Centrifugal filtration system and method for filtering an air stream

Abstract

The present inventive concept pertains to a centrifugal filtration system (100) designed for filtering an air stream. The system includes a rotor system (8) that rotates at a range of speeds and comprises a set of conical discs (3) that filter particles in the air stream. The rotation of the rotor system (8) is controlled to pass through a set of main intermediate speeds within the range of speeds. The system (100) also includes a liquid injection system that injects cleaning liquid into the rotor system (8). The timing of cleaning liquid injection is controlled to coincide with at least one main intermediate speed of the rotor system (8).

Description

[0001] Centrifugal filtration system and method for filtering an air stream.

[0002] Field

[0003] The present disclosure relates to a centrifugal filtration system and method for filtering an air stream.

[0004] Background

[0005] Air filtration systems are crucial in various industries and environments, such as hospitals, clean rooms, data centers, and industrial settings, where the removal of dry particles from the air is essential for maintaining air quality. One method of air filtration involves the use of centrifugal technology in combination with conical discs stacked on top of each other. The conical discs act as sedimentation surfaces, and the rotation of the entire assembly generates centrifugal forces that enhance sedimentation, allowing clean air to exit the system .

[0006] However, several problems are associated with this method of air filtration. One significant issue is that dry particles can become stuck in the conical disc package. Over time, the accumulation of these particles can cause the filtration system to cease functioning effectively. The duration before this occurs can vary depending on the type and amount of particles present in the air.

[0007] This issue directly impacts the efficiency of particle removal, especially for fine dust or aerosols.

[0008] Additionally, the complex geometry of the conical disc package can create areas with reduced airflow or recirculation zones, where particles can become trapped. This issue disrupts the smooth and continuous airflow crucial for effective particle removal, leading to particle accumulation and clogging.

[0009] Particles may also adhere to the surfaces of the cones due to electrostatic forces, van der Waals forces, or surface roughness. While air filtration systems often rely on capturing particles, excessive adhesion can lead to clogging.Lastly, while the cones act as sedimentation surfaces, there may be no mechanism to effectively remove the settled particles from the cones. Without an effective removal mechanism, the system will eventually clog, rendering it ineffective.

[0010] These problems highlight the need for improvements in air filtration systems, particularly those using centrifugal technology and conical discs.

[0011] Summary

[0012] It is an object of the present inventive concept to provide an improved centrifugal filtration system for filtering an air stream.

[0013] A further object is to provide a centrifugal filtration system having an effective removal mechanism for removing settled particles.

[0014] A further object is to provide an improved method for filtering an airstream.

[0015] A further object is to provide a method for effectively removing settled particles.

[0016] Further and alternative objectives may be understood from the following.

[0017] According to a first aspect of the disclosure, a centrifugal filtration system for filtering an air stream comprises a rotor system configured to rotate at a range of speeds, including a set of main intermediate speeds. Rotation of the rotor system is controlled to pass through the set of main intermediate speeds. The rotor system includes a set of conical discs configured to filter particles in the air stream. A liquid injection system injects cleaning liquid into the rotor system, with the timing of cleaning liquid injection controlled to coincide with at least one main intermediate speed of the rotor system. This synchronized injection enhances particle removal efficiency.

[0018] It may in this context be noted that the centrifugal filtration system may be suitable to filter both wet and dry particles. However, the synchronized injection may be particularly suitable to remove dry particles. Hence, it may be said that the centrifugal filtration system may be configured to filter dry particles.

[0019] It may in this context be further noted that the set of conical discs may be configured to filter particles by means of centrifugal forces.

[0020] It may in this context be further noted that the rotor system may be configured to rotate at a speed being at least two times the highest main intermediate speed. The highest mainintermediate speed may be defined as the speed which gives the highest vibration level of the centrifugal filtration system.

[0021] It may in this context be further noted that the cleaning liquid may be, for instance, water or any alcoholic solution.

[0022] Optionally in some examples, each main intermediate speed corresponds to an eigenfrequency of the rotor system, and the timing of the cleaning liquid injection is controlled to occur within a range of -20% to +20% of the eigenfrequency. Precisely timed injections maximizes cleaning efficiency by leveraging vibrations at the eigenfrequencies.

[0023] It may in this context be noted that a main intermediate speed corresponding to an eigen-frequency of the rotor system is to be understood as a rotational speed at which the rotor system is particularly prone to self-enhancing vibrations. If the system operates at or near this speed, the vibrations can build up over time, potentially leading to mechanical failure. In some embodiments, the timing of the cleaning liquid injection may be controlled relative to a major eigenfrequency of the rotor system, wherein a lower limit may be about -20%, -15%, -10%, -5%, -2%, or -1% relative to the major eigenfrequency.

[0024] In some embodiments, an upper limit may be about +1%, +2%, +5%, +10%, +15%, or +20% relative to the major eigenfrequency.

[0025] In some embodiments, illustrative ranges may include about -20% to +20%, -15% to +15%, -10% to +10%, and -5% to +5% relative to the major eigenfrequency.

[0026] Any disclosed lower limit may be combined with any disclosed upper limit, provided that the upper limit is greater than the lower limit.

[0027] Optionally in some examples, the set of conical discs comprises sedimentation surfaces where particles of the airstream settle during rotation of the rotor system. Providing sedimentation surfaces enhances particle settling and subsequent removal of the particles. It may in this context be noted that the set of conical discs may filter particles wherein an inner surface of each conical disc serves as a sedimentation surface. It may further be noted that filtration of particles may occur through the particles adhering to the surfaces of the cones due to gravitational forces.

[0028] Optionally in some examples, the rotor system is configured to operate at a speed greater than at least one of the main intermediate speeds to perform filtration of the air stream. Operating at higher speeds improves filtration efficiency and reduces the overall vibration level of the rotor system .In may in this context be noted that operating at comparably higher speeds may improve filtration efficiency. However, this does not preclude that filtration of particles may be performed when the rotor system operates at a speed being less than at least one of the main intermediate speeds while still achieving a sufficiently high filtration efficiency.

[0029] Optionally in some examples, the liquid injection system injects 50 to 150 ml of cleaning liquid in each cleaning liquid injection. This controlled volume entails a suitable cleaning liquid usage, and further an efficient particle removal.

[0030] Optionally in some examples, a cylindrical housing encloses the rotor system and the liquid injection system. The housing provides structural support and contains the airflow and cleaning liquid flow within the system.

[0031] Optionally in some examples, a set of liquid outlets provides a path for injected cleaning liquid to exit the cylindrical housing. This ensures efficient removal of contaminated cleaning liquid and prevents re-entry of particle(s) into the airflow.

[0032] Optionally in some examples, an inlet pipe introduces the air stream into the cylindrical housing. This controlled entry facilitates efficient filtration.

[0033] Optionally in some examples, an outlet pipe allows filtered air to exit the cylindrical housing. This ensures efficient removal of filtered air.

[0034] Optionally in some examples, the conical discs are stacked on top of each other. This configuration maximizes the total filtration surface area within the cylindrical housing. Optionally in some examples, a rotor shaft is included. The rotor shaft provides rotational support for the conical discs.

[0035] Optionally in some examples, a set of bearings supports the rotor shaft. The bearings enable smooth, high-speed rotation and minimize friction.

[0036] According to a second aspect of the disclosure, a method for filtering an air stream com-prises rotating a rotor system at a range of speeds, including a set of main intermediate speeds. Rotating the rotor system involves rotating a set of conical discs configured to filter particle(s) in the air stream. Rotation of the rotor system is controlled to pass through the set of main intermediate speeds. A liquid injection system injects cleaning liquid into the rotor system, with the timing of cleaning liquid injection controlled to coincide with at least one main intermediate speeds of the rotor system. This method enhances particle removal efficiency by leveraging vibrations at main intermediate speeds.

[0037] Optionally in some examples, each main intermediate speed corresponds to an eigenfre-quency of the rotor system, and the timing of the cleaning liquid injection is controlled to occur within a range of -20% to +20% of a major eigenfrequency. Precise timing entails a high cleaning efficiency by leveraging vibrations at eigenfrequencies.

[0038] In some embodiments, the timing of the cleaning liquid injection may be controlled relative to a major eigenfrequency of the rotor system, wherein a lower limit may be about -20%, -15%, -10%, -5%, -2%, or -1% relative to the major eigenfrequency.

[0039] In some embodiments, an upper limit may be about +1%, +2%, +5%, +10%, +15%, or +20% relative to the major eigenfrequency.

[0040] In some embodiments, illustrative ranges may include about -20% to +20%, -15% to +15%, -10% to +10%, and -5% to +5% relative to the major eigenfrequency.

[0041] Any disclosed lower limit may be combined with any disclosed upper limit, provided that the upper limit is greater than the lower limit.

[0042] Optionally in some examples, the conical discs comprise sedimentation surfaces where particles settle during rotation. This design facilitates particle settling and removal of par-tides.

[0043] Optionally in some examples, filtration is performed by rotating the rotor system at a speed greater than at least one of the main intermediate speeds. Higher speeds enhance filtration efficiency.

[0044] As noted above, in this context it may be noted that operating at comparably higher speeds may improve filtration efficiency. However, this does not preclude that filtration of particles may be performed when the rotor system operates at a speed being less than at least one of the main intermediate speeds.

[0045] Brief Description of the Drawings

[0046] Examples are described in more detail below with reference to the appended figures. Figure 1 illustrates a centrifugal filtration system.

[0047] Figure 2 illustrates a graph depicting the relationship between vibration (measured in mm / s) and speed (measured in rpm) for two exemplary rotor systems of a centrifugal filtration system.Detailed Description

[0048] The detailed description set forth below provides information and examples of the disclosed technology with sufficient detail to enable those skilled in the art to practice the disclosure.

[0049] In the following, brief descriptions with reference to Figures 1 and 2 will initially be provided. These brief descriptions are intended to provide an overview of the centrifugal filtration system 100 and the method steps that are performed. However, more detailed explanations of the features of the centrifugal filtration system 100 and the method steps will also be provided herein.

[0050] Now starting with the brief descriptions with reference to Figures 1 and 2.

[0051] Figure 1 shows a centrifugal filtration system 100, which includes a cylindrical housing 1. The cylindrical housing 1 contains a rotor system 8, a liquid injection system 5, an inlet pipe 6, an outlet pipe 7, and liquid outlets. The cylindrical housing 1 encloses the entire filtration system and provides structural support, ensuring that air and cleaning liquid flow paths are contained within the system itself. The rotor system 8 is a component of the centrifugal filtration system 100 and includes a rotor shaft 2, which rotates a set of conical discs 3. The rotor shaft 2 is supported by bearings 4 within the cylindrical housing 1, allowing it to rotate smoothly at high speeds. The conical discs 3 are stacked on top of each other and serve as sedimentation surfaces where particles settle due to centrifugal forces. The liquid injection system 5 includes a liquid injection nozzle that injects clean cleaning liquid into the rotor system 8. The outlet pipe 7 allows the clean, filtered air to exit the cylindrical housing 1 after particles have been removed by the centrifugal filtration process and liquid injection system 5. The inlet pipe 6 introduces an air stream containing particles into the cylindrical housing 1.

[0052] Figure 2 shows a graph depicting the relationship between vibration (measured in mm / s) and speed (measured in rpm) for two example rotor systems 8. More specifically, the graph illustrates an exemplary first rotor system 8a and an exemplary second rotor system 8b. The x-axis represents the speed in rpm, ranging from 0 to 7000 rpm, while the y-axis represents the vibration in mm / s, ranging from 0 to 20 mm / s. The graph includes several peaks and valleys indicating the speeds and corresponding vibrations of two examples of the rotor system 8. The graph illustrates how the rotor system 8 experiences increased vibrations at these speeds, which are for understanding the timing of injection and the overall operation of the centrifugal filtration system 100.The exemplary first rotor system 8a displays peaks 10 and the peak 11. Peaks 10 show peaks at 1000 rpm corresponding to approximately 6 mm / s, and at 2800 rpm corresponding to approximately 8 mm / s. The peak 11 shows a peak at 2000 rpm corresponding to approximately 13 mm / s.

[0053] The exemplary second rotor system 8b displays the peak 20 and the peak 21. The peak 20 shows a peak at 4200 rpm corresponding to approximately 10 mm / s. The peak 21 shows a peak at 3000 rpm corresponding to approximately 15 mm / s.

[0054] The above section was intended to provide a brief description with reference to Figures 1 and 2. In the following, more detailed explanations of the features of the centrifugal filtration system 100 and the method steps will be provided.

[0055] 1 Component Details

[0056] With reference to Figure 1, this section details the components of the centrifugal filtration system 100, highlighting their individual functions and contributions to the overall filtration process. Understanding these components is for comprehending the system's operation and advantages.

[0057] 1.1 Centrifugal Filtration System

[0058] As discussed above, the centrifugal filtration system 100 includes a rotor system 8 and a liquid injection system 5. The centrifugal filtration system 100 may also include a cylindrical housing 1, liquid outlets, an inlet pipe 6, and an outlet pipe 7. The cylindrical housing 1 may contain the rotor system 8, liquid injection system 5, inlet pipe 6, outlet pipe 7, and liquid outlets. The cylindrical housing 1 encloses the entire filtration system and provides structural support, ensuring that the air and cleaning liquid flow paths are contained within the system. The liquid outlets provide a path for contaminated cleaning liquid, carrying flushed-out particles, to exit the cylindrical housing 1, ensuring effective disposal and preventing re-entry into the airflow. The inlet pipe 6 introduces an air stream containing particles into the cylindrical housing 1. The outlet pipe 7 allows clean, filtered air to exit the cylindrical housing 1 after particle removal by the centrifugal filtration process and liquid injection system 5.

[0059] 1.1.1 Rotor System

[0060] The rotor system 8 utilizes its eigenfrequencies for enhanced cleaning with cleaning liquid injection. It is designed to pass through the main intermediate speeds quickly to avoid excessive vibrations. The rotor system 8 may rotate at a range of speeds, including themain intermediate speeds and a main operational speed. It may also pass through main intermediate speeds quickly and find its own balance at the main operational speed. In this context it may be noted that by finding its own balance is generally meant that the rotor system 8 is able to stabilize itself. Each rotor system 8 comprises components having different attributes, and therefore the eigenfrequencies of different rotor systems 8 will also be different (which is described above with reference to the exemplary first rotor system 8a and the exemplary second rotor system 8b).

[0061] The rotor system may be configured to rotate at a (main operational) speed being at least two times the highest main intermediate speed. The highest main intermediate speed may be defined as the speed which gives the highest vibration level.

[0062] The rotor shaft 2 rotates the conical discs 3, generating a centrifugal force suitable for particle separation. The rotor shaft 2 passes through the main intermediate speeds where cleaning liquid injection is timed.

[0063] The rotor shaft 2 and the set of conical discs 3 are configured to rotate at the same speed. The conical discs 3 are a component of the rotor system 8. The bearings 4 are also a component of the rotor system 8. The bearings 4 support the rotor shaft 2, allowing it to rotate smoothly at high speeds, including at the main operational speed. The bearings 4 minimize friction and ensure the stability of the rotor system 8 during operation, especially during the transition through main intermediate speeds.

[0064] As discussed before, it may in this context be noted that a main intermediate speed corresponding to an eigenfrequency of the rotor system 8 is to be understood as a rotational speed at which the rotor system 8 is particularly prone to self-enhancing vibrations. If the system operates at or near this speed, the vibrations can build up over time, potentially leading to mechanical failure. Furthermore, a main operational speed is to be construed as a speed, generally being greater than the main intermediate speeds, at which the rotor system 8 is intended to rotate such that centrifugal filtration system 100 achieves efficient particle filtration. However, it should be noted that the rotor system 8 may still rotate at a lower speed than the main operational speed such that the centrifugal filtration system 100 still achieves sufficient particle filtration. In that case, such a lower speed is preferably a speed that is not any one of the main intermediate speeds.

[0065] Conical Discs

[0066] The conical discs 3 filter particles in the air stream. The particles in the air stream adhere to the conical discs 3. The conical discs 3 comprise sedimentation surfaces where particles settle during rotation. Particle adherence is enhanced by centrifugal forces generatedduring rotation of the conical discs 3. The conical discs 3 may be stacked on top of each other. The conical discs 3 may be a set of one or more conical discs.

[0067] 1.1.2 Liquid Injection System

[0068] As previously discussed, the liquid injection system 5 is a component of the centrifugal filtration system 100. The timing of cleaning liquid injection is controlled to coincide with the main intermediate speeds of the rotor system 8, specifically within a range of -20% to +20% of the eigenfrequency of the rotor system 8. A typical injection injects 100 ml of cleaning liquid. The frequency of injection varies from weekly to monthly depending on the type and amount of particles being filtered. The liquid injection system 5 may include a liquid injection nozzle for injecting clean cleaning liquid into the system. The liquid injection system 5 entails a high cleaning efficiency by leveraging the vibrations at main intermediate speeds. Cleaning liquid interacts with particles that have settled on the conical discs 3, dislodging them due to the combined effect of cleaning liquid flow and vibrations at main intermediate speeds.

[0069] 2 Operating Centrifugal Filtration System Method Details

[0070] Still with reference to Figure 1, a method for operating the centrifugal filtration system 100 will now described. The method involves a sequence of controlled steps to effectively filter particles from an air stream. These steps include starting the system, accelerating the rotor, introducing the air stream, injecting cleaning liquid, and maintaining operation. Each step is precisely controlled to ensure filtration and minimize system wear.

[0071] 2.1 Starting the System and Accelerating the Rotor

[0072] The process begins by starting the rotor system 8 and gradually increasing its rotational speed. This controlled acceleration is to prevent abrupt changes in momentum that could stress the system's components. The acceleration rate is adjusted based on the specific design of the rotor system 8 and its eigenfrequencies.

[0073] 2.1.1 Introduction of Particles contained in the Incoming Air Stream

[0074] The air stream containing particles to be filtered is introduced into the system via the inlet pipe 6. The air stream's flow rate and particle concentration can vary depending on the application. The system is designed to handle a range of particle sizes and concentrations.2.2 Controlling the Acceleration Rate and Transitioning through Main Intermediate Speeds

[0075] As the rotor accelerates, it passes through main intermediate speeds that correspond to system's eigenfrequencies. These speeds are carefully monitored and controlled to mini-mize vibrations. The transition through these speeds is typically rapid to avoid prolonged exposure to potentially damaging resonance conditions.

[0076] 2.2.1 Minimizing Vibrations and Potential Damage to Rotor System

[0077] Minimizing vibrations is a continuous process throughout the system's operation. The controlled acceleration, rapid transition through eigenfrequencies, and balanced operation at the main operational speed all contribute to reducing vibrations and preventing potential damage to the rotor system 8. Regular maintenance and inspection of the bearings 4 (should there be present bearings 4) and other components further enhance system longevity.

[0078] 2.3 Achieving and Maintaining Main Operational Speed

[0079] Once the rotor passes through the main intermediate speeds, it reaches the main operational speed. This speed is selected to provide efficient filtration performance while minimizing stress on the system. The main operational speed is maintained for the duration of the filtration process.

[0080] 2.3.1 Advantages of Stable Operation at Main Operational Speed

[0081] Stable operation at the main operational speed offers several advantages. It ensures consistent filtration performance, reduces wear on the system's components, and minimizes energy consumption. This stable operation contributes to the system's overall efficiency and longevity.

[0082] 2.4 Timing and Control of Cleaning Liquid Injection

[0083] Cleaning liquid injection is a process where cleaning liquid is injected into the rotor system 8 to dislodge particles that have adhered to the conical discs 3. The timing of cleaning liquid injection is precisely controlled to coincide with the rotor's main intermediate speeds. This synchronization maximizes the cleaning effect by leveraging the vibrations at these speeds. The amount of cleaning liquid injected and the frequency of injection are adjusted based on the particle load and the specific application.2.4.1 Enhancing Particle Removal and Cleaning Efficiency

[0084] The timing of cleaning liquid injection is precisely synchronized with the rotor system 8 main intermediate speeds. These speeds correspond to the system's eigenfrequencies, which are the natural frequencies at which the system vibrates most readily. Injecting cleaning liquid at these specific speeds utilizes controlled vibrations of the rotor system 8, hence maximizing the dislodging of particles from the conical discs 3. The injected cleaning liquid interacts with the particles settled on the conical discs 3, creating a combined effect of cleaning liquid flow and vibration that enhances particle removal. The vibrations help overcome the adhesion forces holding the particles to the discs, while the cleaning liquid flow carries the dislodged particles away from the filtration surfaces. This synchronized approach improves cleaning efficiency compared to injecting cleaning liquid at arbitrary speeds. Injecting cleaning liquid at speeds other than the main intermediate speeds would result in less effective particle removal due to the absence of resonant vibrations. The amount of cleaning liquid injected and the frequency of injection can be adjusted based on the specific particle load and application requirements. In this context, particle load may refer to an amount of particles adhered to the conical discs 3. In any case, and for instance, higher particle loads may necessitate larger cleaning liquid volumes or more frequent injections. Conversely, lower particle loads may require less cleaning liquid and less frequent injections. This adaptability ensures efficient cleaning while minimizing cleaning liquid consumption. In some applications, a pre-wetting step may be introduced before a main cleaning liquid injection. This involves injecting a small amount of cleaning liquid onto the conical discs 3 before accelerating the rotor to the main intermediate speeds. Pre-wetting can help loosen particle and prepare them for more effective removal during the main cleaning liquid injection. Alternatively, a post-wetting step can be implemented after the main cleaning liquid injection. This involves injecting a small amount of cleaning liquid to rinse any remaining particle from the discs after the rotor has slowed down from the main intermediate speeds. Post-wetting can further enhance cleaning efficiency and ensure thorough particle removal.

[0085] 2.5 Disposal of Contaminated Cleaning Liquid

[0086] Upon having removed the settled particles from the conical discs 3, the cleaning liquid will be contaminated. Contaminated cleaning liquid, containing the removed particles, flows out of the cylindrical housing 1 through designated cleaning liquid outlets. This prevents re-entry of particles into the air stream and ensures proper disposal.3 Description of Examples of the Disclosure

[0087] Consider a centrifugal filtration system 100 designed for filtering particles from an air stream in a residential setting. The system's cylindrical housing 1 is constructed from stainless steel for durability and corrosion resistance. The rotor system 8 consists of five conical discs 3 made of lightweight aluminium alloy, stacked on a steel rotor shaft 2 supported by high-precision bearings 4. The liquid injection system 5 uses a nozzle that delivers 50-150, e.g.,100 ml of cleaning liquid per injection. The main intermediate speeds of the rotor system 8 are determined to be 1500 rpm, 3000 rpm, and 4500 rpm through experimentation. During operation, the rotor is accelerated to its main operational speed of 6600-7200 rpm. Cleaning liquid injection is timed to coincide with the rotor's passage through each main intermediate speeds. This configuration is just one example, and variations are possible. For instance, the number of conical discs 3, the material of the housing 1, and the volume of cleaning liquid injected can be adjusted based on the specific application requirements. A benefit of this example configuration is its balance of filtration efficiency, durability, and ease of maintenance, making it suitable for residential use.

[0088] 3.1 Example of Rotor System with Different Eigenfrequencies

[0089] In one example, a rotor system 8 is designed with three conical discs 3 made of aluminium, each with a specific angle and thickness. The rotor shaft 2 is made of stainless steel. This combination of materials and geometry results in eigenfrequencies at 1800 rpm, 3200 rpm, and 4800 rpm. These specific eigenfrequencies are determined through computational modelling and experimental validation. This example demonstrates how the eigenfrequencies can be tailored by adjusting the design parameters of the rotor system 8. An advantage of this design is the ability to target specific vibration modes for sufficient particle removal during cleaning liquid injection.

[0090] 3.1.1 Comparison of First and Second Rotor Systems

[0091] A comparison between two exemplary rotor systems are already provided for in Figure 2. However, in the following, two other rotor systems 8 are compared: one with three conical discs 3 (first rotor system 8) and another with five conical discs 3 (second rotor system 8). Both systems use aluminium discs and a steel rotor shaft 2. The first rotor system 8 has eigenfrequencies at 1500 rpm, 2800 rpm, and 4200 rpm. The second rotor system 8 has eigenfrequencies at 1200 rpm, 2400 rpm, 3600 rpm, and 4800 rpm. This comparison illustrates how the number of conical discs 3 influences the eigenfrequencies of the rotor system 8. The second rotor system 8, with more discs, exhibits more closely spacedeigenfrequencies. This characteristic can be advantageous for certain applications requiring more frequent cleaning cycles.

[0092] 3.2 Example of Liquid Injection System

[0093] A liquid injection system 5 includes a cleaning liquid reservoir, a pump, and a nozzle. The reservoir holds 500 ml of clean cleaning liquid. The pump delivers cleaning liquid to the nozzle at a controlled flow rate. The nozzle is positioned to spray cleaning liquid directly onto the conical discs 3 of the rotor system 8. The system is controlled by a microcontroller that triggers cleaning liquid injection at specific times. In this example, the microcontroller is programmed to inject 80 ml of cleaning liquid each time the rotor system 8 passes through one of its main intermediate speeds. This precise control over cleaning liquid injection ensures efficient cleaning of the conical discs 3 while minimizing cleaning liquid consumption. This example highlights the importance of controlled cleaning liquid delivery for optimal performance. It may in this context be noted that the liquid injection system 5 does not need to be a reservoir with a certain volume, and a pump. It is conceivable that there may be provided a system wherein a hose is mounted to a water tap.

[0094] 3.2.1 Control and Timing of Liquid Injection

[0095] In a specific example, the liquid injection system 5 is controlled to inject cleaning liquid precisely when the rotor system 8 reaches its main intermediate speeds. The rotor system 8 has eigenfrequencies at 1600 rpm, 3100 rpm, and 4700 rpm. The control system monitors the rotor speed and triggers cleaning liquid injection within a tolerance of ±20% (this tolerance is merely an example) of each eigenfrequency. This ensures that cleaning liquid injection occurs at effective speeds for particle removal. The amount of cleaning liquid injected is 50-150, e.g., 90 ml per injection. This example demonstrates the importance of precise timing and control of cleaning liquid injection for high cleaning efficiency.

[0096] 4 Potential Applications

[0097] The centrifugal filtration system 100 has potential applications in various settings requiring efficient air filtration. Its adaptability to different particle sizes and concentrations makes it suitable for diverse environments.

[0098] 4.1 Use in Air Purification Systems

[0099] In air purification systems, this technology offers advantages over traditional methods. The timed cleaning liquid injection enhances particle removal, reducing the frequency of filterreplacements and minimizing maintenance. The system's ability to operate continuously at its main operational speed ensures consistent air quality.

[0100] 4.1.1 Benefits for Indoor Air Quality

[0101] Improved indoor air quality is a direct benefit of using this filtration system. By efficiently removing particles, the system reduces allergens, pollutants, and other airborne contaminants, promoting a healthier living or working space. The system's quiet operation and low maintenance requirements make it ideal for indoor environments.

[0102] 4.2 Industrial Applications

[0103] Industrial settings often generate substantial airborne particles. This system effectively re-moves these particles, contributing to a healthier work environment and reducing equipment wear caused by particle contamination. The system's enclosed design prevents particle leakage, further enhancing its suitability for industrial use.

[0104] 4.2.1 Use in Manufacturing and Processing Facilities

[0105] Manufacturing and processing facilities can benefit from this system's ability to handle high particle loads. The timed cleaning liquid injection effectively cleans the conical discs 3, maintaining filtration efficiency even in challenging environments. The system's robust design and durable components ensure reliable operation in demanding industrial settings.

[0106] The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises," "comprising," "includes," and / or "including" when used herein spec-ify the presence of stated features, integers, actions, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, actions, steps, operations, elements, components, and / or groups thereof.

[0107] It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present disclosure.Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element to another element as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

[0108] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0109] It is to be understood that the present disclosure is not limited to the aspects described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the present disclosure and appended claims. In the drawings and specification, there have been disclosed aspects for purposes of illustration only and not for purposes of limitation, the scope of the disclosure being set forth in the following claims.

Claims

Claims1. A centrifugal filtration system (100) for filtering an air stream comprising:a rotor system (8) configured to rotate at a range of speeds, the rotor system (8) comprising:a set of conical discs (3) configured to filter particles in the air stream; wherein rotation of the rotor system (8) is controlled to pass through a set of main intermediate speeds, the main intermediate speeds being in the range of speeds;a liquid injection system (5) configured to inject cleaning liquid into the rotor sys- tern (8), wherein timing of cleaning liquid injection is controlled to coincide with at least one main intermediate speeds of the rotor system (8).

2. The centrifugal filtration system (100) according to claim 1, wherein each main intermediate speed corresponds to an eigenfrequency of the rotor system (8), and wherein the timing of the cleaning liquid injection is controlled to occur within a range of -20% to +20% of the eigenfrequency.

3. The centrifugal filtration system (100) according to any of claims 1 to 2 , wherein the set of conical discs (3) comprises sedimentation surfaces where particles of the airstream settle during rotation of the rotor system (8).

4. The centrifugal filtration system (100) according to any of claims 1 to 3 , wherein the rotor system (8) is configured to operate at a speed greater than at least one of the main intermediate speeds to perform filtration of the air stream.

5. The centrifugal filtration system (100) according to any of claims 1 to 4 , wherein the liquid injection system (5) injects 50 to 150 ml of cleaning liquid in each cleaning liquid injection.

6. The centrifugal filtration system (100) according to any of claims 1 to 5 , further comprising a cylindrical housing (1) enclosing the rotor system (8) and the liquid injection system (5).

7. The centrifugal filtration system (100) according to claim 6, further comprising a set of liquid outlets providing a path for injected cleaning liquid to exit the cylindrical housing (1)8. The centrifugal filtration system (100) according to any of claims 6 to 7, further comprising an inlet pipe (6) introducing the air stream into the cylindrical housing (1).

9. The centrifugal filtration system (100) according to any of claims 6 to 8 , further comprising an outlet pipe (7) allowing filtered air to exit the cylindrical housing (1).

10. The centrifugal filtration system (100) according to any of claims 1 to 9 , wherein the set of conical discs (3) are stacked on top of each other.

11. The centrifugal filtration system (100) according to any of claims 1 to 10 , further comprising a rotor shaft (2).

12. A method for filtering an air stream comprising:rotating a rotor system (8) at a range of speeds;wherein rotating the rotor system (8) comprises rotating a set of conical discs (3) at the range of speeds, the set of conical discs (3) configured to filter particles in the air stream;wherein rotation of the rotor system (8) is controlled to pass through a set of main intermediate speeds, the critical speeds being in the range of speeds; injecting cleaning liquid into the rotor system (8) using a liquid injection system (5), wherein the timing of cleaning liquid injection is controlled to coincide with at least one main intermediate speeds of the rotor system (8).

13. The method for filtering an air stream according to claim 12, wherein each main intermediate speeds corresponds to an eigenfrequency of the rotor system (8), and the timing of the injection of the cleaning liquid is controlled to occur within a range of -20% to +20% of an eigenfrequency of the rotor system (8).

14. The method for filtering an air stream according to any of claims 12 to 13, wherein the set of conical discs (3) comprise sedimentation surfaces where particle(s) of the airstream settle during rotation of the rotor system (8).

15. The method for filtering an air stream according to any of claims 12 to 14, wherein filtration of the air stream is performed by rotating the rotor system (8) at a speed greater than at least one of the critical speeds.

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