dehydration zone 23. At this time, the filter cake on the filter cloth 201 can be scraped off by a scraper (not shown) provided on the cake unloading part 60 for subsequent process recycling.

[0142] After passing through the filter cloth cleaning zone 24, the filter cloth 201 completes the current filter washing cycle and enters the next new filter washing cycle.

[0143] Example 2

[0144] The embodiment of the present invention further provides a filtering and washing method, which is used in the safety filtering and washing device 100 of each of the above embodiments to filter and wash the oxidation product in the PTA oxidation unit. The specific steps of the filtering and washing method include:

[0145] Step S100: injecting low-pressure steam and / or heating tail gas into the interior of the safety filtering and washing device 100, so that the interior of the safety filtering and washing device reaches a preset working pressure and working temperature;

[0146] Step S200: delivering the oxidation product produced by the PTA oxidation unit into the feed part 50 of the safety filtering and washing device 100 through a delivery pump;

[0147] Step S300: starting the safety filtering and washing device 100 by driving the rotating hub 12, so that the separation filter element 20 in the driven rotating hub 13 continuously rotates in a first rotation direction (eg, clockwise);

[0148] Step S400: providing pressurized gas to the interior of the driven hub 13 through the gas delivery portion 31 of the cover body 30, and providing washing liquid to the interior of the driven hub 13 through the washing portion 32 of the cover body 30, wherein the flow direction of the pressurized gas and the washing liquid is a second rotation direction (e.g., counterclockwise), and the second rotation direction is opposite to the first rotation direction;

[0149] Step S500: the washing liquid enters each washing zone of the graded washing zone 22 in sequence according to the second rotation direction to wash the filter cake in the separation filter element 20 step by step;

[0150] Step S600: the separation filter element 20 adsorbs the oxidation product in the first rotation direction and sequentially passes through the filtration zone 21, the graded washing zone 22 and the dehydration zone 23 to obtain a recyclable filter cake in the dehydration zone 23.

[0151] See also Figure 8, shows a working flow chart of the safety filtering and washing device 100, which includes a liquid supply unit 200, a gas-liquid separation unit 300 and a condensing unit 400 in addition to the safety filtering and washing device 100. The liquid supply unit 200, the gas-liquid separation unit 300 and the condensing unit 400 are integrated with the safety filtering and washing device 100 to form a safety filtering and washing system 1000.

[0152] Specifically, in the safety filtration and washing system 1000, the specific components and specific structures of the safety filtration and washing device 100 can refer to the description of the above embodiments. Meanwhile, on this basis, the countercurrent washing process in Embodiment 2 uses four-stage graded countercurrent washing.

[0153] The graded washing area 22 of the separation filter element 20 is sequentially divided into four parts to achieve four washes, namely, the primary washing area P1, the secondary washing area P2, the tertiary washing area P3 and the quaternary washing area P4. At the same time, corresponding to the division of the graded washing area 22, the washing part 32 in the cover body 30 is also divided into four parts for countercurrent circulation washing, namely, the primary infusion tube group L1, the secondary infusion tube group L2, the tertiary infusion tube group L3 and the quaternary infusion tube group L4.

[0154] Specifically, the liquid supply unit 200 is used to provide the oxidation product slurry to be filtered for the safety filtering and washing device 100. The liquid supply unit 200 includes an overflow tank 210, a filtrate gas-liquid separator 220 and a filtrate recovery tank 230.

[0155] The gas-liquid separation unit 300 is used to gradually recover the washing liquid in a filtering and washing cycle and circulate it step by step to each group of infusion tubes of the washing part 32. Corresponding to the four-stage graded countercurrent washing structure of the safety filtering and washing device 100, a primary gas-liquid separator 301, a secondary gas-liquid separator 302, a tertiary gas-liquid separator 303, a quaternary gas-liquid separator 304 and a washing liquid collection tank 305 are provided.

[0156] At least one condenser is provided in the condensing unit 400, and the gas from the gas-liquid separation unit 300 is collected by the condenser and cooled and liquefied, and the condensate can be recycled to the washing liquid collection tank 305. Preferably, in embodiment 2, a first condenser 401 and a second condenser 402 are provided.

[0157] Before the safety filtering and washing device 100 is started, the oxidation product (CTA slurry, hereinafter referred to as slurry) produced by the PTA oxidation unit is sent to the feed part 50 of the safety filtering and washing device 100 through a transmission pump after multi-stage crystallization.

[0158] At this time, the safety filtering and washing device 100 is in the preparation stage before starting. By controllably inputting waste heat steam such as heated tail gas and low-pressure steam into the interior of the safety filtering and washing device 100 (the interior of the housing 70), the interior of the housing 70 gradually reaches an atmosphere that meets the requirements of the filtering and washing process. The specific atmosphere (such as ambient pressure value, temperature value, humidity value, etc.) can be optimized and set according to the actual process preparation requirements.

[0159] Alternatively, if the amount of slurry in the feed portion 50 exceeds a preset maximum slurry processing capacity of the safety filtering and washing device 100 , the slurry exceeding the preset maximum slurry processing capacity may be recovered through the overflow tank 210 of the liquid supply unit 200 .

[0160] The safety filtering and washing device 100 is started, and the separation filter element 20 starts to rotate clockwise under the drive of the driving unit 10, and a part of the filter cloth 201 starts to absorb the slurry in the filtering area 21. At the same time, the gas delivery part 31 in the cover body 30 starts to deliver pressurized gas in the counterclockwise direction, and the washing part 32 starts to deliver washing liquid step by step in the counterclockwise direction.

[0161] In the filtration zone 21, a part of the filter cloth 201 continuously absorbs the slurry from the feed part 50 during the clockwise rotation. A part of the slurry is a solid mixed substance used to form a filter cake and recovered after washing, and the other part is filtrate. Under the action of the filtration pressure, this part of the filtrate passes through the filter cloth 201 and enters the filtrate gas-liquid separator 220 through the filtrate collection pipeline, wherein the filtrate that has completed the gas-liquid separation is then recovered to the mother liquor system through the filtrate recovery tank 230 for participating in the PTA oxidation reaction again. When the filter cloth 201 leaves the filtration zone 21, the solid mixture in the slurry remains on the filter cloth 201 to form an initial filter cake. The filter cloth 201 carrying the initial filter cake continues to rotate clockwise and is countercurrently washed in the graded washing zone 22.

[0162] In the graded washing area 22, the graded washing area 22 is first divided into the first-level washing area P1 corresponding to the four-level infusion tube group L4 of the washing part 32, and so on, the second-level washing area P2 corresponds to the third-level infusion tube group L3, the third-level washing area P3 corresponds to the second-level infusion tube group L2, and the fourth-level washing area P4 corresponds to the first-level infusion tube group L1.

[0163] The washing liquid can usually be clean process water produced in the PTA preparation process. The pressurized process water first passes through the first-level infusion pipe group L1 to enter the fourth-level washing area P4 of the graded washing area 22 to wash the filter cake. The ionic impurities in the filter cake pass through the filter cloth 201 with the process water and enter the first-level gas-liquid separator 301 through the process water circulation pipeline. After the process water is separated from the gas and liquid in the first-level gas-liquid separator 301, the gas therein enters the first condenser 401 for cooling, and the cooled liquid enters the washing liquid collection tank 305 for recovery. The liquid therein is returned to the second-level infusion pipe group L2 through the delivery pump and enters the third-level washing area P3 of the graded washing area 22 to continue washing the filter cake.

[0164] The process water passing through the tertiary washing area P3 enters the secondary gas-liquid separator 302 through the process water circulation pipeline. After the process water is separated into gas and liquid in the secondary gas-liquid separator 302, the gas therein enters the second condenser 402 for cooling, and the cooled liquid enters the washing liquid collection tank 305 for recovery, and the liquid therein is returned to the tertiary liquid delivery pipe group L3 through the delivery pump and enters the secondary washing area P2 of the graded washing area 22 to continue washing the filter cake.

[0165] The process water passing through the secondary washing area P2 enters the tertiary gas-liquid separator 303 through the process water circulation pipeline. After the process water is separated into gas and liquid in the tertiary gas-liquid separator 303, the gas therein enters the second condenser 402 for cooling, and the cooled liquid enters the washing liquid collection tank 305 for recovery, and the liquid therein is returned to the quaternary liquid delivery pipe group L4 through the delivery pump and enters the primary washing area P1 of the graded washing area 22 to continue washing the filter cake.

[0166] At this point, the process water has completed all washing processes within a filtration and washing cycle after passing through the first-level infusion tube group L1, the second-level infusion tube group L2, the third-level infusion tube group L3 and the fourth-level infusion tube group L4 in sequence. Finally, the process water enters the fourth-level gas-liquid separator 304 through the process water circulation pipeline. After the process water is separated from the gas and liquid in the fourth-level gas-liquid separator 304, the gas therein enters the second condenser 402 for cooling, and the cooled liquid enters the washing liquid collection tank 305 for recovery, and the liquid therein directly flows into the liquid outlet pipe of the washing liquid collection tank 305 and is discharged from the washing liquid outlet. Alternatively, the washing liquid in the washing liquid collection tank 305 can also be sent back to the mother liquor system to continue to participate in the PTA oxidation reaction, so as to realize the recycling of the filtrate.

[0167] In the dehydration zone 23, the filter cake is washed and then dehydrated, dehumidified and dried in the dehydration zone 23. The pressurized gas provided by the gas delivery part 31 of the cover body 30 applies pressure to press out the residual water in the filter cake. After passing through the dehydration zone 23, the filter cloth 201 carrying the filter cake has rotated to the vicinity of the cake unloading part 60, and the cake unloading can be completed by the scraper of the cake unloading part 60. The recovered filter cake enters the pulping device for pulping and then enters the subsequent process flow.

[0168] In the filter cloth cleaning area 24, although the filter cloth 201 has completed cake discharge, there are still filter cake residues on it. Alternatively, a cleaning structure can be provided on the cake discharge part 60, for example, a spraying member can be provided on the scraper to clean the residual solid particles on the surface of the filter cloth 201 by spraying.

[0169] At this point, the separation filter element 20 has completed one filtering and washing cycle, and the above process is repeated to enter the next filtering and washing cycle to achieve continuous production.

[0170] Compared with traditional hydraulic filtering equipment, the safety filtering and washing device 100 and the safety filtering and washing system 1000 of the above-mentioned embodiments have a long life cycle, fewer vulnerable parts, and lower maintenance costs. The maintenance cycle of general hydraulic filtering equipment is once every three months, and each maintenance takes 10-15 days, and the workload of replacing vulnerable parts is large. The maintenance cycle of the safety filtering and washing device 100 can be once every six months, and each maintenance only takes 3-5 days, and the maintenance content is only the inspection, maintenance and replacement of bearing parts.

[0171] The safe filtering and washing device and filtering and washing method for separating PTA oxidation products provided by the embodiments of the present invention have at least one or part of at least one of the following advantages:

[0172] (1) The separation filter element inside the safety filtration and washing device is continuously adsorbed by the oxidation products produced by the PTA oxidation unit through the method of continuous pneumatic pressure filtration. At the same time, the filter cake on the separation filter element is washed step by step in conjunction with the countercurrent circulation washing method, thereby improving the filtration and washing efficiency of the safety filtration and washing device and reducing the installed energy consumption;

[0173] (2) The filter cloth is used to form the separation filter element, which has a simple structure and low cost. The number and arrangement density of the filter cloth can be adjusted according to the impurity composition and content of the filter cake in the actual process flow, and has high adaptability;

[0174] (3) By providing a cover on the outside of the driven hub, it is possible to further prevent the filter cake on the separation filter element in the driven hub from being contaminated by the acidic gas generated by evaporation and sputtering of the slurry;

[0175] (4) By arranging a gas delivery section in the housing for countercurrent gas delivery, on the one hand, the different filtration pressure differences in different process areas of the separation filter element can be independently adjusted by controlling the gas delivery pressure; on the other hand, the backflow of polluted gas generated in the filtration area of ​​the separation filter element can be suppressed by a portion of the pressurized gas that always flows countercurrently in the gas delivery section;

[0176] (5) By arranging a washing section in the housing for countercurrent washing, the washing liquid in one filtering and washing cycle can be recycled to perform multi-stage washing on the filter cake on the separation filter element, thereby reducing the consumption of washing liquid and improving the washing effect, thereby effectively improving the washing efficiency of the filter cake;

[0177] (6) By using a rotary pan seal in the rotary seal part, the friction between the sealing component and the main shaft can be effectively reduced, thereby reducing the output torque of the drive hub and reducing power consumption;

[0178] (7) By using auxiliary pure gas seals and water seals in the rotating seal part, the polluted gas inside the housing of the safety filtration and washing device can be effectively prevented from entering the main shaft and the sealing structure, maintaining a good sealing environment, extending the service life of the main shaft, helping to improve the safety factor of the equipment and process flow, and effectively reducing the maintenance cost of the drive unit;

[0179] (8) The overall structure of the safety filtering and washing device forms a vertical pressure vessel with a compact internal structure, small footprint, and easy and quick installation;

[0180] (9) The filtration area of ​​a single safety filter and washing device is large, which is three times that of a traditional hydraulic pressure filter device, and the processing capacity of a single filter and washing device is twice that of a traditional device, effectively reducing the number of equipment configurations, thereby reducing equipment investment costs and reducing the overall production cost of PTA;

[0181] (10) The safety filtering and washing device has a simple internal mechanical structure and few vulnerable parts, which helps to extend its service life and improve the safety factor. In addition, the long life cycle of each component reduces the maintenance frequency and thus reduces maintenance costs.

[0182] Although some embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the present general inventive concept, the scope of which is defined by the claims and their equivalents.

Claims

1. A safe filtering and washing device for separating oxidation products in a PTA oxidation unit by filtering and washing, characterized in that: The safety filtering and washing device comprises: Spindle; A driving hub, which is disposed at one end of the main shaft and is used to drive the main shaft to rotate; A driven rotating hub, which is arranged at the other end of the main shaft and drives the driven rotating hub to rotate when the main shaft rotates; A separation filter element, the separation filter element is composed of filter cloths, the filter cloths are arranged layer by layer along the circumferential direction of the main shaft and are fixedly arranged on the inner wall of the driven hub; A cover body, the cover body is arranged on the outer side of the driven rotating hub, and the cover body includes a gas delivery part for continuously providing countercurrent pressurized gas to the interior of the driven rotating hub and a washing part for providing countercurrent washing liquid; The filter cloth absorbs the oxidation products and rotates with the driven hub to form a filtering area, a graded washing area and a dehydration area in sequence, and a filter cake that can be recovered after separation is obtained in the dehydration area; Wherein, the washing section includes at least two groups of infusion tubes, one end of each of the at least two groups of infusion tubes is fixed inside the washing section, and the other end of each infusion tube is fixedly connected to a nozzle to spray washing liquid on the filter cloth located in the graded washing area. The air channel of the gas delivery section includes a dehydration section, a washing section and a filtering section corresponding to the dehydration area, the graded washing area and the filtering area respectively along the inlet and outlet direction of the pressurized gas, and air delivery channels are provided on the dehydration section, the washing section and the filtering section for delivering the pressurized gas into the dehydration area, the graded washing area and the filtering area respectively.

2. The safety filtering and washing device according to claim 1, characterized in that: The graded washing area includes at least two washing areas, and the number of partitions of the at least two washing areas is equal to the number of groups of the at least two groups of infusion tubes; The at least two groups of liquid delivery pipes sequentially deliver the washing liquid in the same filtering and washing cycle to each of the at least two washing zones in the direction opposite to the rotation direction of the separation filter element.

3. The safety filtering and washing device according to claim 2, characterized in that: The at least two groups of infusion tubes include a first group of infusion tubes, a second group of infusion tubes and a third group of infusion tubes.

4. The safety filtering and washing device according to claim 3, characterized in that: The at least two washing zones include a first washing zone, a second washing zone and a third washing zone; When the main shaft drives the driven hub to rotate, the first group of infusion tubes is arranged corresponding to the third washing area and sprays washing liquid to the third washing area, the second group of infusion tubes is arranged corresponding to the second washing area and sprays washing liquid to the second washing area, and the third group of infusion tubes is arranged corresponding to the first washing area and sprays washing liquid to the first washing area.

5. The safety filtering and washing device according to claim 1, characterized in that: A part of the pressurized gas passes through the dehydration section, the washing section and the filtering section in sequence through the air inlet of the air passage and is delivered to the corresponding dehydration zone, the graded washing zone and the filtering zone; Another part of the pressurized gas passes through the air inlet of the air passage, sequentially passes through the dehydration section, the washing section and the filtering section, and is discharged from the air outlet of the air passage.

6. The safety filtering and washing device according to any one of claims 1 to 5, characterized in that: The separation filter element further comprises a filter cloth cleaning area, which is arranged behind the dehydration area along the rotation direction of the driven hub and is used to clean the filter cloth after the filter cake is removed; The safety filtering and washing device also includes a shell, wherein the main shaft, the driven hub and the cover are arranged inside the shell, and one end of the main shaft passes through the shell and is connected to the driving hub.

7. The safety filtering and washing device according to claim 6, characterized in that: The safety filtering and washing device further comprises a rotating sealing portion arranged between the housing and an end of the main shaft extending out of the housing. The rotary seal portion comprises: A sealing column, which is a hollow structure and is sleeved on the outside of the main shaft, and the inner wall of the sealing column and the outer side surface of the main shaft form a sealing cavity; A rolling bearing, which is arranged at the end of the sealing column and is used for positioning and supporting between the main shaft and the sealing column; A rotary pan-seal, the rotary pan-seal being used for rotary sealing between the main shaft and the sealing column; A sealing air channel, wherein the sealing air channel is arranged on the sealing column and an air outlet of the sealing air channel is communicated with the sealing cavity, and the gas used for sealing enters the sealing cavity through the sealing air channel; A sealed water channel is provided near the rotary flood seal to prevent polluted gas in the housing from entering the interior of the rotary seal portion.

8. The safety filtering and washing device according to claim 7, characterized in that: The rotary pan-plug seal comprises at least two rotary pan-plug seals, and the at least two rotary pan-plug seals are arranged at one end of the sealing column inside the housing; The sealing lip of the rotary flood seal is arranged to face the polluted gas side in the housing.

9. A filtering and washing method, used for filtering and washing oxidation products in a PTA oxidation unit according to the safety filtering and washing device according to any one of claims 1 to 8, characterized in that: The filtering and washing method comprises: By injecting low-pressure steam and / or heating tail gas into the safety filtering and washing device, the inside of the safety filtering and washing device reaches a preset working pressure and working temperature; The oxidation product produced by the PTA oxidation unit is delivered to the feed section of the safety filtering and washing device by a delivery pump; The safety filtering and washing device is started by driving the rotating hub, so that the separation filter element in the driven rotating hub continuously rotates in the first rotating direction; The gas supply part of the cover body provides pressurized gas to the interior of the driven hub, and the washing liquid is provided to the interior of the driven hub through the washing part of the cover body, and the flow direction of the pressurized gas and the washing liquid is a second rotation direction, and the second rotation direction is opposite to the first rotation direction; The washing liquid enters each washing zone of the graded washing zone in turn according to the second rotation direction to wash the filter cake in the separation filter element step by step; The separation filter element adsorbs the oxidation product in the first rotating direction and sequentially passes through the filtering area, the graded washing area and the dehydration area, and obtains a filter cake that can be recovered after separation in the dehydration area.

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