JP2019500066A - Gas filtration system and method - Google Patents

Abstract

  The present invention provides a filtration system that removes a target gas from a gas to be filtered in space. The system has different modes of operation. Based on the current level of the target gas, the previous history of the detection signal and the detection of the previous operating mode, the degree of filling of the filter with the target gas can be determined. This information and the currently detected level of the target gas are used together to select an operating mode. Specifically, the filter fill and the current contaminant level are used to determine if absorption / desorption is occurring and at what rate these processes occur, which mode of operation is performed. Provides a basis for deciding what to do.

Description

  The present invention relates to a method and apparatus for filtering gaseous contaminants from a gas to be filtered.

  Indoor air pollution has caused significant health damage in many urban areas around the world. Outdoor (eg from motor vehicles and industry) and indoors (from cooking, smoking, burning candles, burning incense, outgassing buildings / decorative materials, use of outgassing firewood, paint, abrasives, etc.) Both face air pollution sources. Indoor pollution levels are often higher than outdoors, especially for volatile organic compounds. At the same time, many people live indoors most of the time, and thus can be exposed to unhealthy levels of air pollution almost continuously.

  One way to improve indoor air cleanliness is to install an indoor air purifier that can continuously circulate indoor air through a cleaning unit that includes one or more air filters (air filters). It is by doing. Another way to improve indoor air cleanliness is by providing continuous ventilation with filtered outside air. In the latter case, the air filter (s) can usually be temperature regulated and ventilated, and the ventilation air is first passed through one or more air filters before releasing the ventilation air indoors. It is included in a heating, ventilation and air conditioning (HVAC) system that can clean the ventilation air drawn from outside. Ventilation with clean air displaces contaminated indoor air and dilutes the level of contamination in the indoor air.

To remove contaminant gases from the air, a number of volatile organic hydrocarbon gas (VOC) and some inorganic gases (NO 2, _{O 3,} radon) activated carbon filters to be able to adsorb / removed / decomposed from the air Is often used. The activated carbon material is usually present as granules contained in a breathable filter frame structure.

Indoor air pollution with formaldehyde (CH ₂ O) gas is a particular problem that affects the health and well-being of many people. Formaldehyde is continuously released from indoor sources, such as building materials, decorative materials, and furniture. Its indoor concentration, when ventilation of the room is insufficient, clean air guidelines concentration (0.05 mg ^{/ m} 3 at 8 hour exposure, 1 hour 0.10 mg / ^{m 3} with exposure) lightly than increasing the related Formaldehyde obtain. Due to outdoor weather conditions, uncomfortable outdoor temperatures, and / or safety concerns, high ventilation conditions achieved by opening windows and doors are not always feasible.

Such activated carbon is also not very effective for removing formaldehyde and / or small amounts of acid gases (SO ₂ , acetic acid, formic acid, HNO _x ) from the air. Alternatively, an impregnated filter material that can chemically absorb these gases from the air can be used. Absorption can occur through acid-base interactions or through chemical condensation reactions. Activated carbon granules can be used as the impregnated support, but hydrophilic fibrous cellulose paper, glass fiber sheet materials, and porous ceramic honeycomb structures are also suitable for this purpose. When using such a filter structure, an indoor air purifier recirculates air within a given enclosure through a filter stack that includes an absorption filter.

  In absorption-based air filters, binding is usually based on chemisorption using, for example, a corrugated tris-based formaldehyde filter or physical adsorption. Such binding exhibits a reversible reaction that not only occurs when absorption filter material is exposed to gaseous contaminants that have an affinity for the filter substrate, but also already binds to the substrate. It means that the gaseous molecules that overcome the energy barrier return to the air (desorption). Thus, when clean air is passed through an absorption filter partially filled with an absorbed gas such as formaldehyde gas, desorption of formaldehyde gas may occur, which makes the absorption filter the source of formaldehyde gas itself .

  In general, the desorption rate increases with increasing packing (amount of gaseous molecules bound to the filter material) or decreasing partial pressure of gaseous contaminants in the gas phase.

  Since desorption requires energy to overcome the forces responsible for holding gaseous contaminants (eg, van der Waals forces, chemical bonds, etc.) bound to the substrate (eg, in the form of heat) The introduction of external energy into the system can increase the desorption rate.

  Another approach that can be used to remove gaseous air pollutants is to break them down into smaller molecules via oxidation. Oxidation occurs naturally but at a relatively low rate. By using a catalyst (eg, titanium oxide in the case of PCO), the oxidation rate can be strongly increased. Applications include photocatalytic oxidation (PCO) and thermal oxidation. Heating the catalyst can also result in an increased oxidation rate.

  Air purifiers that utilize absorption or adsorption based filters to remove gaseous pollutants from indoor air have a number of disadvantages.

  Users often face the problem of manually selecting an operating mode from a number of options without having the background information necessary to make a sound decision. This can lead to discretionary selection and selection of an inappropriate mode (inappropriate is a mode of operation that is more appropriate for this situation than is available, for example, selected by the user) Can mean there is).

  In many products, the mode of operation only differs in fan speed. This can limit the possibilities of the air purifier. Absorption or adsorption based gas filters may release accumulated pollutant gases under certain conditions. This may expose the population to potentially harmful concentrations.

  Absorption or adsorption-based gas filters also have limited capacity for their target molecules and do not intentionally take advantage of the regeneration potential, which can result in a longer lifetime.

  US 2007/105494 A1 discloses a fume hood comprising an improved design for extending the filter life and a system for monitoring the life of the filter. Filter efficiency is determined based on data from sensors located upstream and downstream of the filter.

  CN204593936U discloses an air purifier featuring automatic feedback control based on air quality monitoring. The purpose of CN204593936U is to provide an air purifier that automatically adjusts its settings. A sensor inside the air purifier performs air detection. Based on the sensor data, the settings of the air purifier components are adjusted.

  What is desirable is a filter and filtration method that allows the filter to be operated in an optimal mode of operation in a simple manner.

  The invention is defined by the independent claims. The dependent claims define advantageous embodiments.

An example according to the first aspect of the invention is:
A system for removing a target gas from a gas to be filtered in a space,
A sensor configuration including a gas sensor for detecting the concentration of the target gas in the space;
An air purifier including a filter for filtering the target gas from the air;
A control system including at least a ventilation system that controllably moves air through a filter;
The control system is configured to implement different modes of operation of the filtration system;
The control system is based on the current sensor configuration signal, the previous sensor configuration signal and the previously adopted operating mode,
Determining the degree of filter loading with the target gas and selecting an operating mode based on the filter filling degree and the current sensor configuration signal;
Provide a system.

  This system automatically selects the operating mode taking into account the degree of filling of the filter and the current concentration. These two pieces of information allow the influence of the filter operation to be determined. For example, if the filter is heavily loaded, the filter cannot perform filtering when there is already a relatively low concentration. Instead, the filter operates in the desorption mode.

  Multiple zones and concentrations of the filter filling parameter space may be defined, in which case each may correspond to a different preferred mode of operation. For example, there may be between 3-10 such zones, each zone having an associated mode of operation.

  The filter includes, for example, an absorption filter or an adsorption filter. The filter may be solid or liquid with a chemical that binds the target gas. There may be one or more filters of the same or different types. At least one of the filters has a reversible function and thus performs absorption / adsorption or desorption depending on the filter packing and the prevailing concentration. The control system further determines from the degree of filter filling with the target gas and the current sensor configuration signal to determine when filter regeneration (desorption) is taking place and when air filtration (absorption or adsorption) is taking place. May be configured.

  Note that in this context, the term “desorption” is used to mean the reverse of both adsorption and absorption, ie a release process opposite to the filtration process.

  The control system may include a heater that heats the filter. This may be used to adjust the filter function so that different options are used in different modes.

  The filter may further include a catalytic filter (eg, in addition to the air purifier absorption / adsorption filter), eg, a photocatalytic filter, in which case the control system further includes a light source that illuminates the photocatalytic filter. This provides other options for use in different modes. In other embodiments, a catalytic filter in the form of a thermal catalytic filter may be used, in which case the control system further includes a heat source that heats the thermal catalytic filter.

  The control system is configured to switch off the air purifier, for example, when it is determined that the concentration is above the threshold and the filter is operating in the desorption region. This prevents the air purifier from increasing the room concentration.

  The control system may be further configured to provide an output that indicates when additional ventilation of the space by outside air is desired. This allows the filter to be regenerated using outside air, for example when there is a high filling of indoor pollutants.

  The gas sensor may include a formaldehyde sensor and the filter includes a reversible absorption and / or adsorption formaldehyde filter.

  Note that the sensor configuration may be an integral part of the air purifier system or may be part of a stand alone sensor or sensor box. In the latter case, communication means are provided (eg wirelessly via WiFi) that allow the sensor to communicate the measurement results to the rest of the system.

Examples according to other aspects of the invention include:
A method for controlling a filtration system that removes a target gas from a gas to be filtered in a space comprising:
Detecting the concentration of the target gas in the space;
Filtering the target gas from air using an air purifier;
Implementing different modes of operation of the filtration system,
The method is based on the current detected density, the previously detected density, and the operating mode previously adopted.
Determining the degree of filling of the filter with the target gas;
Selecting an operating mode based on the degree of filter filling and the current sensor configuration signal.
Provide a method.

  This method provides an automatic selection of the operating mode, taking into account the degree of filling of the filter and the current concentration. In this way, a safe and effective mode of operation may be selected without requiring user input.

  Filtering may use an absorption filter or an adsorption filter. The method can determine from the degree of filter filling with the target gas and the currently detected concentration, when filter absorption or adsorption is taking place and when filter desorption is taking place, optionally absorption or adsorption or Determining the rate of desorption may be included.

  One mode of operation may include heating the filter and the other mode of operation may include illuminating the photocatalytic filter.

  The air cleaner may be switched off when it is determined that the concentration is above the threshold and the filter is operating in the desorption region.

  This method may be implemented by a computer program containing code that implements an algorithm.

  Reference will now be made in detail to the present exemplary embodiments, examples of which are illustrated in the accompanying drawings.

1 shows a first example of a gas filtration system. It shows how different operating modes can be defined by different dominant concentrations and filter filling conditions. An air cleaner control method is shown. 2 shows a second example of a gas filtration system.

  The present invention provides a filtration system that removes a target gas from a gas to be filtered in space. The system (and especially the air purifier) has different modes of operation. Based on the detection of the current gastric level of the target gas, the previous history of the detection signal and the previous operating mode, the degree of filter filling with the target gas can be determined. This information and the current detection level of the target gas are used together to select an operation mode. Specifically, the filter fill and the current target gas level are used to determine whether absorption or desorption occurs and at what speed these processes occur, and which operating mode should be performed. Provides a basis for making decisions.

  In this way, the gas filtration system, i.e. the air purifier, can collect and analyze information relating to the proper selection of the operating mode.

  FIG. 1 shows an air purifier where the air flow is from left to right as indicated by the dotted arrows. The air purifier includes a gas sensor 10 that detects the concentration of the target gas. This provides, for example, real-time formaldehyde concentration information. The sensor may be an integral part of the system, or may communicate with the rest of the system, for example wirelessly, away from the main housing of the air cleaner.

  The air purifier further includes an absorption-based gas filter 12 (eg, an activated carbon filter, an impregnation filter for formaldehyde, etc.) that filters the target gas from the air.

  For some examples of filters, the effectiveness or functionality of the filter 12 is dependent on, for example, temperature, and a heater 14 is shown that controls the filter temperature.

  The catalyst 16 may be used as a filter, in which case for a photocatalytic filter, the catalytic activity may be controlled by using a light source 18. In other embodiments, catalyst 16 may be a thermal catalyst, in which case its activity may be controlled by heater 18. A sensor 20 may be provided to detect the state of the catalyst, such as the degree of poisoning with the target gas.

  The entire system may have only absorption-based filters, or the entire system may have both types of filters as shown.

  When a catalyst filter is used, information about whether the catalyst filter needs to be regenerated or needs to be replaced can be provided to the user based on information from the sensor 20.

  A ventilation system such as a fan 22 is provided at the outlet.

  The gas sensor 10 and the catalyst sensor 20 include both sensor configurations. Overall, the heater 14, catalyst 16, light source 18 and fan 22, and master control unit include a control system. At a minimum, the control system includes a ventilation system that controllably moves air through a filter, and other control devices are optional. Their use depends on the type or types of filters used.

  The control system is configured to implement different modes of operation of the gas filtration system.

  A master control unit in the form of a controller 24 is provided for controlling each other element of the control system. The controller 24 considers the current signal from the sensor configuration 10, 20, the previous history of the sensor configuration signal, and the previous mode of operation. Using this information, it is possible to determine the extent to which the target gas fills the filter of the absorption filter and then to select the appropriate operating mode. The mode may be selected based on the degree of filter filling compared to the current concentration of the target gas in the air space to be cleaned.

  The light source 14 has a controllable light intensity, which may be used when a photocatalytic oxidation filter (PCO) is used. The heating element 14 preferably has an adjustable output temperature using feedback control. The fan 22 may have an adjustable speed and the catalyst 16 may have an adjustable and / or temperature. In that case, the different combinations of these adjustable parameters define the operating mode of the overall control system.

  Preferably, the control system includes in addition to the controller 24 a fan and at least one further controllable actuator.

  Information is needed that allows the filling state of the absorption filter to be determined. This may be in the form of data updated by the SoC (system on chip) and stored in the database 26 stored in the SoC or an external server. Sensor 20 provides this information regarding the catalytic filter.

  The controller 24 is responsible for collecting, analyzing and storing information from various sources used in the system. A predetermined set of parameter values for each component is stored to define different operating modes. The controller 24 can then induce the desired mode of operation by controlling the adjustable parameters.

  The idea that forms the basis of the design of the filtration system will be described with reference to FIG. FIG. 2 plots two important factors that determine the desorption and absorption behavior of a gas filter based on the absorption process, which is the filter fill L (x axis) and the ambient ambient concentration c (y axis). In FIG. 2, there is an equilibrium line marked Leq that describes all pairs (L, c) whose level of absorption is equal to the level of desorption.

  All pairs (L, c) above and below this equilibrium line Leq result in net absorption and net desorption, respectively. As the distance from the equilibrium line Leq increases, the desorption rate or the absorption rate gradually increases.

  For air purifiers with absorption-based formaldehyde filters as well as in the home environment, as listed in Table 1 below, pairs (L, c) belong to separate zones, each pair having specific characteristics. Can be made. This table defines the five zones shown in FIG. 2 along with the balance line. In another example, the zone of FIG. 2 can be further subdivided.

  Such a zone definition may be applied to any gas filter based on an adsorption process. In this model, every pair (L, c) is assigned to a specific zone. The actual values for L and c are determined by the specific characteristics of the particular filter.

  Next, an example will be described in which the gas filter is a formaldehyde filter, and thus the gas sensor is a formaldehyde sensor. However, this idea can be applied to other gases or combinations thereof.

In view of the above, it is clear that CH ₂ O filters used in the domestic environment behave very differently depending on the c and L values when the air cleaner is started. For example, when the pair (L, c) is in region A _ab 2 of FIG. 2, the air purifier effectively reduces the indoor CH ₂ O concentration. This gradual decrease reduces the CH ₂ O partial pressure, which results in a decrease in absorption rate. If the filter has a reasonably high capacity, the influence on the filling L during this time can be ignored.

Eventually, the pair (L, c) moves to zone A _ab 1 where the actual removal rate (or real time clean air supply rate, CADR) is significantly reduced. At this point, it is meaningful to improve the removal performance of gaseous pollutants.

  This is optional because the system can track the current position of the Lc diagram, thus having an overview of the current operating state by obtaining and analyzing the relevant state information. In this example, the relevant information is indoor formaldehyde concentration and gas filter filling.

The control system may be configured to adjust the internal control parameters by switching from the first cleaning mode (P1) to the second cleaning mode (P2). Each mode corresponds to a specific set of component parameter values including at least the fan speed. Clean mode 1 is characterized, for example, by high fan speeds, thus high flow rates (preferably in the range of 200 and 400 m ³ / h) and deactivated light source 18. Clean mode 2 uses the same flow rate as clean mode 1, but light source 18 is switched on. For catalysts that operate at room temperature without the need for light, the heating element may be activated to increase the temperature of the catalyst.

  The system does not require a catalytic filter. Without the use of any catalyst, the desorption rate may be adapted to natural ventilation in different operating modes. This can be done by adjusting the fan speed, taking into account the reading from the sensor configuration.

The purpose is to increase the reaction rate of the catalyst, and hence the performance of the air purifier, to compensate for the lower absorption rate of the CH ₂ O filter in zone A _ab 1.

In all cases where the pair (L, c) is below the equilibrium line Leq, a net release of formaldehyde from the CH ₂ O filter occurs. The advantage is that this filter is regenerated. As with the clean mode, it makes sense to consider different scenarios that allow the design of optimized regeneration modes and their proper selection during operation.

Again, the air cleaner is started and the pair value (L, c) is determined. If it enters the zone (shown in FIG. 2) A _des 1, a net release from the formaldehyde filter occurs. The indoor CH ₂ O concentration is below the critical value C _critical also shown in FIG. 2, which represents a safety threshold, for example, below 0.1 mg / m ³ (WHO and GB / T safety threshold for indoor formaldehyde concentration) Can be set to

This situation is basically suitable for regenerating a CH ₂ O filter. The challenge, however, is that regeneration occurs very slowly because of the slow desorption rate (shown in Table 1 above).

  The components of the air cleaner can be operated in a mode optimized for this scenario, regeneration mode 1 (R1).

In this mode, the heating element 14 is activated and the flow rate is reduced (e.g. to a value between 10 and 50 m < ³ > / h). The purpose is to increase the temperature of the CH ₂ O filter. The latter temperature increase, (CH 2 _O due to the higher probability locally CH 2 _O molecules bound to a lower partial pressure and the substrate may overcome the energy barrier required for dissociation of) the desorption rate This leads to an increase, which is the desired result of this mode.

  In other embodiments, the heating element is located upstream rather than downstream of the gas filter.

  Some embodiments may use a moisture source located downstream, such as a configuration that generates water mist instead of and / or with the heating element 14. In such a case, the water that is fed contends to obtain a coupling location in the middle of the filter, thus facilitating the desorption of the gas coupled to the filter. Thus, the operation of the moisture source provides other parameters that can be used differently in different modes of operation.

Compared to zone A _des 1, zone A _des 2 is characterized by a higher desorption rate (shown again in Table 1 above), which does not require heating of the CH ₂ O filter in regeneration mode 2 (R2). Means that. This mode is therefore characterized by a slow flow rate (low fan speed) and an activated light source 18. Both embodiments increase the one-pass efficacy of the catalytic filter required to efficiently remove larger amounts of filter discharge CH ₂ O.

  FIG. 3 illustrates a method for controlling an air purifier (ie, a gas filtration system).

  In step 30, the air cleaner is started. In step 32, the ambient concentration of the target gas such as formaldehyde is measured. In step 34, the database 38 is accessed to obtain the current loading value of the filter used in the air cleaner.

  In step 36, it is determined in which zone of FIG. 2 the filling value and the concentration value are located.

In step 42, it is determined whether the zone is zone A _ab 2, i.e. whether the filter is lightly filled and has a high concentration. If so, the first cleaning mode P1 is adopted in step 43.

Step 44 determines if the zone is zone A _ab 1, that is, if the filter can still be further filled but still has sufficient concentration and filling with less margin. To do. If so, the second cleaning P2 is employed in step 45.

  As described above, the difference between the control settings for the different purification modes P1 and P2 can be, for example, whether the photocatalyst is activated, whether a heater is attached (or the degree of heating), Including providing speed and moisture in the flow.

In step 46, it is determined whether the zone is zone A _des 1, i.e., if the filter is filled more and there is a relatively low concentration. If so, in step 47, the first reproduction mode R1 is adopted.

In step 48, it is determined whether the zone is zone A _des 2, i.e., if the filter is filled more and / or has a lower concentration. If so, the second playback mode R2 is adopted in step 49.

  While the air purifier is operated in any one of these modes, the database is updated so that historical information regarding the mode used is stored. In this way, the characteristics of each mode, the characteristics of the filter (you can communicate these characteristics directly using filter identification or by accessing the database through the Internet, for example), how long they operate The filter fill can be tracked based on whether

In step 50, whether the zone is zone A _des 3, i.e., the concentration is above the critical level and the filter is filled so much that it cannot reduce the concentration level. Determine whether there is. If so, a warning is provided to the user at step 52. If the user does not provide an acknowledgment, the air cleaner is stopped at step 60. If the user provides the receipt of a warning at step 54, the third playback mode R3 is adopted at step 56 and the database is updated again.

  The air purifier continues for the given time monitored in step 58. If time has not elapsed, the cycle is repeated with a new measurement of concentration and an updated value for filter filling. Thus, the cycle continues, possibly with mode changes, until the set time is reached when the cycle moves to step 60.

If step 50 does not confirm operation in zone A _des 3, there is confirmation in step 61 whether the value corresponds to the equilibrium line L _eq . If so, it does not make sense to activate the air purifier, and at step 60 the air purifier is stopped.

  If the zone is not found, there is an error and an error message is given at step 62 before the air purifier is stopped.

This process means that the air purifier can adequately handle the situation where it is powered by the value pair (L, c) in zone A _des 3. In this scenario, operating the purifier increases the CH ₂ O concentration even further above the safety threshold C _critical . This can also occur with a catalytic filter in the filter stack, i.e. when its one-pass efficacy is (typically) less than 100%.

  Automatic mode selection eliminates this risk by identifying this scenario as well as notifying the user of the preparation for playback mode R3.

Preparation can mean, for example, that the user places the air cleaner on the balcony or simply opens the window. The mode is executed only after confirmation by the user in step 52 or only by autonomous detection that this has been done (eg, a sudden change in indoor temperature, CO ₂ or formaldehyde concentration).

If regeneration is performed on the balcony, it is not essential to efficiently remove the desorbed contaminants. This is because the desorbed contaminants dilute rapidly with the outside air. Therefore, the light source 18 can be turned off to save energy in this mode R3. Fan speed can be relatively low (eg, 20 m ³ / h) to save power. If the regeneration takes place over a long period of time, for example at night, the heating element 14 can be off, or the heating element 14 can be on to further promote desorption, thus , The time required for playback can be shortened.

  Thus, the difference between the control settings for different regeneration modes is whether the photocatalyst is activated, whether the heater is turned on (or the degree of heating), the air flow rate, and the humidity in the flow. May include providing minutes.

  If no confirmation is made within a predetermined time period, the purifier is automatically turned off. Corresponding notifications can be sent to the user's mobile device, for example.

  As discussed above, the system can overcome the inherent disadvantages of absorption-based filters, resulting in a cleaner with a longer lifetime. The specific mode of operation design may be optimized to handle different loadings and concentrations, which may further improve performance. As long as the filling and ambient concentrations are known, the mode selection can be fully automated.

  Other embodiments consider additional information such as room temperature, humidity, moisture content in the filter, and the like.

The system shown in FIG. 1 can realize all the modes described above. In one example, filling information can be obtained from a database stored in the CPU of the purifier. If the air cleaner has an internet connection, the storage medium may be an external server. This database can be continuously updated based on information about ambient concentration measured by the CH ₂ O sensor, taking into account the operating time in each mode. External data storage and processing can be useful in filter identification (based on performance or by filter identifier) if more than one filter type is on the market or the performance of the filter is improved. This allows the use of modern software for each filter type.

  Alternatively, filter filling can be derived in real time through other approaches, for example by measuring the one-pass efficacy of the filter by adding additional sensors immediately after the gas filter. This is shown in FIG. 4 where an additional sensor 11 is provided.

  In other embodiments, the one-pass efficacy of the catalyst (eg, the PCO filter of FIG. 1) can also be achieved by placing one gas sensor in front and the other gas sensor behind the catalyst filter (or PCO filter-light source unit). It is determined. This information can be used to display the status of the catalyst and recommend replacement.

  The invention can be applied in the area of indoor air cleaning, more specifically in automatic mode selection of an air cleaner.

  As described above, the system may provide end-of-life predictions by monitoring gas concentrations, usage modes, and other factors such as relative humidity, temperature over time.

  The present invention is of particular interest in removing formaldehyde gas from indoor spaces. The system can be based on known sensor and filter designs, for example as disclosed in WO2013 / 008170 and US6071479. The formaldehyde sensor can selectively measure the ambient formaldehyde gas concentration over time.

An example of a reversible formaldehyde absorption filter is disclosed in US6071479. It features a corrugated paper structure in which a porous paper material is impregnated with a mixture of a base (KHCO3), a wetting agent (Kformate), and an organic amine (Tris-hydroxymethyl-aminomethane (Tris)). . Preferably, the filter impregnation is carried out with an aqueous impregnation solution comprising:
A concentration of KHCO ₃ , preferably selected within the range of 5-15% w / w,
A concentration of Kformate, preferably selected within the range of 5-20% w / w, and a concentration of Tris, preferably selected within the range of 5-25% w / w.

  For that purpose, a certain amount of impregnation solution is incorporated into the paper structure of the filter per unit filter volume and then dried.

  The above example is based on a reversible formaldehyde filter. The present invention may be applied to other reversible filters. For example, activated carbon filters or zeolite filters may be used to adsorb volatile organic hydrocarbon gas (VOC) from air. The same system may be used for such a filter. The required gas sensor is then a VOC sensor that allows detection of (a range of) VOCs that can be adsorbed on or desorbed from the activated carbon or zeolite adsorbent.

  Examples of VOC sensors are photoionization detectors (PID), metal oxide semiconductor (MOX) sensors, and electrochemical sensors.

  The space in which the system is used is typically in an indoor space (i.e., inside a residential or commercial building), but the present invention provides a seal inside an automobile, coach, airplane, train or other vehicle. It may apply equally to other spaces, such as spaces.

  The present invention is of particular interest in indoor air purifiers, ventilation or HVAC (heating, ventilation and air conditioning systems) and other air treatment units.

  As discussed above, embodiments utilize a controller. The controller can be implemented in a number of ways using software and / or hardware to perform the various functions required. A processor is an example of a controller that utilizes one or more microprocessors that may be programmed using software (eg, microcode) to perform the required functions. However, the controller may be implemented with or without a processor, and dedicated hardware that performs some functions and a processor that performs other functions (eg, one or more programmed). Or a combination of a microprocessor and related circuitry).

  Examples of controller components that may be utilized in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field programmable gate arrays (FPGAs).

  In various embodiments, a processor or controller may be associated with one or more storage media, such as volatile and non-volatile computer memory, such as RAM, PROM, EPRON, and EEPROM. A storage medium may be encoded with one or more programs that perform the required functions when executed on one or more processors and / or controllers. The various storage media may be fixed within the processor or controller, or may be portable so that one or more programs stored therein can be loaded into the processor or controller. The computer can in some embodiments be an external device such as a smartphone. In this case, all data needs to be sent from the sensor / air cleaner to such an external device. This may allow the disclosed functionality to be enabled once a service (eg, in the form of an app) is purchased after purchase of the air purifier.

  Those skilled in the art in practicing the claimed invention may understand and implement other modifications to the disclosed embodiments from a study of the drawings, this disclosure, and the appended claims. In the claims, the term “comprising” does not exclude other elements or steps, and the singular expression does not exclude the plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Filter includes absorption filter (Absorption filter) or adsorption filter (adsorption filter). The filter may be solid or liquid with a chemical that binds the target gas. There may be one or more filters of the same or different types. At least one of the filters has a reversible function and thus performs absorption / adsorption or desorption depending on the filter packing and the prevailing concentration. The control system further determines from the degree of filter filling with the target gas and the current sensor configuration signal to determine when filter regeneration (desorption) is taking place and when air filtration (absorption or adsorption) is taking place. Ru is configured.

Filtering uses an absorption filter or adsorption filter. The method can determine from the degree of filter filling with the target gas and the currently detected concentration, when filter absorption or adsorption is taking place and when filter desorption is taking place, optionally absorption or adsorption or Determining the rate of desorption may be included.

Claims (15)

A filtration system for removing a target gas from a gas to be filtered in a space,
A sensor configuration including a gas sensor for detecting the concentration of the target gas in the space;
A filter for filtering the target gas from the air;
A control system including a ventilation system that controllably moves air through the filter;
The control system is configured to implement different modes of operation of the filtration system;
The control system is based on the current sensor configuration signal, the previous sensor configuration signal, and the previous mode of operation.
Determining a filling degree of the filter with the target gas, and selecting an operation mode based on the filling degree of the filter and the current sensor configuration signal,
Filtration system.   The filtration system according to claim 1, wherein the filter includes an absorption filter or an adsorption filter.   The control system determines when the filter is absorbed and when the filter is desorbed from the degree of filling of the filter with the target gas and the current sensor configuration signal, preferably absorption, adsorption, The filtration system of claim 2, further configured to also determine a rate of desorption.   The filtration system according to claim 2 or 3, wherein the control system includes a heater for heating the filter.   The filtration system according to claim 2, wherein the filter further includes a catalyst filter.   The filtration system according to claim 5, wherein the catalytic filter includes a photocatalytic filter, and the control system further includes a light source that illuminates the photocatalytic filter.   The filter is part of an air purifier and the control system determines that the concentration of the air purifier is determined when the concentration is above a threshold and the filter is operating in a desorption region. The filtration system of claim 1, wherein the filtration system is configured to switch off.   The filtration system of claim 1, wherein the control system is further configured to provide an output that indicates when additional ventilation of the space by outside air is desired.   The filtration system of claim 1, wherein the gas sensor includes a formaldehyde sensor and the filter includes an absorbing formaldehyde sensor. A method for controlling a filtration system that removes a target gas from a gas to be filtered in a space comprising:
Detecting the concentration of the target gas in the space;
Filtering the target gas from the air;
Implementing different modes of operation of the filtration system;
The method is
Based on the current detected density, the previously detected density, and the operating mode previously adopted,
Determining the degree of filling of the filter with the target gas;
Selecting an operation mode based on the degree of filling of the filter and the current sensor configuration signal,
Method.   The method according to claim 10, wherein the filtering step uses an absorption filter or an adsorption filter.   From the degree of filling of the filter with the target gas and the currently detected concentration, it is determined when the filter is absorbed or adsorbed and when the filter is desorbed. Preferably, the rate of absorption or adsorption or desorption is also determined. The method of claim 11, comprising the step of determining.   The method of claim 10, wherein one mode of operation includes heating the filter and the other mode of operation includes illuminating a photocatalytic filter.   The filtering step is performed by an air purifier, and the method includes the air purifier when it is determined that the concentration is above a threshold and that the filter is operating in a desorption region. 11. The method of claim 10, further comprising turning off the vessel.   15. A computer program comprising code, the code for performing the method according to any one of claims 10 to 14 when the computer program is running on a processor. A computer program.

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