A preparation device and method for direct coal liquefaction catalyst

Abstract

The present invention discloses a device and method for preparing a direct coal liquefaction catalyst, which belongs to the technical field of catalyst preparation. The device includes a multi-effect filter dryer, a locking hopper, a nitrogen circulation system and a liquid withdrawal storage tank. The multi-effect filter dryer performs solid-liquid separation on a mixture of an iron salt solution and coal powder through a filter element, and after exhausting the residual liquid with low-temperature nitrogen, switches to high-temperature nitrogen to dry the filter cake, and finally uses pulse nitrogen to make the filter cake fall off as catalyst dry powder. The present invention solves the problems of low filtration and drying efficiency, high nitrogen consumption, easy oxidation of catalysts, environmental pollution, and dust hazards in the prior art. The process flow is shortened through an integrated filtration and drying design, and the whole process is closed to avoid oxidation of the catalyst, environmental pollution, and dust hazards. The present invention also provides a catalyst preparation method based on the device. By regulating the nitrogen temperature and flow, the drying efficiency is high, the residual liquid component in the filter cake is reduced, and the catalyst quality and production stability are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and in particular to a device and method for preparing a direct coal liquefaction catalyst. Background Art

[0002] Direct coal liquefaction technology is an important approach for converting coal into liquid fuel. Its core lies in the performance and preparation of the catalyst. Existing catalysts typically consist of iron-based compounds supported on a pulverized coal carrier and require multiple steps, including mixing, filtration, and drying. However, traditional processes present numerous challenges. In industrial-scale production, the efficiency of catalyst filtration and drying directly impacts production capacity and costs. During solid-liquid separation of the mixed liquid, traditional filter presses or centrifuges struggle to achieve continuous operation, and residual liquid in the filter cake requires additional drying equipment, resulting in a lengthy process. Furthermore, the drying process suffers from low utilization and high consumption of high-temperature gases, leading to high energy costs. Furthermore, catalysts are sensitive to oxygen, and existing open-type equipment is prone to oxidative deactivation, compromising product activity. Traditional devices require separate filtration and drying steps, occupying a large footprint and generating dust and material loss during filter cake transfer. Open or semi-closed preparation processes are prone to introducing oxygen, which can lead to catalyst oxidation and reduced catalytic activity, while also causing environmental pollution and dust hazards. The single fixed nitrogen nozzle design makes it difficult to dry the filter cake evenly, and the filter cake is frequently over-dried or agglomerated locally, affecting the drying efficiency and product performance.

[0003] Some catalyst drying devices disclosed in the prior art use multi-stage hot air circulation, but do not have an integrated filtration function and still require pre-separation equipment. Not only are the separation and drying processes lengthy, but the catalyst powder is also susceptible to oxidation and dust hazards during transfer. Another technology reduces the risk of oxidation through vacuum drying, but the equipment is complex, the operation is difficult, and the maintenance and operation costs of the vacuum system are high. Therefore, there is an urgent need to develop an integrated device that integrates filtration, drying, and nitrogen circulation to improve efficiency while reducing energy consumption and ensuring that the catalyst preparation process is sealed throughout. Summary of the Invention

[0004] This invention overcomes existing issues such as low filtration and drying efficiency, high nitrogen consumption, catalyst oxidation, environmental pollution, and dust hazards. It provides a device and method for preparing a direct coal liquefaction catalyst. The integrated filtration and drying design shortens the process flow, while the nitrogen circulation system reduces energy consumption. The closed hopper ensures fully enclosed operation, minimizing catalyst activity loss, environmental pollution, and dust hazards. By regulating nitrogen temperature and flow in stages, drying efficiency is optimized, residual liquid in the filter cake is reduced, and catalyst quality and production stability are improved.

[0005] In order to achieve the above object, the present invention adopts the following scheme:

[0006] A preparation device for a direct coal liquefaction catalyst, comprising:

[0007] A multi-effect filter-dryer comprises a cylinder, a filter element, and a collection pipe; the cylinder is provided with a conical end cap at the lower end and an elliptical end cap at the upper end; a mixed liquid inlet for inputting a mixture of an iron salt solution and coal powder is provided at the bottom of the conical end cap, and a nitrogen inlet is provided in the middle of the conical end cap, the nitrogen inlet including a low-temperature nitrogen inlet and a high-temperature nitrogen inlet; the filter elements are grouped and arranged in the cylinder, each filter element comprising a hollow, breathable frame and a filter bag attached to the frame; the frame comprises a central tube and a peripheral bracket for supporting the filter bag; the central tube is provided with an inlet and outlet hole at the bottom and an inlet connected to the collection pipe at the top;

[0008] A locking hopper connected to the bottom of the conical head of the multi-effect filter-dryer through a discharge valve;

[0009] A nitrogen circulation system, comprising a low-pressure nitrogen storage tank, a high-temperature and high-pressure nitrogen storage tank, a high-pressure nitrogen storage tank, and a booster pump; the outlet of the low-pressure nitrogen storage tank is connected to the inlets of the high-temperature and high-pressure nitrogen storage tank and the high-pressure nitrogen storage tank respectively through the booster pump, the high-pressure nitrogen storage tank is connected to the low-temperature nitrogen inlet of the multi-effect filter dryer through a pipeline, the high-temperature and high-pressure nitrogen storage tank is connected to the high-temperature nitrogen inlet and the manifold outlet through pipelines, and the manifold outlet is further connected to the inlet of the low-pressure nitrogen storage tank through a condenser and a gas-liquid separator;

[0010] The liquid withdrawal storage tank has a liquid inlet and a liquid outlet both connected to the mixed liquid inlet of the multi-effect filter dryer.

[0011] Preferably, the peripheral support of the skeleton includes at least two plum blossom-shaped support frames and multiple skeleton beams for supporting filter bags. The plum blossom-shaped support frames are sleeved on the central tube and the petals are hollowed out. The multiple skeleton beams are arranged at intervals along the outer edge contour of the plum blossom-shaped support frames. The two ends of the skeleton beam are respectively connected to the two plum blossom-shaped support frames, and the extension direction of the skeleton beam is parallel to the axis of the central tube.

[0012] Preferably, upper end covers and lower end covers are respectively provided at both ends of the skeleton beam of the peripheral support of the skeleton, and the two ends of the filter bag are respectively fixed on the upper end cover and the lower end cover. The central tube passes upward through the upper end cover and is connected to the branch pipe extending from the side of the collecting pipe through a flange. A group of filter elements are connected to the same collecting pipe, and multiple collecting pipes are connected to a main pipe. The main pipe is connected to a discharge pipe, an air outlet pipe and an air blow pipe through valves respectively, and the air blow pipe is connected to the outlet of the high-temperature and high-pressure nitrogen storage tank.

[0013] Preferably, a condenser is further included, the inlet of the condenser is connected to the outlet end of the gas outlet pipe, the outlet of the condenser is connected to a gas-liquid separation tank, and the gas outlet of the gas-liquid separation tank is connected to the inlet of the low-pressure nitrogen tank.

[0014] Preferably, the upper end cover is provided with a raised ring and is fixed in the cylinder with a throat clamp; the lower end cover is in an upward tapering plum blossom shape, with its small end welded to the skeleton beam and the large end in contact with the filter bag at the edge of the arc.

[0015] Preferably, a nitrogen-driven sonic soot blower is provided on the elliptical head, the air outlet of the sonic soot blower is a downward-diffusing trumpet shape, and the air inlet is connected to the high-temperature and high-pressure nitrogen storage tank.

[0016] The present application also provides a method for preparing a direct coal liquefaction catalyst, which is based on a preparation device according to any one of the above technical solutions, and comprises the following steps:

[0017] The iron salt solution and the coal powder are mixed to form a mixed liquid, and the mixed liquid is sent to the multi-effect filter dryer from the mixed liquid inlet;

[0018] The mixed liquid is filtered using the filter element of the multi-effect filter-dryer to separate the mixed liquid into a filter cake formed by solid particles on the surface of the filter element and a filtrate after passing through the filter element, and the filtrate is discharged from the multi-effect filter-dryer through a collecting pipe and added to a new mixed liquid configuration;

[0019] When the filter cake reaches a thickness of 5-10mm, stop feeding, close the feed valve, and introduce 25-70℃ nitrogen through the nitrogen inlet on the cone head of the multi-effect filter. Observe the changes in the liquid level in the multi-effect filter dryer. When the liquid level reaches the bottom of the filter element, slowly open the return regulating valve at the mixed liquid inlet at the bottom of the cone to allow the liquid in the filter at the bottom of the filter element to flow out through the return pipeline. At the same time, maintain a positive wind pressure of 50-150kPa at the filter cake to prevent the filter cake from falling off during the return process.

[0020] After the liquid is drained, close the return valve of the mixed liquid inlet and the valve of the low-temperature nitrogen inlet, open the valve of the high-temperature nitrogen inlet, and pass the high-temperature nitrogen into the multi-effect filter dryer to dry the filter cake. The gas-liquid mixture generated during the drying process is discharged from the collecting pipe, and the gas-liquid separation is carried out after passing through the condenser. The separated gas is transported to the low-pressure nitrogen storage tank for recycling, and the condensed liquid is returned to participate in the preparation of the mixed liquid again;

[0021] After the filter cake is dried, close the high-temperature nitrogen inlet valve and the outlet valve of the condenser connected to the collecting pipe, and open the valve between the high-temperature and high-pressure nitrogen storage tank and the collecting pipe outlet. Instantly blow nitrogen into the filter element through the collecting pipe to expand the filter bag, so that the dried filter cake falls off the surface of the filter element and into the conical head to obtain the catalyst dry powder;

[0022] Open the discharge valve at the bottom of the conical head to discharge the catalyst powder into the lock hopper, and then send the catalyst powder to the designated location through the lock hopper. The nitrogen in the low-pressure nitrogen storage tank is pressurized by a pressure pump and then added to the high-pressure nitrogen storage tank and the high-temperature and high-pressure nitrogen storage tank.

[0023] Preferably, a nitrogen-driven sonic soot blower is provided on the elliptical head, the air outlet of the sonic soot blower is a downward-diffusing trumpet shape, and the air inlet is connected to the high-temperature and high-pressure nitrogen storage tank; when the catalyst dry powder is discharged into the locking hopper, the sonic soot blower is started at the same time to remove the catalyst remaining on the surface of the filter bag and the inner wall of the cylinder.

[0024] Preferably, an annular distribution pipe is provided on the inner wall of the cylinder of the multi-effect filter-dryer, the annular distribution pipe being connected to the high-temperature nitrogen inlet, a plurality of vertical branches with independent control valves are arranged at intervals along the circumference of the annular distribution pipe, the vertical branches are provided with vertically arranged nitrogen nozzles, and a temperature sensor is provided in the filter element for collecting average temperature data of the entire filter element;

[0025] When the system detects that the temperature difference E between any two adjacent filter elements exceeds 8°C, the dynamic adjustment mechanism is triggered:

[0026] Immediately increase the opening of the vertical branch valve corresponding to the low-temperature filter element, and set the opening increase ΔK to: ΔK = 0.5 × E%. Simultaneously reduce the opening of the high-temperature filter element branch by the same amount. After an interval of 3 minutes, perform another full-area scan of all filter element temperature data. If the temperature difference between adjacent filter elements is still greater than 3°C, repeat the above adjustment steps. When the temperature difference of all adjacent filter elements is stable within the 3°C range for two consecutive scans, it is determined to be in a regional drying equilibrium state and enter the constant temperature maintenance stage.

[0027] During the constant temperature maintenance phase, the valve opening of each vertical branch is maintained. When the temperature difference E between any two adjacent filter elements is detected to be greater than 8°C, the dynamic adjustment mechanism is triggered again.

[0028] Preferably, a humidity sensor is arranged at the outlet of the upper end of the central tube of the filter element skeleton to continuously monitor the relative humidity of the gas, and the drying process is collaboratively controlled based on the detected gas humidity data. The specific control method is as follows:

[0029] When the relative humidity of the gas at the outlet of a filter element steadily drops to 4.0% ± 0.2%, and the absolute value of the humidity drop rate is less than 0.1% / minute for 10 consecutive minutes, the filter element is judged to have completed drying of the external filter cake and is converted to an inactive filter element. Then the disturbance-free transfer procedure is started:

[0030] Immediately close the valve of the vertical branch pipe corresponding to the filter element where the filter cake drying is completed, and simultaneously open the pressure relief valve at the central pipe of its skeleton to release the internal pressure;

[0031] The released nitrogen flow is dynamically distributed to the vertical branch corresponding to the active filter element that needs the most flow increase. The active filter element is selected by giving priority to the filter element with the lowest temperature change rate. If there are multiple candidates, the one with the largest temperature difference gap is selected. The temperature difference gap is the difference between the current temperature and the target temperature.

[0032] When more than 25% of the filter elements are dried, the nitrogen temperature compensation module is activated to increase the nitrogen temperature output from the high-temperature nitrogen storage tank. The temperature increase ΔT is 0.3×(M1 / M s ), where M1 is the number of active filter elements, M s is the total number of filter elements;

[0033] For conflicts in flow applications from multiple filter cartridges, the released adjustable nitrogen flow is allocated using a three-level arbitration mechanism: the first level allocates 60% of the adjustable flow to the filter cartridge with the lowest temperature, the second level allocates 30% to the filter cartridge with the slowest historical drying speed, and the third level retains the remaining 10% as a system buffer reserve.

[0034] The present invention has at least the following beneficial effects: (1) By combining a multi-effect filter dryer with a nitrogen circulation system, an integrated operation of filtration, drying and nitrogen recovery is realized, the process flow is shortened, equipment investment and energy consumption are reduced, and at the same time, the locking hopper design isolates oxygen, facilitates unloading, and ensures catalyst activity; (2) A condenser and a gas-liquid separation tank are added to efficiently recover and recycle nitrogen in the drying exhaust gas, significantly reducing the demand for fresh nitrogen replenishment and achieving green production; (3) A nitrogen-driven sonic soot blower is used to simultaneously remove residual catalysts from the filter bag and the inner wall of the cylinder during the discharge stage, reducing the frequency of manual cleaning and extending the service life of the filter element; (4) The uniform control of the filter cake drying temperature is achieved through the dynamic adjustment of the annular distribution pipe and the temperature sensor, avoiding local over-drying or agglomeration, improving the consistency of catalyst quality; (5) through the coordinated action of the temperature balance control mechanism between filter elements and the humidity-driven resource dynamic scheduling mechanism, under the premise of ensuring the integrity of the filter cake structure, a breakthrough is made to solve the multi-objective optimization problem of drying uniformity, accurate determination of the end point and resource allocation efficiency in a large multi-filter element system, realizing multi-dimensional coordinated optimization of the drying process, ensuring product quality consistency and system energy efficiency; (6) the present invention can enable the filter bag to withstand a large positive pressure difference by setting a special form of filter element skeleton, thereby preventing the filter bag from being damaged; (7) the present invention can utilize positive air pressure to return the material by designing the skeleton center tube. During the return process, all the liquid above the bottom of the filter element flows out from the collection pipe, and the filter cake stays on the surface of the filter bag, thereby improving the working efficiency of the filter bag. (8) the present invention realizes full-process automated control and full-process closed operation, which is both safe and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the preparation principle of a direct coal liquefaction catalyst of the present invention;

[0036] Figure 2 It is a structural schematic diagram of the multi-effect filter-dryer of the present invention;

[0037] Figure 3 This is a schematic diagram of the connection structure between the filter element and the collection pipe of the present invention;

[0038] Figure 4 A structural schematic diagram of the filter element of the present invention;

[0039] Figure 5 Schematic diagram of another structure of the filter element of the present invention;

[0040] Figure 6 This is a schematic diagram of the plum blossom-shaped support frame structure of the present invention;

[0041] Figure 7 It is a schematic diagram of the upper end cover structure of the present invention;

[0042] Figure 8 This is a schematic diagram of the lower end cover structure of the present invention;

[0043] Figure 9 This is a schematic diagram of the contraction of the filter bag during the filtration process of the present invention;

[0044] Figure 10 This is a schematic diagram of the ventilation and expansion state of the filter bag of the present invention;

[0045] Figure 11 This is a schematic diagram of the annular distribution pipe structure of the present invention.

[0046] In the figure: low-pressure nitrogen storage tank 1, high-temperature and high-pressure nitrogen storage tank 2, high-pressure nitrogen storage tank 3, liquid withdrawal storage tank 4, gas-liquid separation tank 5, condenser 6, multi-effect filter dryer 7, lock hopper 8, booster pump 9, cylinder 701, filter element 702, collecting pipe 703, conical head 704, elliptical head 705, mixed liquid inlet 706, nitrogen inlet 707, central pipe 10, plum blossom-shaped support frame 1101, skeleton beam 1102, upper end cover 12, lower end cover 13, sonic soot blower 14, filter bag 15, annular distribution pipe 16, vertical branch pipe 17. DETAILED DESCRIPTION

[0047] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0048] like Figure 1-10 As shown, the present invention provides a preparation device for a direct coal liquefaction catalyst, which includes:

[0049] The multi-effect filter-dryer 7 comprises a cylinder 701, a filter element 702 and a collection pipe 703; the cylinder 701 is provided with a conical head 704 at the lower end and an elliptical head 705 at the upper end; a mixed liquid inlet 706 for inputting a mixed liquid of an iron salt solution and coal powder is provided at the bottom of the conical head 704, and a nitrogen inlet 707 is provided in the middle of the conical head 704, wherein the nitrogen inlet 707 includes a low-temperature nitrogen inlet and a high-temperature nitrogen inlet; the filter elements 702 are grouped and arranged in the cylinder 701, and each filter element 702 is composed of a porous metal or hollow air-permeable frame and a filter bag 15 attached to the outside of the frame, the frame comprising a central tube 10 and an internal frame for supporting the filter bag 15, the bottom of the central tube 10 is provided with a flow hole for circulating and draining the liquid on the upper part of the filter element 702 and for reverse blowing of nitrogen, and the top is connected to the collection pipe 703;

[0050] A locking hopper 8 connected to the bottom of the conical head 704 of the multi-effect filter-dryer 7 through a discharge valve;

[0051] A nitrogen circulation system comprises a low-pressure nitrogen storage tank 1, a high-temperature and high-pressure nitrogen storage tank 2, a high-pressure nitrogen storage tank 3 and a booster pump 9; the outlet of the low-pressure nitrogen storage tank 1 is connected to the inlets of the high-temperature and high-pressure nitrogen storage tank 2 and the high-pressure nitrogen storage tank 3 respectively through the booster pump 9, the outlet of the high-pressure nitrogen storage tank 3 is connected to a branch of the high-temperature and high-pressure nitrogen storage tank 2, and the combined pipeline is connected to the multi-effect filter 7, the second branch pipeline of the outlet of the high-temperature and high-pressure nitrogen storage tank 2 is respectively connected to the outlet of the collecting pipe 703, the outlet of the collecting pipe 703 is also connected to the filtrate outlet and the inlet of the condenser 6, the outlet of the condenser 6 is connected to the gas-liquid separation tank 5, and the gas discharge pipeline of the gas-liquid separation tank 5 is connected to the low-pressure nitrogen storage tank 1;

[0052] The liquid inlet and liquid outlet of the liquid withdrawal storage tank 4 are connected to the mixed liquid inlet 706 through different pipelines.

[0053] like Figure 2As shown, the multi-effect filter-dryer 7 consists of a cylinder 701, a filter element 702, and a collection pipe 703. The lower end of the cylinder 701 is a conical end cap 704, and the upper end is an elliptical end cap 705. The bottom of the conical end cap 704 is provided with a mixed liquid inlet 706 (for inputting a mixture of iron salt solution and coal powder), and the middle is provided with a nitrogen inlet 707 (including a low-temperature nitrogen inlet and a high-temperature nitrogen inlet). The filter elements 702 are arranged in groups within the cylinder 701. Each filter element 702 is composed of a porous metal or hollow, breathable frame and an attached filter bag 15. The upper and lower ends of the central pipe 10 are evenly provided with holes for liquid circulation. The frame includes the central pipe 10 and a peripheral bracket, and the top is connected to the inlet of the collection pipe 703. The inclined structure of the conical head 704 facilitates the uniform adhesion of solid particles (filter cake) to the outer surface of the filter bag under the pressure differential during the collection of dry catalyst powder. The mixed liquid inlet 706, located at the bottom of the cone, prevents solids in the mixed liquid from settling, and instead carries solid particles to the filter element surface during flow. The elliptical head 705 serves as the top sealing structure for the cylinder 701. Its curved design withstands high pressures and provides space for the installation of the sonic soot blower 14 (referred to in subsequent claims). In practice, the elliptical head 705 can also be configured in other shapes as permitted by regulations. The hollow framework of the filter element assembly (such as the plum blossom-shaped support frame 1101 and framework beam 1102) provides mechanical support, allowing gas and liquid to flow from the cylinder 701 to the filter bag 15 and then into the manifold 703. The densely packed hollow support points prevent deformation or rupture of the filter bag 15 under high pressure. A porous metal plate can also be used instead. The flow holes provided at the bottom of the central tube 10 can effectively drain the clean liquid that has passed through the filter bag, reduce the withdrawal amount of the mixed liquid, the drying efficiency, and the passage of backflushing nitrogen during the withdrawal process.

[0054] After a sufficient amount of the mixed liquid has been filtered to obtain a filter cake of the desired quality, the mixed liquid is stopped from entering the filter element 702 within the cylinder 701. The liquid in the filter element 702 passes through the filter element 702 and enters the collection pipe 703 through the bottom opening of the central tube 10, where it is discharged through the clear liquid outlet. The remaining liquid in the container at the bottom of the filter element 702 is returned to the liquid withdrawal tank 4 to facilitate the drying process. The collection pipe 703 connected to the top of the central tube 10 allows the clear liquid from each group of filter elements 702 to be centrally collected and the filter cakes to be backflushed individually. After drying is complete, nitrogen is introduced into the filter element 702 through the collection pipe 703 to expand the filter bag 15. Because the introduced nitrogen has a large instantaneous gas volume, pulsed backflushing and group-by-group backflushing are required to meet the atmospheric volume per unit time and reduce gas consumption.

[0055] The high-temperature nitrogen inlet and the low-temperature nitrogen inlet of the nitrogen inlet 707 can be set independently or share the air duct inlet. The low-temperature nitrogen is used to drain the liquid in the container above the bottom of the filter element 702 and to assist in draining the liquid in the container below the bottom of the filter element 702 during the material withdrawal stage. The high-temperature nitrogen is used to quickly dry the filter cake and perform pulse backflushing on the dried filter cake to make the filter bag round from the wrinkled state and make the filter cake attached to the filter bag fall off.

[0056] During actual operation, after the mixed liquid enters the cylinder 701 through the mixed liquid inlet 706 at the bottom of the conical head 704, the filter element 702 intercepts solid particles through the filter bag 15 to form a filter cake, and the clear liquid is discharged through the skeleton central tube 10 and the collecting pipe 703. After a round of filtration is completed, when low-temperature nitrogen is introduced, the positive pressure pushes the liquid above the bottom of the filter element in the container to be discharged through the flow hole at the bottom of the central tube 10. After this portion of liquid is completely discharged, the lower return valve of the container is opened and the material is slowly discharged. The filter cake pressure difference is determined by the pressure sensor to be between 50 and 150 kPa to prevent the filter cake from falling off. After the residual liquid at the bottom of the filter element in the container is completely discharged, the low-temperature nitrogen valve, the return valve, and the clear liquid outlet valve are closed. The valve for the high-temperature nitrogen inlet and the valve connected to the condenser are opened, and high-temperature nitrogen is introduced into the cylinder 701. The moisture of the filter cake is removed through thermal convection and osmosis, achieving drying. After drying is completed, nitrogen is introduced into the filter element 702 from the collection pipe 703 in a pulsed form. The filter bag 15 expands repeatedly to shake off the catalyst attached to the surface. The catalyst changes from a filter cake to a dry powder state and is discharged from the lock hopper 8.

[0057] The lock hopper 8 is connected to the bottom of the conical head 704 of the multi-effect filter-dryer 7 via a discharge valve. This sealed container controls the discharge of the catalyst powder via a valve, ensuring a sealed process throughout the entire preparation process. The discharge valve opens only after the filter cake is dried to prevent undried material from entering the finished product. The dried catalyst powder then falls through the conical head 704 into the lock hopper 8. The discharge valve automatically opens and closes according to system commands, ensuring safe transfer of the catalyst. The lock hopper 8 can be equipped with a multi-stage sealing structure (such as a dual valve or airlock) to further prevent internal or external leakage.

[0058] The nitrogen circulation system includes a low-pressure nitrogen storage tank 1, a high-temperature and high-pressure nitrogen storage tank 2, a high-pressure nitrogen storage tank 3, and a booster pump 9. The low-pressure nitrogen storage tank 1 is connected to the high-temperature and high-pressure tank inlets via the booster pump 9. The high-pressure storage tank 3 is connected to the nitrogen inlet of the multi-effect filter, while the high-temperature and high-pressure storage tank 2 is connected to a branch line from the nitrogen inlet of the multi-effect filter to the outlet of the manifold 703. The outlet of the manifold 703 is connected to the inlet of the condenser. After passing through the gas-liquid separator 5, the low-temperature and low-pressure nitrogen returns to the inlet of the low-pressure nitrogen storage tank 1. The nitrogen circulation system realizes the recycling of nitrogen: the low-pressure nitrogen storage tank 1 is used to recover the low-temperature nitrogen after drying and cooling. The low-temperature nitrogen is then boosted by the booster pump 9 and replenished to the high-pressure storage tank 3 and the high-temperature and high-pressure storage tank 2, thus realizing the nitrogen recycling process. The high-temperature and high-pressure storage tank 2 has a nitrogen heating function, providing the high-temperature nitrogen required for drying. The high-temperature nitrogen is distributed through pipes and valves to the high-temperature nitrogen inlet of the multi-effect filter for drying and to the manifold 703 for filter cake removal. The gas-liquid mixture in the drying stage enters the condenser 6 through the collecting pipe 703, and the gas separated by the gas-liquid separation tank 5 returns to the low-pressure storage tank 1, forming a closed-loop system.

[0059] like Figure 1 As shown, after being pressurized, the low-pressure nitrogen is divided into two paths: one path enters high-pressure storage tank 3 to supply low-temperature, high-pressure nitrogen for the material return operation, and the other path enters high-temperature, high-pressure storage tank 2 for heating and drying. After condensation and gas-liquid separation, the drying waste gas returns to low-pressure storage tank 1, achieving zero emissions.

[0060] The liquid inlet and liquid outlet of the liquid withdrawal storage tank 4 are connected to the mixed liquid inlet 706 through different pipelines. When the externally configured mixed liquid is input into the device, it does not need to pass through the liquid withdrawal storage tank 4, because before the filter cake is dried, the residual liquid at the bottom of the filter element 702 in the cylinder 701 must be drained to ensure the drying effect, so the liquid withdrawal storage tank 4 is used to temporarily store the unprocessed mixed liquid, and re-inject it into the mixed liquid inlet 706 through the circulation pipeline to reduce the waste of raw materials. Since the liquid withdrawal storage tank 4 is configured, the liquid withdrawal pipeline can be equipped with a flushing device to regularly remove the sediment in the pipeline to ensure smooth flow of liquid. During the withdrawal stage, the mixed liquid inlet 706 is switched to nitrogen to enter to form a slight positive pressure, and the residual liquid in the container at the bottom of the filter element in the cylinder 701 is pressed into the liquid withdrawal storage tank 4. The liquid in the storage tank 4 will enter the multi-effect filter dryer 7 first when it is fed next time, forming a closed-loop buffer storage effect.

[0061] This device's sealed design, featuring a multi-effect filter-dryer 7 and a lock hopper 8, prevents both internal and external leakage of the catalyst, preventing the escape of dust and hazardous gases. A nitrogen circulation system allows for gas reuse, significantly reducing energy consumption and operating costs. Each component can be controlled through valves and sensors, reducing manual intervention and improving production stability. Filtration, drying, and ash removal functions are integrated into a single device, shortening the process flow and improving space utilization.

[0062] In another technical solution, Figure 4 and Figure 5 As shown, the peripheral support of the skeleton includes at least two plum blossom-shaped support frames 1101 and multiple skeleton beams 1102 for supporting the filter bag 15, as shown in FIG. Figure 6 As shown, the plum blossom-shaped support frame 1101 is sleeved on the central tube 10 and the petals are hollowed out, and multiple skeleton beams 1102 are arranged at intervals along the outer edge contour of the plum blossom-shaped support frame 1101. The two ends of the skeleton beam 1102 are respectively connected to the two plum blossom-shaped support frames 1101, and the extension direction of the skeleton beam 1102 is parallel to the axis of the central tube 10.

[0063] The plum blossom-shaped structure reduces weight by hollowing out the petals, while providing uniform radial support force to prevent the filter bag 15 from being torn due to uneven pressure. The structure of the plum blossom-shaped support frame 1101 is such that it has a convex portion at the position of the petals and a concave portion between the petals, such as Figure 9 As shown, during the filtration process, the filter bag 15 has an inward curvature in the concave portion of the support frame 1101. The outermost shaded portion in the figure is the filter cake, and the cross section of the filter cake is also plum blossom-shaped. When the filter bag 15 is stretched open by ventilation, it has an outward curvature, as shown in FIG. Figure 10 As shown, when the filter bag 15 expands to a cylindrical shape, the filter cake inevitably breaks apart. Supported by this plum blossom support frame 1101, the filter bag 15 has a greater travel distance for contraction and expansion than a conventional cylindrical support structure, allowing the filter cake to fall off quickly during this period of expansion and contraction. The support frame spacing is adjustable, and multiple support frames can be installed to enhance support stability and accommodate varying filtration pressures, bag 15 lengths, or media characteristics.

[0064] like Figure 4 As shown, the ends of the skeleton beam 1102 of the peripheral support of the skeleton are respectively provided with an upper end cover 12 and a lower end cover 13, and the structures of the upper end cover 12 and the lower end cover 13 are respectively as shown in FIG. Figure 7 and Figure 8 As shown, the upper end cover 12 and the lower end cover 13 are welded to both ends of the skeleton beam 1102 to form an integral skeleton.

[0065] The skeleton beams 1102 are slender round steel or round tubes (with an optional diameter of 0.5-3 mm) and are distributed along the outer edge of the plum blossom support frame 1101 to form a grid-like support surface to prevent the filter bag 15 from collapsing. The skeleton beams 1102 have small gaps, ensuring that the filter bag 15 is tightly attached to the skeleton under high pressure, avoiding local stress concentration. After the filter bag 15 is sleeved on the outer periphery of the skeleton, the plum blossom support frame 1101 and the skeleton beams 1102 together form a rigid support body. When the mixed liquid enters the multi-effect filter dryer 7, the solid particles are intercepted by the filter bag 15, and the clean liquid flows into the central tube 10 through the gaps between the skeleton beams 1102 and the hollow petal area. The uniform distribution of the skeleton beams 1102 can effectively withstand the pressure of the filter bag and prevent the filter bag 15 from being crushed.

[0066] Skeleton beams 1102 connect multiple plum blossom-shaped support frames 1101 and extend parallel to the center tube 10, forming a longitudinal support structure. Skeleton beams 1102 are arranged along the edges of the plum blossom-shaped support frames to resist radial pressure on the filter bags 15 during filtration, preventing them from being crushed. Increasing the number of plum blossom-shaped support frames 1101 (for example, adding one every 50 mm) allows for greater pressure differentials and improved device flexibility. During assembly of the filter element 702, the plum blossom-shaped support frames 1101 are welded to the center tube 10. The outer edges of the skeleton beams 1102 are spot welded, creating burr-free welds with a smooth, rounded shape to prevent the filter bags from being scratched. The parallel arrangement of the skeleton beams 1102 facilitates construction and forms a circular surface, ensuring a secure fit to the filter bags and minimizing the pressure drop per unit area, preventing them from being crushed.

[0067] The central tube 10, the upper end cover 12, the lower end cover 13, the plum blossom-shaped support frame 1101, and the skeleton beam 1102 together constitute the filter bag bracket. The filter bag 15 is attached to the outside of the skeleton. During operation, the filter bag fits tightly to the outer surface of the support structure under the influence of the pressure difference. The upper open end of the filter bag 15 is fixed to the upper end cover 12 through a throat clamp. The raised ring on the upper end cover 12 prevents the filter bag from falling off.

[0068] like Figure 3As shown, the central tube 10 passes upward through the upper end cap 12 and is connected to the branch pipes of the manifold 703 via flanges. Multiple groups of filter elements 702 are connected to the same manifold 703, which then converge into a main pipe. Each group of manifolds 703 is equipped with a separate valve. After passing through the valve, the manifolds 703 converge into a main pipe, which then branches into three branches, each connected to the discharge pipe, the air outlet pipe, and the backflush pipe via valves. Each group of filter elements 702 is independently connected to the manifold 703, facilitating operation and backflush. The valve in the backflush branch of the main pipe is a fast-opening pulse valve to facilitate backflush operation. The filtered liquid flows from the central tube 10 into the branch pipe of the manifold 703 and is then discharged through the main pipe. During the withdrawal phase, low-temperature nitrogen gas pushes the liquid in the cylinder 701 above the bottom of the filter element 702 through the filter element 702, then flows into the manifold 703 through the central tube 10. From the main pipe of the manifold 703, it flows out through the filtered liquid outlet. When the withdrawal valve is opened, the liquid in the cylinder 701 below the bottom of the filter element 702 is withdrawn through the withdrawal pipeline into the withdrawal tank 4. During the drying phase, high-temperature nitrogen gas enters the multi-effect filter dryer 7, passes through the filter cake and filter element 702, enters the manifold 703 through the central tube 10, passes through the main pipe of the manifold 703, enters the condenser 6, and then passes through the gas-liquid separator 5. Both nitrogen and liquid are recycled. During the backflush phase, high-temperature nitrogen gas is reversely injected into the filter element 702 through the air blast pipe. During the blow, high-pressure nitrogen gas is instantly released through the air blast pipe, driving the filter bag 15 to expand. The air blast pipe is connected to the outlet of the high-temperature and high-pressure nitrogen storage tank 2, and the instantaneous blow is controlled by a valve. The air blast pipe utilizes a fast-acting valve (such as a pneumatic ball valve with an opening and closing time of ≤0.5 seconds) to ensure instantaneous release of high-pressure nitrogen, generating sufficient impact force to dislodge the filter cake. The blast pressure can be adjusted based on the cake's adhesion (e.g., 0.1-0.6 MPa) to prevent excessive pressure from damaging the filter bag 15. After drying is complete, the system sends a signal to open the air blast pipe valve. High-temperature, high-pressure nitrogen pulses within 0.5 seconds, with the opening and closing time taking no more than 1 second. This nitrogen fills the interior of the filter element 702, causing the filter bag 15 to expand and expand. Due to inertia and gravity, the filter cake falls from the surface of the bag 15 onto the conical end cap 704.

[0069] The modular manifold 703 design increases the integration of the equipment and supports online operation and backflushing of a single filter element 702, making the operation more flexible. The instantaneous gas volume during the backflushing stage is small, which facilitates the design and investment of the backflushing system.

[0070] The device also includes a condenser 6, the inlet of the condenser 6 is connected to the outlet end of the gas outlet pipe, the outlet of the condenser 6 is connected to a gas-liquid separation tank 5, and the gas outlet of the gas-liquid separation tank 5 is connected to the inlet of the low-pressure nitrogen storage tank 1.

[0071] The inlet of the condenser 6 is connected to the outlet end of the gas outlet pipe, the outlet of the condenser 6 is connected to the gas-liquid separation tank 5, and the gas outlet of the gas-liquid separation tank 5 is connected to the inlet of the low-pressure nitrogen storage tank 1.

[0072] Condenser 6 uses a cooling medium (such as circulating water or refrigerant) to cool the gas-liquid mixture (containing water vapor and nitrogen) produced during the drying process to below the dew point (e.g., 20-50°C), condensing the water vapor into liquid water. The interior of condenser 6 can be designed as a shell-and-tube or plate structure, with the heat exchange area (e.g., 10-50 m²) selected based on the processing volume to improve condensation efficiency. A baffle or cyclone device is installed within gas-liquid separator 5 to separate liquid water and nitrogen by gravity and inertia. Liquid water is discharged through the bottom outlet (for reuse in the iron salt solution), while nitrogen returns to low-pressure storage tank 1 through the top outlet. High-temperature nitrogen from the drying stage, carrying water vapor, enters condenser 6. After cooling, the liquid water and nitrogen mixture enters gas-liquid separator 5. The liquid water settles to the bottom of the tank, while the nitrogen returns to low-pressure storage tank 1 through the top pipe. It is pressurized by booster pump 9 and then recycled. After gas-liquid separation, the nitrogen re-enters low-pressure storage tank 1 and is pressurized by booster pump 9 to high-pressure storage tank 3 and high-temperature and high-pressure storage tank 2 to meet the pressure and temperature requirements of different process stages. The low-pressure nitrogen is split into two paths by booster pump 9: one path flows directly to high-pressure storage tank 3 to supply low-temperature nitrogen for material return; the other path flows to a heater for heating and storage in high-temperature and high-pressure storage tank 2 for filter cake drying and aeration. Nitrogen within the system is never discharged; instead, it is recycled through a condensation-separation-compression process. This recycling reduces nitrogen production energy consumption (such as that of the air separation unit) and prevents the leakage of volatile organic compounds (VOCs) or dust, complying with green production requirements. During system operation, flow meters and pressure sensors monitor nitrogen levels in real time, automatically adjusting the power of booster pump 9 and the opening of the storage tank valves to maintain a balanced circulation.

[0073] The closed-loop nitrogen cycle significantly reduces raw material consumption and reduces reliance on external supplies. The entire process is emission-free, effectively preventing environmental pollution and occupational health risks. Heat recovery and gas reuse reduce overall energy consumption and maintenance costs.

[0074] The upper end cover 12 is provided with a raised ring and is fixed in the cylinder 701 in conjunction with the throat clamp; the lower end cover 13 is in the shape of a plum blossom that tapers upward, with its small end welded to the skeleton beam 1102 and the large end in contact with the filter bag 15 at the edge of the arc.

[0075] like Figure 7As shown, the upper end cap 12 features a raised ring (with a diameter slightly larger than the outer diameter of the upper end cap 12) to which the filter bag 15 is secured via a throat clamp. The raised ring increases the contact area between the throat clamp and the upper end cap 12, preventing the filter bag 15 from falling out due to vibration or inflation of the filter element 702. The throat clamp utilizes bolts or a quick-release buckle structure, facilitating quick tightening and release when replacing the filter element 702. When installing the filter element 702, the filter bag 15 is inserted directly onto the frame. The bottom of the filter bag 15 contacts the lower end cap 13 of the frame, and the top of the filter bag 15 is clamped in place by the throat clamp, securing the bag 15 vertically and preventing it from falling out. The rounded edges reduce friction during contraction of the filter bag 15, preventing wear or tear at the bottom of the bag 15. The tapered plum blossom-shaped structure evenly distributes the tension of the filter bag 15 across the frame beam 1102, preventing deformation caused by localized stress concentration. Once the filter bag 15 is inserted into the frame, the large, rounded surface of the lower end cap 13 mates with the bottom of the filter bag 15.

[0076] In another technical solution, a nitrogen-driven sonic soot blower 14 is provided on the elliptical head 705 , the air outlet of the sonic soot blower 14 is a downward-diffusing trumpet shape, and the air inlet is connected to the high-temperature and high-pressure nitrogen storage tank 2 .

[0077] The sonic sootblower 14 utilizes high-temperature, high-pressure nitrogen (pressure range: 0.5-3.0 MPa, temperature: 150-190°C) as its power source. Through the interaction between the sootblower's internal cavity and a vibrating diaphragm (e.g., metal or composite material), the airflow energy is converted into acoustic vibrations (frequency range: 80-150 Hz). The sound waves diffuse downward through the trumpet-shaped outlet, covering the inner wall of the cylinder 701 and the surface of the filter element 702, effectively loosening and removing adhered catalyst residue. The outlet is designed with a gradually expanding trumpet shape (divergence angle: 30-60°, outlet diameter: 50-100 mm). This expands the sound wave propagation range and enhances the uniformity of the sound pressure field, ensuring that the vibration energy is fully applied to the filter bags 15 and the inner wall of the cylinder 701. The trumpet-shaped structure also reduces airflow resistance and improves nitrogen utilization. The air inlet is connected to the high-temperature, high-pressure nitrogen storage tank 2 via a high-temperature-resistant pipeline, ensuring stable operation of the sootblower in high-temperature environments. High-temperature nitrogen can prevent water vapor condensation during the soot blowing process, and at the same time assist in drying residual catalyst through thermal effect, thereby improving removal efficiency.

[0078] The sonic sootblower 14 is fixed to the top center of the elliptical head 705 by flange or welding. The axis of the outlet coincides with the axis of the cylinder 701, ensuring vertical downward radiation of sound waves. The sootblower's start and stop are controlled by an automatic control system. For example, it is activated synchronously during the discharge phase (when the filter cake falls into the lock hopper 8) or intermittently purged based on the pressure differential sensor signal (when the resistance of the filter element 702 increases). The sootblower's operating cycle can be set to last 5-15 seconds each time, with the interval adjusted according to production load (for example, it is activated once after each batch of discharge). When the catalyst powder is discharged into the lock hopper 8, the system automatically opens the outlet valve of the high-temperature, high-pressure nitrogen storage tank 2, and the high-pressure nitrogen is delivered to the sonic sootblower 14 via a pipeline. Once the nitrogen enters the sootblower 14 cavity, it drives the vibrating diaphragm to generate high-frequency sound waves. The sound waves diffuse downward through the trumpet-shaped outlet and penetrate the interior of the cylinder 701. The acoustic pressure vibration loosens and dislodges any residual catalyst particles adhering to the surface of the filter bag 15 and the inner wall of the cylinder 701. These particles then fall by gravity to the conical end cap 704 and eventually pass through the discharge valve into the lock hopper 8. After sootblowing is complete, the valve closes, the nitrogen supply stops, and the system enters the next operating cycle.

[0079] The present application also provides a method for preparing a direct coal liquefaction catalyst, based on a preparation device according to any one of the above schemes, the method comprising the following steps:

[0080] The iron salt solution and the coal powder are mixed to form a mixed liquid, and the mixed liquid is sent to the multi-effect filter dryer 7 through the mixed liquid inlet 706;

[0081] The mixed liquid is filtered using the filter element 702 of the multi-effect filter-dryer 7 to separate the mixed liquid into a filter cake formed by solid particles on the surface of the filter element 702 and a filtrate after passing through the filter element 702. The filtrate is discharged from the multi-effect filter-dryer 7 through the collecting pipe 703 and added to the new mixed liquid configuration;

[0082] When the filter cake reaches a thickness of 5-10 mm, stop feeding, close the feed valve, and introduce 25-70°C nitrogen from the upper end of the multi-effect filter cone head 704. Observe the changes in the liquid level in the multi-effect filter dryer 7. When the liquid level reaches the bottom of the filter element 702, slowly open the material return regulating valve at the bottom of the cone to allow the liquid in the filter at the bottom of the filter element 702 to flow out from the material return pipeline. At the same time, ensure that there is a positive wind pressure of 50-150 kPa on the filter cake to prevent the filter cake from falling off during the return process.

[0083] After the liquid is completely drained, the return valve of the mixed liquid inlet 706 and the valve of the low-temperature nitrogen inlet are closed, and the valve of the high-temperature nitrogen inlet is opened. The high-temperature nitrogen is passed into the multi-effect filter dryer 7 to dry the filter cake. The gas-liquid mixture generated during the drying process is discharged from the collecting pipe 703, passed through the condenser 6 for gas-liquid separation, and the separated gas is transported to the low-pressure nitrogen storage tank 1 for recycling. The condensed liquid is returned to participate in the preparation of the mixed liquid again.

[0084] After the filter cake is dried, close the high-temperature nitrogen inlet valve and the outlet valve of the condenser 6 connected to the collecting pipe 703, and open the valve between the high-temperature and high-pressure nitrogen storage tank 2 and the outlet of the collecting pipe 703. Nitrogen is instantly blown into the filter element 702 through the collecting pipe 703 to expand the filter bag 15, causing the dried filter cake to fall off the surface of the filter element 702 and into the conical head 704 to obtain dry catalyst powder.

[0085] Open the discharge valve at the bottom of the conical head 704 to discharge the catalyst dry powder into the lock hopper 8, and then send the catalyst dry powder to the designated location through the lock hopper 8. The nitrogen in the low-pressure nitrogen storage tank 1 is pressurized by the booster pump 9 and then replenished to the high-pressure nitrogen storage tank 3 and the high-temperature and high-pressure nitrogen storage tank 2.

[0086] The method for preparing a direct coal liquefaction catalyst is based on the device provided in this application and adopts a fully enclosed preparation process. The specific preparation process is as follows: first, an iron salt solution with a mass fraction of 10% to 50% is mixed with coal powder with a particle size not exceeding 74 microns in a mass ratio of 5% to 50% of the coal powder to prepare a suspension, and the suspension is fed into the interior of the device through a corrosion-resistant pump from the mixed liquid inlet 706 at the bottom of the conical head 704 of the multi-effect filter dryer 7. Under the action of the system pressure, the mixed liquid flows through the filter element assembly 702, wherein the solid particles are trapped on the surface of the filter bag 15 to form a filter cake layer, and the filtrate penetrates the filter bag 15 and enters the skeleton center tube 10, and is finally discharged to the external liquid withdrawal tank 4 through the collecting pipe 703. After the discharged filtrate is purified and tested to be qualified, it is accurately reused for a new round of mixed liquid preparation through the liquid circulation pipeline to form a closed-loop circulation system. When the pressure sensor detects that the filter cake thickness reaches 5 to 10 mm (typical control value is around 7 mm), the feed valve automatically closes. Simultaneously, low-temperature nitrogen gas at a temperature of 25 to 70 degrees Celsius is introduced from the top of the conical head 704. The nitrogen pressure is maintained within the range of 50 to 150 kPa (controlled in a closed-loop manner by a pressure transmitter and a regulating valve), creating a stable positive throughflow. After observing the liquid level drop to the bottom of the filter element 702 through the cylindrical sight glass (usually taking 3 to 8 minutes), the operator slowly opens the return valve at the bottom of the cone at an opening rate of 5% per second, allowing any remaining liquid to flow through the return line into the return tank 4. During this process, the positive air pressure fluctuation must not exceed ±10 kPa to prevent the filter cake from falling off before drying is complete.

[0087] After the material return operation is completed, the return valve and the low-temperature nitrogen valve are immediately closed, and the high-temperature nitrogen inlet valve is opened. High-temperature nitrogen gas at a temperature of 100 to 190 degrees Celsius (at a flow rate of 0.5 to 1.5 cubic meters per square meter per minute, depending on the surface area of ​​the filter cake) is introduced into the equipment cylinder 701. As the high-temperature gas flows through the filter cake layer, it carries moisture with it, forming a gas-liquid mixed medium. This mixed medium is then directed through a manifold 703 into a condenser 6 (where the cooling water temperature is controlled below 25 degrees Celsius). The condensate enters the gas-liquid separator 5 for phase separation. The liquid water (with a moisture content of no more than 0.5%) is returned to the liquid distribution system via a pipeline for reuse, while the dry nitrogen (dew point below -40 degrees Celsius) is temporarily stored in the low-pressure nitrogen storage tank 1. The drying phase continues until the filter cake moisture content drops to the required level (which can be determined using an online humidity sensor or temperature prediction model).

[0088] After the drying phase, the high-temperature nitrogen valve and the outlet valve of condenser 6 are closed, and the control valve from high-temperature, high-pressure nitrogen storage tank 2 to manifold 703 is opened. High-pressure nitrogen gas is instantaneously injected at a pressure of 400 to 600 kPa (with a duration strictly controlled between 0.3 and 0.8 seconds), causing the filter bag 15 to expand and deform by at least 15%. Due to structural stress changes, the dried filter cake is completely detached from the surface of the filter element 702 and into the chamber of the conical head 704. The discharge valve at the bottom of the cone (with a diameter of 50 to 100 mm) is opened, and the catalyst powder falls by gravity into the lock hopper 8. The lock hopper 8 performs a three-step standard operation: first, depressurization to atmospheric pressure; second, filling with high-purity nitrogen to replace the internal gas; and third, opening the pneumatic gate valve at the bottom to transfer the catalyst to the designated dry powder storage tank. Simultaneously, the recovered nitrogen in low-pressure nitrogen storage tank 1 is pressurized to a pressure level of 0.8 to 1.2 MPa by a screw booster pump 9. 70% to 80% of this flow is replenished in high-pressure nitrogen storage tank 3 for liquid withdrawal. The remaining 20% ​​to 30% is heated to 180 to 200°C by an electric heater and then stored in high-temperature, high-pressure nitrogen storage tank 2 for subsequent drying cycles. The system is equipped with an automatic nitrogen compensation interface, keeping the cycle loss rate below 3% to maintain pressure balance. The process parameter ranges (such as filter cake thickness 5-10 mm and nitrogen pressure) are optimized after testing. In actual use, they can be adaptively adjusted within a ±20% range based on the characteristics of the coal type, making them suitable for adjustment and optimization of various equipment types.

[0089] This method uses a closed operation throughout the entire process from raw material mixing to finished product delivery, completely isolating the catalyst from oxygen contact and effectively protecting the active components of the catalyst. The nearly full recycling of the filtrate and the closed-loop nitrogen circulation design enable a very high material utilization rate. The precise control of the positive wind pressure and the monitoring of the oxygen content in the lock hopper 8 form a double protection, significantly improving the intrinsic safety level. The high-pressure instantaneous backflush mechanism ensures the complete shedding of catalyst particles, and the uniformity of product particle size is effectively improved. The synergistic effect of graded temperature matching and the energy recovery system brings the comprehensive energy consumption to an advanced high level compared to traditional processes. From the input of the mixed liquid to the output of the dry powder, the entire process is automated, and there is no need for intermediate material transfer operations, which greatly improves production efficiency.

[0090] In another technical solution, a nitrogen-driven sonic soot blower 14 is provided on the elliptical head 705, the air outlet of the sonic soot blower 14 is a downward-diffusing trumpet shape, and the air inlet is connected to the high-temperature and high-pressure nitrogen storage tank 2; when the catalyst dry powder is discharged into the locking hopper 8, the sonic soot blower 14 is started at the same time to remove the catalyst remaining on the surface of the filter bag 15 and the inner wall of the cylinder 701.

[0091] In another technical solution, Figure 11 As shown, an annular distribution pipe 16 is provided on the inner wall of the cylinder 701 of the multi-effect filter-dryer 7. The annular distribution pipe 16 is connected to the high-temperature nitrogen inlet. A plurality of vertical branches 17 with independent control valves are arranged at intervals along the circumference of the annular distribution pipe 16. The vertical branches 17 are provided with vertically arranged nitrogen nozzles. A temperature sensor is provided in the filter element 702 for collecting the average temperature data of the entire filter element 702.

[0092] When the system detects that the temperature difference E between any two adjacent filter elements 702 exceeds 8°C, the dynamic adjustment mechanism is triggered:

[0093] Immediately increase the opening of the valve on the vertical branch pipe 17 corresponding to the low-temperature filter element 702, with the opening increment ΔK set to: ΔK = 0.5 × E%, and simultaneously reduce the opening of the branch pipe of the high-temperature filter element 702 by the same amount; after an interval of 3 minutes, perform another full-area scan of the temperature data of all filter elements 702. If the temperature difference between adjacent filter elements 702 is still greater than 3°C, repeat the above adjustment action; when the temperature difference of all adjacent filter elements 702 is stable within the 3°C range for two consecutive scans, it is determined to be in a regional drying equilibrium state and enter the constant temperature maintenance stage;

[0094] During the constant temperature maintenance phase, the valve opening of each vertical branch pipe 17 is maintained, and when the temperature difference E between any two adjacent filter elements 702 is detected to be greater than 8° C., the dynamic adjustment mechanism is re-triggered.

[0095] To address the uneven drying of the filter cake during the high-temperature nitrogen drying stage, precise control is achieved through the following technical solution: An annular distribution pipe 16 is fixedly installed on the inner wall of the cylinder 701 of the multi-effect filter dryer 7. This annular distribution pipe 16 is made of a high-temperature resistant alloy and is sealed to the high-temperature nitrogen inlet main pipeline via a flange, forming a closed-loop gas supply network. Multiple vertical branches 17 are welded to the lower opening along the circumference of the annular distribution pipe 16. Each vertical branch 17 is equipped with an independently controlled electric regulating valve (such as a angular stroke ball valve or butterfly valve), and the valve opening can be linearly adjusted within the range of 0-100%. Three to five groups of nitrogen nozzles (typically four groups) are provided on the surface of the vertical branch 17. The nozzles are evenly arranged at an angle downward to ensure that the nitrogen flow covers the key area in the middle and lower part of the filter element 702. An armored thermocouple temperature sensor is embedded in the central tube 10 of the skeleton of each filter element 702. The top of the sensor probe extends to the geometric center point of the filter element 702. The overall average temperature of the filter element 702 is collected in real time through the heat conduction effect. The temperature data is uploaded to the central control system every second.

[0096] When the control system detects that the temperature difference E between any two physically adjacent filter elements 702 exceeds a preset threshold (preferably 8°C, but adjustable within a range of 5-10°C), it immediately triggers a dynamic adjustment mechanism: First, it calculates the opening adjustment ΔK (ΔK is 0.5 times the temperature difference percentage, e.g., 5% when E = 10°C). It then increases the opening of the valve on the vertical branch pipe 17 corresponding to the low-temperature filter element 702 (e.g., from 50% to 55%) and simultaneously decreases the opening of the valve on the branch pipe for the high-temperature filter element 702 by the same amount (e.g., from 50% to 45%). After the adjustment is complete, the system enters a 3-minute stabilization period (configurable from 2 to 5 minutes), after which it rescans the temperature data of all filter elements 702. If the temperature difference between adjacent filter elements 702 remains above 3°C (this stabilization threshold is typically set between 1 and 5°C), the above adjustment steps are repeated. If the temperature difference between all adjacent filter elements 702 remains within the 3°C range for two consecutive scans (or multiple scans), the system enters the constant temperature maintenance phase. During this stage, the current valve opening is maintained unchanged (because it has been determined that a single regulation has ended, even if the temperature difference between adjacent filter elements 702 is higher than 3°C but does not reach 8°C during this period, the temperature difference control program will not be triggered). Drying balance is ensured through continuous temperature monitoring. Once the adjacent temperature difference exceeds 8°C again (which may be caused by changes in the local characteristics of the filter cake or changes in the overall drying stage), the system will immediately restart the dynamic adjustment mechanism.

[0097] The annular distribution pipe 16 and vertical branch pipes 17 form a hierarchical gas supply architecture. The annular pipe evenly distributes nitrogen from the main pipeline, while the vertical branch pipes 17 achieve independent flow control in each region. The center temperature of the filter element 702 represents the overall state, avoiding local measurement distortion. A two-way joint adjustment algorithm is used to simultaneously increase flow in low-temperature areas and reduce flow in high-temperature areas to force thermal equilibrium (temperature difference drives flow redistribution). A dual-threshold judgment mechanism is used: an 8°C trigger adjustment ensures timely response, and a 3°C stabilization threshold prevents over-regulation.

[0098] As a practical example, the initial temperature of filter element A is 162°C, and the temperature of adjacent filter element B is 175°C. The temperature difference is 13°C, which is greater than 8°C. The system calculates ΔK = 6.5%, increases the valve opening of branch A by 6.5% (for example, from 50% to 56.5%), and decreases the opening of branch B by 6.5% (from 50% to 43.5%). After stabilization for 3 minutes, the following measurements show that the temperature of A is 169°C and the temperature of B is 171°C, with a temperature difference of 2°C but less than 3°C. The system then enters the constant temperature phase and maintains the current opening until the drying process is complete. If the temperature of A subsequently remains unchanged and the temperature of B suddenly rises to 178°C (the temperature difference again exceeds the threshold), the adjustment process is restarted.

[0099] Through real-time temperature difference feedback and flow redistribution, the circumferential temperature gradient within the cylinder 701 is effectively eliminated, preventing local over-drying or high moisture content of the filter cake; the dual-threshold judgment mechanism can quickly respond to sudden temperature fluctuations and prevent oscillations caused by frequent valve operation; directional nitrogen distribution is achieved only through adjustment of the branch valve opening, without the need to modify the nozzle structure, maximizing the potential of existing equipment; the overall temperature characterization method is closer to the ultimate activity requirements of the catalyst, ensuring product performance consistency from the source.

[0100] A humidity sensor is placed at the outlet of the upper end of the central tube 10 of the filter element 702 skeleton to continuously monitor the relative humidity of the gas. Based on the detected gas humidity data, the nitrogen nozzle opening during the drying process is dynamically and collaboratively adjusted. The specific control method is as follows:

[0101] When the relative humidity of the gas at the outlet of a filter element 702 steadily drops to 4.0% ± 0.2%, and the absolute value of the humidity drop rate is less than 0.1% / minute for 10 consecutive minutes, the external filter cake of the filter element 702 is considered to be dried and the filter element 702 is converted to an inactive filter element 702. Then, the undisturbed transfer procedure is started:

[0102] Immediately close the valve of the vertical branch pipe 17 corresponding to the filter element 702 where the filter cake drying is completed, and simultaneously open the pressure relief valve at the central tube 10 of the skeleton to release the internal pressure;

[0103] The released nitrogen flow is dynamically distributed to the vertical branch pipe 17 corresponding to the active filter element 702 that needs the most flow increase. The active filter element 702 is selected by firstly distributing it to the filter element 702 with the lowest temperature change rate. If there are multiple candidates, the one with the largest temperature difference gap is selected. The temperature difference gap is the difference between the current temperature and the target temperature.

[0104] When more than 25% of the filter element 702 is dried, the nitrogen temperature compensation module is activated to increase the nitrogen temperature output from the high-temperature nitrogen storage tank 2. The temperature increase ΔT is 0.3×(M1 / M s ), where M1 is the number of active filter elements 702, M s The total number of filter elements is 702;

[0105] In the event of flow conflicts among multiple filter cartridges 702, the released adjustable nitrogen flow is allocated using a three-level arbitration mechanism: the first level allocates 60% of the adjustable flow to the filter cartridge 702 with the lowest temperature, the second level allocates 30% to the filter cartridge 702 with the slowest historical drying speed, and the third level retains the remaining 10% as a system buffer reserve.

[0106] To precisely control the drying endpoint and optimize resource allocation, a high-stability infrared absorption humidity sensor (with optional wavelengths of 3μm or 4.26μm, reflecting the characteristic water vapor absorption peak) is installed at the outlet flange of the central tube 10 of each filter element 702. This sensor, embedded in the pipeline via a pressure-resistant, sealed interface, collects relative humidity data every five seconds (with a measurement accuracy of ±0.1% RH). Coordinated control is implemented based on real-time humidity data: when the relative humidity at the outlet of a filter element 702 remains consistently stable within the range of 3.8%-4.2% (the typical threshold is set at 4.0%, adjustable between 3.5%-4.5% based on pulverized coal characteristics), and the absolute rate of humidity decrease is less than 0.1% / minute for 10 consecutive minutes (the rate threshold is configurable between 0.05%-0.15% / minute), the system determines that the external filter cake of that filter element 702 is dried and marks it as inactive. The disturbance-free transfer procedure is then initiated: the first step is to immediately close the master control valve (e.g., an electric ball valve) of the vertical branch pipe 17 corresponding to the filter element 702, and simultaneously open the micro pressure relief valve (diameter 2-5 mm) at the top of the skeleton central tube 10 to slowly release the internal pressure at a rate of 0.4-0.6 kPa / s (preferably 0.5 kPa / s) to avoid damage to the filter cake structure caused by excessive pressure drop; the second step is to dynamically distribute the nitrogen flow (measured by a mass flow meter) released by closing the valve to the active filter element 702 that needs the most flow increase, with the selection logic being to prioritize the filter element 702 with the lowest temperature change rate (e.g., temperature rise < 0.5 kPa / s within 10 minutes). 1°C unit), if multiple filter elements 702 meet the conditions, the one with the largest difference between the current temperature and the target temperature is selected (the target temperature is usually set to 185°C, and the difference range is about 5-15°C); in the third step, when the proportion of filter elements 702 that have completed drying in the system exceeds 25% (the threshold can be set at 20%-30%), the nitrogen temperature compensation module is automatically activated to proportionally increase the output temperature of the high-temperature nitrogen storage tank 2. The amount of temperature increase is calculated based on the ratio of the number of active filter elements 702 to the total number of filter elements 702. For every 10% increase in the proportion of active filter elements 702, the temperature increases by approximately 3°C (for example, when the proportion of active filter elements 702 is 50%, the temperature increases by approximately 1.5°C). When multiple filter elements 702 simultaneously request flow, a three-level arbitration mechanism distributes the adjustable nitrogen flow: the first level allocates 60% of the flow (the ratio can be optimized between 55% and 65%) to the filter element 702 with the lowest current temperature; the second level allocates 30% of the flow (a ratio of 25% to 35%) to the filter element 702 with the slowest historical drying speed (sorted by temperature rise per unit time); the remaining 10% of the flow is temporarily stored in the system's buffer reserve to compensate for unexpected operating conditions. It is important to note that the above-mentioned temperature control and nitrogen flow control for filter element 702 are both achieved through the vertical branch pipe 17 in the area where it is located.

[0107] In the above scheme settings, the absolute threshold (4.0%±0.2%) ensures sufficient drying, the change rate threshold (<0.1% / min) eliminates measurement fluctuation interference, and the pressure relief rate control: the 0.5kPa / s slow release rate matches the filter cake's compressive strength to avoid micro cracks. The temperature change rate priority logic accurately identifies "drying stagnation zones", and temperature difference gap compensation enhances balance. The temperature is linearly increased according to the ratio of 702 active filters to solve the problem of drying power attenuation in the remaining units. The 60-30-10 ratio balances efficiency and fairness, and the buffer reserve can cope with system disturbances.

[0108] To provide a more direct operational example, let's say the humidity in filter A drops to 3.9% and maintains a slow rate of decrease (0.07% / min) for 12 minutes. It's marked as inactive. The valve in branch pipe A is closed, and the pressure relief valve in central pipe A is opened (reducing pressure by 0.5 kPa / s), releasing a flow rate of 20 m³ / h. The temperature change rate of active filter B is 0.8°C / min (the lowest), and the temperature difference gap in C is 12°C (the highest). Filter B 702 is prioritized for flow. At this point, 25% of filter 702s have completed drying (e.g., 4 out of 16 filter 702s have completed drying). Temperature compensation is activated: active filter 702 accounts for 75%, and the temperature increase is 0.3 × 75% = 2.25°C. Simultaneously, filter elements D and E request flow, and arbitration allocates the flow: 60% goes to filter D (the coldest at 162°C), 30% to filter E (the slowest drying at 0.5°C / min), and 10% is retained for backup.

[0109] The dual-factor collaborative judgment criterion fundamentally avoids the risk of single-parameter misjudgment, ensuring that the filter cake is fully dried without excessive dehydration; the coordination of pressure relief rate control and directional flow distribution achieves zero damage to the filter cake structure during the energy reconfiguration process; the temperature compensation module dynamically maintains the drying driving force, and the arbitration mechanism maximizes nitrogen utilization efficiency and reduces ineffective energy consumption; the three-level distribution logic takes into account temperature balance and historical drying progress, maintaining process stability under complex working conditions; the disturbance-free transfer mechanism avoids damage to the filter cake microstructure during the drying stage, providing a basic guarantee for the ultimate activity of the catalyst.

[0110] It should be noted that although the steps are described above in a specific order, this does not necessarily mean that the steps must be performed in this specific order. In fact, some of these steps can be performed concurrently or even in a different order, as long as the required functions can be achieved. The number of devices and processing scales described here are intended to simplify the description of the present invention. Applications, modifications, and variations of the present invention will be apparent to those skilled in the art.

[0111] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A preparation device for a direct coal liquefaction catalyst, characterized in that: include: A multi-effect filter-dryer comprises a cylinder, a filter element, and a collection pipe; the cylinder is provided with a conical end cap at the lower end and an elliptical end cap at the upper end; a mixed liquid inlet for inputting a mixture of an iron salt solution and coal powder is provided at the bottom of the conical end cap, and a nitrogen inlet is provided in the middle of the conical end cap, the nitrogen inlet including a low-temperature nitrogen inlet and a high-temperature nitrogen inlet; the filter elements are grouped and arranged in the cylinder, each filter element comprising a hollow, breathable frame and a filter bag attached to the frame; the frame comprises a central tube and a peripheral bracket for supporting the filter bag; the central tube is provided with an inlet and outlet hole at the bottom and an inlet connected to the collection pipe at the top; A locking hopper connected to the bottom of the conical head of the multi-effect filter-dryer through a discharge valve; A nitrogen circulation system, comprising a low-pressure nitrogen storage tank, a high-temperature and high-pressure nitrogen storage tank, a high-pressure nitrogen storage tank, and a booster pump; the outlet of the low-pressure nitrogen storage tank is connected to the inlets of the high-temperature and high-pressure nitrogen storage tank and the high-pressure nitrogen storage tank respectively through the booster pump, the high-pressure nitrogen storage tank is connected to the low-temperature nitrogen inlet of the multi-effect filter dryer through a pipeline, the high-temperature and high-pressure nitrogen storage tank is connected to the high-temperature nitrogen inlet and the manifold outlet through pipelines, and the manifold outlet is further connected to the inlet of the low-pressure nitrogen storage tank through a condenser and a gas-liquid separator; The liquid withdrawal storage tank has a liquid inlet and a liquid outlet both connected to the mixed liquid inlet of the multi-effect filter dryer.

2. The preparation device of a direct coal liquefaction catalyst according to claim 1, characterized in that: The peripheral support of the skeleton includes at least two plum blossom-shaped support frames and multiple skeleton beams for supporting filter bags. The plum blossom-shaped support frames are sleeved on the central tube and the petals are hollowed out. The multiple skeleton beams are arranged at intervals along the outer edge contour of the plum blossom-shaped support frames. The two ends of the skeleton beam are respectively connected to the two plum blossom-shaped support frames, and the extension direction of the skeleton beam is parallel to the axial direction of the central tube.

3. The preparation device of a direct coal liquefaction catalyst according to claim 2, characterized in that: An upper end cover and a lower end cover are respectively provided at both ends of the skeleton beam of the peripheral support of the skeleton, and the two ends of the filter bag are respectively fixed on the upper end cover and the lower end cover. The central tube passes through the upper end cover upward and is connected to the branch pipe extending from the side of the collecting pipe through a flange. A group of filter elements are connected to the same collecting pipe, and multiple collecting pipes are connected to a main pipe. The main pipe is respectively connected to a discharge pipe, an air outlet pipe and an air blow pipe through valves. The air blow pipe is connected to the outlet of the high-temperature and high-pressure nitrogen storage tank.

4. The preparation device of a direct coal liquefaction catalyst according to claim 3, characterized in that: It also includes a condenser, the inlet of the condenser is connected to the outlet end of the gas outlet pipe, the outlet of the condenser is connected to a gas-liquid separation tank, and the gas outlet of the gas-liquid separation tank is connected to the inlet of the low-pressure nitrogen tank.

5. The preparation device for a direct coal liquefaction catalyst according to claim 3, characterized in that: The upper end cover is provided with a circle of raised rings and is fixed in the cylinder with the help of the throat clamp; the lower end cover is in the shape of a plum blossom that tapers upwards, with its small end welded to the skeleton beam and the large end in contact with the filter bag at the edge of the arc.

6. The preparation device for a direct coal liquefaction catalyst according to claim 1, characterized in that: The elliptical head is provided with a nitrogen-driven sonic soot blower, the air outlet of the sonic soot blower is in a downwardly diffused trumpet shape, and the air inlet is connected to the high-temperature and high-pressure nitrogen storage tank.

7. A method for preparing a direct coal liquefaction catalyst, characterized in that: The preparation device according to any one of claims 1 to 6, the method comprising the following steps: The iron salt solution and the coal powder are mixed to form a mixed liquid, and the mixed liquid is sent to the multi-effect filter dryer from the mixed liquid inlet; The mixed liquid is filtered using the filter element of the multi-effect filter-dryer to separate the mixed liquid into a filter cake formed by solid particles on the surface of the filter element and a filtrate after passing through the filter element, and the filtrate is discharged from the multi-effect filter-dryer through a collecting pipe and added to a new mixed liquid configuration; When the filter cake reaches a thickness of 5-10mm, stop feeding, close the feed valve, and introduce 25-70℃ nitrogen from the low-temperature nitrogen inlet on the cone head of the multi-effect filter. Observe the changes in the liquid level in the multi-effect filter dryer. When the liquid level reaches the bottom of the filter element, slowly open the return regulating valve at the mixed liquid inlet at the bottom of the cone to allow the liquid in the filter at the bottom of the filter element to flow out from the return pipeline. At the same time, maintain a positive wind pressure of 50-150kPa at the filter cake to prevent the filter cake from falling off during the return process. After the liquid is drained, close the return valve of the mixed liquid inlet and the valve of the low-temperature nitrogen inlet, open the valve of the high-temperature nitrogen inlet, and pass the high-temperature nitrogen into the multi-effect filter dryer to dry the filter cake. The gas-liquid mixture generated during the drying process is discharged from the collecting pipe, and the gas-liquid separation is carried out after passing through the condenser. The separated gas is transported to the low-pressure nitrogen storage tank for recycling, and the condensed liquid is returned to participate in the preparation of the mixed liquid again; After the filter cake is dried, close the high-temperature nitrogen inlet valve and the outlet valve of the condenser connected to the collecting pipe, and open the valve between the high-temperature and high-pressure nitrogen storage tank and the collecting pipe outlet. Instantly blow nitrogen into the filter element through the collecting pipe to expand the filter bag, so that the dried filter cake falls off the surface of the filter element and into the conical head to obtain the catalyst dry powder; Open the discharge valve at the bottom of the conical head to discharge the catalyst powder into the lock hopper, and then send the catalyst powder to the designated location through the lock hopper. The nitrogen in the low-pressure nitrogen storage tank is pressurized by a pressure pump and then added to the high-pressure nitrogen storage tank and the high-temperature and high-pressure nitrogen storage tank.

8. The method for preparing a direct coal liquefaction catalyst according to claim 7, characterized in that: The elliptical head is provided with a nitrogen-driven sonic soot blower, the air outlet of the sonic soot blower is a downward-diffusing trumpet shape, and the air inlet is connected to the high-temperature and high-pressure nitrogen storage tank; when the catalyst dry powder is discharged into the lock hopper, the sonic soot blower is started at the same time to remove the catalyst remaining on the surface of the filter bag and the inner wall of the cylinder.

9. The method for preparing a direct coal liquefaction catalyst according to claim 7, characterized in that: An annular distribution pipe is provided on the inner wall of the cylinder of the multi-effect filter-dryer, the annular distribution pipe being connected to the high-temperature nitrogen inlet. A plurality of vertical branches with independent regulating valves are arranged at intervals along the circumference of the annular distribution pipe. The vertical branches are provided with vertically arranged nitrogen nozzles. A temperature sensor is provided in the filter element for collecting the average temperature data of the entire filter element. When the system detects that the temperature difference E between any two adjacent filter elements exceeds 8°C, the dynamic adjustment mechanism is triggered: Immediately increase the opening of the vertical branch valve corresponding to the low-temperature filter element, and set the opening increase ΔK to: ΔK = 0.5 × E%. Simultaneously reduce the opening of the high-temperature filter element branch by the same amount. After an interval of 3 minutes, perform another full-area scan of all filter element temperature data. If the temperature difference between adjacent filter elements is still greater than 3°C, repeat the above adjustment steps. When the temperature difference of all adjacent filter elements is stable within the 3°C range for two consecutive scans, it is determined to be in a regional drying equilibrium state and enter the constant temperature maintenance stage. During the constant temperature maintenance phase, the valve opening of each vertical branch is maintained. When the temperature difference E between any two adjacent filter elements is detected to be greater than 8°C, the dynamic adjustment mechanism is triggered again.

10. The method for preparing a direct coal liquefaction catalyst according to claim 9, characterized in that: A humidity sensor is installed at the outlet of the upper end of the central tube of the filter element skeleton to continuously monitor the relative humidity of the gas. The drying process is coordinated and controlled based on the detected gas humidity data. The specific control method is as follows: When the relative humidity of the gas at the outlet of a filter element steadily drops to 4.0% ± 0.2%, and the absolute value of the humidity drop rate is less than 0.1% / minute for 10 consecutive minutes, the filter element is judged to have completed drying of the external filter cake and is converted to an inactive filter element. Then the disturbance-free transfer procedure is started: Immediately close the valve of the vertical branch pipe corresponding to the filter element where the filter cake drying is completed, and simultaneously open the pressure relief valve at the central pipe of its skeleton to release the internal pressure; The released nitrogen flow is dynamically distributed to the vertical branch corresponding to the active filter element that needs the most flow increase. The active filter element is selected by giving priority to the filter element with the lowest temperature change rate. If there are multiple candidates, the one with the largest temperature difference gap is selected. The temperature difference gap is the difference between the current temperature and the target temperature. When more than 25% of the filter elements are dried, the nitrogen temperature compensation module is activated to increase the nitrogen temperature output from the high-temperature nitrogen storage tank. The temperature increase ΔT is 0.3×(M1 / M s ), where M1 is the number of active filter elements, M s is the total number of filter elements; For conflicts in flow applications from multiple filter cartridges, the released adjustable nitrogen flow is allocated using a three-level arbitration mechanism: the first level allocates 60% of the adjustable flow to the filter cartridge with the lowest temperature, the second level allocates 30% to the filter cartridge with the slowest historical drying speed, and the third level retains the remaining 10% as a system buffer reserve.

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