Abstract:
A system for gas cleaning has at least one casing ( 1 ) with a first chamber ( 31 ) into which the gas to be cleaned can be flowed and with a second chamber ( 33 ) from which the cleaned gas exits. A filter device ( 35 ) can have the gas flow through it and can be arranged between the chambers. The filter device has filter media both for the separation of solid particles and for dehumidifying the gas by separating out coalesced liquid. The system has, upstream of the filter device ( 35 ), an arrangement ( 11, 37 ) for preliminary dehumidification of the gas.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a system for gas cleaning having at least one housing with a first chamber into which the gas to be cleaned can flow and with a second chamber from which the cleaned gas emerges. Between these two chambers, a filter device is provided through which a gas can flow, and which has filter media both for separation of the solid particles and for dehydration of the gas by precipitation of coalesced liquid. 
     BACKGROUND OF THE INVENTION 
     Systems of this type are known to be designed to eliminate not only dirt due to solid loading, but also to remove the pertinent gaseous media. If the liquid particles coalesce on the filter device located within the housing. The systems are also called coalescers. These systems are often used in conjunction with exhaust gas-generating processes, where exhaust gas flows with comparatively high temperatures and optionally with very high pressures. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a gas cleaning system having especially good cleaning action ensuring very extensive dehydration. 
     This object is basically achieved according to the present invention by a system having an arrangement for preliminary dehydration through which the gas flows before it flows into the actual coalescer housing. The gas is in the preconditioned state promoting residual dehydration by coalescence on the respective filter medium. This preconditioning yields extensive dehydration such that the cleaned gas can optionally be returned to the process. 
     Preferably, the arrangement for preliminary dehydration is located on or in the housing of the filter device. 
     In advantageous embodiments, the arrangement for preliminary dehydration has at least one cyclone. The use of a cyclone leads to a durable and reliable construction since no moving parts are necessary. 
     Embodiments in which the pertinent cyclone is integrated into the housing containing the coalescer is characterized by an especially compact construction. 
     The housing in the normal installation position preferably defines a longitudinal axis extending at least partially vertically. The first chamber is located in the lower section of the housing and is bordered laterally by a circular ring surface, preferably concentric to the longitudinal axis. On the housing, there can be an inflow opening for the gas to be cleaned, such that the gas is tangentially incident on the circular ring surface, so that the circular ring surface forms a cyclone for preliminary dehydration. 
     In these embodiments the housing on the lower end can be closed off by a collecting tank holding the liquid precipitated during preliminary dehydration. 
     Between the collecting tank and the circular ring surface of the cyclone, a floor part can form a drain funnel for the liquid precipitated on the cyclone as the lower boundary of the cyclone. 
     Preferably, the housing can hold a filter device extending along its longitudinal axis and made such that for the gas to be cleaned it provides an inner cavity surrounded by the filter media. Between the exterior wall and the inside wall of the housing, the second chamber is located which the cleaned gas enters after it has flowed out of the inner cavity of the filter device through the filter elements to the outside. 
     On the top end of the circular ring surface forming the cyclone the housing can have a floor separating the first chamber from the second chamber. On the floor, a seat is made forming a passage and receiving a connection sleeve of the filter device. The sleeve leads into the interior cavity of the filter device. Via the sleeve gas dehydrated beforehand flows from the cyclone into the cavity of the filter device. 
     Above this floor, that is, in the region belonging to the second chamber, the housing can have a widening forming a chamber for collection of the fluid coalesced on the filter device and removed from the chamber via an evacuation opening provided in the wall of the housing. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring to the drawings which form a part of this disclosure: 
         FIG. 1  is a front elevational view of a gas cleaning system according to one exemplary embodiment of the present invention with two coalescer housings which can be operated in alternation; 
         FIG. 2  is a front elevational view in section of one coalescer housing of  FIG. 1 , drawn schematically simplified; 
         FIG. 3  is a rear elevational view in section similar to  FIG. 2 , but with the coalescer housing being turned by 180° relative to  FIG. 2  and being shown without the filter device located in it; 
         FIG. 4  is a bottom plan view in section of the coalescer housing taken along line IV-IV of  FIG. 3 ; and 
         FIG. 5  is an exploded perspective view of the filter device which can be used for the system according to the present invention with only the filter media and stabilizing support elements being shown. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is explained below using an exemplary embodiment in which two coalescer housings  1  are used and are made identical, except for the arrangement of the housing openings which is in mirror image. A transfer fitting  3  in the manner conventional in the technology enables transfer of the gas flow supplied to the housings  1  and of the gas flow emerging from them is assigned to the housings  1  such that one housing  1  or the other is activated in alternation. As is to be seen in  FIG. 1 , the transfer fitting  3  as a control element has a transfer lever  5 , depending on its operating position the gas flow being fed from an entry fitting  7  into one housing or the other, from which the gas flow is discharged via an exit fitting  9 . The gas enters at the housings  1  each via one inflow opening  11 . The cleaned gas flow emerges from the respective housing  1  via an outflow opening  13 . A pressure equalization line  15  extends between the housings  1  in  FIG. 1 . 
       FIGS. 2 to 4  show details of one exemplary embodiment of the coalescer housing  1  usable in a system according to the present invention. As is apparent, the housing  1  is made as an elongated body which is square in cross-sectional outline, with a longitudinal axis  17 . In the normal installation position of the housing  1 , the longitudinal axis  17  is aligned vertically. On the top end, the housing  1  is closed by a cover part  19  screwed to it. Sealing elements  21  form a pressure-tight seal. A central vent opening  23  is in the cover part  19 . 
     The housing  1 , on the opposite, lower end, is closed off by a collecting tank  25  screwed to it. Likewise, sealing elements  27  form a pressure-tight seal between the collecting tank  25  and the housing  1 . On the bottom, the collecting tank  25  has an evacuation opening  29 . 
     The different longitudinal sections of the interior of the housing  1  are each made circularly cylindrical, with the interior of the housing  1  being divided fundamentally into two chambers, specifically a first chamber  31  connected to the inflow opening  11  into which the gas to be cleaned flows, and a second chamber  33  ( FIG. 2 ) in which the cleaned gas which emerges from this second chamber  33  via the outflow opening  13 . 
     The first chamber  31  and the second chamber  33  are separated from one another by a filter device  35  through which the gas can flow and which is schematically shown in  FIG. 2  only in outline. 
     The part of the first chamber  31  which directly adjoins the inflow opening  11  forms a cyclone for preliminary dehydration of the gas. For this purpose the inflow opening  11  is aligned to an inner circular ring surface or cylindrical surface  37  of the housing  1  such that the gas flow entering via the inflow opening  11  is incident on the circular ring surface  37  creating a cyclone effect. The cyclone effect causes preliminary dehydration as a result of the centrifugal forces acting on the flow which is flowing along the circular ring surface  37 . 
     As shown by  FIGS. 2 and 3 , between the top end of the collecting tank  25  and the lower end of the circular ring surface  37  of the cyclone, a floor part  39  for the cyclone forms a floor which is recessed in the manner of a funnel with a central drain opening  41 . Via opening  41 , liquid precipitated in the cyclone drains into the collecting tank  25 . 
     Above the circular ring surface  37 , the housing  1  has a floor  43  separating the first chamber  31  from the second chamber  33 . A seat  47  on floor  43  forms a passage  45  and a receiver for the connection sleeve  48  (see  FIG. 2 ) of the filter device  35 . This connection sleeve  48  leads into the inner cavity of the filter device  35  so that the gas which has been dehydrated beforehand in the cyclone travels from the cyclone into the interior of the filter device  35 . 
     As has been shown, especially good dehydration action of the cyclone occurs when a relief-like profile in the form of a spiral is on the wall bordered to the top by the cyclone chamber or flow chamber. As is apparent from  FIGS. 2 to 4 , for this purpose the bottom side of the floor  43  bordering first flow chamber  31  to the top is not made with a smooth surface, but has a profile formed by a projecting rib  71  extending in a spiral with grooves between its turns. As  FIG. 4  shows, the spiral  73  formed in this way extends helically, from its outer start  75  located on the inflow opening  11 , to the inside and against the direction of cyclone flow on the circular ring surface  37 . A configuration such as this promotes settling of droplets falling onto the floor part  39 . Depending on the flow conditions, a different number of spiral turns is possible. 
     As is shown in  FIG. 5 , the inner cavity of the filter device  35  is surrounded by the filter media and support elements through which the gas dehydrated beforehand flows from the inside to the outside. The filter media is such that both precipitation of the solid particles and dehydration take place by precipitation of coalesced liquid. For this purpose, the filter device as inner layers  51  used for particle precipitation has wire cloth and filter paper folded into a star shape. To the outside a perforated sheet  53  adjoins for stabilization. About sheet  53  there is a glass fiber fabric  55  for coalescence. A wire cloth  57  for drainage follows, over which a perforated sheet  59  for stabilization is located. About sheet  59  is a needle felt  61  for draining the liquid. A metal basket  63  finally forms the outer enclosure of the unit. 
     As  FIGS. 2 and 3  show, above the floor  43  in the housing  1 , a widening belonging to or in the second chamber  33  forms a collection chamber  65  for collection of the liquid coalesced on the filter device  35 . That fluid can be drained via a drain or evacuation opening  67 . An opening  69  is designed and provided for connection of the pressure equalization line  15  ( FIG. 1 ) in the upper region of the housing  1 . Openings  23 ,  29 ,  67  and  69  additionally provided in the housing, besides the inflow opening  11  and the outflow opening  13 , are each provided with pressure-tight fittings (not shown). 
     While the present invention is described using one example in which two coalescer housings  1  can be operated in alternation by actuating a transfer fitting  3 , a different system structure with only one coalescer housing or a different number of housings can be provided. Instead of a cyclone integrated into the housing  1 , preliminary dehydration could take place differently, for example, with one or more cyclones connected upstream from the housing. The use of cyclones connected next to one another can likewise be provided, especially in cases in which gas flows of different volumetric flows or different flow velocity must be handled. 
     While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.