EP2406011A1

EP2406011A1 - Method for purifying an air flow and purification device

Info

Publication number: EP2406011A1
Application number: EP10711996A
Authority: EP
Inventors: Manfred H. Langner
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-03-13
Filing date: 2010-03-04
Publication date: 2012-01-18
Also published as: WO2010102749A1; DE102009012680A1

Abstract

In a method for purifying an air flow, wherein in an air flow containing impurities and odors a dielectrically impeded discharge is forced in order to generate a plasma before the air flow is subsequently guided through activated carbon (26) or a comparable filter material, the air flow is initially redirected in an inlet area and the flow velocity is subsequently reduced in order to force a separation of particle-shaped impurities which is caused by centrifugal forces.

Description

- 1 - LAN 6352 PC

Method for cleaning an air flow and cleaning device

The invention relates to a method for purifying an air flow, wherein a dielectrically impeded discharge is forced into a stream of air containing impurities and odors, and thereby a plasma is generated, before the air flow is subsequently passed through activated carbon or a comparable filter material.

Such a cleaning method for filtering out odors and impurities from an air flow is known, for example, from DE 10 2004 053 030 A1. It has been found that by generating a plasma in the airflow by passing it through a region in which a dielectrically impeded discharge is constantly forced by applying an alternating voltage, the particles contained in the air flow, and in particular the odorous molecular compounds ionized and / or dissociated, which in combination with a subsequent activated carbon filter or a comparable absorbent filter material, a surprisingly improved cleaning performance and detectable odor reduction can be achieved. Odor filters based on this process are already being offered and sold as standalone filter devices or as components of airflow treatment devices. It is known from practice that such odor filter in

Cleaning devices can be integrated, which use additional cleaning and / or filtering procedures

confirmation head - 2 - LAN 6352 PC

may or may have corresponding components in order to remove not only odors, but also particulate impurities from the air stream can.

With increasing number of individual process steps or cleaning and filter components usually increases the flow resistance for the air flow to be cleaned considerably. Nevertheless, in order to ensure a sufficient suction for the air flow in a suction and at the same time a sufficient

To be able to maintain the flow rate of the air flow, while the air flow flows through the individual components of the cleaning device, often large-volume cleaning systems with possibly more means for flow generation or

Maintaining the air flow can be provided. In addition, an increase in noise with increasing cleaning effect is usually unavoidable.

While, for example, in industrially used

Cleaning devices often a sufficient space can be provided and a separate sound insulation of the cleaning device or additional sound-insulating measures are readily possible, meet such conditions

Extractor hoods or regularly used in inhabited premises supply air, exhaust air and circulating air systems not to.

It is therefore regarded as an object of the invention to design an already known cleaning method of the type mentioned in such a way that if possible - 3 - LAN 6352 PC

small space requirement an effective cleaning of air flow of particulate impurities and odors is made possible.

This object is achieved in that the air flow is deflected in a suction and the flow rate is subsequently reduced to force a centrifugal force deposition of particulate impurities. Investigations have shown that the combination of a previously carried out centrifugal separation of particulate contaminants with a subsequent plasma-based elimination smallest, so far not separated particles and odors a comprehensive, highly effective and low noise cleaning an air flow with low space requirement is possible. This can be attributed inter alia to the fact that, in contrast to other mechanical cleaning processes in the centrifugal separation of particulate impurities, the flow velocity is reduced after a deflection, for example, by a widening of a cross-sectional area of a flow channel to improve the effect of centrifugal force deposition. The reduced flow rate has an advantageous effect in the subsequent purification steps, since individual particles or molecule compounds each stay longer in the region of the individual purification stages and can be separated or eliminated more effectively from the air flow. The reduction of the flow velocity is not enforced due to an increased flow resistance, but by the expansion of a cross-sectional area in the flow channel - 4 - LAN 6352 PC

brought about, which can be done extremely quietly with a suitable design and design of the flow channel and the deflection caused by the centrifugal force deflection.

In order to be able to separate out the smallest particulate impurities and, in particular, a blue smoke arising from the combustion of fat from the air flow, provision is made for electrostatic particle separation to take place in a further process step prior to the generation of the plasma.

An improved separation of moisture and small liquid droplets can be achieved by guiding the air flow through an open-pored, hydrophilic foam material in a further process step after the diversion and reduction of the flow velocity and optionally before the electrostatic particle separation. In the air flow located aerosols and

Liquid droplets and in particular small droplets of fat are deposited in the open-pore hydrophilic foam material from the air flow and collect below or in a lower region of the foam material. By a suitable specification of

Pore size and the expansion of the foam material in the flow direction, despite a relatively low flow resistance, an effective separation of moisture and small liquid droplets can be achieved. - 5 - LAN 6352 PC

According to an advantageous embodiment of the inventive concept it is provided that the purified air flow is supplied to a heat exchanger in a subsequent process step. If the purification process for purifying the supply air is used, for example, in clean rooms or the like, additional conditioning and, if appropriate, air conditioning of the clean rooms can be achieved by the heat exchanger. If the cleaning method according to the invention is used for exhaust hoods or recirculation hoods in the private or commercial food preparation, the frequently heated runoff can be cooled to the ambient temperature before it leaves a cleaning device, or an energy recovery can be carried out before the cleaned airflow leaves the environment ,

In order to enable as maintenance-free operation of the centrifugal force-related deposition of particulate impurities and to additionally strengthen the cleaning effect is provided that at intervals a cleaning of the suction by means of at least one spray liquid spraying a spray nozzle is feasible. The cleaning liquid can be carried out automatically depending on contamination of the suction area. If, with the use of suitable sensors, a strongly increasing contamination of the air flow by particles or the like is detected, the cleaning liquid can be sprayed during operation in order to improve the cleaning effect by depositing an additional separation of in - 6 - LAN 6352 PC

To allow the air flow entrained or entrained particles.

The invention also relates to a cleaning device for an air flow containing impurities and odors, with a plasma generating device which forces a dielectrically impeded discharge to generate the plasma by means of alternating voltage, and with a filter device containing an activated carbon or a comparable filter material. According to the invention, the cleaning device has a housing with a slot-like inlet opening for the air flow and with a flow channel opening into the inlet opening, wherein in the curved flow channel a rounded or thickened one

End region exhibiting, extending substantially parallel to the slot-like inlet opening deflecting element is arranged. By suitably dimensioning the slot-like inlet opening and a configuration of the flow channel and the deflecting element adapted thereto, it is possible to establish advantageous flow conditions in an area in front of the slot-like inlet opening, which cause contaminants and odors located in this area to be efficiently sucked into the cleaning device and can be deposited or eliminated during a flow through the cleaning device.

According to a particularly advantageous embodiment of the inventive concept it is provided that the cleaning device arranged a laterally adjacent to the slot-like inlet opening - 7 - LAN 6352 PC

Transfer passage has, which deflects the air flow sucked through the inlet opening and the parallel to the slot-like inlet opening successively arranged plasma generating device and filter device supplies. Investigations have shown that, for example, at a width of the slot-like inlet opening of 2-3 cm, which extends in the longitudinal direction over 1 to 2 m, already usual flow volume of 1500 m ³ / h, for example, at a subsequent one-sided or double-sided

Extraction or deflection of the sucked air flow over the entire extent of the slot-like inlet opening to be able to ensure a substantially uniform pressure distribution. Flow velocities of, for example, 5-10 m / s are achieved in the region of the slot-like inlet opening, which, in conjunction with a suitably dimensioned flow channel and a deflecting element adapted thereto, enables effective centrifugal force-dependent separation of particulate contaminants with simultaneously low noise development.

It is provided that an electrostatic filter unit is arranged between the deflecting element and the plasma generating device. The electrostatic filter unit is used to separate larger particles from the air flow, so that the following cleaning components such as the plasma generating device and the activated carbon filter are freed of a corresponding particle load, so that both the cleaning effect of these components increases, as well as their rapid addition or - 8 - LAN 6352 PC

Impairment of the cleaning performance is prevented by impurities.

In addition, it can be provided that an open-pore hydrophilic foam is arranged between the deflection element and the plasma generation device, which can in particular effectively deposit moisture and small liquid droplets.

In order to prevent the aerosols and in particular fat droplets deposited preferentially in the open-cell hydrophilic foam igniting and confirming or destroying the cleaning device by the resulting fire, it is provided that a flame protection device is arranged between the deflecting element and the plasma generating device. The flame protection device is expediently arranged in the flow direction either after the deflecting element or immediately before a subsequently arranged open-pore hydrophilic foam and prevents the foam material possibly loaded with numerous fat droplets from burning up.

In order to facilitate a cleaning, in particular in the suction region of the cleaning device, it is provided that the cleaning in the region of the curved running flow channel inspection openings or releasably attachable flow channel wall elements. In this way, a cleaning of the intake, in which the centrifugal separation of particulate

Impurities takes place, noticeably relieved. In addition, it can be provided that the access openings a - 9 - LAN 6352 PC

Facilitate access to and possibly removal of individual cleaning components. In addition, in other areas of the cleaning device or the housing of the cleaning device further flaps or access openings may be provided to enable or facilitate the maintenance and repair of the individual cleaning components.

To at least in some areas of the cleaning device automated cleaning of adhering

To enable contamination or deposits, it is provided that at least one spray nozzle spraying a cleaning liquid is arranged in the region of the flow channel. A plurality of spray nozzles are expediently arranged along the slot-like inlet opening in such a way that the cleaning liquid sprayed through the spray nozzles can dissolve and remove deposits due to centrifugal force in the area of the flow channel without the sprayed cleaning liquid passing through the slot-like

Entrance opening could escape. In order to be able to collect and reuse the sprayed cleaning liquid, it is provided that a collection channel for sprayed cleaning liquid is provided below the slot-like inlet opening, which opens into a collecting sump.

In order to influence the temperature of the purified air flow discharged from the cleaning device and, if appropriate, to be able to specify, it is provided that a heat exchanger is arranged in front of an outlet opening for the air flow from the cleaning device. - 10 - LAN 6352 PC

To be able to minimize the unavoidable noise during operation of the cleaning device as low as possible without additional soundproofing measures is provided that between the deflecting element and the

Plasma generating device is arranged a fan. The fan is expediently arranged approximately centrally between the slot-like inlet opening and an outlet opening for the air flow. In particular, in cases where in addition to the centrifugal force deposition and the plasma generating device further cleaning components are arranged and surround the fan on both sides and thereby shield a noise, the fan can be operated without additional sound insulation, which in turn would usually be associated with a significant flow resistance and would have affected or reduced the effect of the fan.

By a suitable adjustment of the individual components to each other and a suitable dimensioning and shaping of the cleaning device and the components contained therein can be realized in a small space a compact and very quiet cleaning device. It has been shown that precisely by this combination and arrangement of individual cleaning methods or components of a cleaning device described above, the effectiveness of the individual method steps or components are advantageously matched and due to occurring synergistic effects a noticeable effect on the individual performances of individual purification stages enable increased effectiveness. - 11 - LAN 6352 PC

Embodiments of the inventive concept will be explained in more detail, which are illustrated in the drawing. It shows:

1 shows a schematic sequence of individual method steps of the method according to the invention for cleaning an air flow,

Fig. 2 is a front sectional view of a cleaning device and

Fig. 3 is a sectional view of the cleaning device shown in Fig. 2 from another direction.

In the method sequence of a cleaning method according to the invention shown in FIG. 1 by way of example only, in a first method step 1, the air to be cleaned is sucked through a slit-like inlet opening of a cleaning device explained in more detail in the following FIGURE and deflected along a curved flow channel, in order subsequently to reach bottom an extension of the cross-sectional area of the flow channel to be braked. Due to the forced deflection, a centrifugal force-dependent deposition of particulate contaminants on an outer wall of the flow channel is brought about. This separation of particulate impurities is enhanced, or supported by the subsequent reduction, or lowering of the

Flow velocity of the air flow, since at lower speeds, especially larger particles - 12 - LAN 6352 PC

are no longer entrained by the slow flow of air and settle on the side walls of the flow channel.

The sucked and freed in a first step 1 of larger particles air flow is then redirected depending on the design and shape of the cleaning device again and fed to the subsequently usually rectilinearly arranged cleaning stages.

In a subsequent method step 2, the air flow is passed through a flame guard to avoid that especially fatty deposits could ignite in a subsequent cleaning stage and thereby damage or destroy the cleaning device.

In a method step 3, the air flow is passed through an open-pored, hydrophilic foam material, by means of which moisture and liquid droplets are deposited. Due to the open-pore configuration of the filter material, the deposited droplets in the foam material can flow downwards due to gravity and be collected or removed there.

Subsequently, in a method step 4 particles still present in the air flow are separated as far as possible by means of electrostatic filtering methods and contamination of subsequent purification stages with these particles is avoided. - 13 - LAN 6352 PC

Subsequently, in a method step 5 by means of a fan device, the flow rate is adjusted and optionally maintained in order to ensure a reliable discharge of the sucked air flow through the cleaning device can. The

Ventilation device is advantageously surrounded on both sides by other cleaning components, so that no troublesome fan noise penetrate to the outside without costly soundproofing measures.

Subsequently, the air flow is conducted in a known manner in the process steps 6 and 7 by a plasma that is generated by means of alternating voltage by forced dielectrically impeded discharges, or subsequently passed through an activated carbon filter. In process steps 6 and 7, odors are eliminated and final impurities are deposited. Due to the already previously performed cleaning components accumulate hardly any impurities in the activated carbon filter, so that long maintenance intervals are possible and the operation of the cleaning device is facilitated.

Before the cleaned air flow leaves the cleaning device, it is passed through a heat exchanger in a last method step 8 in order to be able to adjust or specify the temperature of the cleaned air flow to the environment and possibly recover subsequently no longer usable heat energy.

An example shown in Figs. 2 and 3

Cleaning device 9 has a housing 10 with a slot-like inlet opening 11. The slit-like - 14 - LAN 6352 PC

Inlet opening 11 extends almost over the entire length of the cleaning device 9 and has a width, or opening width of about 2 to 3 cm. A curved flow channel 12 begins with the slot-like inlet opening 11. The flow channel is guided around a deflecting element 13 with a rounded, thickened end area 14 and then widens in a slowing down area 15.

A schematically indicated by arrows 16 air flow is sucked through the slot-like inlet opening 11 into the flow channel 12 and deflected around the deflecting element 13. Supported by the reduction in a flow velocity of the air flow taking place in the deceleration region 15, particles are deposited on the centrifugal force 12 preferably on a side wall 17 of the flow channel 12 opposite the deflection element 13.

In the flow channel 12, two spray nozzles 18 are arranged rotatably and optionally movable, which can spray at intervals or continuously a cleaning liquid for cleaning the flow channel 12 of deposits and the like. In addition, particulate impurities can, if necessary, be washed out of the air flow by means of a spray in a manner already known. The slot-like inlet opening 11 is formed on a bottom edge opposite the thickened end region 14 of the deflecting element 13 by a channel-shaped collecting sump 19 for

Cleaning fluid limited. The sprayed cleaning liquid, for example, water if necessary - 15 - LAN 6352 PC

with added detergent, is collected in the sump 19 and fed to a reuse, or dissipated in case of excessive contamination.

The sucked through the slot-like inlet opening 11 and through the flow channel 12 with the

Slowing down area 15 passed air flow is then deflected again by a laterally arranged next to the slot-like inlet opening 11 transfer channel 20, to be subsequently supplied to the straight above and along the slot-like inlet opening 11 arranged subsequent cleaning components. In this way, a very compact design is possible, can be arranged at the same time very small amount of space and combined with each other numerous cleaning components.

The air flow diverted through the transfer passage 20 is then first through a flame guard 21, through a layer of an open-pore, hydrophilic

Foam material 22 and passed through an electrostatic filter 23.

Following this and before subsequent cleaning components is a fan 24, by means of which the flow rate of the air flow can be maintained and, if necessary, increased. The fan 24 is surrounded on all sides by cleaning components and by the housing 10 of the cleaning device 9, so that an unavoidable noise development of the fan 24 is insulated even without expensive soundproofing measures by the surrounding cleaning components. One - 16 - LAN 6352 PC

Otherwise additional flow resistance necessarily associated with protective measures can be avoided, so that the cleaning device 9 with lower power consumption can achieve better results.

Subsequently, a plasma generating device 25, an activated carbon filter 26 and a heat exchanger 27 are arranged before the air flow exits through an outlet opening 28 from the cleaning device 9 again.

The housing 10 of the cleaning device 9 has in the region of the above the slot-like inlet opening 11 arranged cleaning components inspection openings, or inspection flaps 29, which allow maintenance of the individual cleaning components. In addition, in the region of the deflecting element 13 at least partially removable, the deflecting element 13 forming bottom flaps 30 are arranged to facilitate maintenance and cleaning of the flow channel 12. In place of as

Bottom flaps 30 formed, removable portions 13 of the deflector 13 can also be other flow channel side walls hinged or removable to facilitate cleaning and maintenance.

Claims

- 17 - LAN 6352 PC method for cleaning an air flow and cleaning devices

A method of purifying an airflow, wherein in a contaminant and odor-containing airflow, a dielectrically impeded discharge is forced and thereby a plasma is generated before the airflow is subsequently passed through activated carbon or a comparable filter material, characterized in that the airflow is in an entrance area deflected and the flow rate is then reduced to force a centrifugal separation of particulate impurities.

2. The method according to claim 1, characterized in that in a further process step (4) takes place before the generation of the plasma, an electrostatic particle separation.

3. The method according to claim 1 or claim 2, characterized in that in a further process step (3) after the deflection and reduction of the flow rate and optionally before the electrostatic particle separation, the air flow through an open-cell, hydrophilic foam material (22) is performed. - 18 - LAN 6352 PC

4. The method according to any one of the preceding claims, characterized in that the purified air flow in a subsequent process step (8) is fed to a heat exchanger (27).

5. The method according to any one of the preceding claims, characterized in that at intervals a cleaning of a flow channel (12) by means of at least one spray liquid spraying a spray nozzle (18) is feasible.

6. cleaning device for an air flow containing impurities and odors, with a plasma generating device, which forces a dielectrically impeded discharge to generate the plasma by means of AC voltage and with a charcoal or a comparable filter material-containing filter device, characterized in that the cleaning device (9) a Housing (10) having a slot-like inlet opening (11) and with a in the inlet opening (11) opening out flow channel (12), wherein in the curved running flow channel (12) having a rounded or thickened end portion (14), essentially parallel to the slot-like inlet opening (11) extending deflecting element (13) is arranged.

7. Cleaning device according to claim 6, characterized in that the cleaning device (9) has a laterally adjacent to the slot-like inlet opening (11) arranged transfer channel (20) which deflects the through the inlet opening (11) sucked air flow - 19 - LAN 6352 PC

and the parallel to the slot-like inlet opening

(11) arranged one behind the other

Plasma generating device (25) and the filter device (26) supplies.

8. Cleaning device according to claim 7, characterized in that between the deflecting element (13) and the plasma generating device (25) an electrostatic filter unit (23) is arranged.

9. Cleaning device according to one of claims 6-8, characterized in that between the deflecting element (13) and the plasma generating device (25) an open-cell, hydrophilic foam (22) is arranged.

10. Cleaning device according to one of claims 6-9, characterized in that between the deflecting element (13) and the plasma generating device (25) a flame guard (21) is arranged.

11. Cleaning device according to one of claims 6-10, characterized in that the cleaning device (9) in the region of the curved running flow channel (12) has inspection openings (29) or releasably attachable flow channel wall elements.

12. Cleaning device according to one of claims 6-11, characterized in that in the region of the flow channel

(12) at least one spray liquid spraying a spray nozzle (18) is arranged. - 20 - LAN 6352 PC

13. Cleaning device according to one of claims 6-12, characterized in that in front of an outlet opening (28) for the air flow from the cleaning device (9), a heat exchanger (27) is arranged.

14. Cleaning device according to one of claims 6-13, characterized in that between the deflecting element (13) and the plasma generating device (24), a fan (24) is arranged.