Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Waste gas purifier
Reexamination Certificate
1998-09-16
2001-02-13
Tran, Hien (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Waste gas purifier
C422S171000, C422S175000, C422S177000, C422S180000, C422S198000, C422S200000, C422S206000, C422S211000, C422S222000, C165S166000, C165S167000
Reexamination Certificate
active
06187273
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a reactor for catalytically processing gaseous fluids in which, along with a catalytic reaction, a heat exchange takes place.
2. Description of the Prior Art
The use of catalysts for purification of outgoing air, e.g., of a solvent-containing industrial air and air used in technical synthesis, is known. The outgoing air is conducted through a reactor in which a catalyst is provided. It is typical for a catalytic oxidation that, on one side, the processed fluid is heated to a predetermined temperature so that a catalytic reaction can take place and that, on the other hand, during a catalytic reaction, heat is released by an exothermal reaction. As a result, it is necessary to evacuate the released heat to avoid overheating and destruction of the catalyst and to supply heat, especially at the beginning of the reaction. To this end, it has already become known to provide outgoing air reactors in which the flow direction is periodically changed.
With a high technical output, a particular drawback of conventional reactors consists in that, during the change of the flow direction, the air which remains in the former inlet is discharged without being purified. It was also suggested to conduct catalytic purification of the outgoing air in a rotatable catalyzer. At that, the stream of outgoing air due to the rotational movement of the catalyzer, flows through the catalyzer interchangeably radially or axially. However, the use of rotatable parts presents problems from the sealing point of view and, in addition, the change of the flow direction results in the creation of so-called dead volume of non-purified air.
Accordingly, an object of the present invention is a reactor of the above-mentioned type that would enable a continuous operation without a forced change of the flow direction.
SUMMARY OF THE INVENTION
According to the present invention, this and other objects of the present invention, which will become apparent hereinafter, are achieved by so arranging the fluid path-defining elements in the reactor housing that channel-shaped structures, having sectionally arranged catalytically acting regions, are formed. It has been found out that with such an arrangement, different temperature zones can be obtained at the same flow direction of the fluid. It is exactly this distribution of the temperature zones is desirable or required for catalytic purification of the outgoing gases.
It was proved to be especially advantageous when the structures have a non-flat outer surface, e.g., a corrugated outer surface. The corrugated structure of plates provides for forming flow channels between respective plates with a very high local heat and mass transfer at the plates. Furthermore, providing a reactor with a plurality of fluid channels which are formed by corrugated plates and which extend substantially parallel to each other, permitted to achieve a very large heat transfer area per unit volume of the reactor. This effect is advantageously used when, according to the invention, the outgoing air flows through two adjacent channels in accordance with a counterflow principle.
To this end, the fluid flow is divided so that fluid flows in the same direction only in every other channel. Thereby, it is achieved that in the first corrugated plate region, which does not have a catalyst, the heat from air, which has already passed the catalyst and which was heated by an exothermal reaction, is transferred to this plate region and the air, which has yet to be subjected to the catalytic treatment and which flows in the adjacent channel, is preheated due to heat transfer. In the second corrugated plate region, which likewise does not have a catalyst, the same heat transfer takes place, but in the opposite direction.
In accordance with a further development of the invention, it is contemplated that fluid flows through two respective, connected with each other, adjacent channels, so that the reaction heat which is generated in a fluid stream, can be transferred to the same stream for preheating. Instead of being sealed, the channels can end in a common collecting channel, with branching therefrom into respective adjacent channels. Such flow configuration results in that the fluid is compulsorily delivered to the reactor at the same pressure.
In an advantageous embodiment of the invention, it is contemplated to provide in the collecting channel a device for extracting and/or addition of heat. Thereby, the thermal content can alternatively be regulated in accordance with the course of the reaction strong exothermal or less than strong exothermal. By an appropriate shaping of the plate's outer surface, a very high heat and mass transfer between the fluid and the wall is achieved, as well as a predetermined uniform dwell time and a homogeneous mixing in the fluid phase.
The shape of the plate's outer surface, in view of the very high heat transfer, is based upon the fact that, for example, during the catalytic purification of solvent-containing outgoing air, the concentration of harmful material is low and is further reduced by catalysis-generated heat. As a result, a small temperature difference exists between the incoming air and the outgoing air. This leads to a relatively little heating of the air during the reaction and, therefore, to a small temperature difference between the purified air after the reaction and the non-purified air before the reaction. In order to bring the air, which is admitted into the reactor, to a reaction temperature, the relatively small quantity of heat, which is contained in the outgoing air at small concentration of solvents, should be transferred to the incoming air as completely as possible.
In accordance with the invention, with the above-described autothermal reactor types, the use of strong exothermal or strong endothermal reactions requires a uniform heat addition or heat extraction because, otherwise, the catalyst is destroyed or, when endothermal reaction takes place, quenching of the reaction takes place. Further, according to the invention, additional heating and/or cooling channels are contemplated in addition to the already described fluid path-defining structures. These are advantageously provided between two respective fluid paths.
The constructional forms are adapted to particular requirements, e.g., for autothermal operation, the outer surfaces of the heat receiving and heat releasing zones can, for a different heat and mass transfer, be layed out as a reaction zone.
According to a further advantageous embodiment of the invention, it is contemplated to displace the described plates relative to each other so that adjacent plates form contacting each other opposite wave-shaped structures. The wave-shaped structures can have different height dimensions and can be spaced from each other a different distance.
It can also be very advantageous to use plates having opposite orientation so that the plates support each other. With this construction, the best results are achieved. The possible adaptation of the fluid-path defining structures to particular operational requirements permits to so change the temperature profile of the reactor and to shift the functional zones of the reactor, that both the temperature profile and the functional zones would correspond to different load conditions of the reactor.
REFERENCES:
patent: 3910042 (1975-10-01), Yuge et al.
patent: 3972685 (1976-08-01), Hanaoka
patent: 5700434 (1997-12-01), Gaiser
patent: 5846494 (1998-12-01), Gaiser
Tran Hien
Wood & Brown, LLP
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