Gas separation: apparatus – Solid sorbent apparatus – With means regenerating solid sorbent
Reexamination Certificate
1999-05-27
2001-03-06
Spitzer, Robert H. (Department: 1724)
Gas separation: apparatus
Solid sorbent apparatus
With means regenerating solid sorbent
C096S129000, C096S130000, C096S146000
Reexamination Certificate
active
06197097
ABSTRACT:
PRIORITY CLAIM
This application is based on and claims the priority under 35 U.S.C. §119 of German Patent Application 198 23 611.5, filed on May 27, 1998, the entire disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
The invention relates to an apparatus for cleaning an airstream to remove noxious substances and odor causing matter, especially from air circulating through a passenger carrying compartment. The apparatus includes a filter capable of adsorbing noxious and odorous matter by desorption to thereby regenerate the filter.
BACKGROUND INFORMATION
German Patent Publications DE 39 35 656 A1; DE 41 29 069 A1 and DE 19 546 672 A1 disclose devices for cleaning an airstream. These devices include an endless filter belt running over two rollers arranged in parallel inside of chambers through which the filter belt travels and wherein the filter belt is heated for desorption of noxious and odorous matter. Conventionally it is necessary to simultaneously desorb noxious and odorous matter from the entire volume of the filter before the filter can again be exposed to the air flow to be cleaned for again loading the filter belt with noxious and odorous matter. Simultaneously desorbing the entire filter belt is not efficient. Another drawback is seen in the fact that the quantity of adsorbing medium is limited due to the need for minimizing the pressure loss caused by the airstream passing through the filter belt. Satisfying these conditions becomes more and more difficult the larger the volume of the airstream to be cleaned and/or the larger the loading degree of noxious and odorous matter becomes. Thus, there is room for improvement.
It is further known to use two filters which are exposed to the air to be cleaned alternately. Thus, one filter does the cleaning job while the other filter is being desorbed or vice versa. Such structures require a relatively large structural volume for the two separate filters. Such space is frequently not available, especially in a passenger vehicle for removing noxious and odorous matter from the passenger compartment space, or rather from the air circulating in the passenger compartment.
OBJECTS OF THE INVENTION
In view of the foregoing it is the aim of the invention to achieve the following objects singly or in combination:
to provide a small volume apparatus for cleaning an airstream by removing noxious and odorous matter by desorption;
to make sure that even a high degree of noxious and odorous matter in a filter is completely removed;
to expose filter sections sequentially to desorption while other filter sections are simultaneously working to clean an airstream; and
to move the filter relative to a desorption device or vice versa while heating at least sections of the filter for the removal of noxious and odorous matter.
SUMMARY OF THE INVENTION
According to the invention a filter for cleaning an airstream by removing noxious and odorous matter by thermal desorption to thereby regenerate the filter is characterized in that filter sections are heatable one after the other for the desorption of the noxious and odorous matter. An air exit side of the filter is provided with an air discharge for removing the desorbed noxious and odorous matter. The air discharge is so arranged that its cross-sectional flow area overlaps or at least coincides with the flow area of at least one currently heated filter section.
According to the invention at least one filter section at a time is exposed to the airstream to be cleaned also during the desorption so that there is no need to move the filter into or through a special chamber where it would not be exposed to the airstream to be cleaned. Thus, the invention avoids a desorbing chamber, thereby reducing the volume of the apparatus without reducing its efficiency.
By aligning the air discharge for removing desorbed matter sequentially with at least one filter section after another through relative movement between the air discharge and the filter, one filter section after another is desorbed while simultaneously being exposed to the airstream to be cleaned. The present filter does not require to be run over continuously rotating rollers so it is not necessary to make the filter as an endless belt, whereby the advantage is obtained that the filter itself can be pleated to thereby increase the available filter surface area. Preferably, the pleats run across the relative motion direction. Furthermore, the effective filter surface area can be substantially increased while maintaining a minimal structural volume of the entire apparatus. The enlarged pleated filter surface area is capable of adsorbing a respectively large quantity of noxious and odorous matter without causing any significant pressure drop in the air flow to be cleaned as it passes through the filter for the adsorption of the noxious and odorous matter.
As mentioned, either the filter or the air discharge is made movable for movement relative to the other component. Thus, for example the filter may be arranged in a rectangular stationary frame while the air discharge is movable from filter section to filter section or the air discharge may be stationary and the filter sections are moved stepwise into register with the discharge port for the desorption. In another embodiment each filter section can be provided with a temporarily effective air discharge in a sequential order so that there is practically no relative movement.
The velocity of the relative movement between filter section and the air discharge is controllable in closed loop fashion either in response to the volume of the air flow to be cleaned or in response to the degree of loading of noxious and odorous matter in the air flow or in response to both of these factors air volume and loading. The sequential formation of air discharge channels in stationary positions over or on at least one filter section at a time is similarly controllable in closed loop fashion.
The sequential heating of the filter sections can be accomplished, for example by a heat radiating source such as a microwave source or an infrared radiation source. In a preferred embodiment the heat source is integrated into the movable air discharge. In the embodiment with a microwave heat source the filter is preferably made of a filter material capable of absorbing microwaves.
In the embodiment with an electric filter heater it is preferred that the filter material itself is electrically conductive or equipped with an electrical conductor that is heatable. The electrical resistance heater can for example be provided as a wire mesh that carries the filter material in a surface area distribution or the filter material may be integrated into the wire mesh electric resistance heater. However, it is preferred that the filter material itself, namely the adsorption material, is made of an electrically conductive material capable of simultaneously working as a heater and as a filter in order to keep the thermal mass of the filter as small as possible.
An electrically conductive filter material is preferably made of carbon fibers woven into a textile fabric. It has been found that a textile fabric made of regenerated cellulose fibers can be readily converted into a carbon fiber fabric by oxidation, for example of a viscous silk also known as rayon. British Patent 1,310,011 describes, for example the production of such a carbon fiber fabric.
The apparatus of the invention is suitable for cleaning any airstream of noxious and odorous matter. However, the primary application of the present apparatus is for cleaning an airstream that is to enter the interior of a passenger space such as a compartment in a passenger vehicle, in an aircraft or in a train. However, the use of the present apparatus, for example for air-conditioning purposes in buildings is also possible.
REFERENCES:
patent: 2639000 (1953-05-01), Edwards
patent: 4259092 (1981-03-01), Matsuo et al.
patent: 4269611 (1981-05-01), Anderberg
patent: 4391616 (1983-07-01), Imamura
patent: 4479361 (1984-10-01), Osher
patent: 4871607 (1989-10-01), Kuma et
Ertl Harald
Goebel Johann
Kunz Sabine
Daimler-Chrysler AG
Fasse W. F.
Fasse W. G.
Spitzer Robert H.
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