Automatic air filtration system for continuous aerosol removal

Abstract

An air purification system comprising: a housing having an airflow path internally formed between an inlet for polluted air containing particulate material and a clean air outlet, a particulate collection system disposed in the airflow path, the collection system comprising at least three filtration stages in series, coarse, neutral and fine filtration stages are arranged in a gradient manner and each stage has dual filter elements, each of which contains automatic means for detecting clogged "twin" filter elements, removing clogged filter elements from the airflow path while switching to clean "twin" filter elements, and removing clogged "twin" filter elements from the airflow path while switching to clean "twin" filter elements. The clogged "twin" filter elements are cleaned while maintaining continuous airflow through the system, and only a single "twin" filter element is exposed to the airflow per stage at any time, where an inline suction fan is subsequently placed on the downstream side of each filter stage and controlled by a preset airflow sensor to maintain the target airflow.

Description

Technical Field

[0001] As we learn to live with a growing awareness of airborne viruses such as COVlD-19 and other air pollutants such as smoke and dust from bushfires, people are seeking ways to effectively clean and improve the air quality in their homes, schools, and workplaces. As a result, air purifiers and air filtration systems are becoming increasingly popular, and there is a great demand for efficient air purification equipment. The present invention relates to such an apparatus that uses a combination of filters to efficiently clean the air to remove particulates and pathogens. The air filtration system of the present invention requires very little maintenance and is capable of self-cleaning while ensuring a continuous supply of clean air. Background Art

[0002] According to the World Health Organization and the Environmental Protection Agency, polluted breathing air is a major potential problem for respiratory health issues worldwide. Recent large-scale scenarios, such as airborne infectious diseases and aerosol-laden particulate matter (PM) generated by the atmosphere and anthropogenic activities, have resulted in air pollution with undeniable global health and economic impacts. If left untreated, long-term exposure to poor air quality can lead to decreased lung function and respiratory problems, as well as causing lung cancer and ultimately cardiovascular-related deaths. While these are the main focuses of ongoing efforts around the world to mitigate the long-term severity, air quality appears to be deteriorating as populations grow and civilization advances. It is clear that the treatment of related diseases will impose huge costs on governments, taxpayers, and society through increased demand for health services and medications. The present invention introduces a low-maintenance air filtration system for producing improved air quality suitable for preventing health-related problems caused by airborne particulate matter.

[0003] With regard to current and future airborne infectious diseases (such as SARS Cov2), science explains that the transmission mechanism of these infections is via droplets exhaled by infected people, which can travel tens of meters in the air. There is evidence that this is an important route of infection in indoor environments. It is therefore very important that national authorities recognize the reality of similar virus variants being transmitted through the air in the future and take effective measures to prevent further spread of the virus, especially by removing droplets carrying the virus from indoor air through proper ventilation.

[0004] PM is a general term for a large class of chemically and physically distinct substances that exist as discrete particles (liquid droplets or solids) of a wide range of sizes. In general, if the ambient concentration of fine particulate matter exceeds 75 μg / m 3Air is considered polluted if it is breathed (i.e. PM2.5 aerodynamic diameter ≤ 2.5 μm). Particles can be emitted directly or formed in the atmosphere by transformation of gaseous emissions such as sulfur oxides (SOX), nitrogen oxides (NOX), ammonia (NH3), and volatile organic compounds (VOCs). Their chemical and physical properties vary greatly over time and contribute to secondary particle formation. It is well known that many natural or anthropogenic factors may modify the size and charge of aerosols. Examples of such factors include cosmic rays in space, radiation from radioactive materials in the air and on Earth, atmospheric lightning, electromagnetic radiation, high-temperature discharges, and static electricity caused by particle collisions. Studies on human breath deposition of particles have shown that particles with aerodynamic diameters > 0.5 μm and 2-5 μm have the highest deposition fractions at an average inspiratory flow rate of 1.2 m3 / h [0.7 ft3 / min]. In addition, smaller particles have been found to be more susceptible to electrostatic interactions with the charge of surrounding particles.

[0005] Science shows that exposure to air pollution can come from sources inside buildings (e.g., inside homes, schools, and other indoor spaces). Indoor air pollutants from biological sources (e.g., mold; dust mites; pet dander (skin flakes); and feces and body parts of cockroaches, rodents, and other pests or insects) can cause allergic reactions, exacerbate existing asthma, and promote other respiratory syndromes that can have significant health effects. PM and NO2, previously discussed as outdoor air pollutants, can also pollute indoor air when they are emitted from gas stoves, gas or oil furnaces, fireplaces, wood stoves, and kerosene or gas space heaters. Indoor concentrations of these combustion byproducts can reach very high levels, especially during the winter months when use of fireplaces and space heaters is more prevalent. Molecular interactions between pollutants (as gases or aerosols) can affect their stability and transmission through indoor air flow.

[0006] A general understanding of some of the basic principles and issues of filter design can be used when deciding on a filtration method. For example, in the case of mechanical filtration, since the filter will function to remove particles from an airstream (where there is a high amount of particulate matter above the "selected size"), the particles collect as a cake on the upstream side of the mechanical filter. This ultimately causes the filter to essentially block the passage through which the air passes, resulting in a pressure differential (i.e., pressure drop) across the side of the filter.

[0007] Various air filters or gas filter devices have been developed for the removal of particulates, as shown in Table 1 below. One of the common methods of removing PM from indoor spaces is to use air purifiers that rely on HEPA filters or ozone-based technology. However, as shown in Table 1 below, HEPA filters are expensive to maintain in the long term, and ozone-based purifiers have been found to cause harmful effects on human health. The present invention is intended to provide a more efficient system that addresses the shortcomings of prior art systems. Table 1 below provides a comparison of commercially available filtration devices.

[0008] Table 1 (Comparison of commercially available methods for removing aerosol particles from the air):

[0009]

[0010]

[0011] Patent specification CN112403125 discloses an air filtration system for removing airborne particles. However, the device disclosed in CN112403125 has several disadvantages. One of the main disadvantages of the system disclosed in CN112403125 is that the device cannot provide a continuous supply of clean air without affecting the filtration efficiency and flow due to filter clogging. The device cannot be used during unclogging because it does not provide a self-cleaning mechanism while continuing to provide a clean air flow. In addition, the above system uses a soot blowing device to clean the filter, which may be less efficient, or uses a catalytic method, which is an expensive option.

[0012] The present invention aims to address the inherent deficiencies of prior art systems by removing airborne pathogens and contaminants without the need for periodic component replacement, thereby minimizing any impact on the environment while increasing the efficiency, consistency and cost of servicing larger spaces. The present invention can be achieved using renewable resources such as solar energy and ceramics combined with advances in nano-engineering to provide a higher standard of air quality for a variety of spaces.

[0013] The air purification system defined in this invention absorbs harmful aerosol compounds from the atmosphere and efficiently produces pollution-free breathing air using renewable resources. It relies on three main technologies:

[0014] (a) Sustainable production of silica filter sheets (composite porous ceramics) with customizable morphology, specific surface area, and pore size. Pore sizes ranging from 10nm to 2.5um combined with the enhanced chemical and physical stability of the composites enable this technology to effectively capture airborne pathogens and PM2.5 pollutants and become a viable component of future healthy and energy-efficient spaces.

[0015] (b) Solar-supported automation (electric valves and pressure drop sensors) and ventilation (inline electric fans): The work presented in this part relies on a fully solar-powered electronic programming system to facilitate the flow of outside air over the porous surface of the filter gradient using renewable energy.

[0016] (c) Built-in system purification and pollutant treatment technology: An advantage of the proposed product over commercially available systems is that the collected pollutants will not be returned to the environment as it does not involve any filters that typically have a limited lifespan. Hazardous aerosols collected by the proposed technology will be treated through built-in cleaning and collection procedures (as per relevant EPA recommendations), all supported by self-generated electricity. Summary of the invention

[0017] In order to overcome the shortcomings of the prior art air purification system, the present invention defines an air purification system, which includes the following features.

[0018] a housing having an internally formed airflow path communicating between an inlet for incoming contaminated air containing particulate material and an air outlet for discharging clean filtered air from which the particulate material has been removed;

[0019] A collection system, provided in the airflow path, to collect particulate material;

[0020] The collection system comprises:

[0021] At least three stages of filters, which are positioned in a gradient arrangement and each stage has two identical filter elements (double filter elements);

[0022] The dual filter elements each contain a self-cleaning device; and

[0023] A device that allows the filter stage to ensure continuous airflow when the self-cleaning mechanism is used.

[0024] The main features of the present invention are to provide a device for self-cleaning clogged filter surfaces and to provide a dual filter arrangement that allows continuous airflow when the self-cleaning device is in operation. To achieve this, the device of the present invention consists of two identical elements of each type of filter element in the airflow path, only one of the dual filter elements being in operation at any time. As soon as the first filter becomes clogged, it is removed from the filtered airflow path via automatic communication between the electrical components, thereby triggering the self-cleaning mechanism. At the same time, the second "twin" filter will take over the filtering process. This prevents any interruption in the filtering process.

[0025] The present invention has several advantages over the prior art. The main differences between the present invention and the prior art are:

[0026] (i) Highly efficient (>95%) removal of particles and aerosols in the range of 2.5μm-5μm.

[0027] (ii) Combining advanced features of automatic filtration, fan-assisted flow-pressure differential aerodynamics and porous ceramic manufacturing.

[0028] (iii) Higher specificity due to consistent pore size for capturing pathogen aerosols and PM2.5 (particulate matter) in the air.

[0029] (iv) High regeneration capacity and minimal maintenance requirements, due to the automatic self-cleaning of the filter elements and their chemical stability to solvents, no filter waste is generated.

[0030] (v) Exploiting the interaction between the electrostatic charges of particles as well as their size and physical behavior to maximize filtration efficiency without the use of high pressure.

[0031] (vi) The gradient arrangement between the filter elements ensures a longer service life of the system.

[0032] (vii) Taking advantage of continuous data monitoring from atmospheric pollution sensors (PM and pathogens in the air) to enable more effective removal of pollutant-laden aerosols when needed.

[0033] (viii) In contrast to prior art filtration methods (which lose effectiveness due to poor adsorbent regeneration capabilities and other problems associated with handling adsorbents at the end of their useful life), ceramics are derived from renewable alumina / silica, which are abundant in nature and can even be recycled (as by-products derived from ferrosilicon or silicon metal alloy processing) and the filter elements are automatically self-cleaning.

[0034] (ix) The device can be designed into any desired geometry and allows for a wide range of applications to fit any architectural space and application. This could be useful in supporting clinically critical spaces to accommodate patients with respiratory and / or cardiovascular sensitive backgrounds and / or responding to pandemic or bushfire issues.

[0035] Detailed description of the invention

[0036] The main features of the present invention are discussed in further detail below.

[0037] The air purification system of the present invention includes a combination of filters positioned in a gradient arrangement. The filter elements are arranged in series (several consecutive steps), each filter uses a different filter material and has a specific pore size for removing specific particulate matter, and the filter with a larger pore size is responsible for removing larger PM at the early stage of the process. In a preferred embodiment, the ceramic filter with the smallest pore size is located at the end of the downstream of the device (i.e., the last filter in the filter device). This allows efficient removal of fine aerosols. Alternative filter materials may include (but are not limited to) thermosetting polyalkylene derivative materials, which can be (but are not limited to) made into coils or pleated shapes and are resistant to corrosion by airflow and most industrial solvents.

[0038] Another key feature of the present invention is an automatic self-cleaning device that is activated when the filter surface becomes clogged with collected particulate matter. The automatic self-cleaning device includes:

[0039] (a) The pressure drop activates the sensor, which is located on the downstream side of the filter compared to the direction of airflow.

[0040] (b) A first electric valve located downstream of the filter relative to the air flow direction. The first electric valve is coupled to the pressure drop sensor.

[0041] (c) A second set of electric valves, located on the upstream side of the filter and in communication with the first valve. Once the filter surface is clogged by the signal from the sensor due to the pressure drop caused by the clogged filter, both the electric valves and the sensor are activated. Once activated, both electric valves tightly block the air passage (wind duct) and remove the clogged filter from the filtration process. This means that the clogged filter will not participate in filtration until its cleaning process is completed, and the unclogging process occurs in an airtight space.

[0042] (d) A third electric valve located at the bottom of each filter compartment to drain any waste water generated during the cleaning process.

[0043] (e) A set of electric cleaning spray nozzles, which are located on different sides of the filter surface. For filters with larger pore sizes, the electric spray nozzles are located on the downstream side of the airflow and spray in the opposite direction of the airflow. For filters with finer pore sizes (such as ceramic filters with a pore size of 5um), the spray nozzles are located on the upstream side of the filter and spray on the surface of the ceramic filter in the direction of the airflow. The electric spray nozzles are connected to the discharge electric valves and are activated by a preset time delay compared to the first set of electric valves. This means that at the beginning of the filter unclogging process, the first and second valves are activated and block the airflow into the air duct. Then, after a delay of a few seconds, both the electric spray nozzles and the electric discharge valves are activated, open and discharge wastewater for a period of time, and complete the filter cleaning process. At the completion of the cleaning process, both the electric nozzles and the electric discharge valves return to their closed positions and remain closed, deactivated together with the first and second electric valves and the filter itself that is subsequently cleaned, and they remain non-participating in filtering until the next signal from the pressure drop sensor is received.

[0044] Another key feature of the present invention is the use of dual filter elements (duplicate filters). For each filter in the gradient filter arrangement, there is an exact "twin" filter element that will replace the first filter set once the first filter is clogged and removed from the filtering process via activation of the first and second sets of electric valves. The air passage for each of the dual elements can be automatically closed or opened by using electric valves.

[0045] A set of inline suction fans located at different positions in the airflow path facilitates the passage of air through the filter housing. The fans are located at the end of the air outlet, connected to the associated air gap on the downstream side of each filter group. This means that the air gap of each filter group collects the filtered air. Each air gap is shared between the retained "twin" filter and the working filter and has an opening for each of these filter groups. The openings have a first electric valve and a sensor for measuring the pressure drop across each group of filters. This ensures a continuous airflow.

[0046] The purpose of the air gap is to help evenly distribute the vacuum force generated by the suction fan and support the corresponding filter to more effectively remove particles specific to its pore size. It also acts as a connector to allow air to pass from one filter with a larger pore size in the gradient system through the suction fan and into the next filter with a smaller pore size in the gradient system.

[0047] The inline fans of the present invention are designed to produce continuous airflow and can be shared between the "twin" filter group and the working filter group, which means that one inline fan can be connected to each air gap shared between the "twin" filter element and the working filter group, and can therefore serve the filters that are functional at this time.

[0048] The constant operation of inline fans helps to provide a constant positive pressure to the respective rooms they supply air to, thus protecting the interior from polluted atmosphere entering inside. Even though they are grid dependent, the fans are designed to be energy efficient and cost effective and can also be powered by cost-effective renewable energy sources such as solar. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Combine the following Figure 1-13 The preferred embodiment of the novel air filtration system of the present invention is further described.

[0050] Figure 1 is a three-dimensional schematic diagram of the present invention, showing each component of the gradient hybrid filtration system.

[0051] Figure 2 is a two-dimensional schematic diagram of the present invention, showing each component of the gradient mixing filtration system.

[0052] Figure 3 is an embodiment of the invention, illustrating the appropriate size of the device to create adequate airflow for an office with four adult occupants. This illustrates the effect of the size and thickness of a single ceramic disc on the overall size of the ceramic module. The fixed parameters between the comparisons are: hole size (4-5.5um), total flow rate (83CFM) supplied corresponding to x4 adult occupants according to regulatory requirements.

[0053] Figure 4 is a schematic diagram of the assembly 2 and 3 filters of the proposed ventilation device, showing the air flow channels and each filter element of the dual filter.

[0054] Figure 5 is a schematic diagram showing details of a single ceramic filter disc.

[0055] Figure 6 This is an example of the concentration of particulate matter PM 2.5 μm in the air before filtering through a ceramic filter (4-5.5 μm pore size) at an air flow rate of 120 fpm (103 CFM).

[0056] Figure 7 This is an example of the concentration of particulate matter PM 2.5 μm in the air after filtering through a ceramic filter (4-5.5 μm pore size) at an air flow rate of 120 fpm (103 CFM).

[0057] Figure 8 This is an example of the concentration of particulate matter PM 0.3 μm in the air before filtering through a ceramic filter (4 μm pore size) at an air flow rate of 120 fpm.

[0058] Fig. 9: Example of PM0.3μm concentration in the air after filtering through a ceramic filter (4μm pore size) at an air flow rate of 120fpm.

[0059] Fig.10 Schematic diagram showing the filtration efficiency of ceramic filters between independent experiments; percentage of 5μm particles after filtration relative to unfiltered air. The lower the PM concentration in the filtered air, the higher the filtration efficiency. The amount of PM5μm particles in the filtered air only accounts for <5% of the total PM content in the unfiltered air.

[0060] Fig.11 Schematic diagram showing the filtration efficiency of ceramic filters between independent experiments; percentage of 2.5μm particles after filtration relative to unfiltered air. The lower the PM concentration in the filtered air, the higher the filtration efficiency. The amount of PM2.5μm particles in the filtered air only accounts for <5% of the total PM content in the unfiltered air.

[0061] Fig.12 is a diagram showing the filtration efficiency of ceramic filters between independent experiments. The amount of particulate matter (PM0.3, PM2.5, PM5 μm) in the filtered air accounts for only <5% of the total PM content in the unfiltered air.

[0062] Fig.13 is a schematic diagram of the location of CO2 activated vents as an optional part of the apparatus of the present invention. The effectiveness of the ventilation process of the apparatus of the present invention can be improved if the room is equipped with a CO2 sensor coupled to an automatic vent above the wall to release stale air and help maintain a positive pressure within the ventilation room. DETAILED DESCRIPTION

[0063] like Figure 1 , 2 As shown in Figure 3, a large number of individual ceramic filter discs (3) are installed in each ceramic filter holder (1). A certain degree of flow and a large ceramic surface area are required to overcome the pressure difference caused by the ceramic micro-sized pores of the ceramic filter. The required flow is supplied by an internal suction fan located on the downstream side of the ceramic filter holder (1). The ceramic filter holder 1 includes an air gap (4) for evenly distributing air within the ceramic filter holder (1). A partition (5) is located between the two main ceramic filter holders to maintain the airtightness and separation of the dual filters from each other. As shown in Figure 3, a large number of individual ceramic filter discs (3) are installed in each ceramic filter holder (1). Figure 3 As shown, each filter stage comprises a double filter set (2). Figure 1 and 2 The filter assembly 2 (6) shown typically has a pore size of 12 μm. Figure 1 and 2The filter assembly 3 (7) shown has a typically larger pore size of 37 μm. Figure 1 and 2 The electrostatic (pre-charge) filter (8) shown is an optional feature. Figure 1 and 3 The housing or outer protective capsule (9) shown is made of lightweight insulating aluminum. Figure 1 and 2 As shown, the electric valve (10) is located upstream of each filter. The electric valve coupled to the pressure drop sensor (11) is located downstream of each filter. Figure 1 and 2 An inline suction fan (12) is located downstream of each filter, as shown. Figure 1 and 2 A drain pipe (13) coupled to a specific electric valve is located at the bottom of each filter group, as shown. Figure 1 and 2 The electric spray nozzle (14) is used for filter cleaning. The particle sensor (15) is located directly behind the front protection screen (17). The front protection screen (17) is used to remove larger coarse particles from the air flow.

[0064] Figure 3 The present invention is described for use in a typical room with four adults. Figure 3 As shown, the diameter of the non-ceramic filter assembly is 0.3 meters. The depth of the ceramic assembly is typically 0.73 meters. The height of the ceramic assembly is 1.1 meters, and the diameter of the ceramic assembly is typically 1.6 meters.

[0065] like Figure 1 and 2 As shown, air is drawn in through the inlet via the front protective screen and passes through a number of filter elements starting from assembly 3 .

[0066] Component 3 in this embodiment is made of a filter mesh #1200 element that captures PM with a size of about 37 μm. This component can be made of an aluminum mesh fastened in an aluminum frame, or any other porous material. A thermally stable polyalkylene derivative material that can be (but is not limited to) made into a coil or pleated shape with a large air contact surface area, fastened by a rigid material to avoid collapse, and resistant to airflow and industrial solvents. Figure 1 and 2 As shown, assembly 3 comprises a dual filter set. The pore size of this assembly may be any other size, depending on the application and the desired result of removing any particular aerosol.

[0067] The assembly 3 also includes an electric valve (10) located before the filter and an electric valve coupled to a pressure drop sensor (11) located after the filter, such as Figure 1 and 2In addition, the assembly 3 also includes a plurality of electric nozzles (14) for cleaning the clogged filter element and a drain pipe (DP) coupled to another electric valve to drain the cleaning liquid from the filter housing.

[0068] Figure 1 and 2 The filter element of the assembly 2 shown is made of filter mesh #400 that captures PM of approximately 12 μm in size. This assembly can be made of aluminum mesh fastened in an aluminum frame, or any other porous material. A thermally stable polyalkylene derivative material that can be (but is not limited to) made into a coil or pleat shape with a large air contact surface area, fastened by a rigid material to avoid collapse, and resistant to airflow and industrial solvents. Figure 1 and 2 As shown, assembly 2 comprises a dual filter set. The pore size of this assembly may be any other size, depending on the application and the desired result of removing any particular aerosol.

[0069] Component 2 is similar to component 3 and further includes an electric valve (10) located before the filter and an electric valve located after the filter and coupled to a pressure drop sensor (11), such as Figure 1 and 2 In addition, the assembly 3 also includes a plurality of electric nozzles (14) for cleaning clogged filter elements and a drain pipe (DP) coupled to another electric valve for draining cleaning liquid from the filter housing.

[0070] Figure 1 and 2 The assembly 1 shown is designed to capture smaller particles having a diameter of 2.5 μm to 5 μm. The pore size of this filter is 4-5.5 μm. Assembly 1 consists of two "twin" ceramic filter holders, which include a large ceramic surface area (the sum of the surface areas of a large number of individual ceramic filter discs), surrounded by large air voids and both contained in an insulating aluminum capsule ( Figure 1 A and B). The air voids containing the pre-filtered air distribute the intake air evenly over the total surface of the ceramic filter disc supported by the ceramic filter holder. The ceramic filter holder may be an insulated hollow metal connected to an inline fan. Alternatives to the ceramic filter housing may be (but not limited to) thermally stable polyalkylene derived materials which may be (but not limited to) made into coil or pleat shapes with a larger air contact surface area and whose pore size corresponds to the pore size of the current ceramic filters.

[0071] Figure 1 and 2 As shown, an inline fan (12) is located on the downstream side of the air gap and ceramic assembly to generate sufficient airflow to overcome the pressure drop ( Figure 2 A).

[0072] like Figure 3 As shown, the required flow rate for the fan (and device) to accommodate a room with four adult occupants is equivalent to 74-83 FCM (feet per minute). Figure 3 Details of the corresponding required scale of the apparatus for this example are also shown. However, the combination of gas flow and apparatus scale can be tailored to the application to accommodate any type of geometry and size.

[0073] Table 2 below shows a brief comparison of the final size of the ceramic assembly as affected by the pore size and thickness of the individual ceramic discs. As shown in Table 2, the smaller the thickness and diameter of the individual filter discs, the higher the airflow efficiency and therefore less surface area is required, which is more desirable in our case as the size and overall production cost are more manageable.

[0074] Table 2 Effect of the size and thickness of a single ceramic disc on the overall size of the ceramic module

[0075]

[0076] A preferred embodiment of the present invention may include an electrostatic (pre-charge) filter (8) which is affected by the relative humidity of the atmosphere, e.g. Figure 1 and 2 As shown. The filter in the present invention can be made into any type of geometry and is a flat filter fabric of polypropylene nature fastened in an aluminum frame and is easily replaced manually. The reason for this assembly to be non-automated is that the cleaning and drying process of the polypropylene fabric takes a longer time to complete. Therefore, manual replacement is considered more appropriate at this level. However, any pre-filled filter material with more hydrophobicity can potentially be a better choice, making this filter more suitable for automation.

[0077] Finally, if Figure 1 and 2 As shown, a smooth screen plate (17) is also located at the front of the device before the intake air reaches the module 3. The purpose is to reduce the initial load of larger particles in the intake air before the intake air is subjected to the intensive filtering of the device.

[0078] The arrangement of the self-cleaning assembly of the present invention is as follows Figure 1 and 2 As shown, and described with reference to the following figure:

[0079] (a) Filter cleaning is required to achieve low back pressure and clogging risk, as well as to support continuity of filtration operation.

[0080] (b) The present invention consists of two individual filter assemblies that are precisely "twinned" so that one is always operating while the other is being cleaned and unblocked (via an automatic cleaning system).

[0081] (c) The cleaning system includes a set of electric jet sprayers coupled to a pressure drop sensor. The electric jet sprayers are activated by a signal from an air flow sensor (pressure drop sensitive). The sensor is coupled to an electric valve (referred to as the first electric valve) and is located after all filters (including ceramic assembly 1 and filter assemblies 2 and 3). The pressure drop sensor is coupled to the first electric valve and is located on the downstream side of the filter surface.

[0082] (d) Each filter with a different pore size captures a specific particle that is larger than its pore size at a different rate. The filters continue to accumulate particles to a certain level (on their upstream side) until the pressure drop across the filter reaches a certain defined level for that specific filter. At that stage, that specific filter has reached the end of its effective filtration life, and the entire filtration system needs to be cleaned for continued operation.

[0083] (e) A pressure drop sensor located on the downstream side of each filter is coupled to an electric valve that activates once the pressure drop increases and reaches a specified level for that particular filter, meaning the filter is clogged and needs cleaning. This activates the electric valves on both sides of that particular filter to close and air seal the upstream and downstream sides of the filter. This simultaneously activates the "twin" filter to take over the filtering operation ( Figure 1 -B).

[0084] (f) Activation of the "twin" filter begins with the simultaneous opening of the corresponding electric valves on both sides of the "twin" filter (type 1 and type 2 electric valves). The opening of the valves causes the air flow to be directed to the cleaning element of the "twin" filter without interrupting the filtering operation and the air flow when cleaning the clogged filter.

[0085] (g) Process of cleaning clogged filters: As described in “Automatic Unclogging” above, the signal from the pressure drop sensor automatically activates the two “electric valves” (Type 1 and Type 2 electric valves) located at both ends of each dual system (upstream and downstream in the direction of air flow), isolating the section to be cleaned from the rest of the running filtration.

[0086] (h) The electric nozzle is responsible for cleaning the clogged filter. The electric nozzle is located in two different positions relative to the filter: for the component 1 ceramic filter, the electric nozzle is located upstream of the filter side, while for the component 2 and 3 mesh filters, the electric nozzle is located downstream of the filter side. This arrangement is to reverse clean the mesh filter by pushing water to the filter in the opposite direction of the airflow so that the clogged PM can be forced from the back of the filter, thereby cleaning the surface.

[0087] (i) For ceramic filters, the electric nozzle sprays water on the same side of the filter due to the tiny pore size of the filter and the resistance to water flow. Therefore, according to the manufacturer's recommendation, surface washing (same side as the airflow direction) can more effectively remove blocked PM from the ceramic filter surface.

[0088] (j) The activation of the electric nozzles is also synchronized by the opening of another set of electric valves which open the drain pipe located at the bottom of each filter. Each cleaning cycle will take approximately 10 minutes. At the end of the cleaning cycle, all electric valves and electric cleaning nozzles are restored to the inactive mode and the electric valves remain closed to protect the cleaned filters. This arrangement is continuous until the signal from the twin sensors of the running filter element indicates that the running filter element is blocked, thereby activating the cleaning cycle of the blocked filter element and restoring the clean filter element of the "twin" filter.

[0089] (k) The nature of all electric valves is that when they are not in use they will remain airtight thereby avoiding leakage of filtered air into the surrounding environment.

[0090] According to the present invention, the positive pressure continuously generated in the room keeps the indoor space from the influence of the surrounding environment. This positive pressure inhibits atmospheric pollutants and particulate matter from entering the protected space.

[0091] In the present invention, a set of inline suction fans located on the downstream side of each filtration stage promotes the supply of positive pressure and sufficient airflow. The sufficient amount of air passing through the fans is controlled by a preset airflow sensor connected to the fans for automatically adjusting the airflow. Therefore, the system is able to ensure positive pressure and continuously provide sufficient air.

[0092] like Fig.13 As shown, the effectiveness of the ventilation process of the device of the present invention requires that the room be equipped with a CO2 sensor coupled to an automatic vent on the upper wall to release stale air and maintain a positive pressure in the ventilation room.

[0093] The system of the present invention enables continuous filtering operation while reducing the load on the filter membrane and performing effective self-cleaning. The continuous filtering capability of the present invention relies on the continuous positive pressure differential generated in a series of inline fans (energy cost-effective) and the automatic unclogging of the system. The automated operating cost of the system is negligible, as shown in Table 3 below. The operating cost of each electrical component of the present invention is shown in Table 3.

[0094] The present invention can also be used for alternative arrangements for recycling indoor air to eliminate any residual PM pollutants in indoor spaces. This arrangement is very useful for treating pollutants that may enter indoor spaces via leaks in buildings or pollutants generated by indoor activities of residents (such as PM caused by cooking oil or from heating equipment). Unlike the use of multiple filters discussed above, only one of the dual filters is needed to achieve these purposes. For example, indoor air filtration may only require a combination of component 1 or gradient filters. They can be manufactured in any size and geometry as required.

[0095] To increase the effectiveness of the ventilation process of the present invention, it is useful that the room is equipped with a CO2 sensor coupled to an automatic vent above the wall to release any stale air and maintain a positive pressure within the ventilation room ( Fig. 9 ).

[0096] Among atmospheric factors, the effect of humidity on PM mean diameter has been a subject of interest for many researchers. It has been shown that the agglomeration rate of particles increases with increasing atmospheric humidity because increased liquid bridging forces increase the agglomeration velocity, which may affect the electrostatic interactions between particles. In general, at higher atmospheric humidity, the concentration of larger aerodynamic (agglomerated) aerosols increases due to the higher agglomeration rate. On the other hand, under dry atmospheric conditions (when relative humidity is low), the concentration of smaller aerodynamically charged particles is expected to increase.

[0097] Therefore, another embodiment of the present invention considers the importance of the charging mechanism of PM and combines additional electrostatic filtration to improve filtration efficiency. This is particularly applicable in dry atmospheric conditions, when finer PM sizes are more prevalent. If the overall charge of the aerosol particles is negligible or the aerodynamic size is large enough (>0.5μm), mechanical filtration will adequately remove the particles from the airflow. Since very fine particles easily break down into the surrounding environment and are susceptible to electrostatic forces at lower relative humidity (i.e., this is in contrast to higher humidity conditions where particles become larger due to water bridging and agglomeration), small fine particulate matter can be more effectively captured by electrostatic filters under dry conditions.

[0098] It should be noted that fine dust tends to form a very compact dust layer on the filter element surface and naturally raises the system pressure drop, requiring frequent cleaning. However, once the larger particles are filtered out in advance in the gradient filtration system, the remaining smaller but similarly charged particles will be collected on the downstream filter element surface. These "similar" charged smaller particles tend to repel each other on the filter element surface, forming a more porous dust layer. This reduces the clogging of PM on the filter surface to a certain extent, thereby extending the service life of the filter element.

[0099] As the concentration of dust cake collected on the upstream side of the filter increases, the pressure drop downstream also increases. This can negatively impact the function of the filter (i.e., the life of the filter). The life of the filter is related to the surface area of ​​the filter, the airflow rate through the system, and the concentration of particles in the airflow. For any given system, the combined effect of these factors determines the pressure drop across the filter. Therefore, for any given application, reducing the PM load collected from the upstream side of the filter will reduce the pressure drop across the filter, thereby extending the life of the filter. This phenomenon is more effective using a gradient filtration device (rather than just a single filter mechanism) to capture a variety of PM aerosols with different aerodynamic sizes. Therefore, the present device uses a gradient arrangement in which filters with larger pore sizes are located upstream of filters with smaller pore sizes. In this way, larger aerosols are captured upstream of the device and smaller particles are subsequently removed from the airflow by the associated filters downstream in the airflow.

[0100] Criteria for the type of filter material suitable for the gradient arrangement in the present device include: (a) being porous with uniform pore size, (b) being resistant to corrosion by acidic and alkaline components of the gas stream, (c) being resistant to dilute industrial solvents, and (d) having low electrostatic susceptibility (except for the pre-charged electrostatic filter, which is not permanently affixed to the present device) and (e) being flexible if the application requires the filter to be in the form of a coil or sheet. Examples of such materials include (but are not limited to) porous thermally stable polyester-derived materials, ceramics, acrylics, or aluminum materials.

[0101] Although various embodiments of the present invention have been described above, it should be understood that they are presented by way of example only, and not by way of limitation. It is obvious that various changes in form and details can be made to adapt to different situations without departing from the spirit and scope of the present invention for those skilled in the relevant art. Therefore, the present invention should not be limited by any of the exemplary embodiments described above.

[0102] List of reference numerals used in the specification to illustrate the detailed description of the present invention:

[0103] 1: Ceramic filter holder: A large number of individual ceramic filter discs installed within each ceramic holder. A certain flow rate and large ceramic surface area are required to overcome the pressure difference caused by the ceramic micro-sized pores of the ceramic filter. The required flow rate is provided by an internal suction fan located on the downstream side of the ceramic filter holder.

[0104] 2: Dual filter set.

[0105] 3: Ceramic individual filter discs, which are fixed in large numbers on a ceramic filter holder, thus forming a large ceramic surface area.

[0106] 4: Air gap, used for uniform air distribution.

[0107] 5: Partition, between the two "twin" ceramic filter holders, to keep the double filters airtight and separate from each other.

[0108] 6: Filter assembly 2 (12um pore size).

[0109] 7: Filter assembly 3 (37um pore size).

[0110] 8: Electrostatic (pre-charge) filter.

[0111] 9: The equipment's external protective capsule is made of lightweight insulating aluminum.

[0112] 10: Electric valve, located on the upstream side of the filter.

[0113] 11: Electric valve, coupled to the pressure drop sensor and located on the downstream side of the filter.

[0114] 12: Inline suction fans, located downstream of each filter.

[0115] 13: Drain pipe, coupled to a specific electric valve and located at the bottom of each filter bank.

[0116] 14: Electric spray nozzle for filter cleaning.

[0117] 15: Particle matter sensor.

[0118] 17: Front protection screen, removes larger coarse particles from the air flow.

[0119] 18: Diameter of non-ceramic filter components, in Figure 3 In a preferred embodiment, it is 0.3 meters.

[0120] 19: Depth of the ceramic assembly, 0.73 meters in the preferred embodiment.

[0121] 20: Height of ceramic component, in Figure 3 In a preferred embodiment, it is 1.1 meters.

[0122] 21: The diameter of the ceramic component, in Figure 3 In a preferred embodiment, it is 1.6 meters.

[0123] 22: The air gap diameter of the filter assembly, in Figure 4 The largest hole size in is >0.4 m.

Claims

1. An air purification system, comprising a housing having an internally formed airflow path, the airflow path communicating between an inlet for incoming contaminated air containing particulate material and an air outlet for discharging clean filtered air from which the particulate material has been removed, a collection system, arranged in the airflow path, for collecting particulate material, the collection system comprising at least three stages of filters, which are positioned in series in a gradient arrangement of filter pore sizes, and each stage having two identical filter elements (dual filter elements) arranged in parallel, the three stages of the gradient arrangement comprising a first coarse filter group, a second medium filter group and a third fine filter group, each of the dual filter elements comprising a device for automatic blockage detection, automatic self-cleaning, automatic self-removal from the airflow path and automatic switching to a cleaning filter of the dual filter element, a device allowing filtering stages, thereby ensuring continuous airflow when a filter cleaning mechanism is used, and only one of the dual filter elements is exposed to the airflow path in the housing and is in effect at any time, wherein, In operation, once a filter element becomes clogged, it is removed from the filtering airflow path by triggering a self-cleaning mechanism, while a second "twin" filter element is engaged to take over the filtering process as the passage of air through the filter housing is facilitated by a set of inline suction fans located on the downstream side of each filtering stage in the airflow path, wherein the passage of a sufficient amount of air through the fans is controlled by a preset airflow sensor connected to the fan for automatically adjusting the airflow to continuously ensure sufficient airflow.

2. The air purification system according to claim 1, wherein: The automatic self-cleaning device comprises: A pressure drop activated sensor located on the downstream side of the filter compared to the air flow direction; A first set of electric valves, which are located on the downstream side of the filter compared to the air flow direction and are coupled to a pressure drop sensor; a second set of electric valves located on the upstream side of the filter and in communication with the first set of valves, wherein once the filter surface is clogged by a signal from a sensor due to a pressure drop caused by a clogged filter, both the electric valves and the sensor are activated and both valves operate simultaneously during operation, wherein both electric valve sets block the air passage in an airtight manner and remove the clogged filter from the filtration process and simultaneously engage a clean air filter, while automating the operation of all three stages of gradient filtration; and A control panel that connects and automatically communicates with all electrical components to control sensors and electric valves.

3. The air purification system according to claim 2, comprising: A set of electric cleaning spray nozzles located on different sides of the filter surface; A third electric valve located at the bottom of each filter compartment to drain any waste water used by the spray nozzles during the cleaning process; and • Electric spray nozzles located on the downstream side of the airflow, spraying in the opposite direction of the airflow, for larger pore size filters, and communicating with the drain electric valves, activated with a preset time delay compared to the first and second sets of electric valves.

4. A method of using the automatic air purification system according to claim 3, the method comprising the following steps: Isolating the clogged filter from the air flow path while opening the air passage to the parallel "twin" filter by operating the valve via a pressure control device; When the upstream side of the filter surface becomes clogged, a signal is sent via a pressure sensor to operate the valve, resulting in a pressure differential between the two faces of the filter. Opening the "twin" filter channels located in parallel with the clogged filter by opening the "twin" filter valves located upstream and downstream of the "twin" filter to allow uninterrupted airflow; • Simultaneously close the valves located downstream and upstream of the clogged filter to isolate the clogged filter from the air flow path, thereby allowing the clogged filter to be cleaned. Ensure continuity of airflow when a clogged filter is isolated and removed from the channel and a parallel clean "twin" filter is engaged; Controlling the electric valve via the control panel via communication between the pressure sensor and the electric valve.

Images