WO2016078661A1

WO2016078661A1 - Air-filter system for ventilation systems

Info

Publication number: WO2016078661A1
Application number: PCT/DK2015/000044
Authority: WO
Inventors: John Steen Jensen
Original assignee: Jsj Consult Aps
Priority date: 2014-11-20
Filing date: 2015-11-04
Publication date: 2016-05-26
Also published as: DK201400676A1; DK178543B1

Abstract

The present invention relates to an air-filter system and a ventilation system comprising such a system. The air-filter system comprises a filter support frame especially constructed so as to provide an increased surface area of filter material available for filtering an air-stream compared to conventional filters.

Description

AIR-FILTER SYSTEM FOR VENTILATION SYSTEMS

Technical field of the invention

The present invention relates to an air-filter system and a ventilation system comprising such a system. Background of the invention

Filters for most residential and commercial air filtration and air handling equipment are typically removable, replaceable, rigid, framed units. Rigid framed filters can be time consuming to replace or clean and often require frequent replacement, typically monthly. This also requires an added amount of attention by an industrial or commercial maintenance staff or residential unit owner. The filters often go unchanged as users forget to change the filter regularly, which results in an increased energy consumption, poor heating/cooling quality (for high-volume air conditioner (HVAC) systems), and increased maintenance and repair costs. This shortfall has been well known and several attempts have been made in the past to provide long lasting filters.

Hence, there is a need for an energy efficient ventilation system that needs a minimum of attendance. US4378980 discloses a gas borne particle filtering apparatus having a filter medium with inlet and outlet openings in a staggered sawtooth cross-sectional configuration in a casing for the filter medium positioned such that the gas passes along and between the sawteeth on both sides of the filter medium. A screened belt or support for the filter medium is described. The apparatus is particularly suited to cleaning heated or cooled air in a confined work space in a factory containing small micron sized particles so that the air can be recycled.

US1982639 discloses an air filtering apparatus so arranged as to insure thorough and complete removal of all impurities from the air passed there through. The apparatus is arranged and operated such that the resistance to the flow through the filter medium is kept at a minimum. US3438588 discloses a roll filter wherein a filter mat is advanced from a freely rotatable supply roll onto a take-up roll, which is driven with a constant angular speed so as to gradually increase the peripheral speed of the mat to a maximum peripheral speed as the diameter of the take-up roll increases. The mat is guided in a zigzag path intermediate the supply and take-up rolls by two rows of guide rolls one of which rows is freely rotatable and the other of which rows is driven so that the rolls have a constant peripheral speed at least as great as the maximum peripheral speed of the take-up roll.

Summary of the invention

A first aspect relates to an air-filter system (100) comprising:

- An enclosure ( 01) adapted for receiving an air stream to be filtered from an inlet (102) and for passing on a filtered air stream through an outlet (104);

- A supply unit (108) for supplying a filter material (103);

- A filter support frame (106) positioned within the enclosure (101) and mounted to the enclosure so as to outline the inlet (102);

- A take-up reel (110) for advancing filter material (103);

- A filter material (103) on said supply unit (108), extending from said supply unit (108), and around at least a part of the filter support frame

(106) to the take-up reel (110);

wherein the filter support frame extends from the inlet (102) and into the enclosure (101); wherein the filter support frame (106) comprises a distal end (112) from the inlet (102), a proximal end (114) from the inlet (102), and a body part (116);

wherein the filter material (103) is in the form of a filter bag assembly (122) comprising a plurality of filter bags (124); wherein the individual filter bag (124) has an open end (126) and a closed end (128); wherein the filter bag assembly (122) is mounted such that the open end (126) of the individual filter bag (124) is facing the filter support frame (106) when in contact therewith.

A second aspect relates to an air-filter system (100) comprising: - An enclosure (101) adapted for receiving an air stream to be filtered from an inlet (102) and for passing on a filtered air stream through an outlet (104);

- A supply unit (108) for supplying a filter material (103);

- A filter support frame (106) positioned within the enclosure (101);

- A take-up reel (110) for advancing filter material (103);

- A filter material (103) on said supply unit (108), extending from said supply unit (108), and around at least a part of the filter support frame (106) to the take-up reel (110);

wherein the filter support frame extends from the inlet (102) and into the enclosure (101);

wherein the filter support frame (106) comprises a plurality of rollers (107) moveably supporting the filter material, and positioned within the enclosure such that the rollers (107), the enclosure (101), and the filter material form a filter bag assembly (122) comprising a plurality of filter bags with an open (126) end and a closed end (128), wherein the open end (126) of the individual filter bag (124) faces the inlet.

Disclosed herein is an air-filter system for use in a ventilation system. The air- filter system comprises an enclosure adapted for receiving an air stream to be filtered from an inlet and for passing on a filtered air stream through an outlet, a supply unit for supplying a filter material, a filter support frame positioned within the enclosure and mounted to the enclosure so as to outline the inlet, and a take- up reel for advancing filter material.

The air-filter system further comprises a filter material on said supply unit, extending from said supply unit, and around at least a part of the filter support frame to the take-up reel. The filter support frame extends from the inlet and into the enclosure.

In a first aspect, the filter support frame comprises a distal end from the inlet, a proximal end from the inlet, and a body part. The filter material is in the form of a filter bag assembly comprising a plurality of filter bags. The individual filter bag has an open end and a closed end, and the filter bag assembly is mounted such that the open end of the individual filter bag is facing the filter support frame when in contact therewith. This is to allow the air-stream to flow through the support frame and into the individual filter bags to further increase the surface area of the filter system. The filter bags may be rolled up on the supply system, and will only expand when coming into contact with, i.e. being rolled on or slided over the support frame, where the air-stream is flowing through.

In a second aspect, the filter support frame comprises a plurality of rollers moveably supporting the filter material, and positioned within the enclosure such that the rollers, the enclosure, and the filter material form a filter bag assembly comprising a plurality of filter bags with an open end and a closed end. The open end of the individual filter bag faces the inlet.

By installing a system according to the above in e.g. a building or structure, the air-stream entering into the building or structure can be filtered in an energy efficient manner, since the air-stream passes through an increased filter surface area compared to the conventional systems with air filters mounted perpendicular to the inlet, and hence the air-stream. The increased filter surface area reduces the energy needed to force the air-stream through the filter.

Another advantage with using the system of the present invention is that the filter system allows for an automatic exchange of filter material - thereby reducing the need for system service.

Specifically for the first aspect, in one or more embodiments, the filter material extends from the supply unit and around at least a part of the body part of the filter support frame to the take-up reel.

Specifically for the first aspect, in one or more embodiments, the distal end of the filter support frame is impermeable to the airstreams. This is advantageous because the air stream is then directed through the filter material that is situated around the body of the filter support frame.

Specifically for the first aspect, in one or more embodiments, the body part of the filter support frame is tubular. The tubular shape increases the surface area of filter material around the filter support frame, and furthermore facilitates the drawing/sliding of the filter material over the body part of the filter support frame, when replacement is needed due to contamination or clogging/choking. Specifically for the first aspect, in a preferred embodiment, the body part has an essentially circular cross-section to further improve the sliding effect. The cross- section is in the same plane as the filter material is drawn over the body part during replacement. An essentially circular cross-section is to be understood as also covering an oval cross-section. The oval cross-section is especially good for situations where there is little space for installation of the system. This shape allows for a thinner system where the surface area of the support frame is retained.

In one embodiment, the body part has a circular cross-section to further improve the sliding effect.

When the body part of the filter support frame is tubular, it may be difficult to obtain full coverage of filter material around the filter support frame, when the filter material extends from the supply unit and around at least a part of the filter support frame to the take-up reel.

Specifically for the first aspect, in one or more embodiments, the air-filter system further comprises a guide unit arranged for guiding the filter material around the body part of the filter support frame. Such a unit reduces the risk of air stream leaving the support frame unfiltered. In one embodiment, the guide unit is in the form of an air sluice chamber. In one embodiment, the guide unit is a part of the filter support frame. Specifically for the first aspect, in one embodiment, the individual filter bags have at least four sidewalls of filter material extending from an open end of the filter bag assembly to a closed end of the filter bag assembly, wherein the sidewalls connect to close the filter bag assembly, two of the sidewalls of filter material being opposed to each other across the filter bag and being spaced from each other at the open end of the filter bag assembly.

The following embodiments relates to both the first and the second aspects. In one or more embodiments, the air-filter system further comprises a drive-motor for operating the take-up reel.

In one or more embodiments, the air-filter system further comprises a drive-motor control unit configured to control the frequency and length of filter material advancement by activation/deactivation of the drive-motor.

In one or more embodiments, the drive-motor control unit is configured to receive information about the energy consumption of the ventilation system, and wherein the energy consumption exceeds a predetermined level, the drive-motor control unit is configured to activate the drive-motor. This is advantageous because the energy consumption of the ventilation system (especially the energy consumption of the fans) is an indicator of how well the air filter functions. The more

contaminated or clogging/choked that the filter is the more energy is needed to force the air-stream through the filter.

In one or more embodiments, the inlet and/or outlet is adapted for insertion into a duct system for taking in outside air and delivering it to a confined space.

In another embodiment, the support frame is arranged to form individual channels spanning the length from the proximal end to the distal end. This allows the air- stream to be guided across the entire surface area of the filter material. Filters have been used in cleaning air for centuries. The collection efficiency of a filter depends on many parameters, such as the fibre diameter, the filter's packing density, filter thickness, particle diameter, airflow velocity, etc. In order to increase the efficiency in the removal of fine particles from the air at a given operating velocity, either smaller fibre diameter, thicker fibre bed, higher packing density, or a combination of the above approaches can be applied. All tend to increase the pressure drop across the filter. Thus, as a general rule in fibrous (and fabric) filtration, the higher the efficiency of the filter, the higher the pressure loss it has. Such a high-pressure loss in turn means a more restrictive airflow, or a higher operation cost if a certain flow rate is to be maintained.

Electrically charged fibres can attract airborne particulates toward a fibre surface without altering any mechanical characteristics of the filter. Thus, electrical forces can enhance the filter efficiency without increasing the pressure drop across the filter. By charging a filter, higher efficiency at lower pressure drop, higher dust loading capacity, more airflow rate, and less maintenance can be achieved.

An electrical field can be produced in a filter by (1) charging the fibre elements, (2) charging the airborne particles, and/or (3) applying an electric field across the fibre elements. Such methods are disclosed in EP0646416, hereby incorporated by reference.

In one or more embodiments, the filter material comprises electrically chargeable fibres.

In one or more embodiments, the air-filter system further comprises means for electrically charging the filter material. In one or more embodiments, the air-filter system further comprises means for electrically charging the particles within the air stream passing through the inlet.

In one or more embodiments, at least one of the rollers moveably supporting the filter material is configured to electrically charge the filter material. In one or more embodiments, the means for electrically charging the filter material is configured to apply an opposite electrical charge, e.g. positive, than the electrical charge, e.g. negative, applied by the means for electrically charging the particles within the air stream passing through the inlet.

In one or more embodiments, the means for electrically charging the filter material is configured to apply an electrical charge to the filter material when the take-up reel is activated. This allows for a more efficient electrical charging of the entire surface of the filter material.

In one or more embodiments, the means for electrically charging the particles within the air stream passing through the inlet is inactive while the means for electrically charging the filter material is active. This is to avoid that a current will be formed between the two.

In one or more embodiments, the roller configured to electrically charge the filter material comprises a metal core with a non-conductive polymer coating, and wherein the metal core is connected to a high-voltage DC power supply. In one or more embodiments, wherein when the roller is configured to electrically charge the filter material, the metal core is connected to a high-voltage DC power supply by means adapted to move with the rolling motion of the roller, such as a skid. The use of charging particles and filter are especially useful for removing ultrafine particles from exhaust air from diesel engines. This is important on e.g. a passenger ship driven by diesel engines, where the exhaust air may be sucked into the ventilation system for ventilating the cabins. In one or more embodiments, the filter material is electrically pre-charged before mounted on the filter support frame.

In one or more embodiments, the high-voltage DC power supply is positioned within the roller. In one or more embodiments, the air-filter system further comprises an ozone filter, preferably positioned on the outlet side of the filter material. This may be important, as the charging means may generate ozone from the oxygen in the air. In one or more embodiments, the ozone filter is a carbon filter.

Disclosed herein is also a ventilation system comprising a duct system for taking in outside air and delivering it to a confined space, an air flow generator; and an air-filter system according to the present invention.

Brief description of the figures

Figure 1 shows an air-filter system in accordance with various embodiments of the invention in relation to the first aspect. Figure 1A is a front view of Figure 1B; and Figure 2 shows a filter bag assembly in accordance with the first aspect. Figure 2A is a front view of Figure 2B; and

Figure 3 shows a sectional view of the air-filter system in accordance with various embodiments of the invention in relation to the second aspect.

Description of a preferred embodiment

Figure 1 shows an air-filter system in accordance with various embodiments of the invention in relation to the first aspect. The air-filter system 100 comprises an enclosure 101 adapted for receiving an air stream to be filtered from an inlet 102 and for passing on a filtered air stream through an outlet 104. The enclosure may be a part of a ventilation system into which the air-filter system is build. The air- filter system further comprises a supply unit 108 for supplying a filter material 103; a filter support frame 106 positioned within the enclosure 101 and mounted to the enclosure so as to outline the inlet 102; and a take-up reel 110 for advancing filter material 103. The filter material 103 on the supply unit 108 extends from said supply unit 108, and around the filter support frame 106 to the take-up reel 110. A small part of the filter support frame is not covered by filter material, since different parts of the filter will have to pass each other to move around the support frame. The part not covered by filter material is minimized by a support frame 118 arranged for guiding the filter material around the body part

116 of the filter support frame 106. The filter support frame extends from the inlet 102 and into the enclosure 101.

The filter support frame 106 comprises a distal end 112 from the inlet 102, a proximal end 114 from the inlet 102, and a body part 116. The distal end 112 of the filter support frame 106 is impermeable to the airstreams. The body part 116 of the filter support frame (106) is tubular and has an essentially circular cross- section.

The preferred embodiment as disclosed in figure 1 also comprises a drive-motor

117 for operating the take-up reel 110, and a drive-motor control unit 118 configured to control the frequency and length of filter material advancement by activation/deactivation of the drive-motor 117. The drive-motor control unit is also 120 is configured to receive information from a ventilation system about the energy consumption, and wherein the energy consumption exceeds a

predetermined level, the drive-motor control unit 120 is configured to activate the drive-motor 117.

Also disclosed is the embodiment, wherein the inlet 102 and/or outlet 104 is adapted for insertion into a duct system for taking in outside air and delivering it to a confined space.

Figure 2 shows a filter bag assembly in accordance with various embodiments of the invention in relation to the first aspect. The filter material is in the form of a filter bag assembly 122 comprising a plurality of filter bags 124. The individual filter bag 124 has an open end 126 and a closed end 128 and the bag assembly 122 is mounted such that the open end 126 of the individual filter bag 124 is facing the filter support frame when in contact therewith.

Figure 3 shows a sectional view of the air-filter system in accordance with various embodiments of the invention in relation to the second aspect. The air-filter system 100 comprises an enclosure 101 adapted for receiving an air stream to be filtered from an inlet 102 and for passing on a filtered air stream through an outlet (not shown). The enclosure may be a part of a ventilation system into which the air-filter system is build. The air-filter system further comprises a supply unit 108 for supplying a filter material 103; and a filter support frame positioned within the enclosure 101. The filter support frame 106 comprises a plurality of rollers 107 moveably supporting the filter material 103, and positioned within the enclosure 101 such that the rollers 107, the enclosure 101 , and the filter material 103 form a filter bag assembly comprising a plurality of filter bags 124 with an open 126 end and a closed end 128, and where the open end 126 of the individual filter bag 124 faces the inlet.

The air-filter system further comprises a take-up reel 110 for advancing filter material 103. The filter material 103 on the supply unit 108 extends from said supply unit 108 and around the filter support frame (here shown as a plurality of rollers 107) to the take-up reel 110.

The preferred embodiment as disclosed in Figure 3 also comprises a drive-motor 117 for operating the take-up reel 110, and a drive-motor control unit 118 configured to control the frequency and length of filter material advancement by activation/deactivation of the drive-motor 117. The drive-motor control unit 120 is also configured to receive information from a ventilation system about the energy consumption, and wherein the energy consumption exceeds a predetermined level, the drive-motor control unit 120 is configured to activate the drive-motor

References

100 air-filter system

101 enclosure

102 inlet

103 filter material

104 outlet

106 filter support frame

107 rollers

108 supply unit

110 take-up real

112 distal end

114 proximal end

116 body part

117 drive motor

118 guide unit

120 drive motor control unit

122 filter bag assembly

124 individual filter bag

126 open end

128 closed end

Claims

1. An air-filter system (100) comprising:

- An enclosure (101) adapted for receiving an air stream to be filtered from an inlet (102) and for passing on a filtered air stream through an outlet (104);

- A supply unit (108) for supplying a filter material (103);

- A filter support frame (106) positioned within the enclosure (101);

- A take-up reel (110) for advancing filter material (103);

(106) to the take-up reel (110);

characterized in that the filter support frame (106) comprises a plurality of rollers (107) moveably supporting the filter material, and positioned within the enclosure such that the rollers (107), the enclosure (101), and the filter material form a filter bag assembly (122) comprising a plurality of filter bags with an open (126) end and a closed end (128), wherein the open end (126) of the individual filter bag (124) faces the inlet.

2. An air-filter system (100) comprising:

- An enclosure (101 ) adapted for receiving an air stream to be filtered from an inlet (102) and for passing on a filtered air stream through an outlet (104);

- A supply unit (108) for supplying a filter material (103);

- A take-up reel (110) for advancing filter material (103);

- A filter material (103) on said supply unit (108), extending from said supply unit ( 08), and around at least a part of the filter support frame

(106) to the take-up reel (110);

characterized in that the filter material (103) is in the form of a filter bag assembly (122) comprising a plurality of filter bags (124); wherein the individual filter bag (124) has an open end (126) and a closed end (128); wherein the filter bag assembly (122) is mounted such that the open end

(126) of the individual filter bag (124) is facing the filter support frame (106) when in contact therewith.

An air-filter system according to claim 2, wherein the filter support frame (106) comprises a plurality of rollers (107) moveably supporting the filter material.

An air-filter system according to any one of the claims 1-3, further comprising means for electrically charging the filter material (103).

An air-filter system according to any one of the claims 1 or 3, wherein at least one of the rollers (107) moveably supporting the filter material is configured to electrically charge the filter material (103). 6. An air-filter system according to claim 5, wherein the roller configured to electrically charge the filter material (103) comprises a metal core with a non-conductive polymer coating, and wherein the metal core is connected to a high-voltage DC power supply. 7. An air-filter system according to any one of the claims 1-6, further

comprising means for electrically charging the particles within the air stream passing through the inlet.

8. An air-filter system according to any one of the claims 1-7, wherein the inlet (102) and/or outlet (104) is adapted for insertion into a duct system for taking in outside air and delivering it to a confined space.

9. A wind turbine comprising an air-conditioning system configured to control the climatisation of an interior of a nacelle of the wind turbine, wherein the air-conditioning system comprises one or more air inlet systems configured to ventilate the interior with air intake from outside of the wind turbine; wherein the air inlet systems comprises one or more air filter systems according to claims 1-7, configured to filter the air intake.

10. A ventilation system comprising:

- A duct system for taking in outside air and delivering it to a confined space;

- An air flow generator; and

- An air-filter system according to any one of the claims 1 -7.