A tubular filter device and method of operation

Abstract

The application discloses a tubular filter device and an operation method, which comprise a filter pressure-bearing pipe, a filter screen body, a blowdown pipe, an inlet gate valve, an outlet pipe, an exhaust gate valve, a high-pressure soot blowing nozzle, a differential pressure gauge and a controller. The filter screen body is installed in the pressure-bearing pipe, and a filter screen blowdown opening is inserted into the blowdown pipe. The differential pressure gauge measures the pressure difference between two sides of the filter screen in real time, and the controller automatically executes a non-stop or stop cleaning process according to the comparison between the pressure difference and a threshold value: the inlet gate valve is kept open, the high-pressure soot blowing nozzle is pulsed to blow and discharge particulate matters; or the inlet gate valve is closed, and then reverse blowing is performed and followed by forward flushing. The device does not need to disassemble flanges or cut pipes, realizes non-stop cleaning, avoids secondary pollution, is reliable in sealing, and is suitable for filtering of working medium of a micro-channel heat exchanger under high-temperature and high-pressure working conditions.

Description

Technical Field

[0001] This invention discloses a tubular filtration device and its operating method, belonging to the field of fluid filtration. Background Technology

[0002] With the rapid development of closed-loop power generation technologies such as supercritical carbon dioxide (sCO2) cycles, the demand for high-efficiency heat exchange equipment is becoming increasingly urgent. Against this backdrop, microchannel heat exchangers, represented by printed circuit board heat exchangers (PCHEs), are increasingly widely used in closed-loop systems due to their significant advantages, including compact structure, high heat transfer efficiency, and excellent high-pressure resistance. However, the internal flow channels of microchannel heat exchangers are extremely small (typically on the millimeter scale), making them highly sensitive to particulate impurities in the circulating working fluid. Tiny particles generated during system operation, pipe wear, or installation residue can easily accumulate within the microchannels, leading to blockage and severely impacting heat exchange efficiency. Therefore, to effectively reduce the risk of blockage in microchannel heat exchangers, high-precision filtration devices are typically installed on the working fluid inlet pipes.

[0003] Under extreme operating conditions of high temperature and high pressure, the mainstream filters are currently divided into two main types: flanged filters and welded filters. Flanged filters are connected by flange bolts. Their advantage lies in the fact that during later maintenance, the filter element can be directly removed for cleaning or replacement by disassembling the flange, without creating additional on-site welds, thus ensuring the cleanliness of the pipeline interior. Welded filters, on the other hand, have the filter body directly welded to the pipeline, offering advantages such as good sealing, compact structure, and low cost.

[0004] However, all of the existing filters mentioned above have significant drawbacks. Flanged filters, operating under high temperature and pressure, require extremely large flanges and fasteners, resulting in high manufacturing costs. Furthermore, the disassembly and maintenance of large-size high-pressure flanges are extremely difficult, making them highly susceptible to sealing surface damage or leakage. Welded filters, when needing cleaning or with clogged filter elements, require complete cutting through the pipeline to remove the filter element. This not only creates new weld joints during reinstallation but also easily introduces new metal shavings, welding slag, and other welding impurities into the pipeline during cutting and re-welding, posing a secondary threat of clogging to the downstream microchannel heat exchanger. In summary, neither existing flanged nor welded filters can adequately meet the long-term stable operation requirements of high-temperature, high-pressure closed-loop systems. The key technical challenge in the field of microchannel heat exchanger filtration technology is how to ensure reliable sealing under extreme conditions while reducing the overall manufacturing cost and maintenance difficulty of the filtration device and preventing the introduction of secondary contaminants into the pipeline during cleaning and maintenance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention discloses a tubular filtration device, the technical solution of which is as follows: A tubular filtration device includes: a filter pressure-bearing pipe; an end cap disposed at the end of the filter pressure-bearing pipe; a drain pipe connected to the filter pressure-bearing pipe; an exhaust gate valve installed at the outlet end of the drain pipe; an inlet gate valve installed on the working fluid inlet side of the filter pressure-bearing pipe; an outlet pipe installed on the side wall of the filter pressure-bearing pipe; a filter screen body disposed inside the filter pressure-bearing pipe, the filter screen body including a filter screen inlet ring, a filter screen cylinder, a filter screen support block, a filter screen conical neck, and a filter screen drain outlet, the filter screen inlet ring contacting a filter screen positioning block disposed on the inner wall of the filter pressure-bearing pipe, the filter screen drain outlet inserted into the drain pipe, and the filter screen support block connected to the filter screen cylinder; a high-pressure soot blowing nozzle facing the outer surface of the filter screen cylinder; and a differential pressure gauge installed on the filter pressure-bearing pipe for measuring the pressure difference between the inlet side of the filter screen cylinder and the outer side of the filter screen cylinder. The controller is electrically connected to the differential pressure gauge, the inlet gate valve, the exhaust gate valve, and the high-pressure soot blowing nozzle.

[0006] The present invention also discloses an operating method based on the above-mentioned tubular filtration device, characterized by comprising the following steps: Step 1: Under normal filtration conditions, keep the inlet gate valve open. The working fluid enters the filter body through the inlet gate valve and flows into the space outside the filter body through the filter cylinder and the filter on the filter conical constriction. The filtered working fluid flows out through the outlet pipe. The particulate impurities carried by the working fluid are trapped inside the filter body. Step 2: The differential pressure gauge collects the pressure difference between the inlet side of the filter cylinder and the outer side of the filter cylinder in real time. and the pressure difference value Send to the controller; Step 3: The controller will record the differential pressure value. With the aforementioned blockage pressure difference threshold When comparing, If necessary, return to step one; Step 4: When At that time, the controller determines the current differential pressure value. Is it less than the maximum allowable pressure difference? If yes, then execute the cleanup process without shutting down the system; otherwise, execute the cleanup process with the system shut down.

[0007] Beneficial effects 1. No need to disassemble flanges or cut pipes, convenient maintenance and reliable sealing. Employing an integrated pressure-bearing pipe structure, the filter body is installed internally. Through the installation of a drain pipe, exhaust valve, and high-pressure soot blowing nozzle, the filter can be cleaned online without shutting down and during shutdown. The cleaning process eliminates the need to disassemble flange bolts or cut welded pipes, avoiding the risk of flange sealing surface damage or leakage under high temperature and pressure conditions. It also eliminates the potential for secondary contamination from metal shavings, welding slag, and other impurities introduced by cutting and re-welding, ensuring the long-term stable operation of the closed-loop system.

[0008] 2. Achieve intelligent blockage monitoring and automatic cleaning control. By setting a differential pressure gauge to measure the pressure difference between the inlet and outer sides of the filter body in real time, and comparing this pressure difference with the preset clogging pressure difference threshold and the maximum allowable pressure difference by the controller, the degree of filter clogging can be accurately determined, and the system can automatically select to perform a non-stop cleaning process or a shutdown cleaning process. This intelligent control strategy avoids the lag and uncertainty of manual judgment, and improves the adaptability and operational reliability of the filtration device.

[0009] 3. Dynamically adjust cleaning time to improve cleaning efficiency and save on working fluids. During the non-stop cleaning process, the controller dynamically calculates the cleaning time based on the current measured differential pressure value, the blockage differential pressure threshold, and the maximum allowable differential pressure. When the blockage is more severe, the cleaning time is extended accordingly to ensure thorough removal of particulate matter; when the blockage is minor, the cleaning time is automatically shortened to reduce the consumption of high-pressure working fluid and disturbance to the system, achieving precise and efficient cleaning control.

[0010] 4. Optimized cleaning mode combining pulse soot blowing and differential pressure linkage The high-pressure soot blowing nozzle employs a pulse-jet spray method, with the pulse frequency and pulse width duty cycle dynamically adjusted according to the pressure difference range: low-frequency, low-duty-cycle pulses are used for minor clogging to avoid excessive impact; high-frequency, high-duty-cycle pulses are used for severe clogging to enhance the purging effect. This optimized mode effectively removes particles embedded in the filter screen while reducing mechanical fatigue damage to the filter screen structure, thus extending the filter screen's service life.

[0011] 5. The clogging pressure differential threshold is set based on theoretical formulas to adapt to different operating conditions. The controller can calculate the clogging pressure threshold based on the target filtration flow rate, working fluid dynamic viscosity, effective filtration length of the filter cylinder, permeability coefficient, flow area, and safety factor. This threshold can be automatically adjusted according to changes in the properties of the working fluid and the filter structure parameters, avoiding the problem of false triggering or delayed triggering under different operating conditions due to a fixed threshold, thus improving the adaptability and accuracy of the control system.

[0012] 6. Compatible with multiple cleaning modes to adapt to different levels of blockage. When the differential pressure does not exceed the maximum allowable differential pressure, a non-stop cleaning process is performed, and the system can restore its filtration performance without shutdown. When the differential pressure reaches the maximum allowable differential pressure, the system automatically switches to a shutdown cleaning process. First, the inlet gate valve is closed for high-pressure purging, and then the inlet gate valve is opened to utilize the upstream working fluid for forward flushing, ensuring thorough cleaning even in cases of severe blockage. The two modes work together, ensuring both the economy of continuous system operation and providing a reliable means of handling extreme blockages.

[0013] 7. The filter design is flexible, allowing for adjustment of the flow area and resistance. The filter cylinder and the tapered nozzle of the filter screen can be made of sintered filter material, which provides high filtration accuracy and strength. By adjusting the length of the filter screen, the flow area can be changed, thereby adjusting the filtration resistance to adapt to different application scenarios with varying flow rates and pressure drop requirements. The outlet pipe can be configured as a single or multiple pipes, facilitating flexible connection to downstream equipment such as microchannel heat exchangers.

[0014] 8. Suitable for extreme high-temperature and high-pressure conditions, especially suitable for inlet filtration of microchannel heat exchangers. The tubular filter device of this invention has no flanges, strong pressure resistance, and excellent sealing performance, enabling it to withstand high-temperature and high-pressure conditions in closed-loop systems such as supercritical carbon dioxide circulation. Simultaneously, its online cleaning function and secondary pollution control features effectively protect downstream microchannel devices such as printed circuit board heat exchangers from particulate matter clogging, significantly improving system heat exchange efficiency and service life. Attached Figure Description

[0015] Figure 1 This is a schematic diagram showing the external shape and composition of a tubular filtration device according to the present invention.

[0016] Figure 2 This is a schematic cross-sectional view of the internal structure of a tubular filtration device according to the present invention.

[0017] Figure 3 This is a schematic diagram of the filter body of a tubular filtration device according to the present invention.

[0018] The filter includes a pressure-bearing pipe 1, an outlet pipe 2, a cap 3, a drain pipe 4, an exhaust gate valve 5, an inlet gate valve 6, a filter screen body 7, a filter screen positioning block 8, a high-pressure blowing nozzle 9, a filter screen inlet ring 10, a filter screen cylinder 11, a filter screen conical constriction 12, a filter screen drain outlet 13, and a filter screen support block 14. Detailed Implementation

[0019] Example 1 A tubular filtration device, serving as an upstream working fluid filtration unit in a printed circuit board heat exchanger, can efficiently intercept particulate matter in the working fluid within a high-temperature, high-pressure supercritical carbon dioxide circulation system. It features both online non-stop cleaning and automatic shutdown cleaning functions, with the entire cleaning process requiring no flange disassembly or pipe cutting. The specific structure of the device is as follows.

[0020] The filter pressure pipe is a thick-walled seamless steel pipe, with both ends sealed by welded end caps, forming a closed cavity capable of withstanding pressures exceeding 25 MPa. An inlet gate valve is installed on the working fluid inlet side of the filter pressure pipe to control whether the upstream working fluid enters the filtration device. An outlet pipe is located in the middle of the side wall of the filter pressure pipe. The number of outlet pipes can be set to one or more depending on the interface requirements of the downstream microchannel heat exchanger; in this embodiment, two symmetrically distributed outlet pipes are used to ensure uniform outflow of the filtered working fluid. A drain pipe is connected to the center of the bottom of the filter pressure pipe, and an exhaust gate valve is installed at the outlet end of the drain pipe. This drain pipe is used to discharge the working fluid carrying particulate matter during the cleaning process from the system.

[0021] The filter body has an overall cylindrical structure, consisting of a filter inlet ring, a filter cylinder, a conical nozzle, a drain outlet, and filter support blocks. The filter cylinder is a cylindrical filter layer. The conical nozzle is located at the downstream end of the filter cylinder, its diameter gradually decreasing until it connects with the drain outlet. This conical nozzle design facilitates the collection of particles towards the drain outlet under the influence of gravity and airflow. The filter inlet ring is welded to the upstream opening of the filter cylinder, and its outer diameter is larger than that of the filter cylinder. The filter support blocks are evenly distributed circumferentially and welded to the rear middle part of the outer wall of the filter cylinder. They are used to support the filter cylinder during installation and maintain an annular gap between it and the inner wall of the filter's pressure pipe. The filter body is inserted into the filter's pressure pipe from the upstream opening until the drain outlet is inserted to a certain depth. Simultaneously, the filter inlet ring is in close contact with the filter positioning block pre-welded to the inner wall of the filter's pressure pipe, thus limiting the axial position of the filter body and preventing displacement under the impact of the working fluid. Because the contact sealing surfaces between the filter screen inlet ring and the positioning block are precision machined, most of the working fluid is forced to enter the filter screen cylinder from the inner hole of the filter screen inlet ring, rather than flowing through a bypass. The filter screen cylinder and the tapered neck of the filter screen can be made of sintered filter material to obtain a uniform pore distribution and high mechanical strength.

[0022] The high-pressure sootblowing nozzle is inserted obliquely into the side wall of the filter's pressure-bearing pipe, with its nozzle penetrating the pipe wall and facing the outer surface of the filter screen cylinder. The external interface of this nozzle is connected to the same high-pressure working fluid source (e.g., high-pressure carbon dioxide gas from a system bypass), and a solenoid valve is installed on the pipeline to control the start / stop and pulse mode of the blowing. Alternatively, the high-pressure sootblowing nozzle can be replaced with an ultrasonic sootblower, which uses high-frequency vibration to dislodge particles from the filter screen surface. A differential pressure gauge is installed on the filter's pressure-bearing pipe, with its high-pressure side interface connected to the working fluid channel upstream of the filter screen inlet ring, and its low-pressure side interface connected to the annular space between the outer side of the filter screen cylinder and the inner wall of the filter's pressure-bearing pipe. Therefore, the differential pressure gauge can measure the pressure difference between the filter screen inlet side and the outer side of the filter screen cylinder in real time. This pressure difference directly reflects the degree of clogging in the filter screen cylinder: when the amount of particles deposited on the inner surface of the filter screen increases or becomes embedded in the filter screen pores, the flow resistance of the working fluid through the filter screen increases, and the pressure difference rises accordingly.

[0023] The controller is a programmable logic controller (PLC). Its input port is electrically connected to the signal output terminal of the differential pressure gauge, and its output ports are electrically connected to the actuators of the inlet gate valve, the exhaust gate valve, and the solenoid valves on the high-pressure soot blowing nozzle. The controller's internal memory stores the clogging differential pressure threshold DPth and the maximum allowable differential pressure DPmax, with DPth set to be less than DPmax. DPth is not a fixed empirical value but is automatically calculated by the controller using theoretical formulas based on system operating conditions and filter structure parameters (see below for details). DPmax is a fixed value, taking the smaller of the filter body structural strength and the system's maximum allowable pressure drop.

[0024] The following describes in detail the operation process of the tubular filter device, which includes the normal filtration stage, the real-time monitoring and judgment stage, the non-stop cleaning stage, and the shutdown cleaning stage.

[0025] Under normal filtration conditions, the controller keeps the inlet gate valve fully open, the exhaust gate valve closed, and the high-pressure soot blowing nozzle inactive. The upstream high-pressure working fluid, carrying a certain concentration of particulate matter, enters the filter's pressure-bearing pipe through the inlet gate valve. Due to the sealing effect of the filter screen inlet ring and the positioning block, the working fluid flows entirely into the filter screen body. Driven by pressure, the working fluid passes through the filter screen cylinder and the micropores on the filter screen's conical constriction. Particulate matter, because its size is larger than the filter screen pore diameter, is trapped on the inner surface of the filter screen cylinder or embedded in the filter layer. The clean working fluid enters the annular space between the outer side of the filter screen cylinder and the inner wall of the filter's pressure-bearing pipe, and then flows downstream to the printed circuit board heat exchanger through the outlet pipe. As operating time accumulates, the amount of trapped particulate matter gradually increases, reducing the effective flow area of ​​the filter screen and causing an increase in flow resistance through the filter screen.

[0026] The differential pressure gauge continuously measures the differential pressure DP between the inlet side of the filter screen and the outer side of the filter screen cylinder at a sampling frequency of at least once per second, and sends the differential pressure to the controller in real time. The controller compares DP with a pre-stored clogging differential pressure threshold DPth. As long as DP < DPth, the controller determines that the filter screen has not reached the clogging degree requiring cleaning, and keeps the current normal filtering state unchanged.

[0027] When the differential pressure gauge detects that DP gradually increases and reaches DPth, the controller enters the cleaning decision logic. First, it is determined whether the current DP is less than the maximum allowable differential pressure DPmax. Since DPth itself is smaller than DPmax, DP reaches DPth first and has not reached DPmax in most cases. At this time, the controller determines that the non-stop cleaning method can be adopted to avoid the loss of power generation efficiency caused by system shutdown.

[0028] The controller then starts the non-stop cleaning process. The specific execution process of the process is as follows: the controller keeps the inlet gate valve fully open, and simultaneously sends an opening command to the actuator of the exhaust gate valve to open the exhaust gate valve. The controller also sends a pulsed opening signal to the solenoid valve on the pipeline of the high-pressure soot blowing nozzle, so that the high-pressure working medium is ejected at high speed from the nozzle in a pulsed form, and impacts the outer surface of the filter screen cylinder. The high-pressure working medium forms local eddy currents and pressure fluctuations during the impact process. Part of the working medium passes through the micropores of the filter screen and flows backward into the filter screen, stripping off the particulate matter deposited on the inner surface of the filter screen or embedded in the pores of the filter screen; the other part of the working medium flows along the outer surface of the filter screen cylinder, carrying the stripped particulate matter to move downstream. Due to the guiding effect of the tapered necking of the filter screen, the particulate matter converges to the sewage outlet of the filter screen under the entrainment of the working medium, and then is discharged out of the device through the sewage pipe and the open exhaust gate valve. Since the inlet gate valve is always open, the upstream working medium continuously performs forward scouring on the inside of the filter screen, forming a synergistic effect with the reverse pulse purging, which significantly improves the cleaning efficiency.

[0029] During the non-stop cleaning process, the controller dynamically adjusts the cleaning duration according to the currently measured differential pressure DP. A reference cleaning duration t0 is stored in the controller, which is the shortest time calibrated through experiments to basically remove blockages when the differential pressure reaches DPth. The actual cleaning duration tc is calculated according to the following formula: Where tc is the actual cleaning time in seconds; t0 is the baseline cleaning time in seconds, which is 30 seconds in this embodiment; DP is the measured differential pressure value at the start of cleaning in Pascals; DPth is the clogging differential pressure threshold in Pascals; and DPmax is the maximum allowable differential pressure in Pascals. The principle behind this formula is that the greater the differential pressure exceeds the threshold, the more severe the clogging, and the longer the required cleaning time should be. When the differential pressure approaches DPmax, the cleaning time approaches infinity, meaning that cleaning without stopping the system may not be effective, and cleaning by stopping the system is necessary. This also corresponds to the subsequent cleaning mode switching logic. During the cleaning process, the controller continuously receives the real-time differential pressure value from the differential pressure gauge. Once it detects that DP drops below DPth, it immediately stops the pulse injection of the high-pressure sootblowing nozzle and closes the exhaust valve, ending the cleaning process and restoring the system to normal filtration. This feedback control mechanism avoids the waste of working fluid and filter fatigue caused by over-cleaning.

[0030] To further improve purging efficiency and reduce mechanical impact on the filter structure, the controller controls the high-pressure sootblowing nozzle to use a pulse jet method, and the pulse parameters are dynamically adjusted according to the pressure difference range. Specifically, the controller internally sets two pressure difference ranges: a light clogging range (DPth ≤ DP ≤ 1.2·DPth) and a severe clogging range (DP > 1.2·DPth). When DP is in the light clogging range, the controller sets the pulse frequency fp to a range of 0.5Hz to 2Hz (1Hz in this embodiment) and the pulse width duty cycle (Duty) to a range of 10% to 30% (20% in this embodiment). Low-frequency, short pulses can gently blow away loosely attached particles from the surface without forcing them deeper into the filter pores. When the filter element (DP) is in a severely clogged state, the controller automatically switches to pulse mode, setting the pulse frequency (fp) to a range of 5Hz to 20Hz (10Hz in this embodiment) and the pulse width duty cycle (Duty) to a range of 30% to 60% (50% in this embodiment). The high-frequency, long pulses generate stronger shock waves and vibrations, effectively breaking down and removing small particles embedded deep within the filter. This dynamic adjustment method ensures effective cleaning while minimizing filter fatigue damage and extending the filter's lifespan.

[0031] If, despite the above non-stop cleaning procedure, the differential pressure gauge reading (DP) continues to rise and eventually reaches the maximum permissible differential pressure (DPmax), the controller determines that the filter screen is severely clogged and performance cannot be restored without stopping the system; a shutdown cleaning procedure must be performed. In this case, the controller first closes the inlet gate valve, cutting off the supply of the upstream working fluid, while keeping the exhaust gate valve open. Then, the controller sends a continuous opening signal (no longer in pulse mode) to the high-pressure sootblowing nozzle, causing the high-pressure working fluid to be ejected from the nozzle at a constant high-speed airflow, impacting the outer surface of the filter screen cylinder. Because the inlet gate valve is closed, there is no forward flow inside the filter screen. After the high-pressure working fluid passes through the filter screen and enters the interior, it mainly carries the detached particles in the reverse flow towards the filter screen drain port, and is discharged through the drain pipe and exhaust gate valve. The controller maintains this purging state for a first preset time T1, where T1 is 60 seconds, to fully loosen and remove the accumulated dirt inside the filter screen.

[0032] After completing the first preset duration of reverse purging, the controller opens the inlet gate valve. At this time, the upstream high-pressure working fluid re-enters the filter screen, working in conjunction with the still-open high-pressure sootblowing nozzle. The forward-flowing high-pressure working fluid rapidly blows the loosened but still residual particles inside the filter screen towards the filter screen's conical constriction and drain port, achieving forward flushing. Forward flushing continues for a second preset duration, T2, which is 30 seconds. During this process, due to the opening of the inlet gate valve, the system's working fluid circulation resumes, but the impact on the downstream heat exchanger due to a short-term shutdown is within acceptable limits. After completing the above two steps, the controller closes the high-pressure sootblowing nozzle and the exhaust gate valve, keeping the inlet gate valve fully open, and the system re-enters normal filtration mode. The differential pressure value reported by the differential pressure gauge should have significantly decreased to below DPth.

[0033] To ensure that the clogging differential pressure threshold DPth can adapt to changes in the properties of different working fluids and filter structure parameters, rather than using a fixed empirical value, the controller has a self-calculation function. After the system is initially installed or the filter is replaced, the operator inputs the target filtration flow rate Q, the dynamic viscosity MU of the working fluid, the effective filtration length L of the filter cylinder, the permeability coefficient KF of the filter cylinder, and the flow area AF of the filter cylinder through the human-machine interface. The controller automatically calculates and stores DPth according to the following theoretical formula:

[0034] Where Q is the target filtration flow rate in cubic meters per second; MU is the dynamic viscosity of the working fluid in Pascal-seconds; L is the effective filtration length of the filter cylinder in meters; KF is the permeability coefficient of the filter cylinder in square meters; AF is the flow area of ​​the filter cylinder in square meters; and BETA is a dimensionless safety factor ranging from 1.2 to 1.5, with 1.3 used in this embodiment. This formula is derived from Darcy's law: at a certain flow rate, the pressure drop of the working fluid through a porous medium is directly proportional to the dynamic viscosity and filtration length, and inversely proportional to the permeability and flow area. The safety factor BETA is introduced to provide a certain safety margin, avoiding premature cleaning due to fluctuations in the working fluid properties or localized unevenness of the filter. The DPth calculated by this formula can be automatically adjusted according to changes in operating conditions. For example, when the system switches to different working fluids (such as switching from supercritical carbon dioxide to helium), the change in MU will be directly reflected in DPth, thus avoiding the problem that a fixed threshold is too sensitive under low viscosity working fluids or reacts too slowly under high viscosity working fluids.

[0035] The aforementioned device and method organically combine pulse purging of high-pressure sootblowing nozzles, dynamic duration adjustment of differential pressure feedback, pulse parameter switching based on differential pressure range, automatic decision-making for both non-stop and stop modes, and threshold calculation based on theoretical formulas, forming a complete and highly intelligent tubular filtration device and its operation method. Throughout its entire lifecycle, filtration and cleaning operations can be completed without disassembling any flanges or cutting pipes, fundamentally solving the problems of easy leakage in flanged filters, secondary pollution introduced during cleaning of welded filters, and the inability to perform online maintenance in existing technologies. It is particularly suitable for inlet filtration scenarios of microchannel heat exchangers in supercritical carbon dioxide Brayton cycles.

[0036] Example 2 This embodiment provides an operation method based on the above-described tubular filter device. This method automatically selects and executes the corresponding cleaning process through real-time monitoring and logical judgment of the differential pressure signal by the controller. The method is described in detail below according to steps one through four.

[0037] Step 1: Filtration process under normal filtration conditions After the system starts up and enters stable operation, the controller first executes the normal filtration process. The controller keeps the inlet gate valve fully open while ensuring the exhaust gate valve is closed, and the high-pressure soot blowing nozzle remains inactive. The high-pressure working fluid from upstream, carrying a certain concentration of particulate matter, enters the filter pressure pipe through the inlet gate valve. Due to the tight contact between the filter screen inlet ring and the filter screen positioning block, the working fluid cannot bypass and flows entirely into the filter body. Driven by pressure, the working fluid passes through the filter screen cylinder and the micropores on the filter screen's conical constriction. Particulate matter, because its size is larger than the filter screen pore diameter, is trapped on the inner surface of the filter screen cylinder or embedded in the filter layer. The clean working fluid enters the annular space between the outer side of the filter screen cylinder and the inner wall of the filter pressure pipe, and then flows downstream to the printed circuit board heat exchanger through the outlet pipe. As operating time accumulates, the amount of trapped particulate matter gradually increases, the effective flow area of ​​the filter screen decreases, and the flow resistance through the filter screen increases. This change in resistance directly determines the pressure difference between the filter screen inlet side and the outer side, providing a physical basis for monitoring in subsequent steps.

[0038] Step 2: The differential pressure gauge collects the differential pressure value in real time and sends it to the controller. During normal filtration, a differential pressure gauge continuously measures the real-time pressure difference between the filter cylinder inlet and the outer side of the filter cylinder at a sampling frequency of at least once per second. This pressure difference is denoted as DP. The high-pressure side interface of the differential pressure gauge is connected to the working fluid channel upstream of the filter inlet ring, and the low-pressure side interface is connected to the annular space between the outer side of the filter cylinder and the inner wall of the filter pressure-bearing pipe. Therefore, the measured DP value accurately reflects the resistance overcome by the working fluid through the filter. The differential pressure gauge transmits the acquired DP signal to the controller in real time via an analog or digital interface. The controller has a high-speed sampling buffer to store the DP sequence over a recent period for trend analysis and noise filtering.

[0039] Step 3: The controller compares the differential pressure value DP with the blockage differential pressure threshold DPth, and decides whether to return to Step 1 based on the comparison result. A blockage differential pressure threshold DPth and a maximum allowable differential pressure DPmax are pre-stored in the internal memory of the controller, and DPth is set to be smaller than DPmax. Wherein, DPth is not a fixed empirical value, but is automatically calculated by the controller through a theoretical formula according to system working conditions and filter screen structure parameters (the specific calculation method is detailed in step four); DPmax is the smaller value between the structural strength of the filter screen body and the maximum pressure drop allowed by the system, and is a fixed value. The controller compares the real-time received DP with DPth. As long as DP < DPth, the controller determines that the filter screen has not reached the blockage degree requiring cleaning, the system remains in the normal filtration state, that is, it returns to step one to continue executing the filtration process. The comparison process is cyclically executed at the frequency of the scanning cycle of the controller, and the scanning cycle usually does not exceed 100 milliseconds, so as to ensure rapid response to the blockage state. Meanwhile, the controller can also perform a moving average processing on DP to eliminate false triggering caused by instantaneous pressure fluctuation, and only when DP is greater than or equal to DPth in three consecutive sampling cycles, the judgment logic of step four is entered.

[0040] Step 4: When DP ≥ DPth, the controller determines whether DP is less than DPmax, and executes a non-stop cleaning process or a shutdown cleaning process according to the judgment result When the controller detects that DP reaches or exceeds DPth, it enters the cleaning decision logic. First, it is determined whether the current DP is less than DPmax. Since DPth itself is smaller than DPmax, under most working conditions DP reaches DPth first and has not reached DPmax, at this time the controller determines that the non-stop cleaning method can be adopted, so as to avoid production loss caused by system shutdown. If DP directly reaches or exceeds DPmax due to misoperation, serious damage of the filter screen or extreme working conditions, the controller determines that the shutdown cleaning process must be executed. The two processes are described in detail below respectively.

[0041] Execution process of non-stop cleaning process When the judgment result is to execute the non-stop cleaning process, the controller operates according to the following sub-steps.

[0042] Sub-step 4.1: The controller keeps the inlet gate valve in a fully open state to ensure continuous forward flow of upstream working medium; meanwhile, it sends an opening instruction to the actuator of the exhaust gate valve to fully open the exhaust gate valve and form a sewage discharge path.

[0043] Sub-step 4.2: The controller sends a pulsed opening signal to the solenoid valve on the high-pressure sootblowing nozzle, causing the high-pressure working fluid to be ejected at high speed from the nozzle in pulse form, impacting the outer surface of the filter screen cylinder. During the impact, the high-pressure working fluid forms local eddies and pressure fluctuations. Part of the working fluid flows back into the filter screen through the micropores, peeling off particles deposited on the inner surface of the filter screen or embedded in the pores; the other part of the working fluid flows along the outer surface of the filter screen cylinder, carrying the peeled particles downstream. Due to the guiding effect of the conical constriction of the filter screen, the particles are carried by the working fluid to the filter screen drain port, and then discharged outside the device through the drain pipe and the open exhaust gate valve. Since the inlet gate valve is always open, the upstream working fluid continuously performs forward flushing of the filter screen interior, forming a synergistic effect with the reverse pulse purging, significantly improving the cleaning efficiency. It should be noted that the high-pressure sootblowing nozzle in this embodiment can also be replaced by an ultrasonic sootblower, which uses high-frequency vibration to dislodge the attached particles, and can also achieve non-stop cleaning.

[0044] Sub-step 4.3: The controller dynamically adjusts the cleaning time based on the currently measured differential pressure value DP. The controller internally stores a baseline cleaning time t0, which is the shortest time, experimentally calibrated, to essentially clear the blockage when the differential pressure just reaches DPth. The actual cleaning time tc is calculated using the following formula:

[0045] Where tc is the actual cleaning time in seconds; t0 is the baseline cleaning time in seconds, which is 30 seconds in this embodiment; DP is the measured differential pressure at the start of cleaning in Pascals; DPth is the clogging differential pressure threshold in Pascals; and DPmax is the maximum allowable differential pressure in Pascals. The physical meaning of this formula is that the greater the differential pressure exceeds the threshold, the more severe the clogging, requiring a longer cleaning time to effectively remove particulate matter. Theoretically, when DP approaches DPmax, the required cleaning time approaches infinity. Therefore, in actual control, once DP reaches or exceeds DPmax, the controller will no longer attempt to clean without stopping the system but will directly switch to the shutdown cleaning process, which is consistent with the judgment logic in step four.

[0046] Sub-step 4.4: During the cleaning process, the controller continuously receives real-time DP values ​​from the differential pressure gauge. Once the DP drops below DPth, the controller immediately stops the pulse jetting from the high-pressure sootblowing nozzle and closes the exhaust valve. The cleaning process ends, and the system returns to the normal filtration state of step one. This closed-loop feedback control mechanism avoids the waste of working fluid and filter fatigue caused by over-cleaning.

[0047] Sub-step 4.5: To further improve purging efficiency and reduce mechanical impact on the filter structure, the controller also controls the high-pressure sootblowing nozzle to use a pulse jet method during the non-stop cleaning process, and the pulse parameters are dynamically adjusted according to the pressure difference range. The controller internally sets two pressure difference ranges: the mild clogging range is defined as DPth ≤ DP ≤ 1.2·DPth, and the severe clogging range is defined as DP > 1.2·DPth. When DP is in the mild clogging range, the controller sets the pulse frequency fp to a range of 0.5Hz to 2Hz (1Hz in this embodiment), and the pulse width duty cycle (Duty) to a range of 10% to 30% (20% in this embodiment). Low-frequency, short pulses can generate gentle shock waves that blow away loosely attached particles without pressing them deeper into the filter pores, while reducing fatigue damage to the filter material. When the filter (DP) is in a severely clogged state, the controller automatically switches to pulse mode, setting the pulse frequency (fp) to a range of 5Hz to 20Hz (10Hz in this embodiment) and the pulse width duty cycle (Duty) to a range of 30% to 60% (50% in this embodiment). High-frequency, long pulses generate stronger impact energy and vibration effects, effectively breaking down and removing small particles embedded deep within the filter. This dynamic adjustment of pulse parameters based on the degree of clogging maximizes the filter's lifespan while ensuring effective cleaning.

[0048] The execution process of shutdown and cleanup procedures If, despite executing the above non-stop cleanup procedure, the differential pressure gauge reading continues to rise and eventually reaches the maximum permissible differential pressure DPmax, or if the DP is already greater than or equal to DPmax at the initial judgment in step four, then the controller determines that a shutdown cleanup procedure must be executed. The specific sub-steps of the shutdown cleanup procedure are as follows.

[0049] Sub-step 4.6: The controller closes the inlet gate valve, cuts off the supply of the upstream working fluid, and keeps the exhaust gate valve in the open state at the same time.

[0050] Sub-step 4.7: The controller sends a continuous open signal to the high-pressure soot blowing nozzle (no longer using pulse mode), causing the high-pressure working fluid to be ejected from the nozzle at a constant high-speed airflow, impacting the outer surface of the filter screen cylinder. Since the inlet gate valve is closed, there is no forward flow inside the filter screen. After the high-pressure working fluid passes through the filter screen and enters the filter screen, it mainly carries the detached particles in a reverse flow towards the filter screen drain port, and is discharged through the drain pipe and exhaust gate valve. The controller maintains this reverse purging state for a first preset time T1, where T1 is 60 seconds. The design basis is that 60 seconds of continuous purging is sufficient to loosen and partially discharge most of the hard particles embedded deep within the filter screen.

[0051] Sub-step 4.8: After completing the first preset duration of reverse purging, the controller opens the inlet gate valve. At this time, the upstream high-pressure working fluid re-enters the filter screen, working in conjunction with the still-open high-pressure sootblowing nozzle. The forward-flowing high-pressure working fluid quickly blows the loosened but still residual particles inside the filter screen towards the filter screen's conical constriction and drain port, achieving forward rinsing. Forward rinsing continues for a second preset duration T2, which is 30 seconds. This duration is determined based on experience to thoroughly remove residues without excessively affecting the system's circulation.

[0052] Sub-step 4.9: After completing the above two steps, the controller closes the high-pressure soot blowing nozzle and the exhaust gate valve, while keeping the inlet gate valve fully open. The system then re-enters the normal filtration state of step one. At this point, the DP value fed back by the differential pressure gauge should have significantly decreased to below DPth.

[0053] Extended explanation of the threshold self-calculation function To ensure that the clogging differential pressure threshold DPth can adapt to changes in the properties of different working fluids and filter structure parameters, rather than using a fixed empirical value, the controller has a self-calculation function before executing step four or during system initialization. After the system is initially installed or the filter is replaced, the operator inputs the target filtration flow rate Q, the dynamic viscosity MU of the working fluid, the effective filtration length L of the filter cylinder, the permeability coefficient KF of the filter cylinder, and the flow area AF of the filter cylinder through the human-machine interface. The controller automatically calculates and stores DPth according to the following theoretical formula:

[0054] Where Q is the target filtration flow rate in cubic meters per second; MU is the dynamic viscosity of the working fluid in Pascal-seconds; L is the effective filtration length of the filter cylinder in meters; KF is the permeability coefficient of the filter cylinder in square meters; AF is the flow area of ​​the filter cylinder in square meters; and BETA is a dimensionless safety factor, ranging from 1.2 to 1.5, and 1.3 in this embodiment. This formula is derived from Darcy's law: for porous media, under laminar flow conditions, the volumetric flow rate is proportional to the pressure drop, and the proportionality coefficient is determined by the permeability, viscosity, thickness, and area of ​​the medium. The safety factor BETA is introduced to reserve a certain safety margin and avoid premature cleaning due to fluctuations in the working fluid properties, local unevenness of the filter, or measurement errors. The DPth calculated by this formula can be automatically adjusted according to changes in operating conditions. For example, when the system switches to different working fluids (such as switching from supercritical carbon dioxide to helium), the change in MU will be directly reflected in DPth, thus avoiding the problem that a fixed threshold is too sensitive under low viscosity working fluids or reacts too slowly under high viscosity working fluids.

[0055] The above operating method strictly follows the sequence of steps one through four, organically integrating real-time differential pressure monitoring, dynamic threshold calculation, cleaning time adjustment based on differential pressure ratio, pulse parameter switching based on differential pressure range, and automatic decision-making for both non-stop and stop modes. This forms a complete and highly adaptive intelligent filtration control method. Throughout the entire operating lifecycle, filter clogging can be determined and cleaned without manual intervention, significantly reducing maintenance costs and fundamentally solving the drawbacks of existing technologies such as the frequent disassembly of flange filters and the need to cut pipes for cleaning welded filters.

[0056] Many specific details have been set forth in the foregoing description to provide a thorough understanding of the present invention. However, the above description is merely a preferred embodiment of the present invention, and the present invention can be implemented in many other ways different from those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed above. Furthermore, any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, using the methods and techniques disclosed above, without departing from the scope of the present invention. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A tubular filtration device, characterized in that, include: Filter pressure pipe; A cap is provided at the end of the pressure-bearing pipe of the filter; a drain pipe is connected to the pressure-bearing pipe of the filter; An exhaust gate valve is installed at the outlet end of the drain pipe; an inlet gate valve is installed on the working fluid inlet side of the filter pressure pipe; an outlet pipe is installed on the side wall of the filter pressure pipe; a filter screen body is disposed inside the filter pressure pipe, the filter screen body including a filter screen inlet ring, a filter screen cylinder, a filter screen support block, a filter screen conical constriction, and a filter screen drain port, the filter screen inlet ring is in contact with a filter screen positioning block disposed on the inner wall of the filter pressure pipe, the filter screen drain port is inserted into the drain pipe, and the filter screen support block is connected to the filter screen cylinder; a high-pressure soot blowing nozzle faces the outer surface of the filter screen cylinder; a differential pressure gauge is installed on the filter pressure pipe to measure the pressure difference between the inlet side of the filter screen cylinder and the outer side of the filter screen cylinder; a controller is electrically connected to the differential pressure gauge, the inlet gate valve, the exhaust gate valve, and the high-pressure soot blowing nozzle.

2. The tubular filter device according to claim 1, characterized in that, The filter cylinder and the tapered neck of the filter are made of sintered filter material.

3. The tubular filter device according to claim 1, characterized in that, The number of outlet pipes is one or more.

4. The tubular filter device according to claim 1, characterized in that, The high-pressure soot blowing nozzle was replaced with an ultrasonic soot blower.

5. The tubular filter device according to claim 1, characterized in that, The controller stores a blockage pressure differential threshold. and maximum permissible pressure difference ,and Less than .

6. A method of operating the tubular filtration device according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Under normal filtration conditions, keep the inlet gate valve open. The working fluid enters the filter body through the inlet gate valve, flows through the filter cylinder and the filter screen on the conical constriction of the filter screen, and flows into the space outside the filter cylinder. The filtered working fluid flows out through the outlet pipe, and the particulate impurities carried by the working fluid are trapped inside the filter body. Step 2: The differential pressure gauge collects the pressure difference between the inlet side of the filter cylinder and the outside of the filter cylinder in real time. and the pressure difference value The differential pressure value is sent to the controller; Step 3: The controller sends the differential pressure value... With the aforementioned blockage pressure differential threshold When comparing, If so, return to step one; Step four: When At that time, the controller determines the current differential pressure value. Is it less than the maximum allowable pressure difference? If yes, then execute the cleanup process without shutting down the system; otherwise, execute the cleanup process with the system shut down.

7. The operating method according to claim 6, characterized in that, The non-stop cleaning process includes: keeping the inlet gate valve open, opening the exhaust gate valve, and simultaneously controlling the high-pressure blowing nozzle to spray high-pressure working fluid into the filter pressure pipe. The high-pressure working fluid impacts the surface of the filter screen cylinder, blowing out particles deposited on the inner surface of the filter screen cylinder or embedded in the filter screen. The blown-out particles, along with the working fluid, enter the drain pipe through the filter screen drain port and are then discharged through the exhaust gate valve. During the cleaning process, the controller adjusts the pressure differential value accordingly. Dynamically adjust cleaning time The cleaning time Determined by the following formula: in, The preset baseline cleaning time, in seconds, refers to the time taken at the pressure differential value. Exactly equal to the blockage pressure differential threshold The shortest effective cleaning time was determined experimentally; the controller continuously monitored the differential pressure value during the cleaning process. ,when Drop to below When this occurs, stop cleaning and close the exhaust valve.

8. The operating method according to claim 6, characterized in that, The shutdown and cleaning process includes: closing the inlet gate valve, opening the exhaust gate valve, and simultaneously controlling the high-pressure soot blowing nozzle to blow high-pressure working fluid into the filter pressure pipe. The high-pressure working fluid impacts the surface of the filter screen cylinder, blowing out particles deposited on the inner surface of the filter screen cylinder or embedded in the filter screen; after keeping the high-pressure soot blowing nozzle open for a first preset time, opening the inlet gate valve, using the upstream working fluid to blow particulate impurities in the filter screen cylinder towards the filter screen drain port and the drain pipe, and finally discharging them through the exhaust gate valve; after completing the above steps, closing the high-pressure soot blowing nozzle and the exhaust gate valve, while keeping the inlet gate valve open, and returning to step one.

9. The operating method according to claim 7, characterized in that, In the non-stop cleaning process, the high-pressure soot blowing nozzle adopts a pulse jet method with a pulse frequency of Pulse width and duty cycle According to the pressure difference value Dynamic adjustment: when In to When the interval is reached, the controller sets the pulse frequency. The value ranges from 0.5Hz to 2Hz, and the pulse width duty cycle... The value range is 10% to 30%; when Greater than At that time, the controller sets the pulse frequency. The value range is from 5Hz to 20Hz, and the pulse width duty cycle is... The value ranges from 30% to 60%.

10. The operating method according to claim 6, characterized in that, The controller also calculates the clogging pressure threshold based on the physical properties of the working fluid and the structural parameters of the filter cylinder. The calculation formula is as follows: in, The target filter flow rate is expressed in cubic meters per second. The dynamic viscosity of the working fluid is expressed in Pascal-seconds. The effective filtration length of the filter cylinder is expressed in meters. The permeability coefficient of the filter cylinder is expressed in square meters. The flow area of ​​the filter cylinder is expressed in square meters. The safety factor ranges from 1.2 to 1.5.

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