Air treatment

Abstract

An air treatment apparatus is provided comprising a sorbent material for sorbing one or more air pollutants from an air stream, a desorption assembly arranged to desorb the pollutants from at least a portion of the sorbent material, and a photocatalytic reactor arranged to receive air containing desorbed pollutants and treat the air by performing photocatalytic degradation on the one or more desorbed pollutants. The air treatment apparatus further comprises a spacer volume provided in an air stream path between the desorption assembly and the photocatalytic reactor, the spacer volume being arranged to receive air containing desorbed pollutants from the desorption assembly, and a spacer volume outlet valve provided between the spacer volume and the photocatalytic reactor, the spacer volume outlet valve being arranged to control delivery of air containing desorbed pollutants from the spacer volume to the photocatalytic reactor.

Description

TECHNICAL FIELD

[0001] The present invention relates to an air treatment apparatus and a filter arrangement and a monolithic adsorption filter suitable for use in such an air treatment apparatus. BACKGROUND

[0002] Air treatment apparatuses treat air to remove pollutants. Conventional air treatment apparatuses use only particulate filters, which physically capture particles in the air by size exclusion, with high efficiency particulate air (HEPA) filters capable of removing at least 99.97% of 0.3 pm particles. Some air treatment apparatuses use activated carbon filters to filter volatile chemicals from the air. Activated carbon is a well-known carbonaceous material that, after treatment, has a large number of open or accessible micropores and mesopores that can increase the surface area for adsorption or chemical reactions. For example, WO2016 / 128734 describes a fan assembly having a tubular, barrel-shaped filter mounted on a cylinder of the fan assembly. The filter comprises a two-layer structure of filter media, including an outer layer of pleated HEPA filter, which surrounds an inner layer of activated carbon cloth.

[0003] When used for air purification, activated carbon filters pollutants by adsorption, and so has a limited capacity, such that the activated carbon filter eventually needs to be replaced if filtration performance is to be maintained. It is therefore desirable to be able to regenerate such adsorption filters to avoid the need for replacement. One way of achieving such regeneration is to desorb the pollutants from the adsorption filter before discharging them to the external environment, or to destroy the pollutants using a technique such as photocatalytic oxidation (PCO), the latter being preferred because it does not require the air treatment apparatus to be able to vent to the external environment. However, the destruction of desorbed pollutants is not straightforward. In particular, desorption of pollutants from an adsorption filter produces high concentrations, and exposure of a photocatalyst to high concentrations of pollutants can permanently damage the photocatalyst, rendering it ineffective. While this problem can be circumvented by controlling the rate of release of pollutants, this approach requires detailed knowledge of the desorption process and precise control of the heating applied. Furthermore, this approach extends the desorption process, during which time the adsorption filter is unable to perform any filtration. SUMMARY

[0004] According to a first aspect of the application, there is provided an air treatment apparatus. The air treatment apparatus comprises an adsorbent material for adsorbing one or more air pollutants from an air stream, a desorption assembly arranged to desorb the pollutants from at least a portion of the adsorbent material, and a photocatalytic reactor arranged to receive air containing desorbed pollutants from the desorption assembly and to treat the air by performing photocatalytic degradation of the one or more desorbed pollutants. The air treatment apparatus further comprises a spacer volume disposed in an air flow path between the desorption assembly and the photocatalytic reactor, and a spacer volume outlet valve disposed between the spacer volume and the photocatalytic reactor, the spacer volume being arranged to receive air containing desorbed pollutants from the desorption assembly, the spacer volume outlet valve being arranged to control delivery of the air containing desorbed pollutants from the spacer volume to the photocatalytic reactor.

[0005] The air treatment apparatus according to the first aspect of the application reduces the risk of desorbed pollutants from the adsorbent material permanently damaging a photocatalyst provided to facilitate destruction of the pollutants.

[0006] The spacer volume can be arranged to contain air containing desorbed pollutants received from the desorption assembly. The spacer volume can be arranged to hold all of the air containing desorbed pollutants received from the desorption assembly.

[0007] The spacer volume can be provided by any of one or more conduits and one or more chambers. In particular, the spacer volume can comprise any of a conduit, a chamber, one or more conduits, one or more chambers, or a combination of one or more conduits and one or more chambers. The spacer volume can be provided by one or more holding chambers. The spacer volume can be provided by one or more inflatable chambers, the inflatable chambers being inflatable to increase a volume within the inflatable chambers and deflatable to decrease a volume within the inflatable chambers.

[0008] The spacer volume outlet valve can be arranged to delay delivery of the air containing desorbed pollutants from the spacer volume to the photocatalytic reactor. The spacer volume outlet valve can be arranged to hold the air containing desorbed pollutants in the spacer volume. The spacer volume outlet valve can be arranged to control a rate of delivery of the air containing desorbed pollutants from the spacer volume to the photocatalytic reactor.

[0009] The air treatment apparatus can further comprise a spacer volume inlet valve disposed between the desorption assembly and the spacer volume, the spacer volume inlet valve being arranged to prevent air containing desorbed pollutants contained within the spacer volume from returning to the desorption assembly.

[0010] The air treatment apparatus can further comprise a dilution gas inlet for introducing a dilution gas into the spacer volume and a dilution gas inlet valve arranged to control introduction of the dilution gas through the dilution gas inlet.

[0011] The air treatment apparatus can further comprise an air flow generator for generating an air flow, the air treatment apparatus being arranged such that at least a portion of the air flow generated by the air flow generator passes through the adsorbent material.

[0012] The desorption assembly can comprise a desorption chamber arranged to surround at least a portion of the adsorbent material and a heater comprising arranged to heat the adsorbent material surrounded by the desorption chamber to desorb adsorbed pollutants. The air treatment apparatus can be arranged such that the desorption chamber is interchangeably surround different portions of the adsorbent material.

[0013] The desorption chamber can be arranged to contain the pollutants desorbed from the heated portion of the adsorbent material. The desorption chamber can be arranged to hold all of the pollutants desorbed from the heated portion of the adsorbent material.

[0014] The photocatalytic reactor can comprise a photocatalyst for photocatalytic degradation of one or more pollutants and one or more light sources for illuminating the photocatalyst to facilitate photocatalytic degradation. The photocatalytic reactor can comprise a reactor outlet arranged to discharge treated air from within the photocatalytic reactor. The reactor outlet can be arranged to discharge treated air from the apparatus. The reactor outlet can be arranged to discharge treated air such that it passes through at least a portion of the adsorbent material before being discharged from the apparatus. The air treatment apparatus can further comprise a reactor outlet valve arranged to control the discharge of treated air from the reactor outlet.

[0015] The adsorbent material can comprise a material capable of adsorbing one or more pollutants, thereby removing them from an incoming air flow. The adsorbent material can be a material that allows adsorbed pollutants to be desorbed from at least a portion of the adsorbent material by suitably treating at least a portion of the adsorbent material, for example by heating at least a portion of the adsorbent material. For example, the adsorbent material can comprise a carbon-based material. For example, the adsorbent material can comprise an activated carbon material. For example, the adsorbent material can comprise a monolithic activated carbon.

[0016] The air treatment apparatus can be a domestic air treatment apparatus. The air treatment apparatus can be an air purifier or an air conditioner.

[0017] According to a second aspect of the application, there is provided a filter arrangement for an air treatment apparatus, the filter arrangement comprising a monolithic adsorbent filter and a carrier, the filter being held within a bore defined by the carrier, and the carrier comprising a plurality of elastically deformable supports distributed around a periphery of the carrier. The monolithic adsorbent filter can comprise a carbon-based adsorbent material.

[0018] The filter arrangement can further comprise a housing, the carrier being received within a bore of the housing. The elastically deformable supports can then be configured to partially deform upon receipt of the carrier within the bore of the housing.

[0019] The carrier and the elastically deformable support can be integrally formed. The elastically deformable support can then comprise a plurality of protrusions arranged around a periphery of the carrier. The deformable protrusions can each comprise a profiled damper. The one or more profiled dampers can comprise a radial damper profiled damper, and optionally can comprise a radial tube damper.

[0020] According to a third aspect of the present application there is provided an air treatment apparatus comprising a filter arrangement according to the second aspect.

[0021] According to a fourth aspect of the present application there is provided a monolithic adsorptive filter comprising an inlet face for the introduction of incoming gas to be filtered and an outlet face opposite the inlet face, at least one of the inlet face and the outlet face being curved. The monolithic adsorptive filter can comprise a carbon-based adsorbent material.

[0022] The filter can comprise a plurality of channels extending from the inlet face to the outlet face. The plurality of channels can comprise any regular array of channels and an irregular network of channels or open pores.

[0023] Both the inlet face and the outlet face can be curved. The curvature of the outlet face can be greater than the curvature of the inlet face. The curvature of one or both of the inlet face and the outlet face can be cylindrical.

[0024] According to a fifth aspect of the present application there is provided an air treatment apparatus comprising a monolithic adsorptive filter according to the fourth aspect.

[0025] It will of course be appreciated that features described with reference to one aspect of the present application can be incorporated into other aspects of the application. BRIEF DESCRIPTION OF DRAWINGS

[0026] The present application will be described with reference to the following drawings in which:

[0027] Figure 1 is a schematic view of an example of an air treatment apparatus;

[0028] Figure 2 is a cross-sectional view of an example of an air treatment apparatus;

[0029] Figure 3 is a cross-sectional view of an example of an air treatment apparatus; Figure 2

[0030] Figure 4 is a schematic view of another example of an air treatment apparatus;

[0031] Figure 5A is a perspective view of an example of a filter suitable for use in an air treatment apparatus as described herein;

[0032] Figure 5B is a perspective view of an example of a filter suitable for use in an air treatment apparatus as described herein; Figure 5A ​a plan view of the filter of

[0033] Figure 6A is a perspective view of an example of a filter arrangement suitable for use with the air treatment apparatus described herein; and

[0034] Figure 6B is Figure 6A a front view of the filter arrangement of DETAILED DESCRIPTION

[0035] Examples of air treatment apparatus will now be described, by way of example only, with reference to Figure 1 , 2 and 3. The air treatment apparatus is generally indicated by reference numeral 100 and comprises a housing 131 which houses an airflow generator 120 for generating an airflow through the air treatment apparatus 100.

[0036] In the example shown in Figure 2 and 3 the housing 131 is cylindrical and has a side wall, a lower end and an upper end. The lower end is closed and provides a base (i.e. lower surface) on which the air treatment apparatus 100 rests (i.e. is supported). The air inlet of the air treatment apparatus 100 is then provided in the side wall of the housing 131 and comprises an array of holes (not shown) formed in the side wall of the housing 131. Alternatively, the air inlet can comprise one or more grilles or meshes which are mounted in a window formed in the housing 131.

[0037] The airflow generator 120 is then mounted within the housing 131 with the exhaust port of the airflow generator 120 being provided within a circular aperture 130 provided in the upper end of the housing 131 so that the airflow exhausted from the airflow generator 120 exits the housing 131 of the air treatment apparatus 100 through the aperture 130. The circular aperture 130 thus provides an air outlet for the air treatment apparatus 100.

[0038] The airflow generator 120 comprises a motor 121 and an impeller 122 which is arranged to be driven by the motor 121 to generate the airflow through the air treatment apparatus 100. The impeller 122 has a generally frusto-conical shape and the motor 121 is partially provided within a cavity 132 defined by the rear of the impeller 122.

[0039] The air treatment apparatus 100 further comprises an adsorbent material 101 for adsorbing one or more air pollutants. The adsorbent material 101 is arranged so that at least a portion of the airflow through the air treatment apparatus 100 passes through the adsorbent material 101 so that pollutants present in that portion of the airflow are removed by the adsorbent material 101.

[0040] In the example shown in Figure 2 and Figure 3In the example shown, the adsorbent material 101 is provided by a plurality of curved monolithic carbon filters 101', 101" distributed around the inner periphery of the housing 131 such that they are downstream of an air inlet of the air treatment device 100, which is provided in a side wall of the housing 131, and upstream of the airflow generator 120. Air drawn through the air inlet of the air treatment device 100 by the airflow generator 120 thus passes through the curved monolithic carbon filters 101', 101" before being expelled through the air outlet 130 of the airflow generator 120.

[0041] In Figure 2 and Figure 3 In the example shown, the air treatment device 100 further comprises a pre-filter assembly 133 for pre-filtering the airflow through the air treatment device 100 before the airflow passes through the adsorbent material 101, the pre-filter assembly 133 comprising particulate filter media for filtering particulates in the airflow. For example, such particulate filter media can comprise pleated polytetrafluoroethylene (PTFE) or glass microfiber nonwoven. The pre-filter assembly 133 can further comprise chemical filter media for filtering certain chemical substances from the airflow before the airflow passes through the adsorbent material 101. For example, such chemical filter media can comprise activated carbon filter media, such as pleated carbon cloth or activated carbon particles held between layers of air-permeable material.

[0042] The air treatment device 100 further comprises a desorption assembly 102, 107 arranged to intermittently or periodically desorb pollutants from at least a portion of the adsorbent material 101. To this end, the desorption assembly comprises desorption chambers 107 arranged to interchangeably surround different portions of the adsorbent material 101, and heaters 102 arranged to heat the adsorbent material surrounded by the desorption chambers 107 to desorb adsorbed pollutants. The desorption chambers 107 are further arranged to at least temporarily contain desorbed pollutants from the heated portions 101' of the adsorbent material 101.

[0043] In Figure 2 and Figure 3 In the example shown, the desorption assembly is rotatably mounted within the air treatment device 100 such that the desorption chambers 107 and the heaters 102 can be rotated to move from one of the curved monolithic carbon filters 101', 101" to the other, thereby intermittently or periodically exchanging which portion of the adsorbent material 101 is arranged within the desorption chambers 107. Accordingly, the air treatment device 100 further comprises a rotation assembly arranged to rotate the desorption assembly, the rotation assembly comprising a rotary motor 134 arranged to rotate a drive member 135, and a driven member 136 arranged to be driven by the drive member 135 to rotate the desorption assembly about a rotation axis. In Figure 2 and 3In the example shown, the drive member 135 comprises a pinion gear and the driven member 136 comprises an at least partially circular or arcuate rack provided on the desorption assembly.

[0044] In an alternative arrangement, the desorption assembly can be fixedly mounted within the air treatment device 100, and then the adsorbent material 101 can be rotatably mounted within the housing 131 such that portions of the adsorbent material 101 can be rotated in and out of the desorption chamber 107 in order to intermittently or periodically exchange which portion of the adsorbent material 101 is provided within the desorption chamber 107. In another alternative arrangement, the desorption assembly can be arranged to move longitudinally (i.e. vertically) within the air treatment device 100 to move from one portion of the adsorbent material 101 to another portion, and thereby intermittently or periodically exchange which portion of the adsorbent material 101 is provided within the desorption chamber 107.

[0045] The photocatalytic reactors 103, 104, 105 are arranged to receive air containing pollutants desorbed from the heated portion 101’ of the adsorbent material. In the example shown, the air containing pollutants desorbed from the heated portion 101’ of the adsorbent material 101 passes from the desorption chamber 107 through the conduit 109 into the spacer volume 106, through the conduit 113 into the photocatalytic reactor 103. Figure 2 The photocatalytic reactor 103 comprises a reaction chamber 103 arranged to receive the air containing desorbed pollutants; a photocatalyst 104 (e.g. titanium dioxide, Ti02) for photocatalytic degradation of one or more pollutants arranged on one or more surfaces within the reaction chamber 103; and one or more light sources 105 for irradiating the photocatalyst to promote photocatalytic degradation of the one or more pollutants. In the example shown, the photocatalyst 104 is a thin film of titanium dioxide arranged on the inner surface of the reaction chamber 103. Figure 2 and 3 In the example shown, the light sources 105 are light emitting diodes mounted on an elongate printed circuit board (PCB), which emit ultraviolet (UV) light at a wavelength of approximately 365 nm.

[0046] The air treatment device 100 is configured to provide at least one air flow path (FP) that allows air from outside the device 100 to contact at least one of the one or more light sources 105 without passing through the heated portion 101’ of the adsorbent material 101. In particular, air flows along the flow path (FP) through an unheated portion 101” of the adsorbent material 101. This unheated portion 101” of the adsorbent material 101 is located outside of the desorption chamber 107 and is therefore not exposed to heat generated by the heater 102, such that filtered air passes over the light sources 105 without passing through the heated portion of the adsorbent material 101. As described below, this unheated air passes over and cools the one or more light sources 105.

[0047] The reaction chamber 103 comprises a transparent barrier or partition 123 separating the photocatalyst 104 from the one or more light sources 105. The transparent partition 123 comprises a material that is sufficiently transparent to the ultraviolet (UV) light emitted by the one or more light sources 105 such that the light of the catalysing UV wavelengths that passes through the transparent partition 123 is sufficiently strong to catalyse the decomposition of pollutants by the photocatalyst 104.

[0048] Accordingly, the reaction chamber 103 comprises a first portion 125 comprising the photocatalyst and a second portion 124 comprising the one or more light sources 105, the transparent partition 123 separating the first portion 125 from the second portion 124. The first portion 125 is arranged to receive air comprising pollutants desorbed from the heated portion 101’ of the adsorbent material, the second portion 124 is arranged to receive at least a portion of the airflow that has not passed through the heated portion 101’ of the adsorbent material 101 but has passed through the unheated portion 101” of the adsorbent material 101.

[0049] The air treatment apparatus 100 reduces the likelihood of the photocatalyst 104 becoming “poisoned” by exposure to too many pollutants by providing a separation volume 106 into which pollutants adsorbed by the adsorbent material 101 are released and stored before being transported to the photocatalytic reactor. Accordingly, the separation volume 106 is arranged to receive and hold air comprising desorbed pollutants received from the desorption assembly. Additionally, the air treatment apparatus 100 can further comprise a dilution gas inlet (not shown) arranged to allow dilution gas to be introduced into the separation volume and a dilution gas inlet valve (not shown) arranged to control the introduction of dilution gas through the dilution gas inlet. The introduction of dilution gas into the separation volume allows the concentration of pollutants contained within the separation volume to be reduced, further reducing the likelihood of the photocatalyst 104 becoming “poisoned” by exposure to too many pollutants.

[0050] The operation of the apparatus of Figure 1 , 2 and 3 will now be described with reference to Figures Figure 1 , 2 and 3. The motor 121 rotates the impeller 122 to create an airflow through the air inlet of the air treatment apparatus 100, the airflow passing through the portion of the adsorbent material 101 that is not disposed within the desorption chamber 107. The air treatment apparatus 100 then determines that this portion of the adsorbent material 101 requires regeneration and so initiates the regeneration process for this portion of the adsorbent material 101. In the first step of the regeneration process, the portion of the adsorbent material 101 to be regenerated is disposed within the desorption chamber 107 and is preferably sealed within the desorption chamber 107. In the example shown in Figure 2 and Figure 3 this step involves actuating the rotation assembly to rotate the desorption assembly so as to interchange the curved monolithic carbon filter currently disposed within the desorption chamber 107 with the curved monolithic carbon filter 101’ to be regenerated.

[0051] In the second step of the regeneration process, the heater 102 is activated to heat the portion 101'of the adsorbent material 101 surrounded by the desorption chamber 107 to desorb the adsorbed pollutants. Prior to or during heating of the portion 101'of the adsorbent material 101, the spacer volume inlet valve 108 disposed between the desorption chamber 107 and the spacer volume 106 is opened, allowing air and pollutants to move from the desorption chamber 107 to the spacer volume 106, and the spacer volume outlet valve 112 disposed between the spacer volume 106 and the reaction chamber 103 of the photocatalytic reactor is closed, preventing air containing desorbed pollutants from reaching the photocatalytic reactor. This approach does not require slow and precisely controlled heating of the adsorbent material 101, but rather allows for rapid heating and desorption. Additionally, prior to or during heating of the portion 101'of the adsorbent material 101, the desorption chamber inlet valve 114 is opened to allow air to enter the desorption chamber 107, thereby preventing the desorption chamber 107 from becoming under pressure.

[0052] While movement of desorbed pollutants from the desorption chamber 107 to the spacer volume 106 can be achieved using thermal expansion generated by heating with the heater 102 alone, movement of air and pollutants from the desorption chamber 107 to the spacer volume 106 during the second step can be facilitated by increasing the volume of the spacer chamber 110 defining the spacer volume 106. For example, this can be achieved by moving a movable portion 111 of the spacer chamber 110. The movable portion 111 can then comprise pleats or folds that facilitate expansion of the spacer chamber 110. In the example shown, the spacer chamber 110 is a relatively flat cylindrical chamber positioned towards the bottom of the air treatment device 100. Figure 2 And Figure 3 In the example shown, the spacer volume outlet valve 112 is fully open to provide a constant, controlled flow of air and pollutants to the reaction chamber 103 of the photocatalytic reactor, the flow rate being sufficiently restricted that a desired amount of pollutants (e.g. substantially all of the pollutants) can be removed from the air stream without causing irreversible poisoning of the photocatalyst 104.

[0053] In the third step of the regeneration process, which begins after desorption is determined to be complete, the spacer volume inlet valve 108 between the desorption chamber 107 and the spacer volume 106 is closed. The heater 102 can then be deactivated and the heated portion 101'of the adsorbent material 101 is allowed to cool. The spacer volume outlet valve 112 is at least partially open, allowing air containing desorbed pollutants to be transported from the spacer volume 106 to the photocatalytic reactor. In the example shown, the spacer volume outlet valve 112 is fully open to provide a constant, controlled flow of air and pollutants to the reaction chamber 103 of the photocatalytic reactor, the flow rate being sufficiently restricted that a desired amount of pollutants (e.g. substantially all of the pollutants) can be removed from the air stream without causing irreversible poisoning of the photocatalyst 104. Figure 2 And 3 In the example shown, the spacer volume outlet valve 112 is fully open to provide a constant, controlled flow of air and pollutants to the reaction chamber 103 of the photocatalytic reactor, the flow rate being sufficiently restricted that a desired amount of pollutants (e.g. substantially all of the pollutants) can be removed from the air stream without causing irreversible poisoning of the photocatalyst 104.

[0054] To facilitate movement of air and pollutants from the separation volume 106 to the photocatalytic reactor during the third step, the volume of the separation chamber 110 defining the separation volume 106 can be reduced. This can be achieved, for example, by moving a moveable portion 111 of the separation chamber 110, the pleating or folding of which facilitates the contraction of the separation chamber 110. The flow of air containing desorbed pollutants to the photocatalytic reactor can then be controlled by controlling the contraction of the separation chamber 110.

[0055] During this third step, the light sources 105 of the photocatalytic reactor are activated such that they irradiate the photocatalyst 104 provided on one or more surfaces within the reaction chamber 103. Air delivered from the separation volume 106 to the reaction chamber 103 is therefore treated by photocatalytic degradation of desorbed pollutants present in the air. In Figure 1 、 2 In the example shown in Figures 1 to 3, air containing desorbed pollutants is delivered from the separation volume 106 to the reaction chamber 103 at a controlled rate and the photocatalytic reactor is arranged to treat the air as it flows through the reaction chamber 103. In particular, the photocatalytic reactor is arranged such that air delivered from the separation volume 106 to the reaction chamber 103 enters the reaction chamber 103 through a reactor inlet 115, flows through the reaction chamber 103 at a controlled rate, and is exhausted from a reactor outlet 116, the air being treated by photocatalytic degradation as it flows from the reactor inlet 115 to the reactor outlet 116.

[0056] After passing through the photocatalytic reactor 103, the air stream can be exhausted from the air treatment apparatus 100. Alternatively, the air treatment apparatus 100 can be arranged such that air exhausted from the photocatalytic reactor passes through a filter, such as the adsorbent material 101, before the air stream exits the air treatment apparatus 100. For example, the photocatalytic reactor can be arranged to exhaust treated air such that the treated air passes through at least a portion of the adsorbent material 101 before being exhausted from the air treatment apparatus 100. This approach provides that any pollutants that are not completely degraded within the photocatalytic reactor and thus remain in the treated air can still be adsorbed by the adsorbent material 101 before the treated air is exhausted from the air treatment apparatus 100.

[0057] The skilled person will appreciate that more than one chamber can be used to define a separation volume. Similarly, one or more conduits can be used in conjunction with or in place of one or more chambers to define a separation volume. Such multiple conduits and chambers can be used in series and / or in parallel to define a separation volume.

[0058] The above examples show how the heated portion 101” comprises a first filter and how the unheated portion 101” comprises a second filter. Of course, the heated portion 101” and the unheated portion 101” can be provided by one filter.

[0059] In the example shown in Figure 1 , 2 and 3, the air treatment apparatus 100 is a domestic air filtration / purification unit. The skilled person will appreciate that the air treatment apparatus can be an air conditioning unit, typically used to cool and / or heat air. Alternatively or additionally, the air treatment apparatus can be a commercial air treatment unit, for example suitable for use in public areas.

[0060] Another example of an air treatment apparatus according to the present application will now be described with reference to Figure 4 The air treatment apparatus 200 is similar to the apparatus described above with reference to Figure 1 , 2 and 3, in that the apparatus 200 comprises a separation volume 106 arranged to receive air containing contaminants desorbed from the heated portion 101’ of the adsorbent material 101. Figure 4 Features in Figure 1 , 2 and 3 having the same reference numerals correspond to those described with reference to Figure 1 , 2 and 3, and operate in the same way.

[0061] In the example shown in Figure 4 The reaction chamber 103 of the photocatalytic reactor is arranged to store the air containing contaminants received from the separation volume 106 before allowing the treated air to be discharged from the photocatalytic reactor. Thus, the reaction chamber 103 is arranged to receive and hold the air containing desorbed contaminants received from the separation volume 106. To this end, the photocatalytic reactor comprises a reactor inlet 115 through which the air containing desorbed contaminants is received from the separation volume 106; a reactor outlet 116 arranged to discharge treated air from within the photocatalytic reactor; and a reactor outlet valve 212 for controlling the discharge of treated air from the photocatalytic reactor. In order to maintain the pressure within the reaction chamber 103 when air containing desorbed contaminants is received from the separation volume 106, the volume of the reaction chamber 103 can be increased. For example, this can be achieved by moving a moveable portion 211 of the reaction chamber 103. The moveable portion 211 can then comprise pleats or folds which facilitate expansion and contraction of the reaction chamber.

[0062] In use, a "batch" of air containing pollutants can be expelled from the separation volume 106 by opening the separation volume outlet valve 112. To facilitate the movement of air and pollutants from the separation volume 106 to the photocatalytic reactor, the volume of the separation chamber 110 defining the separation volume 106 can be reduced. This can be achieved, for example, by moving the moveable portion 111 of the separation chamber 110, the pleats or folds of which contribute to the contraction of the separation chamber 110. The flow of air containing desorbed pollutants to the photocatalytic reactor can then be controlled by controlling the contraction of the separation chamber 110.

[0063] The movement of the moveable portion 211 expanding the reaction chamber 103 maintains the pressure within the reaction chamber 103 and can also serve to draw air containing desorbed pollutants from the separation volume 106 into the reaction chamber 103. The reactor outlet valve 212 is closed during the transfer of air containing desorbed pollutants to the reaction chamber 103 so that it is retained within the reaction chamber 103.

[0064] Once this "batch" of air has been transferred to the reaction chamber 103, the separation volume outlet valve 112 is closed and the air in the reaction chamber 103 is treated by activating the light source 105 of the photocatalytic reactor so that it illuminates the photocatalyst 104 provided on one or more surfaces within the reaction chamber 103. The air contained in the reaction chamber 103 is therefore treated by the photocatalytic degradation of the desorbed pollutants present in the air. Once the treatment is complete, the treated air is allowed to exit the photocatalytic reactor by opening the reactor outlet valve 212. The movement of the moveable portion 211 causes the volume of the reaction chamber 103 to be reduced again, thereby maintaining the pressure within the reaction chamber 103 and can also serve to expel the treated air from the photocatalytic reactor.

[0065] Figure 5A and 5B An example of a sorption filter suitable for use with the air treatment apparatus described herein is shown. The sorption filter is generally indicated by reference numeral 1000. The filter 1000 comprises a carbon-based sorption material, such as activated carbon, and is monolithic. In particular, the filter 1000 has a rigid open structure comprising an inlet face 1001 for the introduction of incoming gas to be filtered and an outlet face 1002 opposite the inlet face. The filter 1000 further comprises a plurality of channels 1003 extending from the inlet face 1001 to the outlet face 1002. The plurality of channels 1003 can comprise any regular array of channels and irregular networks of channels and / or open pores.

[0066] In Figure 5A and 5B In the example shown, both the inlet face 1001 and the outlet face 1002 are curved. In particular, the inlet face 1001 is curved in a first direction and the outlet face 1002 is curved in a second direction opposite the first direction. The plurality of channels 1003 extend from the inlet face 1001 to the outlet face 1002 in a direction that is perpendicular to the first and second directions. Figure 5BIt will be seen that the inlet face 1001 and the outlet face 1002 have the same curvature, both being cylindrical. However, this need not be the case. For example, the inlet face and the outlet face can have different curvatures. For example, the outlet face can have a greater curvature than the inlet face. The provision of curved inlet and outlet faces provides a more adaptable filter and facilitates filtering of different geometries. In particular, the adsorptive filter described above is optimised for use in a circumferential array of filters disposed within an at least partially cylindrical air handling apparatus. Such an adsorptive filter also facilitates the use of a rotating assembly to effect intermittent or periodic exchange of the filters disposed within the desorption chamber.

[0067] Figure 6A and 6B An example of a filter arrangement suitable for use with the air handling apparatus described herein is shown. The filter arrangement is generally indicated by reference numeral 2000 and comprises a unitary adsorptive filter 2001 and a carrier 2002, the filter being held within a carrier aperture 2003 defined by the carrier 2002. The carrier 2002 comprises a plurality of elastically deformable supports 2004 distributed around a periphery 2006 of the carrier 2002. If the filter arrangement 2000 is subjected to an undesired impact, the elastically deformable supports 2004 reduce the likelihood of the filter 2001 being damaged. The supports provide a cushioning to reduce the risk of the filter 2001 being damaged.

[0068] In Figure 6A and 6B In the example shown, the carrier 2002 is integrally formed from silicone, the carrier 2002 comprising filter retaining portions 2007 integrally formed with the elastically deformable supports 2004. However, the skilled person will appreciate that the carrier need not be integrally formed. For example, the filter retaining portions 2007 need not be integrally formed with the supports 2004.

[0069] In the example shown, the elastically deformable supports 2004 are provided by a plurality of protrusions 2005 arranged around the periphery of the carrier. In this example, each deformable protrusion 2005 is in the form of a radial damped profile damper. However, the skilled person will appreciate that other arrangements of elastically deformable supports can be used. For example, each support can be in the form of an axial damped profile damper. Alternatively, the filter arrangement can be provided with different types of supports, for example, some radial damped profile dampers and some axial damped profile dampers.

[0070] In Figure 6A and 6BIn the example shown, the filter arrangement 2000 further comprises a housing 2008 within which the carrier 2002 is received within a housing aperture 2011 defined by the housing 2008. The housing aperture 2011 and the carrier 2002 are configured such that the support 2004 is at least partially deformed when the carrier 2002 is received within the housing aperture 2011. In the example shown, the housing 2008 comprises an aperture defining body portion 2009 and a flange portion 2010 extending around the periphery of the aperture defining body portion 2009. The housing 2008 is integrally formed from a plastics material. In use, the aperture defining body portion 2009 is received within a suitable aperture of an air handling device (none shown).

[0071] The skilled person will appreciate that other shapes of filter can be used. For example, the filter need not be square or rectangular, it can be circular.

[0072] For the avoidance of doubt, the skilled person will appreciate that the housing is not an essential part of the filter arrangement of the present aspect of the application.

[0073] The skilled person will appreciate that the filter arrangements described above can be used with other arrangements described herein. For example, the filter arrangements can be used with filters having one or more curved surfaces, such as those described above in relation to Figure 5A and 5B Furthermore, the filter arrangements can be used in air handling devices as described above in relation to Figures 1 to 3

[0074] In the foregoing description, reference has been made to integers or elements having known, obvious or foreseeable equivalents; such equivalents are incorporated herein as if separately set forth. The true scope of the present application is defined by the appended claims, which should be construed in accordance with the full breadth permitted by law. The reader's attention is directed to both the following claims and the preceding description and a combination thereof will serve for industrial purposes. Moreover, it is not intended to limit the scope of the application to the exact details shown and described, for it will be apparent that many modifications and variations can be made in form, function, and implementation without departing from the scope of the application as set forth in the following claims.​

Claims

1. An air treatment apparatus comprising: adsorbent material for adsorbing one or more air pollutants from an air stream; a desorption assembly arranged to desorb the pollutants from at least a portion of the adsorbent material; a photocatalytic reactor arranged to receive air containing desorbed pollutants and to treat the air by performing photocatalytic degradation on one or more of the desorbed pollutants; a spacer volume provided in the air stream path between the desorption assembly and the photocatalytic reactor, the spacer volume arranged to receive air containing desorbed pollutants from the desorption assembly, and a spacer volume outlet valve provided between the spacer volume and the photocatalytic reactor, the spacer volume outlet valve arranged to control delivery of air containing desorbed pollutants from the spacer volume to the photocatalytic reactor, wherein the desorption assembly comprises a desorption chamber arranged to interchangeably surround at least a portion of the adsorbent material and a heater arranged to heat the adsorbent material surrounded by the desorption chamber to desorb the adsorbed pollutants, wherein the desorption assembly is rotatably mounted within the air treatment apparatus such that the desorption chamber and the heater are rotatable to exchange which portion of the adsorbent material is arranged within the desorption chamber, wherein the photocatalytic reactor comprises a reaction chamber, wherein the reaction chamber comprises a first portion containing a photocatalyst and a second portion containing one or more light sources and separated from the first portion, wherein the first portion is arranged to receive air containing pollutants desorbed from the heated portion of the adsorbent material and the second portion is arranged to receive at least a portion of the air stream that has not passed through the heated portion of the adsorbent material but has passed through an unheated portion of the adsorbent material.

2. The air treatment device of claim 1, wherein, the spacer volume is arranged to contain air containing desorbed pollutants received from the desorption assembly.

3. The air treatment device of claim 1, wherein, the spacer volume is provided by any one of one or more conduits and one or more chambers.

4. The air treatment device of any one of claims 1-3, wherein, the spacer volume is provided by one or more holding chambers.

5. The air treatment device of any one of claims 1-3, wherein, the spacer volume outlet valve is arranged to delay delivery of air containing desorbed pollutants from the spacer volume to the photocatalytic reactor.

6. The air treatment device of any one of claims 1-3, wherein, the spacer volume outlet valve is arranged to control a rate of delivery of air containing desorbed pollutants from the spacer volume to the photocatalytic reactor.

7. The air treatment apparatus of any one of claims 1-3, further comprising a spacer volume inlet valve provided between the desorption assembly and the spacer volume, the spacer volume inlet valve arranged to prevent air containing desorbed pollutants contained within the spacer volume from returning to the desorption assembly.

8. The air treatment apparatus of any one of claims 1-3, further comprising a dilution gas inlet for introducing a dilution gas into the spacer volume and a dilution gas inlet valve for controlling introduction of the dilution gas via the dilution gas inlet.

9. The air treatment apparatus of any one of claims 1-3, further comprising an air stream generator for generating an air stream, the air treatment apparatus arranged such that at least a portion of the air stream generated by the air stream generator passes through the adsorbent material.

10. The air treatment device of claim 1, wherein, the desorption chamber is arranged to contain pollutants desorbed from the heated portion of the adsorbent material.

11. The air treatment device of any of claims 1-3, wherein, The photocatalytic reactor includes a reactor outlet arranged to discharge treated air from within the photocatalytic reactor.

12. The air treatment device of claim 11, wherein, The reactor outlet is arranged to discharge treated air from the apparatus.

13. The air treatment device of claim 11, wherein, The reactor outlet is arranged to discharge treated air such that the treated air passes through at least a portion of the adsorbent material before being discharged from the apparatus.

14. The air treatment apparatus of claim 11, further comprising a reactor outlet valve for controlling the discharge of treated air from the photocatalytic reactor.

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