FLUE GAS PURIFICATION APPARATUS

Abstract: A "flue gas purification apparatus" consists of two or more parallel fluidized beds separated by herring-like inner louvered perforated wall. All fluidized beds move in downward direction while the velocities may differ between the beds. The velocity of particular bed is controlled by worm gear assembly at the bottom of respective bed. The flue gases are introduced from the side and are led first into outer fluidized bed or beds and then toward the center of the reactor where they are turned upward by buoyancy. The gases exit through the exit shafts.

Description: FLUE GAS PURIFICATION APPARATUS IPC B01 J8/08 B01 J8/12 B01 D53/08 B01 D53/34 FIELD OF THE INVENTION The invention relates to apparatus for cleaning flue gas exiting from various industrial installations emitting gas containing paniculate impurities, such as heavy metal aerosols; gaseous organic impurities, such as low-volatility organic compounds, polychlorinated dibenzodioxins (PCDD), polychlorinated dibenzofurans (PCDF); gaseous inorganic and acidifying impurities, e.g. HF, HCl, SO2, SO3, nitrogen oxides; and gaseous trace elements, such as heavy metals and compounds thereof. The said installations comprise of waste incinerators; furnaces utilizing coal, oil, and gas; foundries and other metal forming facilities; furnaces burning flue gas contaminated by organic pollutants and/or odors; - cement and/or ceramic kilns. BACKGROUND OF THE INVENTION DE 21 60 400 claims apparatus for desulphurization of flue gas using the fluidized bed consisting of active charcoal and coke through which the flue gas are led perpendicularly to the main direction of the fluidized bed. The lowest part of the reactor is showed to form a downward oriented funnel. The side walls through which the gas enters the reactor are shown to be perforated although no type of perforation is claimed. The ideas of fluidized bed, cross inlet flow of impure gas, and active charcoal and/or coke particles contained within the bed will be used in the present invention. DE 26 26 939 claims the regeneration of the adsorbents comprising the fluidized bed by first leading the adsorbents through the outer portion of flue purification apparatus and then reinserting the adsorbents through the central portion of the apparatus. Thus, this invention has outlined layered approach, i.e. the idea of flue gas being cleaned in stages by passing through two adjacent fluidized beds consisting of same material. DE 32 28 984 describes, but not claims, the gas outlets from the upper portion of the reactor from within the fluidized bed. It claims the idea of protecting these outlets by two connected V-forming shields whereas the upper shields are without perforations and lower shields are made of perforated sheets. This idea is further explored in DE 35 23 417 whose claims pertain mainly to the forms of outlets which split the fluidized bed into several streams. DE 38 17 686 introduces, without claiming, the idea of perforated walls where the perforations assume the general shape of the louvers if observed from the cross-section. This idea is further explored in EP 0 399 416 and later in DE 4040 246 which in addition describes, but not claims, the idea of cross flow inlets and countercurrent flow outlets to and from fluidized bed, respectively. It, however, claims the angle a obtained by interconnecting the middle points of the louvers whereby said angle forms the funnel-shape like outlet for the fluidized bed. TECHNICAL PROBLEMS Technical problems which arise through the use of state-of-the art are: • if solely the cross flow of the flue gas is used this prevents the mixing of said gas with adsorbent and causing that the gas entering on the bottom of the perforated area always reacts with already partly reacted charcoal and/or coke while the gas entering on the top of the perforated are reacts with the fresh charge; This means that the gas will not be purified to desired degree but does provide for efficient use of the adsorbent charcoal; • if solely vertical flow of flue gas is used the countercurrent approach precludes the use of several layers of fluidized bed unless the adsorbents are introduced twice in succession, which is costly and fouling prone solution; • if simply perforated wall is used as an inlet to the fluidized bed the fouling may occur; furthermore, the momentum of incoming gas is mainly horizontal which causes the gas to prematurely turn upward and the efficiency of the adsorbent fluidized bed is not as good as desired; • if louvers are used to introduce the flue gas into fluidized bed the fouling will occur unless the angle of the louver is large enough to prevent fouling; • if the whole body of fluidized bed is moving with the same speed the desired purification of gas is usually not achieved; in addition, since the pollutants may excrete from the gas and clump with the particles forming the fluidized bed the fouling may occur thus increasing pressure drop through the apparatus. DESCRIPTION OF THE INVENTION To overcome problems, some of which are presented in the previous section, we propose the apparatus for cleaning of flue gas using fluidized bed with said bed consisting of some chemically active adsorbent material, e.g. charcoal, said gas being produced in various industrial installations and containing paniculate impurities, such as heavy metal aerosols; gaseous organic impurities, such as low-volatility organic compounds, polychlorinated dibenzodioxins (PCDD), polychlorinated dibenzofurans (PCDF); gaseous inorganic and acidifying impurities, .e.g. HF, HCl, SO2, SO3, nitrogen oxides; and gaseous trace elements, such as heavy metals and compounds thereof (henceforth pollutants). The apparatus has the following characteristics: • the apparatus uses the chemical principles of adsorption, sorption, and catalyst processes; • the apparatus comprises of fluidized bed consisting of adsorbent medium/a and/or catalyst medium/a (henceforth medium); said medium contained within the metal housing of particular design; said medium consisting of particles of various shapes and sizes; • the flue gas purified by said apparatus are in contact with adsorbent medium - the pollutants contained in these gas bind to the surface of the medium by adsorption, react chemically with elements contained within said medium; medium may also serve as catalyst to facilitate chemical reaction of gas components; • the efficiency of said apparatus is influenced by type of medium and length of time during which the flue gas are in contact with particles forming said medium; • the flue gas are introduced in mainly horizontal direction through louvered wall; initial momentum of said gas is directed downward; • the flue gas first meander through the outer fluidized bed; said fluidized bed moving in general downward vertical direction between two adjacent walls consisting of louvers; the line which is obtained if the center points of the louvers in cross sectional view are connected is either vertical or almost vertical, digressing not more than 10° from the vertical position; the fluidized bed travels downward and the gas are driven upward by buoyancy and have to overcome first the momentum of downward travelling fluidized bed and their own downward oriented momentum introduced by passage through the louvers - because of these competing forces the gas in effect travel in general horizontal direction through said outer portion of the fluidized bed; during the travel dust particles (aerosols) contained in the gas are deposited on the medium particles and some of the pollutants either react with the medium, are adsorbed by the medium, or the reaction is facilitated with medium serving as catalyst; • the outer fluidized bed moves significantly faster than the main, inner, fluidized bed; different velocities are obtained by using different worm gears for removing the medium at the bottom of said apparatus; the outer fluidized bed serves mainly for first contact with adsorbent medium and initially roughly cleans the incoming flue gas, hence desirable faster exchange of medium. Also, by increasing the velocity of the fluidized bed the gas makes longer paths meandering through the particles and does not clump with the medium particles; the pressure drop through said apparatus is therefore lower; the ratio of medium vs. flue gas is also lower due to increased contact time between gas and medium particles; • the worm gears utilized control the velocity of the fluidized bed in particular section: the outer sections move with different velocity and this is controlled through different rotational speed of worm gears. Each set of gears can have its own velocity which is used to such flow path of gases meandering through the bed to attain desired purification results: exact velocities are determined either by calculation or by trial-and-error tests of the actual embodiment. • the partially purified flue gas exits the outer fluidized bed and enters the inner fluidized bed through louvers, each louver having general inverted V shape with cut-off vertex and with narrower part pointing upward; this shape has two favorable effects - upon exiting from the outer fluidized bed the general direction is already turning upward due to buoyancy and gas does not have to alter the momentum direction prematurely, the second effect being that the fluidized bed slips over the louvers is not as prone to fouling as if the louvers would be shaped differently - upon entering into the inner fluidized bed the momentum is again directed downward which benefits the contact time of gas and medium, analogous to the effects within the outer fluidized bed, explained previously; the movement of the flue gases is shifted from generally downward to generally horizontal to finally generally upward in true countercurrent fashion which facilitates the adsorption of heavily soiled gases with already contaminated particles and already partially purified gases with cleaner medium; purified gas exits through the shafts inserted in the upper portion of the fluidized bed and connected to the main exit tube; • the imaginary boundaries of inner fluidized bed obtained by connecting the innermost edges of the louvers are rectangular in the upper portion and in form of the downward narrowing funnel in the lower portion of said fluidized bed - this shape provides for sufficient mass flow of gas per unit of cross sectional area (see DE 40 40 246 for better description of mass flow); • the inner and outer fluidized bed media may consist of different particle materials, e.g. the outer fluidized bed comprising of adsorption medium and inner of adsorption medium which also serves as a catalyst; • the reagent is introduced to flue gases prior to entering the reactor, the reagent used to reduce nitrogen oxides into nitrogen by facilitating catalytic conversion within the fluidized bed of the reactor. • the apparatus may consist of more than two adjacent fluidized beds if better efficiency or higher purity of flue gases is required, the adjacent fluidized beds separated by inverted V-form louvered walls. • the apparatus may consist of several units which clean the gases sequentially, so called modular arrangement. The apparatus as outlined above have significant advantages over existing state-of-the art comprising of: • the mass of adsorbent medium per volume of flue gas can be lower due to faster velocity of the outer fluidized bed; • there is less fouling as the speed of heavily contaminated medium forming the outer fluidized bed (which is more prone to fouling than less contaminated medium) is higher than less contaminated medium in the inner fluidized bed; • there are several stages of cleaning achieved by first stripping the dust particles in the outer fluidized bed and then continuing with other processes outlined previously; • by using different medium for outer and inner fluidized beds significant savings can be achieved if both media are tailored for its specific purpose: the outer medium leaning toward stripping of aerosols and first, rough, purification of the gas, and inner medium primarily suited for final gas purification. PREFERRED EMBODIMENT Embodiment 1 is shown in Figure 1. The flue gases (1) enter from the side and travel through the pre-mixing chamber (2) to enter the outer fluidized bed (5a) through downward oriented louvers forming the penetrated wall (3). If one imagines lines connecting the innermost points of louvers (11) such lines are almost vertical for most of their lengths differing +-5° from the vertical. This louvered wall changes the direction of flue gases in such a fashion that they are originally oriented downward. Within the outer fluidized bed (5a) the buoyancy changes the direction slightly upward. This direction is schematically depicted using assumed flowpaths (10a, 10b). In outer fluidized bed the gases are cleaned for the first time. After this phase the gases exit through another louvered wall with louvers (4) in form of inverted V shape some of which have cut-off vertices. These louvers change the direction of gas momentum from partially upward to partially downward to again achieve the advantage described in the Description of the invention. Then the gases enter the inner fluidized bed (5b) where they get through the second stage of cleaning process. If one connects the innermost points of louvers (thus defining the edge of innermost fluidized bed) such imaginary lines (12) depict the vessel which is rectangular at the top and then changes into downward narrowing funnel. During the process the gases turn upward due to buoyancy, pass through the bulk of the incoming fluidized bed (5c) in the countercurrent fashion achieving further purification and exit through exit shafts (8) at the top. The bed material is introduced through the openings at the top of the vessel (9). At the bottom of each fluidized bed there is a worm gear assembly (6) which controls the velocity of respective fluidized bed. The rotational velocities of worm gear assemblies are linked to the velocity of respective fluidized beds thus achieving desired results in terms of contact time and ratio of adjacent fluidized bed scrubbing efficiency. Embodiment 2 is shown in figure 3. The difference between this embodiment and embodiment 1 is in use of plurality of materials for fluidized beds. First, the flue gases (1) pass through the louvered wall described in embodiment 1 into the outer fluidized bed (5a) consisting of some fluidized bed material. Then the gases pass through the downward V oriented louvers described in embodiment 1 into the inner fluidized bed (5b) consisting of some other fluidized bed material as the outer fluidized bed material. Apart from that embodiment 2 does not differ from embodiment 1. Embodiment 3 is further extension of embodiments 1 and 2 in such a way that plurality of fluidized beds are added so that they form consecutive fluidized bed through which the gases should pas and thus achieving greater scrubbing efficiency within same apparatus. In this case the additional louvered walls are constructed appropriately. DESCRIPTION OF THE DRAWINGS Figure 1 shows a crossection of preferred embodiment 1 of an "Flue gas purification apparatus", Figure 2 shows 3 D projection of said apparatus, and Figure 3 shows a crossection of preferred embodiment 2 of said apparatus. The reference numbers found in figures refer to: I. inlet for flue gases; 2. pre-mixing chamber; 3. inlet louvered wall; 4. inverted V-shape louvered wall; 5a. outer fluidized bed; 5b. inner fluidized bed; 5c. bulk fluidized bed; 5d. upper fluidized bed; 5e. inner fluidized bed consisting of different material than outer fluidized bed; 6. worm gear assembly; 7. lower fluidized bed; 8. exit shaft; 9. fluidized bed material inlet; 10a., 10b. gas flowpath; I I . imaginary wall obtained by connecting innermost points of louvers of outer fluidized bed; 12. imaginary wall obtained by connecting innermost points of louvers of inner fluidized bed 13. opening for outer fluidized bed material inlet; 14. opening for inner fluidized bed material inlet.

Claims: CLAIMS 1. Flue gas purification apparatus, said gas formed on incineration of waste, for example industrial and/or domestic refuse; formed by furnaces utilizing coal, oil, and gas; formed by foundries and other metal forming facilities; formed by furnaces burning flue gas contaminated by organic pollutants and/or odors; formed by cement and/or ceramic kilns, and containing pollutants in form of particulate impurities, such as heavy metal aerosols; gaseous organic impurities, such as low- volatility organic compounds, polychlorinated dibenzodioxins (PCDD), polychlorinated dibenzofurans (PCDF); gaseous inorganic and acidifying impurities, e.g. HF, HCl, SO2, SO3, nitrogen oxides; and gaseous trace elements, such as heavy metals and compounds thereof, and said bed comprising of particles able to filter and/or adsorb and/or chemically react and/or facilitate catalytic reaction of said pollutants with said particles and/or other components of said gas, said fluidized bed contained in housing, said gas introduced through the louvered wall characterized by at least two adjacent fluidized beds (5a, 5b) contained in housing; said beds moving in downward direction; said beds separated by inner wall (4); said wall being perforated to allow passage of gases. 2 Flue gas purification apparatus, said gas formed on incineration of waste, for example industrial and/or domestic refuse; formed by furnaces utilizing coal, oil, and gas; formed by foundries and other metal forming facilities; formed by furnaces burning flue gas contaminated by organic pollutants and/or odors; formed by cement and/or ceramic kilns, and containing pollutants in form of particulate impurities, such as heavy metal aerosols; gaseous organic impurities, such as low- volatility organic compounds, polychlorinated dibenzodioxins (PCDD), polychlorinated dibenzofurans (PCDF); gaseous inorganic and acidifying impurities, e.g. HF, HCl, SO2, SO3, nitrogen oxides; and gaseous trace elements, such as heavy metals and compounds thereof, and said bed comprising of particles able to filter and/or adsorb and/or chemically react and/or facilitate catalytic reaction of said pollutants with said particles and/or other components of said gas, said fluidized bed contained in housing, said gas introduced through the louvered wall characterized by at least two adjacent fluidized beds (5a, 5b); said beds moving with different velocity. 3. Apparatus as claimed in claims 1 through 2, characterized by at least one wall between two adjacent fluidized beds (4); said wall consisting of louvers with inverted V-shape with the vertex of said shape either cut-off or connected; narrower portion of said shape pointing upward with the side surfaces of said shape of either equal or different length. 4. Apparatus as claimed in claim 1 through 2, characterized by the fluidized beds (5a, 5b) containing the particles of different materials within same fluidized bed. 5. Apparatus as claimed in claim 1 through 2, characterized by the fluidized beds (5a, 5e) containing the particles of same material within each fluidized bed but with the particles material differing between adjacent fluidized beds. 6. Apparatus as claimed in claim 1 through 2, characterized by the combination of fluidized beds (5a, 5e) consisting of particles of same and different materials. 7. Apparatus as claimed in claims 1 through 2 characterized by the shape of outer fluidized bed, the walls (11) of said bed being vertical and/or differing at most +- 5° from the vertical axis, said walls defined as the line connecting the innermost edges of the louvers comprising said walls. 8. Apparatus as claimed in claims 1 through 7 characterized by the shape of innermost fluidized bed walls (12) said shape in upper portion of said walls being rectangular and transforming into funnel shape narrowing downward in the lower portion of said walls said shape defined as the line connecting the innermost edges of the louvers comprising said walls. 9. Apparatus as claimed in claims 1 through 8 characterized by introducing the reagent into flue gases prior to entering the reactor, said reagent used to reduce nitrogen oxides into nitrogen by facilitating catalytic conversion within the fluidized bed. 10. Apparatus as claimed in claim 2 characterized by use of plurality of worm gear assemblies (6) to control the velocity of said fluidized beds; said assemblies defining the velocities of said fluidized beds by virtue of their respective rotational speed. AMENDED CLAIMS [received by the International Bureau on 10 May 1996(10.05.96); original claims 1-10 replaced by amended claims 1-9 (2 pages)] 1. Flue gas purification apparatus, characterized by at least one wall between two adjacent fluidized beds (4); said wall consisting of louvers with inverted V-shape with d e vertex of said shape either cut-off or connected; narrower portion of said shape pointing upward with the side surfaces of said shape of either equal or different length. 2. Flue gas purification apparatus, characterized by a shape of innermost fluidized bed walls (12) said shape in upper portion of said walls being rectangular and transforming into funnel shape narrowing downward in the lower portion of said walls, said shape defined as the line connecting the innermost edges of the louvers comprising said walls. 3. Apparatus as claimed in claims 1 through 2, characterized by at least two adjacent fluidized beds (5a, 5b) contained in housing; said beds moving in downward direction; said beds separated by inner wall (4); said wall being perforated to allow passage of gases; said beds moving with different velocity. 4. Apparatus as claimed in claim 1 through 3, characterized by the fluidized beds (5a, 5b) containing the particles of different materials within same fluidized bed. 5. Apparatus as claimed in claim 1 through 3, characterized by the fluidized beds (5a, 5e) containing the particles of same material within each fluidized bed but with the particles material differing between adjacent fluidized beds. 6. Apparatus as claimed in claim 1 through 3, characterized by the combination of fluidized beds (5a, 5e) consisting of particles of same and different materials. 7. Apparatus as claimed in claims 1 through 3 characterized by the shape of outer fluidized bed, the walls (11) of said bed being vertical and/or differing at most +- 5° from the vertical axis, said walls defined as the line connecting the innermost edges of the louvers comprising said walls. 8. Apparatus as claimed in claims 1 through 3 characterized by introducing the reagent into flue gases prior to entering the reactor, said reagent used to reduce nitrogen oxides into nitrogen by facilitating catalytic conversion within the fluidized bed. 9. Apparatus as claimed in claims 1 through 3 characterized by use of plurality of worm gear assemblies (6) to control the velocity of said fluidized beds; said assemblies defining the velocities of said fluidized beds by virtue of their respective rotational speed.

Inventors: KRECA IVO, KUCAN LADISLAV, ZERJAL EMIL, KRECA, IVO, KUCAN, LADISLAV, ZERJAL, EMIL
Applicants: KOVINSKA IND VRANSKO, KRECA IVO, KUCAN LADISLAV, ZERJAL EMIL, KOVINSKA INDUSTRIJA VRANSKO, KRECA, IVO, KUCAN, LADISLAV, ZERJAL, EMIL
Application year: 1995
Main classification: B01D53
IPC codes: B01D53, B01J8