Chemical Filter Assembly

Abstract

The filter assembly has a housing defining an inlet and an outlet. A plurality of chemical filter elements are disposed within the housing and arranged in series with respect to the fluid flow. A spacing region is between the series of adjacent filter elements. Also disclosed is an assembly including a housing and first and second chemical filter elements. The second chemical filter element is downstream of the first chemical filter element. Each chemical filter element has a sheet of chemical filter material having a first edge and a second edge. A first flow path is defined parallel to a surface of the first sheet and extends from the first edge to the second edge. A second flow path is defined parallel to a surface of the second sheet and extends from the first edge to the second edge.

Description

[Technical field]

[0001]

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 271,867, filed October 26, 2021, which is incorporated by reference in its entirety.

[0002] The present disclosure relates generally to a filter assembly and, more particularly, to a chemical filter assembly. Summary of the Invention

[0002]

[0003] Certain embodiments of the technology disclosed herein relate to a filter assembly including a housing, a first chemical filter element, and a second chemical filter element. The first chemical filter element includes a first sheet of a first chemical filter material having a first edge and a second edge. A first filtration flow path is defined parallel to a surface of the first sheet and extends from the first edge to the second edge. The second chemical filter element includes a second sheet of a second chemical filter material having a first edge and a second edge. A second filtration flow path is defined parallel to a surface of the second sheet and extends from the first edge to the second edge. The first chemical filter element and the second chemical filter element are disposed within the housing. The second chemical filter element is disposed downstream of the first chemical filter element.

[0003]

[0004] In some embodiments, the assembly further comprises a spacing region between the first and second chemical filter elements, the spacing region defining a flow path from the first chemical filter element to the second chemical filter element. Additionally or alternatively, the assembly further comprises a particulate filter disposed in the spacing region, the particulate filter comprising a particulate filtration medium through which the flow path extends. Additionally or alternatively, the first chemical filter element further comprises a stack of multiple layers of the sheet of the first chemical filter material including the first sheet, the first filtration flow path being defined between adjacent layers in the stack. In some embodiments, the first chemical filter element has a stack of multiple flow path layers defining a first filtration flow path, each flow path layer being disposed between and abutting layers of the sheet of the first chemical filter material in the stack.

[0004]

[0005] Additionally or alternatively, the first sheet of the first chemical filter material is configured in a coil about a central axis. In some embodiments, the first chemical filter element further comprises a flow path layer abutting the first sheet of the first chemical filter material, where the flow path layer defines the first filtration flow path and is configured in a coil about a central axis.

[0005]

[0006] Additionally or alternatively, the first sheet of the first chemical filter material has an embossment extending between the first edge and the second edge. Additionally or alternatively, the first sheet of the first chemical filter material has one or more holes extending completely through the first sheet of the first chemical filter material. Additionally or alternatively, the filter assembly has a third chemical filter element including a third sheet of a third chemical filter material having a first edge and a second edge, where a third filtration flow path is defined parallel to a surface of the third sheet and extends from the first edge to the second edge. Additionally or alternatively, the filter assembly has a spacing region defining a flow path from the second chemical filter element to the third chemical filter element.

[0006]

[0007] Additionally or alternatively, the first chemical filter material comprises a base-impregnated sorbent. Additionally or alternatively, the first chemical filter material includes an acid-impregnated sorbent. Additionally or alternatively, the second chemical filter material comprises an acid-impregnated sorbent. Additionally or alternatively, the second chemical filter material comprises a base-impregnated sorbent. Additionally or alternatively, the first edge is opposite the second edge of the first sheet of chemical filter material. Additionally or alternatively, the fourth chemical filter element has a fourth sheet of fourth chemical filter material having a first edge and a second edge, a fourth filtration flow path defined parallel to a surface of the fourth sheet and extending from the first edge to the second edge. Additionally or alternatively, a spacing region defines a flow path from the third chemical filter element to the fourth chemical filter element. Additionally or alternatively, the fourth chemical filter material has a mesoporous sorbent.

[0007]

[0008] Additionally or alternatively, the assembly includes a fifth chemical filter element including a fifth sheet of a fifth chemical filter material having a first edge and a second edge, where a fifth filtration flow path is defined parallel to a surface of the fifth sheet and extends from the first edge to the second edge. Additionally or alternatively, the assembly includes a spacing region defining a flow path from the fourth chemical filter element to the fifth chemical filter element. Additionally or alternatively, the fifth chemical filter material includes an acid impregnated sorbent.

[0008]

[0009] Certain other embodiments disclosed herein relate to a filter assembly including a housing defining an inlet and an outlet; a plurality of chemical filter elements within the housing arranged in series with respect to fluid flow from the inlet to the outlet; and a spacing region between adjacent filter elements in the series.

[0010] In some embodiments, each of the chemical filter elements includes a chemical filter material configured as a sheet having a first edge and a second edge and defining a filtration flow path extending parallel to a surface of the sheet, the filtration flow path extending from the first edge to the second edge.Further or alternatively, a first of the plurality of chemical filter elements includes a flow path layer defining the filtration flow path, the flow path layer abutting the surface of the sheet between the first edge and the second edge.Further or alternatively, a first of the plurality of chemical filter elements includes a stack of multiple layers of a sheet of chemical filter material, the filtration flow path being defined between adjacent layers in the stack.In some embodiments, the first of the plurality of chemical filter elements further includes a stack of multiple flow path layers defining the first filtration flow path, each of the flow path layers being disposed between and abutting layers of the first sheet of chemical filter material in the stack.

[0009]

[0011] Additionally or alternatively, the sheet of first chemical filter material is configured in a coil about a central axis. Additionally or alternatively, the sheet has an embossment extending between the first edge and the second edge. Additionally or alternatively, the first sheet of first chemical filter material has one or more holes extending completely through the first sheet of first chemical filter material. Additionally or alternatively, one or more of the chemical filter elements are adsorptive filter elements. Additionally or alternatively, at least one of the chemical filter elements is a chemisorptive coated substrate. Additionally or alternatively, a first chemical filter element of the plurality of chemical filter elements includes an adsorbent impregnated with a base.

[0010]

[0012] Additionally or alternatively, a second chemical filter element of the plurality of chemical filter elements comprises an acid-impregnated sorbent and is downstream of the first chemical filter element. Additionally or alternatively, a first chemical filter element of the plurality of chemical filter elements comprises an acid-impregnated sorbent. Additionally or alternatively, a second chemical filter element comprises a base-impregnated sorbent and is downstream of the first chemical filter element. Additionally or alternatively, the plurality of chemical filter elements further comprises a third chemical filter element downstream of the second chemical filter element. Additionally or alternatively, the plurality of chemical filter elements further comprises a fourth chemical filter element comprising a mesoporous sorbent, the fourth chemical filter element being downstream of the third chemical filter element. Additionally or alternatively, the plurality of chemical filter elements further comprises a fifth chemical filter element downstream of the fourth chemical filter element. Additionally or alternatively, the first edge is opposite a second edge of the first sheet of chemical filter material.

[0013] The above summary is not intended to describe each embodiment or every implementation. Rather, a more complete understanding of the example embodiments will become apparent and appreciated by reference to the following detailed description of example embodiments and claims, when taken in conjunction with the accompanying drawing figures.

[0014] The present technology may be more fully understood and appreciated in consideration of the following detailed description of various embodiments in conjunction with the accompanying drawings, in which: [Brief description of the drawings]

[0011] [Figure 1]

[0015] 1 is a schematic exploded view of an exemplary filter element. [Diagram 2]

[0016] 1 is a schematic diagram of an exemplary filter element. [Diagram 3]

[0017] 1A is a schematic diagram of an example sheet of filter material.

[0018] 1B is a schematic diagram of another exemplary sheet of filter material. [Figure 4]

[0019] 1 shows a schematic diagram of another exemplary filter element. [Diagram 5]

[0020] 1 shows a schematic diagram of yet another exemplary filter element. [Figure 6]

[0021] 1 shows a schematic diagram of yet another exemplary filter element. [Figure 7]

[0022] 1 shows a schematic diagram of yet another exemplary filter element. [Figure 8]

[0023] 1 shows a schematic diagram of an exemplary filter assembly. [Figure 9]

[0024] 13 is a set of test results relating to different filter materials and different contaminants. [Figure 10] 13 is a set of test results relating to different filter materials and different contaminants. [Figure 11] 13 is a set of test results relating to different filter materials and different contaminants. [Figure 12] 13 is a set of test results relating to different filter materials and different contaminants. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012]

[0025] The figures are drawn primarily for clarity and, as a result, are not necessarily drawn to scale. Additionally, various structures / components, including but not limited to fasteners, electrical components (wiring, cables, etc.), etc., may be shown diagrammatically or removed from some or all of the figures to better illustrate aspects of the illustrated embodiment or where the inclusion of such structures / components is not necessary for an understanding of the various exemplary embodiments described herein. However, the absence of showing / description of such structures / components in a particular figure should not be construed as limiting the scope of the various embodiments in any way.

[0026] The technology disclosed herein relates to systems and assemblies that perform multi-stage chemical filtration. Such systems and assemblies may be advantageous in the context of air and liquid filtration. One particular exemplary environment in which the technology may be implemented is a fuel cell environment. For example, a chemical filtration system or assembly may be incorporated into the intake air stream to protect the hydrogen cells in the fuel cell from contaminants. Other potential applications of the current technology include purification of post-combustion flue gas streams for industrial processing, automotive applications, petrochemical processes, or air purification in buildings and aircraft.

[0027] Certain implementations of the present technology selectively remove certain chemical contaminants at different stages. Such configurations can advantageously prevent certain chemical contaminants from negatively interfering with downstream filtration processes, such as by deactivating the chemical filter material. Such configurations can advantageously improve the life of the filter assembly, or at least the life of the individual filter elements within the filter assembly. The present technology can advantageously improve the selectivity of the filter assembly for removing very small amounts of certain contaminants. In certain embodiments, the filter assembly incorporates multiple chemical filtration stages in a single filter housing. Such configurations can advantageously reduce energy consumption and increase productivity due to the reduced enthalpy gradient required to regenerate one assembly as opposed to two separate units.

[0013] definition

[0028] As used herein, an "adsorbent" is defined as a material configured to form a surface bond with one or more chemical moieties. As used herein, "adsorption" encompasses "physisorption," which is the physical binding of chemical moieties, and "chemisorption," which is a chemical bond resulting from a chemical reaction.

[0029] A chemical filter element is a filter element configured to remove one or more chemical species from a fluid stream. Chemical filter elements include adsorbent materials and reactive chemicals, such as chemicals selected to react with specific types of contaminants.

[0030] A "flow face" is the area defined by the media within a filter element where fluid flows into or out of the media.

[0031] As used herein, "interparticle pores" refers to the void spaces between particles, such as the void spaces between fibers forming a sheet, or other types of particles.

[0032] As used herein, "intraparticle pore" refers to an opening defined by the surface of a particle, such as a sorbent fiber, or a type of particle other than a fiber, such as a granule or bead.

[0033] As used herein, "micropore" refers to a pore having a diameter of less than 2 nm.

[0034] As used herein, "mesopores" and "mesoporous" refer to pores with diameters between 2 nm and 50 nm.

[0035] "Macropore" refers to a pore with a diameter greater than 50 nm.

[0036] As used herein, "particulate filtration media" refers to a material configured to capture particles from a fluid stream.

[0037] Filter elements consistent with the technology disclosed herein may be arranged for "flow-by" filtration, meaning that the contaminant-containing fluid flowing through the filter from an inlet flow surface to an outlet flow surface is directed approximately parallel to the surfaces (e.g., top and bottom surfaces) of one or more layers of filter media, such that the material flows "near" the surfaces of the filter media, rather than through them. Such an arrangement is generally perpendicular to conventional filter arrangements in which the fluid flows directly through the pore structure of the filter material (i.e., through the filter material, such as from a top plane to a bottom plane).

[0014] Chemical Filter Materials

[0038] Filter materials consistent with the technology disclosed herein include general chemical filter materials. In various embodiments, the filter material is configured as a sheet, meaning that the material is relatively thin and has two opposing major surfaces. The thickness of the sheet extends from one major surface to the opposite major surface. The sheets of filter material may each have a thickness of at least 0.15 mm, and typically no greater than 10 mm. The sheets are typically configured into filter elements for flow-by filtration. Such configurations are described in more detail below.

[0039] The sheet of chemical filter material can be configured as a sheet of mesh or screen with relatively small intersecting fibers or strands. The screen may be composed of an adsorbent material or a non-adsorbent substrate. In certain other embodiments, the sheet of chemical filter material may be configured as a mat, where the adsorbent material or non-adsorbent substrate is compressed with a binder material to form a relatively homogenous sheet of filter material.

[0040] The sheet of filter material chemistry may define inter-particle pores, which are void spaces defined by intersecting fibers (when the filter material is configured as a screen) and / or between particles in the sheet (when the filter material is configured as a screen and when the filter material is configured as a mat). The inter-particle pore size may be designed or selected taking into account the size of the contaminants to be captured by a particular layer and / or taking into account the resistance to fluid flow across the filter material as evidenced by parameters such as pressure drop. The inter-particle pores defined by the sheet of filter material may be constructed to allow fluid flow, while the filter material area surrounding the inter-particle pores is configured to capture and retain contaminants.

[0041] The sheet of chemical filter material may also have intra-particle pores. The intra-particle pores may include one or more of micropores, mesopores, and macropores. The intra-particle pores may accommodate trapping, chemical adsorption impregnation, and / or diffusion of contaminants. In certain embodiments, the size of the macropores of the sheet of chemical filter material may range from 50 nm to 200 microns, more specifically from 50 nm to 100 microns, more specifically from 1 to 50 microns, more specifically from 50 nm to 25 microns, more specifically from 50 nm to 15 microns, or even more specifically from 50 nm to 10 microns, as measured in a flow-through orientation. In some embodiments, the sheet of chemical filter material may include an adsorbent material, such as activated carbon, silica gel, or molecular sieves. In some embodiments, the chemical filter material is a microporous adsorbent material. In some embodiments, the chemical filter material does not define pores.

[0042] The sorbent sheets can be coated, reacted, impregnated or washed with specific chemical moieties to modify the chemical filtration performance of the sorbent, hi some embodiments, the sorbent sheets are impregnated with salts.

[0043] In some embodiments, the chemical filter material is a non-adsorbent substrate, such as a cellulose web, that is coated with a chemical adsorbent. The chemical filter material may be a non-adsorbent substrate that is coated with an acid or base impregnation. The non-adsorbent substrate may be dip coated, in some embodiments.

[0044] Chemical filter materials can be configured to maintain relatively high selectivity, adsorption capacity, and retention for certain chemical constituents, such as acid gases such as nitrogen oxides, sulfur dioxide, and hydrogen sulfide, siloxanes, ammonia, n-butane, volatile organic compounds, aromatic hydrocarbons (e.g., benzene, toluene, xylene, etc.), and the like.

[0015] Acid Gas Filter Materials

[0045] In some embodiments, the chemical filter material is configured to remove acid gases from a fluid stream. In some embodiments, the sheet of chemical filter material has an adsorbent or non-adsorbent substrate impregnated with a base, such as potassium carbonate (K2CO3). Other bases, such as sodium carbonate (Na2CO3), sodium bicarbonate (NaHCO3), potassium hydroxide (KOH), potassium iodide (KI), or sodium hydroxide (NaOH), may be used as the impregnating agent.

[0046] In some embodiments, the acid gas filter material is configured to partially bind H2SOx / H2S contaminants in the form of HSOx-OH or HS-OH functional groups through impregnation of a relatively weakly basic chemical adsorbent. Such a configuration may advantageously contribute to the reduction of NH3 species, since the partially neutralized acid may act as an additional adsorbent for ammonia. In some embodiments, both acidic and basic contaminants may be captured by the acid gas filter material.

[0047] In one example, the acid gas filter material is activated carbon impregnated with potassium carbonate. In another particular example, the acid gas filter material is a granular microporous activated carbon mesh impregnated with 6-7% KI and 3-4% KOH. The carbon mesh size is 12×20. One particular exemplary product is supplied by Haycarb PLC, Colombo, Sri Lanka. In yet another particular example, the chemical filter material is a mesh granular microporous activated carbon material impregnated with 5% potassium iodide and 7.5% sodium hydroxide. The mesh carbon size can be 8×200, although other mesh sizes are also contemplated. One particular example product is grade RPPE 1034 supplied by Haycarb PLC. Other examples of impregnating agents for activated carbon to filter acid gases include iron oxide and potassium permanganate.

[0016] Ammonia Filter Materials

[0048] In some embodiments, the chemical filter material is configured to remove ammonia from the fluid stream. In some embodiments, the chemical filter material is impregnated or coated with an acid. In some embodiments, the chemical filter material is an acid impregnated adsorbent. In some embodiments, the chemical filter material is an acid coated non-adsorbent substrate. In various embodiments, the acid is citric acid. In some embodiments, the acid is not phosphoric acid due to its relatively high vapor pressure.

[0049] In one particular example, the chemical filter material is a granular microporous activated carbon mesh material impregnated with 22% citric acid. The mesh carbon size can be 8×16, although other mesh sizes are contemplated. One particular material is supplied by Haycarb PLC (Colombo, Sri Lanka).

[0017] Test procedures for adsorption and retention of alkanes, siloxanes and VOCs

[0050] Thirteen commercially available carbonaceous adsorbents, some of which contained impregnating agents, were screened for static adsorption of toluene, siloxane, pentane, and hexane volatile organic compounds (VOCs) by beaker testing. Approximately 0.1 g of adsorbent was placed in a glass vial and heated to 80° C. for 72 hours to degas pre-adsorbed species. The degassed sample was then sealed in a jar containing 5 mL of the desired vapor and saturated at 25° C. for 24 hours, except for siloxane. The saturation temperature was 40° C., since siloxane has no vapor pressure at ambient conditions. The adsorption capacity was calculated from the initial weight gain of the adsorbent after saturation in the jar.

[0051] The covers were then removed from the jars and the samples were heated to 40°C. Mass loss was recorded at set increments over a period of one week. From this, the retention of the contaminant samples was calculated. Note that because the jars were open to the environment, the sorbents had the opportunity to adsorb water and other environmental species such as carbon dioxide, and therefore the calculated retention is an approximation. The chart below provides a brief description of each of the commercial sorbents tested.

[0018] [Table 1]

[0052] In general, a particular filter material was considered desirable for filtering a particular contaminant if it had relatively good adsorption and retention of the target species compared to other target species. A filter material with high adsorption to a target species but low retention was generally considered undesirable for filtering that species. Furthermore, a filter material with high adsorption to a first species was generally considered undesirable if it also had high adsorption / retention to one or more other species. Furthermore, a filter material with a retention capacity greater than 100% was also generally considered undesirable because the data would suggest that other species were being adsorbed during the retention phase. Because the tests were conducted under static conditions, the results can be considered a rough approximation of the performance of the material under dynamic, actual working conditions. Specific test results are discussed below for each of the contaminant types tested.

[0019] Alkane Filter Materials

[0053] In certain embodiments, the chemical filter material is configured to remove alkanes from the fluid stream. The chemical filter material may be specifically configured to remove butane from the fluid stream. In various embodiments, the chemical filter material is configured to capture and retain alkanes such as butane.

[0054] The adsorption / retention results for pentane and hexane from the above test procedure are shown in Figures 9A-9B and 10A-10B, respectively. It should be noted that the carbons performed similarly regardless of chain length, meaning that the removal of pentane may predict the removal of the target pollutant, butane, in some embodiments. Many of the carbon materials adsorbed similar amounts of alkanes. However, the alkane retention of Sample 3, Sample 5, and Sample 12 each appeared relatively good, meaning that they may all be effective butane adsorbents. However, Sample 12 also adsorbed other chemicals relatively well, so further analysis under dynamic conditions with multiple types of chemical pollutants is needed to predict its adsorption. Between Samples 3 and 5, Sample 3 had a slightly higher retention, which appears to be a relatively important performance heuristic. It is noted that Sample 11 had a relatively good alkane adsorption capacity, but a relatively low retention capacity. However, the above performance of Sample 11 may be desirable in certain embodiments.

[0055] In an embodiment, the chemical filter material is a microporous sorbent impregnated with one or more bases. The sorbent may be a microporous sorbent material. The sorbent may have a range of pore sizes, with one example being a pore size distribution of micropores and mesopores from 0.1 nm to 50 nm. In one particular example, the chemical filter material is a mesh granular microporous activated carbon material impregnated with 5% potassium iodide and 7.5% sodium hydroxide. The mesh carbon size may be 8×200, although other mesh sizes are also contemplated. One particular product example is grade RPPE 1034 supplied by Haycarb PLC. In another example, the alkane filter material is a granular microporous activated carbon mesh impregnated with 6-7% KI and 3-4% KOH. The carbon mesh size may be 12×20. One particular exemplary product is supplied by Haycarb PLC. In yet another example, the alkane filter material can incorporate granular activated carbon, such as Nuchar RGC, supplied by Ingevity, headquartered in North Charleston, South Carolina, USA. Such granular activated carbon can be configured as sheets, such as screens or mats.

[0020] Siloxane Filter Materials

[0056] In some embodiments, the chemical filter material is configured to remove siloxanes from the fluid stream. Generally, the siloxane capacity and retention of the chemical filter material is relatively high. In various embodiments, the chemical filter material is a mesoporous adsorbent.

[0057] The results of siloxane adsorption / retention from the above test procedure are shown in Figures 11A-11B. First, it should be noted that the retention capacity of almost all carbons was greater than 100%, while at the same time the adsorption capacity was relatively low. This indicates that the siloxane was not truly adsorbed, but rather the weight gain was caused by other species (such as water and / or carbon dioxide). Of course, the exception was Sample 10, which although this material adsorbed significantly more contaminants than the other samples, the retention did not exceed 100%, potentially indicating that it did indeed capture the siloxane target.

[0058] In one particular example, the siloxane filter material incorporates water washed activated carbon, such as product number RGUW 1016, supplied by Haycarb PLC (Colombo, Sri Lanka). In yet another example, the alkane filter material incorporates granular activated carbon, such as Nuchar RGC, supplied by Ingevity (Headquarters: North Charleston, South Carolina, USA). Such activated carbon can be configured as sheets, such as screens or mats.

[0021] VOC filter materials

[0059] In some embodiments, the chemical filter material is configured to remove volatile organic compounds (VOCs) from a fluid stream. In some embodiments, the chemical filter material is configured to remove toluene from a fluid stream. The chemical filter material generally has a relatively high capacity and retention for VOCs. In various embodiments, the chemical filter material comprises a sorbent having a pore size of less than 2 nm. A sorbent with a relatively small pore size can advantageously retain particularly small chemicals.

[0060] The toluene adsorption / retention results collected according to the above test procedure are shown in Figures 12A and 12B, respectively. Based on the data, there were four carbons identified as potential candidates for aromatic VOC filtration: Sample 2, Sample 7, Sample 12, and Sample 13. The specific VOC filtration material selected may depend on the specific embodiment in which the filter material is used, and the dynamic behavior of the material in real conditions. It should be noted that the filter material of Sample 12 is considered a candidate VOC filter material, but this carbon also adsorbs alkanes (discussed above), and therefore further analysis is required to predict the adsorption behavior under dynamic conditions.

[0061] In one particular example, the VOC filter material is a carbon air filter media, such as product H&V 5224 V2 supplied by Hollingsworth & Vose (Hatfeld, Germany). In yet another example, the VOC filter material is an activated carbon bead web impregnated with 1.1% by weight potassium carbonate (K2CO3). In yet another example, the VOC filter material is a water-washed activated carbon and PTFE (polytetrafluoroethylene) web, where the activated carbon is impregnated with potassium carbonate. In yet another example, the VOC filter material is a carbon laminate with meltblown granular media disposed on each surface of the carbon. The carbon layers are constructed in a mat configuration, which is granular carbon with a binder.

[0022] Filter Elements

[0062] 1 is an exemplary exploded schematic diagram of an exemplary chemical filter element consistent with various embodiments of the technology disclosed herein. Chemical filter element 100 comprises a first sheet of a first chemical filter material 110a having a first edge 112 and a second edge 114. Second edge 114 is opposite first edge 112 relative to filter element 100. First sheet 110a has a surface 111. Filter element 100 defines a first filtration flow path 130 from first edge 112 to second edge 114. First filtration flow path 130 is parallel to surface 111. First edge 112 is opposite second edge 114 relative to surface 111.

[0063] In this example, filter element 100 has a stack of multiple layers of sheets of chemical filter material 110, including a first sheet of material 110a. The multiple layers of sheets of filter material 110 are stacked such that a surface 111 of each sheet is generally parallel to the surfaces 111 of the other layers in the stack. Filtration flow channels 130 are defined between adjacent layers of sheets of filter material 110 in the stack. In this manner, there are multiple filtration flow channels 130.

[0023]

[0064] Similar to the first filter material sheet 110a, the chemical filter material sheets 110 each have a first edge 112, a second edge 114, a first surface 116, and a second surface 118. The first surface 116 is opposite the second surface 118. The first edge 112 cooperatively defines a first flow face 102 of the filter element 100, and the second edge 114 cooperatively defines a second flow face 104 of the filter element 100. The distance between the first flow face 102 and the second flow face 104 is the length of the filtration flow path 130 across the filter element 100. The flow path length may generally be configured to balance the pressure drop across the filter element and the desired exposure time of the contaminated fluid to the filter material within the filter element. Thus, the flow path length is not particularly limited. In some embodiments, the flow path length is at least 2 cm or 4 cm. The flow path length may generally be less than 160 cm. In some embodiments, the flow path length is less than 20 cm. In certain embodiments, the channel length ranges from 5 to 15 cm, 7 to 13 cm, or 9 to 11 cm.

[0065] The sheets of chemical filter material 110 may have a variety of configurations, which are described in more detail below. Generally, each sheet of chemical filter material 110 is identical, meaning that each sheet of chemical filter material 110 is made of the same combination of materials in the same configuration. However, in some embodiments, the sheets of chemical filter material 110 may each be the same filter material, but with different sheet sizes or physical configurations.

[0066] In this example, the channel layer 120 abuts the first sheet of chemical filter material 110. The channel layer 120, among other things, defines filtration channels 130 between the sheets of filter material 110. The channel layer 120 is a structure configured to direct fluid flow through the filter element 100 primarily along the surface of one or more sheets of filter material 110. The channel layer 120 can extend between a first flow face 102 and a second flow face 104 of the filter element 100. The channel layer 120 can have a first edge 122 that cooperates to define the first flow face 102, a second edge 124 that cooperates to define the second flow face 104, a first surface 126, and a second surface 128. The filtration channels 130 extend from the first edge 122 to the second edge 124. The filtration channels 130 are adjacent to the first surface 116 of the first sheet of filter material 110a. The filtration channel 130 is generally planar. The thickness of the filtration channel 130 is the thickness extending from the first surface 126 to the second surface 128.

[0067] The filter element in this example includes a plurality of channel layers 120. The sheets of chemical filter material 110 and the channel layers 120 are in an alternating stacked relationship such that the channel layers 120 are disposed between and abut the layers of sheets of filter material 110 in the stack.

[0024]

[0068] In some embodiments, the flow path layer 120 is configured to promote mixing of the fluids flowing through the filter element 100. In some embodiments, the flow path layer 120 is configured to minimize pressure drop. In some embodiments, the flow path layer 120 is comprised of a chemical filter material, such as a sorbent material.

[0069] The flow path layer 120 can be configured as a mesh or screen type structure with relatively large intersecting fibers or strands compared to the sheet of filter material. In some embodiments, the flow path layer 120 each comprises relatively large fibers, and the corresponding large pores of the flow path layer contribute to the permeability of the filter element. In some embodiments, the flow path layer 120 can be configured of a sponge or foam material that defines relatively large pores that cumulatively define the filtration flow paths 130. The flow-by filters disclosed herein are configured so that fluid generally flows across the surfaces of the layers, but the size of the pores or openings is measured in a flow-through direction perpendicular to the surface of the sheet of filter media. That is, the pore size is measured and selected to provide the desired flow characteristics for the flow-by configuration, even if the filter is not positioned relative to the material to flow through the thickness of the filter material.

[0070] A common technique used to measure the pore size of either or both of the flow path layer and the first sheet of the first chemical filter material is capillary flow porometry. This technique uses capillary theory to calculate the pore size based on the relationship between the surface tension of the liquid, the pressure, and the diameter of each pore. This measurement method uses a non-reactive liquid to completely wet and fill the pores of the porous material with a fluid that has a very low contact angle with the material. The saturated material is then pressurized with a non-reactive gas while measuring the pressure and air flow until all of the liquid is forced out of the pores. In this technique, smaller pore sizes require more pressure to force the liquid out of the pores, and larger pore sizes have the opposite effect. The collected data is then compared to pressure and flow measurements of clean, dry samples to calculate the pore size distribution. In this measurement, the mean flow pore size is defined as the point where the wet sample air flow is equal to half the dry sample air flow.

[0071] In general, for various embodiments, the mean flow pore size of the flow path layer, as measured in a flow-through orientation using the techniques described above and / or other techniques, is greater than the mean flow pore size of the sheet of chemical filter material (also measured in the flow-through direction). In some embodiments, the chemical filter material does not define pores.

[0025]

[0072] The thickness, spacing, and arrangement of the fibers or strands, along with the overall thickness of the flow channel layer, can be varied to achieve the desired filtration performance. In one exemplary embodiment, the overall thickness of the flow channel layer is in the range of about 200 μm to 5000 μm, more specifically in the range of 200 μm to 2000 μm, and more specifically in the range of 500 μm to 1000 μm, although the thickness can be less than or greater than these thickness ranges.

[0073] 1, the first flow face 102 is opposite the second flow face 104 relative to the filter element 100. In various embodiments, the first flow face 102 is parallel to the second flow face 104. Each of the sheets, filter material 110, and flow path layer 120 may be planar. The surfaces of the first sheet of filter material 110a and the flow path layer 120 are each substantially flat in the current embodiment, but may be alternatively configured as described in more detail herein.

[0026]

[0074] In some embodiments, the edges of the flow path layers 120 and the edges of the sheets of filter material 110 are generally positioned relative to one another in the stack. In certain embodiments, to maximize the amount of material available for filtration in a given volume, the stack generally fills the housing or other structure in which it is placed. However, in some embodiments, the stack of sheets of filter material 110 and flow path layers 120 can include layers of different sizes and / or shapes such that the edges of the various layers can be staggered in regular or irregular arrangements along the stack. In any of the configurations in which the edges of the layers are not aligned along a plane, the flow face is the non-planar area cumulatively defined by the edges of the layers that face the direction in which the material flows into or out of the filter element 100.

[0075] Additionally, while the first edge 112 and second edge 114 of each of the layers of filter material 110 are parallel in this example, in some other embodiments, the first edge 112 is non-parallel to the second edge 114. Further, in some embodiments, the first edge 112 and / or second edge 114 of a first sheet of filter material 110a is non-parallel to the first edge 112 and / or second edge 114 of another sheet of filter material in the stack. Further, while the edges of the filter material are shown as forming straight lines, in some embodiments, one or more of the edges can form curves or line segments having an intersection.

[0076] In use, the stack of alternating sheets of filter material and flow path layers can be placed into a housing or other structure that, when placed into the housing, compresses the layers a desired amount and / or maintains the stack of layers at a particular level of compression. In one exemplary embodiment, the surface area of ​​the chemical filter material at the flow face of the compressed stack of material defines about 40-80% of the total area of ​​the flow face.

[0077] The number of layers in the stack forming the filter element can vary widely, but can be in the range of 5 to 30 layers per inch, more specifically 10 to 20 layers per inch, and even more specifically 15 to 25 layers per inch. However, it is understood that a particular filter element may incorporate more or fewer layers. The number of layers may depend on factors such as the volume of the fluid stream that the filter element is configured to accommodate and the amount of the particular contaminant that the filter element is configured to remove from the fluid stream. In one embodiment, the filter element 100 is 0.5 m 3 / min~23m 3 In one embodiment, the filter element 100 is configured to accommodate a fluid flow rate in the range of 3-6 m / min. 3 / min, 5~11m 3 / min or 6~13m 3 In one embodiment, the filter element 100 is configured to accommodate a fluid flow in the range of 6-13 m / min. 31 / min range, however, the filter element can be configured to accommodate greater and lesser fluid flow rates depending on the particular operating environment of the filter element.

[0027]

[0078] FIG. 2 shows a schematic example of a filter element 200 according to an embodiment. Descriptions of filter elements elsewhere herein generally apply to the present description unless inconsistent with the present design. The exemplary filter element 200 has a first flow surface 202 and a second flow surface 204. The exemplary filter element 200 defines a filtration flow path 230 from the first flow surface 202 to the second flow surface 204. The filter element 200 is comprised of multiple layers of filter material 210 in a laminated configuration. Each of the layers of filter material 210 has a surface 211. The filtration flow path 230 extends generally parallel to the surface(s). The first flow surface 202 can be defined by a first edge 212 of each of the multiple layers of the sheet of chemical filter material 210. The second flow surface 204 can be defined by a second edge 214 of each of the multiple layers of the sheet of chemical filter material 210. Thus, the filtration channels 230 extend from the first edge 212 to the second edge 214 of each of the sheets of filter material 210 .

[0079] The filter element 200 of Figure 2 corresponds to the filter element shown in Figure 1, with the channel layers alternating with the sheets of filter material in the stack. In certain other embodiments, the filter element 200 omits the channel layers, such that each layer of the stack is a sheet of filter material. In such an example, each sheet of filter material 210 abuts at least one adjacent sheet of filter material 210.

[0028]

[0080] In some embodiments, the sheets of filter material 210 are each individual, separate sheets. However, in certain other embodiments, the sheets of filter material 210 may be defined by a single, elongated sheet of filter material 210 that is pleated to define the individual sheets of filter material 210. For example, each sheet of filter material 210 can be joined to one or more adjacent sheets along a third edge 216 and a fourth edge 218 opposite the third edge 216, where the third edge 216 and the fourth edge 218 define a fold between the adjacent sheets.

[0081] While this exemplary filter element 200 forms a cube or rectangular prism, it will be understood that filter elements consistent with the technology disclosed herein may be of a variety of other shapes. In some embodiments, the filter element may define, for example, a cylindrical shape. In some embodiments, the filter element may define a non-geometric shape. Additionally, as discussed with reference to FIG. 1, the edges of a sheet of filter material are not necessarily aligned and are not necessarily parallel, and thus the corresponding flow faces 202, 204 of the filter element 200 defined by the edges are not necessarily planar, and if they are planar, the flow faces 202, 204 are not necessarily parallel to one another.

[0029]

[0082] In some embodiments, one or more layers of filter material 210 may have one or more holes 215 that extend completely through the sheet of filter material 210 (i.e., from a first surface to a second surface). One or more holes 215 are discontinuities that penetrate across the surface of filter material 210, as opposed to, for example, holes between particles that form the structure of the sheet of filter material 210. Holes 215 may be formed in the sheet of filter material after the sheet of filter material is formed. In some embodiments, holes 215 have a maximum cross-sectional dimension (e.g., diameter or diagonal measurement) between 50 μm and 5000 μm. The cross-sectional dimensions of holes 215 may be equal or may have a variety of cross-sectional dimensions. The shapes of holes 215 may be the same or different. Holes 215 may be uniformly positioned across the surface of filter material sheet 210 or randomly positioned across filter material sheet 210. In some embodiments, the holes 215 may form a pattern across the sheet of filter material 210 and / or form a gradient in which the density of holes across the sheet of filter material 210 varies across the sheet of filter material 210 .

[0030]

[0083] In some embodiments, the holes 215 in one layer of filter material are not aligned with the holes 215 in an adjacent layer of filter material. The holes 215 generally allow fluid to flow from a first filtration flow path defined between a first pair of adjacent sheets of filter material in the filter element 200 to a second filtration flow path defined between a second pair of adjacent sheets of filter material. The one or more holes can advantageously reduce the pressure drop from the first flow surface 202 to the second flow surface 204 of the filter element 200. It is noted that the incorporation of such holes 215 does not substantially change the overall flow path of fluid through the filter element 200, i.e., the filtration flow path 230 is recognized as being substantially planar.

[0084] In various embodiments where each of the layers forming filter element 200 is a sheet of filter material 210, each of the sheets of filter material can be substantially flat. In other embodiments, the sheets of filter material can define spacer structures on one or more surfaces that are configured to create channels with an abutting sheet of filter material 210. In some embodiments, the spacer structures include embossments extending between a first edge and a second edge.

[0031]

[0085] 3A and 3B show schematic examples of sheets of embossed filter material 310, 350. Such sheets of filter material 310, 350 can be laminated with other sheets of filter material for the filter elements described above, or for other filter element configurations disclosed herein, such as the coiled arrangement described in more detail below.

[0086] The sheet of filter material in FIG. 3A has a first surface 311, a first edge 312, and a second edge 314, the second edge 314 being opposite the first edge 312. The sheet of filter material 310 is configured to define a filtration flow path in a direction parallel to the first surface 311 from the first edge 312 to the second edge 314. The first surface 311 has an embossment 313 that extends between the first edge 312 and the second edge 314. In this example, the embossment 313 is a separate ridge that extends outwardly from the first surface 311. The embossment 313 helps to define a filtration flow path 330 across the first surface 311 from the first edge 312 to the second edge 314. The filtration flow path 330 is generally defined around the embossment 313. When sheet of filter material 310 is stacked with an abutting sheet of filter material, filtration channels 330 are defined in the spaces between the abutting sheets of filter material, first surface 311, and embossments 313. The abutting sheets of filter material may also define embossments on one or more surfaces.

[0087] In some embodiments, the second surface of the filter material 310 (opposite the first surface 311) also defines embossments. The embossments may be of a different configuration as compared to the embossments on the first surface 311 or of the same configuration. While this exemplary embossments are shown as separate nodules, in other embodiments the embossments may be a plurality of separate elongated ridges. Additionally, while in this example the embossments are protrusions, in other embodiments one or more of the embossments may be depressions, an example of which is shown and described with reference to FIG. 3B.

[0088] The sheet of filter material in FIG. 3B has a first surface 351, a first edge 352, and a second edge 354, the second edge 354 being opposite the first edge 352. The sheet of filter material 350 is configured to define a filtration flow path in a direction parallel to the first surface 351 from the first edge 352 to the second edge 354. The first surface 351 has embossments 353 extending between the first edge 352 and the second edge 354. In this particular embodiment, one or more embossments 353 extend from the first edge 352 to the second edge 354. In this example, the embossments 353 are individual channels in the first surface 351. The embossments 353 serve to define a filtration flow path 360 across the first surface 351 from the first edge 352 to the second edge 354. The filtration flow path 360 is generally defined by the embossments 353. When sheet of filter material 350 is stacked with an abutting sheet of filter material, filtration channels 360 are defined in the spaces between the abutting sheets of filter material, first surface 351, and embossments 353.

[0089] In this example, the embossments 353 extend from the first edge 352 to the second edge 354, but in other embodiments, one or more of the embossments 353 can extend to an intermediate distance between the first edge 352 and the second edge 354. Here, the embossments 353 are wavy, but in other embodiments, the embossments are straight. The wavy embossments 353 can advantageously mix the flowing fluid to maximize the interaction between the chemical components in the flowing fluid and the filter material 350. In this example, the embossments 353 extend in a direction generally parallel to the filtration flow path 360, but in other embodiments, the embossments can extend in a direction generally perpendicular to the filtration flow path. Instead of being formed as depressions in the surface of the filter material 350 as described above, the embossments can be formed as protrusions extending outward from the surface of the filter material 350.

[0090] Similar to the description of FIG. 3A, a second surface opposite the first surface 351 may also have embossments, or the second surface may be substantially flat without embossments.

[0032]

[0091] FIG. 4 shows another exemplary flow-by filter element consistent with some examples. Descriptions of filter elements elsewhere in this specification generally apply to the present description unless inconsistent with the present design. The exemplary schematic filter element 400 of FIG. 4 includes a sheet of chemical filter material 410 having a first surface 416, a second opposing surface 418, a first edge 412, and a second opposing edge 414. A filtration flow path 430 is defined parallel to the first surface 416. The filtration flow path 430 extends from the first edge 412 to the second edge 414.

[0092] 1 and 2, in this example, the filter element 400 is comprised of a sheet of filter material 410 in a coiled configuration about a central axis x. The sheet of filter material 410 is elongated. A first edge 412 of the sheet of filter material 410 defines a first flow surface 402, and a second edge 414 defines a second flow surface 404. Each of the first edge 412 and the second edge 414 is an elongated edge of the sheet of filter material 410.

[0093] While this example shows the filter media in a generally cylindrical configuration with a generally circular cross-section, it will be understood that other coiled configurations are possible, hi one embodiment, the cross-section of the coiled media through the central axis x may be oval or polygonal.

[0094] In this example, the channel layer 420 abuts the sheet of filter material 410 and has a first edge 422 that cooperate to define a first flow face 402, a second edge 424 that cooperate to define a second flow face 404, a first surface 426, and an opposing second surface 428 (not directly visible). The channel layer 420 may correspond to channel layers described elsewhere herein, except as specified in the current discussion and / or figures. The channel layer 420 defines filtration channels 430 from the first flow face 402 to the second flow face 404. The filtration channels 430 extend axially, i.e., from the first edge 422 to the second edge 424 of the channel forming layer 420. The filtration channels 430 abut the first surface 416 of the sheet of filter material 410.

[0095] In this example, the flow channel layer 420 is an elongated sheet. The flow channel layer 420 is arranged in a coil around a central axis x. The flow channel layer 420 is in contact with an adjacent filter material sheet 410, and the pair of layers 410, 420 is wound or coiled around itself or around a core 440 extending along the longitudinal axis x to form the filter element 400. In this configuration, fluid can flow across the rolled surface of the first sheet of filter material 410 along the flow channel layer 420 from the top (with respect to the figure) of the coiled layer (i.e., one end of the filter element 400) to the bottom (i.e., the opposite end of the filter element 400) of the coiled layer. Alternatively, the fluid can flow in the opposite direction (i.e., from the bottom of the roll to the top of the roll with respect to the figure). The first flow face 402 is opposite the second flow face 404 with respect to the filter element 400. In this example, the first flow face 402 is parallel to the second flow face 404. The first sheet of filter material 410 and the channel layer 420 are each substantially flat in this embodiment, although in some instances, one or both of the layers define a plurality of embossments, as described above with reference to Figures 3A and 3B.

[0033]

[0096] It should be noted that unlike the previously disclosed embodiments, here the sheet of filter material 410 does not extend generally in a plane. Rather, the sheet of filter material 410 is coiled, and thus each of the surfaces 416, 418 is also coiled. However, the filtration flow passages 430 extend in an approximately straight line in the axial direction from one flow surface to the other.

[0034]

[0097] It should be noted that in various implementations, such as the alternative embodiment of Figure 4, the channel layer is omitted. In such examples, the sheet of filter material may define an embossment extending between a first edge 412 and a second edge 414, as described above. Additionally, as described above with reference to Figure 2, in some embodiments, the sheet of filter material may have one or more holes extending through the sheet of filter material 410.

[0035]

[0098] FIG. 5 illustrates yet another exemplary filter element consistent with certain embodiments. Descriptions of filter elements elsewhere herein generally apply to the present description unless inconsistent with the present design. The exemplary schematic filter element 500 of FIG. 5 includes a first sheet of filter material 510 having a first edge 512 defining a first flow face 502, a second edge 514 defining a second flow face 504, a first surface 516, and a second surface (not visible) opposite the first surface. Abutting the first sheet of filter material 510 is a flow path layer 520. The flow path layer 520 includes a first edge 522 cooperating to define the first flow face 502, a second edge 524 cooperating to define the second flow face 504, and a first surface and a second surface (not visible) opposite the first surface. The flow channel layer 520 defines a filtration flow channel 530 from a first flow face 502 to a second flow face 504 of the filter element 500. The filtration flow channel 530 extends from a first edge 522 to a second edge 524. The filtration flow channel 530 is parallel to and abuts at least one surface of the filter material 510. Multiple filtration flow channels 530 may be defined between adjacent layers of filter material 510 in the stack.

[0099] In this example, the sheets of filter material 510 and the sheets of flow path layers 520 are alternating disks in a stacked configuration. Each flow path layer 520 abuts at least one adjacent first sheet of filter material 510. Each of the disks of the first sheet of filter material 510 and the flow path layers 520 are stacked along a longitudinal axis x to form the filter element 500. Each of the disks defines an opening, which generally overlaps to define a portion of a filtration flow path. The stack of disks cumulatively defines an outer circumferential surface, which is a first flow surface 502, and an inner circumferential surface, which is a second flow surface 504. In this example, the outer circumferential surface and the inner circumferential surface are shown as cylindrical, although other shapes are certainly contemplated.

[0010] The filtration flow paths 530 that cross each layer of the filter media 510 are generally linear. In an example consistent with the present embodiment, the fluid is configured to flow radially from one flow surface to the other flow surface. For example, the fluid is configured to flow in a flow-by manner from the first flow surface 502 of the element to the opening (second flow surface 504) of the filter element 500, or from the opening (second flow surface 504) to the first flow surface 502. That is, the flow of the fluid through the filter element 500 is generally perpendicular to the longitudinal axis x. Unlike some of the examples above, in this example, the first flow surface 502 is not opposite the second flow surface 504. In this example, the first flow surface 502 surrounds the second flow surface 504. More specifically, in this example, the first flow surface 502 is concentric with the second flow surface 504, meaning that the first flow surface 502 and the second flow surface 504 share a central axis x.

[0101] In various embodiments, the flow channel layer 520 may be omitted. In some embodiments, one or both surfaces of each sheet of filter material 510 may have one or more embossments, as described above. In other embodiments, each sheet of filter material 510 may have no embossments.

[0036]

[0102] FIG. 6 illustrates yet another exemplary filter element with a flow-through configuration consistent with the technology disclosed herein. The filter element descriptions elsewhere herein generally apply to the present description unless inconsistent with the present design. The layer materials may generally be consistent with the following discussion. The exemplary schematic filter element 600 includes a first layer 610 of a sheet of filter material having a first edge 612 defining a first flow surface 602, a second edge 614 defining a second flow surface 604, a first surface 616, and a second surface 618 (not directly visible) opposite the first surface. A second layer of a sheet of filter material 620 is adjacent to the first sheet of filter material 610. The second sheet 620 includes a first edge 622 that cooperates to define the first flow surface 602, a second edge 624 (partially visible) that cooperates to define the second flow surface 604, a first surface 626, and a second surface 628 (not directly visible). The second sheet of filter material 620 defines a filtration flow passage 630 from the first flow surface 602 to the second flow surface 604. The filtration flow passage 630 extends from the first edge 612, 622 to the second edge 614, 624. The filtration flow passage 630 is generally parallel to the surfaces of the sheets of filter material 610, 620.

[0103] The first layer of filter material 610 and the second layer of filter material 620 are in an alternating stacked relationship such that the second layer of filter material 620 is disposed between the two first layers of filter material 610. A plurality of filtration flow paths 630 are defined between adjacent layers of filter material 610, 620 in the stack. In this embodiment, the first layer of filter material 610 is of fluted configuration, meaning that the first layer of filter material 610 defines flutes 613 extending from the first flow surface 602 to the second flow surface 604. The flutes 613 are a type of spacer structure instead of the embossments described above. The flutes 613 specifically define the filtration flow paths 630 between the first flow surface 602 and the second flow surface 604. The first layer of filter material 610 is generally a sheet of filter material. The second filter material layer 620 may be the same type of filter material sheet as the first filter material layer 610, although the structural configuration of the second filter material layer 620 is different. In this example, each of the second layers of filter material 620 is substantially planar.

[0104] First flow face 602 is opposite second flow face 604 relative to filter element 600. In this example, first flow face 602 is parallel to second flow face 604, but in other embodiments, flow faces 602, 604 are not parallel. As with the previous embodiment, edges of first layer of filter material 610 and second layer of filter material 620 are generally positioned relative to one another in the stack.

[0037]

[0105] 7 is yet another exemplary schematic diagram of an exemplary chemical filter element 700 consistent with various embodiments of the technology disclosed herein. Chemical filter element 700 includes a first sheet of a first chemical filter material 710 having a first edge 712 and a second edge 714. Second edge 714 is opposite first edge 712 relative to filter element 700. First sheet 710 includes a first surface 711 and a second surface 713. Filter element 700 defines a first filtration flow path 730 from first edge 712 to second edge 714. First filtration flow path 730 is parallel to surface 711.

[0106] In this example, the filter element 700 has multiple layers of sheets of chemical filter material 710 (including a first sheet 710 of filter material), each layer extending radially outward from a filter core 732. The filter core 732 may be a plug that helps define filtration flow paths 730 across the multiple sheets of filter material. The filter core 732 may be configured to prevent fluid flow from bypassing the filter material 710. Each of the multiple sheet layers 710 has a third edge 716 bonded to the filter core 732 and a fourth edge 718 positioned radially outward from the third edge 716 and the filter core 732. In this example, the surfaces 711, 713 of each sheet are not parallel to the surfaces 711, 713 of the multiple other layers in the filter element 700. The first filtration flow paths 730 are defined between adjacent layers of sheets 710 in the filter element 700.

[0107] Similar to the first filter material sheet 710, the chemical filter material sheets 710 each have a first edge 712, a second edge 714, a first surface 711, and a second surface 713. The first surface 711 is opposite the second surface 713. The first edge 712 cooperates to define a first flow face 702 of the filter element 700, and the second edge 714 cooperates to define a second flow face 704 of the filter element 700. Thus, the first flow face 702 is opposite the second flow face 704 relative to the filter element 700. In one embodiment, the first flow face 702 is parallel to the second flow face 704, although other configurations are contemplated in which the first flow face 702 is not parallel to the second flow face 704. The sheets of filter material 710 (and the flow path layer, if included) may each be planar, as shown. The distance between first flow surface 702 and second flow surface 704 is the length of a filtration flow path 730 across filter element 700 .

[0108] The first edge 712 and second edge 714 of each of the layers of filter material 710 are parallel in this example, but in other embodiments, the first edge 712 is not parallel to the second edge 714. Furthermore, in some embodiments, the first edge 712 and / or second edge 714 of a first sheet of filter material 710 is not parallel to the first edge 712 and / or second edge 714 of another sheet of filter material within the filter element 700. Furthermore, while the edges of the sheets of filter material 710 are shown as forming straight lines, in some embodiments, one or more of the edges can form curves or line segments having intersections. In this example, the sheets of filter material 710 are each generally planar, but in other embodiments, the sheets of filter material 710 can each define discontinuities, such as holes or embossments.

[0109] The sheets of chemical filter material 710 may have a variety of configurations, as described elsewhere herein. Generally, each sheet of chemical filter material 710 is identical, meaning that each sheet of chemical filter material 710 is composed of the same combination of materials in the same configuration. However, in some embodiments, each sheet of chemical filter material 710 may be the same filter material, but with different sheet sizes or alternating configurations. Further, in this example, each of the multiple sheets of filter material are separate, discrete sheets. However, in other embodiments, the multiple sheets of filter material are formed from a continuous sheet of pleated chemical filter material. In such configurations, the third edge 716 and the fourth edge 718 of each of the multiple filter material sheets 710 may be folds that separate one sheet of filter material from an adjacent sheet of filter material.

[0110] In this example, the channel layer is omitted, although in some other embodiments, multiple channel layers may be disposed between adjacent sheets of filter material 710. If included, the channel layer may be coincident with the channel layers described above, but in this embodiment, is coupled to the filter core 732 at one edge and extends radially outward from the filter core 732.

[0111] A fourth edge 718 of each of the plurality of sheets of filter material forms a peripheral boundary of the filter element 700. In various embodiments, the filter element 700 is configured to be received by a housing that blocks fluid flow around the outer boundary of the filter element 700 and directs fluid flow from the first edge 712 to the second edge 714 across the sheet of filter material 710. In certain embodiments, the housing is sized to displace the fourth edge 718 of each of the plurality of sheets of filter material upon insertion into the housing such that each of the plurality of sheets of filter material bends to form a curved surface between the third edge 716 and the fourth edge 718.

[0038] Filtration Assembly

[0112] A filtration assembly consistent with the technology disclosed herein can incorporate multiple chemical filter elements as described above. The filter elements are generally arranged in series along a filtration flow path. Each chemical filter element can be configured to target a particular chemical species within its intended operating environment. In some embodiments, each chemical filter element in an assembly is configured to target a different chemical species than the other chemical filter elements in the assembly. In some embodiments, each of the chemical filter elements in an assembly is constructed of a different type of chemical filter material, meaning that each chemical filter element has a chemical filter material with a different pore size distribution and / or different chemical treatment than the other chemical filter elements in the assembly.

[0113] 8 is an exemplary filter assembly consistent with the technology disclosed herein. Filter assembly 800 includes a housing 850. Housing 850 defines an inlet 852 and an outlet 854. A plurality of chemical filter elements 810a-e are disposed within housing 850. Filter elements 810a-e are disposed in series with respect to fluid flow from inlet 852 to outlet 854. Spacing regions 860a-d are between successive adjacent filter elements 810a-e.

[0114] Each of the chemical filter elements 810a-e may correspond to the chemical filter elements described herein with reference to Figures 1-7. Thus, each of the chemical filter elements 810a-e may include a chemical filter material configured as a sheet having a first edge and a second edge, each defining a filtration flow path extending parallel to a surface of the sheet, the filtration flow path extending from the first edge to the second edge. Although the first edge and the second edge are not necessarily specifically visible in Figure 8, the first edge defines a first flow face 802a-e of each filter element 810a-e, and the second edge defines a second flow face 804a-e of the filter element 810a-e.

[0115] Although not visible in this view, one or more of the plurality of filter elements 810a-e may have a flow path layer that defines a filtration flow path, as described above. Such a flow path layer may abut a surface of the sheet of filter material between a first edge and a second edge, as described above. Additionally, one or more of the chemical filter elements 810a-e may be constructed from a stack of multiple layers of a sheet of chemical filter material, with the filtration flow paths defined between adjacent layers in the stack. Such exemplary configurations are described above with reference to Figures 1, 2, 5, and 6. In certain embodiments, the filter element may have a stack of multiple flow path layers that define a first filtration flow path, with each flow path layer being disposed between and abutting layers of the sheet of first chemical filter material in the stack, as described above with reference to Figures 1, 5, and 6.

[0116] One or more of the plurality of filter elements 810a-e can include a sheet of filter material arranged in a coiled configuration about a central axis, as described above with reference to FIG. 4. The filter elements 810a-e can include a flow path layer in a coiled configuration about a central axis. The filter elements 810a-e can include an embossment defined by the sheet extending between a first edge and a second edge. One or more of the plurality of filter elements 810a-e can include a sheet of filter material with one or more holes extending completely through the sheet.

[0117] One or more of the plurality of filter elements 810a-e can include a plurality of sheets of filter material arranged to extend radially outward from a filter core as described above with reference to FIG. 7. The filter elements 810a-e can include a flow path layer. The filter elements 810a-e can include an embossment defined by the sheet extending between a first edge and a second edge. One or more of the plurality of filter elements 810a-e can include a sheet of filter material with one or more holes extending completely through the sheet.

[0039]

[0118] In various embodiments, the filter assembly is configured to form a seal around each flow face of the filter elements 810a-e to prevent the fluid to be filtered from bypassing the flow path extending through each filter element. The seal may be, for example, a gasket disposed between the filter element and the inner surface of the filter housing 850 at a location adjacent or abutting each flow face. In some embodiments, the individual filter elements 810a-e may each be housed separately such that each filter element 810a-e has an element housing configured to be inserted into the filter assembly housing 850. The element housing may define a flow path through the filter elements 810a-e from a first flow face to a second flow face and prevent the fluid from bypassing the filter material of the filter element. In such an example, a seal may be defined between the filter element housing and the filter assembly housing 850.

[0119] One or more of the plurality of chemical filter elements 810a-e may be an adsorptive filter element, hi some embodiments, at least one of the chemical filter elements is a chemisorptive coated substrate.

[0040]

[0120] In some embodiments, the one or more chemical filter elements include an acid gas filter material, such as a non-adsorbent substrate coated with a base. In one example, the one or more chemical filter elements include a sorbent impregnated with a base. In an exemplary embodiment, the first chemical filter element 810a includes a sorbent impregnated with a base. In some embodiments, the filter element with the acid gas filter material is in the most upstream position in the filter assembly. Such a configuration can advantageously neutralize and / or remove acid gases from the fluid stream before the acid gases negatively interact with subsequent filter elements in the assembly, for example, promoting degradation of the subsequent filter elements.

[0041]

[0121] In some embodiments, one or more chemical filter elements include an ammonia filter material, such as an acid-coated non-adsorbent substrate or an acid-impregnated sorbent. In an exemplary embodiment, a second chemical filter element 810b of the plurality of chemical filter elements 810a-e includes an acid-impregnated sorbent. The acid-impregnated sorbent may be, for example, citric acid. In this example, the filter element with the ammonia filter material is positioned downstream of the filter element with the acid gas filter material. Although ammonia can contribute to the deactivation of various chemical filter materials, in some embodiments, ammonia is not as corrosive to the filter assembly as acid gas.

[0122] Locating an ammonia filter element downstream of an acid gas filter element can advantageously provide an opportunity for the trapped ammonia to trap various acidic species (e.g., CO2, SOx, NOx, and H2S) that may remain in the fluid stream after exiting the filter element having the acid gas filter material. Without being bound by theory, it is believed that ammonia traps the H2S in citric acid. + Combines with NH4 + After forming NH3, it can react with acid anions to act as a secondary neutralizing agent. As a result, the ammonia filter element can advantageously exhibit acid gas removal over time, as the ammonia filter material becomes saturated with ammonia and can act as an additional acid species chemisorbent.

[0042]

[0123] In an embodiment, one or more chemical filter elements include an alkane filter material. The chemical filter elements may be specifically adapted to remove butane from the fluid stream. In an exemplary embodiment, a third chemical filter element 210c of the plurality of filter elements 810a-810e has an alkane filter material. In an embodiment, the third chemical filter element 810c is downstream of the second chemical filter element 810b.

[0043]

[0124] In some embodiments, one or more of the plurality of chemical filter elements 810a-e include a siloxane filter material. In one example, a fourth chemical filter element 210d of the plurality of chemical filter elements 810a-e includes a siloxane filter material. In some embodiments, the siloxane filter element is downstream of the acid gas filter element, the ammonia filter element, and the alkane filter element. In this example, the fourth filter element 810d is disposed downstream of the third filter element 810c.

[0044]

[0125] In some embodiments, one or more of the plurality of chemical filter elements 810a-e includes a VOC filter material. In one example, a fifth chemical filter element 810e of the plurality of chemical filter elements 810a-e includes a VOC filter material. In some embodiments, the VOC filter element is downstream of the acid gas filter element, the ammonia filter element, and the alkane filter element. In some embodiments, the VOC filter element is downstream of the siloxane filter element. In some other embodiments, the siloxane filter element is downstream of the VOC filter element. In this example, the fifth chemical filter element 810e is downstream of the fourth chemical filter element 810d.

[0126] In this example, filter assembly 800 has five chemical filter elements 810a-e, although fewer chemical filter elements or more filter elements may be incorporated into assembly 800.

[0045]

[0127] Spacing regions 860a-d may be defined between adjacent chemical filter elements 810a-e. Spacing regions 860a-d define a flow path from an upstream chemical filter element (e.g., first chemical filter element 810a) to a downstream chemical filter element (e.g., second chemical filter element 810b). Spacing regions 860a-d may advantageously reduce pressure drop along filtration flow path 830 from housing inlet 852 to housing outlet 854. Spacing regions 860a-d may advantageously promote gas mixing, thereby enhancing exposure of contaminants to the chemical filter material. In certain embodiments, spacing regions 860a-d may advantageously prevent one or more chemical filter elements 810a-e from reacting with adjacent chemical filter elements 810a-e, such as when a base-impregnated sorbent is disposed adjacent to an acid-impregnated or acid-washed sorbent. Spacing regions 860a-d may advantageously prevent migration of chemicals between adjacent chemical filter elements 810a-e. In some embodiments, the filter assembly does not have a spacing region between at least two adjacent chemical filter elements 810a-e.

[0046]

[0128] In an embodiment, the particle filters 870a-d are disposed in the spacing regions 860a-d downstream of one or more of the chemical filter elements 810a-e. The particle filters 870a-d may each be advantageously configured to capture any particles shed by the chemical filter elements 810a-e. The particle filters 870a-d generally have a flow-through configuration in which fluid flows through the sheets of filter media of the particle filters 870a-d. Thus, a flow path extends through each of the particle filters 870a-d. In an embodiment, the assembly 800 omits the particle filters 870a-d disposed in the spacing regions. In an embodiment, the particle filter 870e is disposed adjacent to the housing outlet 854 and across the filtration flow path 830. Such a particle filter 870e may be disposed at the outlet 854 or between the outlet 854 and the last chemical filter element in series (the fifth chemical filter element 810e in this example). In one embodiment, the particulate filter is disposed within housing 850 upstream of the most upstream chemical filter element (here, first chemical filter element 810a).

[0047]

[0129] In some embodiments, one or more of the particulate filter elements incorporate a chemical filtration component, such as a sorbent or chemically reactive fiber, hi other embodiments, each of the particulate filter elements is free of a chemical filtration component.

[0130] The length of the filtration flow path 830 of the filter assembly 800 corresponds to at least the sum of the flow path length of each of the plurality of filter elements 810a-e, the length of each spacing region 860a-d (if included), and the distance between the last filter element 804e in series and the downstream particulate filter 870e (if included). The length of the filtration flow path 830 from the inlet 852 to the outlet 854 of the filter assembly 800 is not particularly limited and can generally be a balance between the desired pressure drop across the assembly at the required fluid flow rate and filtration efficiency. In various embodiments, the length of the filtration flow path 830 from the inlet 852 to the outlet 854 of the filter assembly 800 is at least 20 cm. In various embodiments, the length of the filtration flow path 830 from the inlet 852 to the outlet 854 of the filter assembly 800 is less than 1500 cm, 1000 cm, 500 cm, or 100 cm. In one embodiment, the length of filtration flow path 830 from inlet 852 to outlet 854 of filter assembly 800 is in the range of 40-60 cm. In one particular example, the length of filtration flow path 830 from inlet 852 to outlet 854 of filter assembly 800 is 50 cm.

[0048] Exemplary Filtration Assembly

[0131] Embodiment 1: A filter assembly comprising:

[0132] housing;

[0133] a first chemical filter element comprising a first sheet of a first chemical filter material having a first edge and a second edge, wherein a first filtration flow path is defined parallel to a surface of the first sheet and extends from the first edge to the second edge; and

[0134] a second chemical filter element including a second sheet of a second chemical filter material having a first edge and a second edge, wherein a second filtration flow path is defined parallel to a surface of the second sheet and extends from the first edge to the second edge, wherein the first chemical filter element and the second chemical filter element are disposed within the housing, and the second chemical filter element is disposed downstream of the first chemical filter element; a filter assembly.

[0049]

[0135] Embodiment 2: A filter assembly as described in any one of embodiments 1 and 3-22, further comprising a spacing region between the first chemical filter element and the second chemical filter element, wherein the spacing region defines a flow path from the first chemical filter element to the second chemical filter element.

[0050]

[0136] Embodiment 3: The filter assembly of any one of embodiments 1, 2 and 4-22, further comprising a particle filter disposed in the spacing region, wherein the particle filter comprises a particle filtration medium and the flow path extends through the particle filtration medium.

[0051]

[0137] Embodiment 4: A filter assembly as described in any one of embodiments 1 to 3 and 5 to 22, wherein the first chemical filter element further comprises a stack of multiple layers of sheets of the first chemical filter material including the first sheet, and the first filtration flow path is defined between adjacent layers in the stack.

[0052]

[0138] Embodiment 5: A filter assembly as described in any one of embodiments 1 to 4 and 6 to 22, wherein the first chemical filter element further comprises a stack of a plurality of flow path layers defining the first filtration flow path, wherein each of the flow path layers is disposed between and abuts a layer of the sheet of the first chemical filter material in the stack.

[0053]

[0139] Embodiment 6: The filter assembly of any one of embodiments 1-5 and 7-22, wherein the first sheet of the first chemical filter material is configured in a coil about a central axis.

[0054]

[0140] Embodiment 7: A filter assembly as described in any one of embodiments 1-6 and 8-22, wherein the first chemical filter element further comprises a flow path layer abutting the first sheet of the first chemical filter material, wherein the flow path layer defines the first filtration flow path and is coiled about a central axis.

[0141] Embodiment 8: A filter assembly as described in any one of embodiments 1-7 and 9-22, wherein the first sheet of the first chemical filter material has an embossment extending between the first edge and the second edge.

[0142] Embodiment 9: A filter assembly as described in any one of embodiments 1-8 and 10-22, wherein the first sheet of the first chemical filter material has one or more holes extending completely through the first sheet of the first chemical filter material.

[0055]

[0143] Embodiment 10: A filter assembly described in any one of embodiments 1-9 and 11-22, wherein the third chemical filter element includes a third sheet of a third chemical filter material having a first edge and a second edge, and wherein a third filtration flow path is defined parallel to a surface of the third sheet and extends from the first edge to the second edge.

[0144] Embodiment 11: The filter assembly of any one of embodiments 1-10 and 12-22, further comprising a spacing region defining a flow path from the second chemical filter element to the third chemical filter element.

[0145] Embodiment 12: The filter assembly of any one of embodiments 1-11 and 13-22, wherein the first chemical filter element comprises a sorbent impregnated with a base.

[0146] Embodiment 13: The filter assembly of any one of embodiments 1-12 and 14-22, wherein the first chemical filter element comprises an acid-impregnated sorbent.

[0147] Embodiment 14: The filter assembly of any one of embodiments 1-13 and 15-22, wherein the second chemical filter material comprises an acid-impregnated adsorbent.

[0148] Embodiment 15: The filter assembly of any one of embodiments 1-14 and 16-22, wherein the second chemical filter material comprises a sorbent impregnated with a base.

[0149] Embodiment 16: A filter assembly described in any one of embodiments 1 to 15 and 17 to 22, wherein the first edge is opposite the second edge of the first sheet of chemical filter material.

[0056]

[0150] Embodiment 17: A filter assembly described in any one of embodiments 1 to 16 and 18 to 22, wherein the fourth chemical filter element includes a fourth sheet of a fourth chemical filter material having a first edge and a second edge, and wherein a fourth filtration flow path is defined parallel to a surface of the fourth sheet and extends from the first edge to the second edge.

[0151] Embodiment 18: The filter assembly of any one of embodiments 1-17 and 19-22, further comprising a spacing region defining a flow path from the third chemical filter element to the fourth chemical filter element.

[0152] Embodiment 19: The filter assembly of any one of embodiments 1-18 and 20-22, wherein the fourth chemical filter material comprises a mesoporous adsorbent.

[0057]

[0153] Embodiment 20: The filter assembly of any one of embodiments 1-19 and 21-22, further comprising a fifth chemical filter element including a fifth sheet of a fifth chemical filter material having a first edge and a second edge, wherein a fifth filtration flow path is defined parallel to a surface of the fifth sheet and extends from the first edge to the second edge.

[0154] Embodiment 21: The filter assembly of any one of embodiments 1-20 and 22, further comprising a spacing region defining a flow path from the fourth chemical filter element to the fifth chemical filter element.

[0155] Embodiment 22: The filter assembly of any one of embodiments 1 to 21, wherein the first chemical filter material comprises a chemisorptive coated substrate.

[0058]

[0156] Embodiment 23: A filter assembly comprising:

[0157] a housing defining an inlet and an outlet;

[0158] a plurality of chemical filter elements within the housing arranged in series with respect to fluid flow from the inlet to the outlet; and

[0159] a series of spacing regions between adjacent said filter elements.

[0160] Embodiment 24: A filter assembly as described in any one of embodiments 23 and 25 to 40, wherein each chemical filter element includes a chemical filter material configured as a sheet having a first edge and a second edge and defines a filtration flow path extending parallel to a surface of the sheet, wherein the filtration flow path extends from the first edge to the second edge.

[0161] Embodiment 25: A filter assembly described in any one of embodiments 23-24 and 26-40, wherein a first chemical filter element of the plurality of chemical filter elements comprises a flow path layer defining the filtration flow path, wherein the flow path layer abuts the surface of the sheet between the first edge and the second edge.

[0162] Embodiment 26: A filter assembly described in any one of embodiments 23 to 25 and 27 to 40, wherein a first chemical filter element of the plurality of chemical filter elements comprises a stack of multiple layers of sheets of chemical filter material, wherein a filtration flow path is defined between adjacent layers in the stack.

[0163] Embodiment 27: A filter assembly described in any one of embodiments 23 to 26 and 28 to 40, wherein a first chemical filter element of the plurality of chemical filter elements further comprises a stack of a plurality of flow path layers defining a first filtration flow path, wherein each flow path layer is disposed between and abuts layers of the sheet of the first chemical filter material in the stack.

[0164] Embodiment 28: A filter assembly according to any one of embodiments 23-27 and 29-40, wherein the sheet of first chemical filter material is configured in a coil around a central axis.

[0165] Embodiment 29: A filter assembly described in any one of embodiments 23 to 28 and 30 to 40, wherein the sheet has an embossment extending between the first edge and the second edge.

[0166] Embodiment 30: A filter assembly according to any one of embodiments 23-29 and 31-40, wherein the sheet of first chemical filter material has one or more holes extending completely through said sheet.

[0167] Embodiment 31: A filter assembly described in any one of embodiments 23 to 30 and 32 to 40, wherein one or more of the chemical filter elements is an adsorptive filter element.

[0168] Embodiment 32: Chemical The filter assembly of any one of embodiments 23-31 and 33-40, wherein at least one of the chemical filter elements comprises a chemisorptive coated substrate.

[0169] Embodiment 33: The filter assembly of any one of embodiments 23-32 and 34-40, wherein a first chemical filter element of the plurality of chemical filter elements comprises a sorbent impregnated with a base.

[0170] Embodiment 34: A filter assembly according to any one of embodiments 23-33 and 35-40, wherein a second chemical filter element of the plurality of chemical filter elements comprises an acid-impregnated adsorbent and is downstream of the first chemical filter element.

[0171] Embodiment 35: The filter assembly of any one of embodiments 23-34 and 36-40, wherein a first chemical filter element of the plurality of chemical filter elements comprises an acid-impregnated sorbent.

[0172] Embodiment 36: A filter assembly according to any one of embodiments 23 to 35 and 37 to 40, wherein a second chemical filter element comprises an adsorbent impregnated with a base and is downstream of the first chemical filter element.

[0173] Embodiment 37: The filter assembly of any one of embodiments 23-36 and 38-40, wherein the plurality of chemical filter elements further comprises a third chemical filter element downstream of the second chemical filter element.

[0174] Embodiment 38: A filter assembly described in any one of embodiments 23 to 37 and 39 to 40, wherein the plurality of chemical filter elements further includes a fourth chemical filter element comprising a mesoporous adsorbent, wherein the fourth chemical filter element is downstream of the third chemical filter element.

[0175] Embodiment 39: The filter assembly of any one of embodiments 23 to 38 and 40, wherein the plurality of chemical filter elements further comprises a fifth chemical filter element downstream of the fourth chemical filter element.

[0176] Embodiment 40: A filter assembly according to any one of embodiments 23 to 39, wherein the first edge is opposite the second edge of the first sheet of chemical filter material.

[0059]

[0177] It should also be noted that the term "configured," as used in this specification and the appended claims, describes a system, apparatus, or other structure that is constructed to perform a particular task or adopt a particular configuration. The term "configured" may be used interchangeably with similar terms such as "deployed," "built," and "manufactured."

[0178] All publications and patent applications in this specification are indicative of the level of ordinary skill in the art to which this technology pertains. All publications and patent applications are incorporated herein by reference to the same extent as if each individual publication or patent application was specifically and individually indicated by reference. In the event of any inconsistency between the disclosure of this application and the disclosure of any document incorporated herein by reference, the disclosure of this application shall control.

[0179] This application is intended to cover any adaptations or variations of the present subject matter. It is to be understood that the above description is intended to be illustrative, and not limiting, and that the claims are not limited to the exemplary embodiments described herein.

Claims

1. housing; a first chemical filter element including a first sheet of a first chemical filter material having a first edge and a second edge, wherein a first filtration flow path is defined parallel to a surface of the first sheet and extends from the first edge to the second edge; and a second chemical filter element including a second sheet of a second chemical filter material having a first edge and a second edge, wherein a second filtration flow path is defined parallel to a surface of the second sheet and extends from the first edge to the second edge; The filter assembly, wherein the first chemical filter element and the second chemical filter element are disposed within the housing, and the second chemical filter element is disposed downstream of the first chemical filter element.

2. 10. The filter assembly of claim 1, further comprising a spacing region between the first chemical filter element and the second chemical filter element, wherein the spacing region defines a flow path from the first chemical filter element to the second chemical filter element.

3. The filter assembly of claim 2 , further comprising a particulate filter disposed in the spacing region, wherein the particulate filter comprises a particulate filtration medium and the flow path extends through the particulate filtration medium.

4. 4. The filter assembly of claim 1, wherein the first chemical filter element further comprises a stack of multiple layers of sheets of the first chemical filter material including the first sheet, the first filtration flow path being defined between adjacent layers in the stack.

5. 4. The filter assembly of claim 1, wherein the first chemical filter element further comprises a stack of a plurality of flow path layers defining the first filtration flow path, wherein each of the flow path layers is disposed between and abuts a layer of the sheet of the first chemical filter material in the stack.

6. 4. The filter assembly of claim 1, wherein the first sheet of the first chemical filter material is configured as a coil about a central axis.

7. 4. The filter assembly of claim 1, wherein the first chemical filter element further comprises a flow path layer abutting the first sheet of the first chemical filter material, the flow path layer defining the first filtration flow path and being coiled about a central axis.

8. 4. The filter assembly of claim 1, wherein the first sheet of the first chemical filter material has an embossment extending between the first edge and the second edge.

9. 4. The filter assembly of claim 1, wherein the first sheet of the first chemical filter material has one or more holes extending completely through the first sheet of the first chemical filter material.

10. a housing defining an inlet and an outlet; a plurality of chemical filter elements within the housing arranged in series with respect to fluid flow from the inlet to the outlet; and a spacing region between adjacent filter elements in the series; a filter assembly.

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