Patent Publication Number: US-2016220941-A1

Title: Portable wet scrubber

Description:
RELATED APPLICATIONS 
     This application claims the benefit of Canadian patent application no. 2880360 filed Jan. 30, 2015. This application is herein incorporated by reference in their entirety for all purposes. 
     FIELD OF THE INVENTION 
     This disclosure relates to apparatus for removing particulates from a gas stream and more particularly a portable wet scrubber. 
     BACKGROUND OF THE INVENTION 
     Wet scrubbers have numerous industrial applications. They are capable of collecting basically any type of dust, including flammable, explosive, moist, or sticky dusts. Wet scrubbers are often selected for applications where the particulate in a dirty gas stream is combustible. A wet scrubber eliminates explosion potential of particulates by using fluids, such as water, to remove particulates from the dirty gas stream. 
     In wet scrubbers the cleaning of a contaminated or dirty gas stream having very fine particulates is typically effected by water or other liquid which is set in turbulence by the gas stream. The mixing or scrubbing action of the gas stream with the water causes the particulates to transfer to the water. The particulates transferred to the water settle in the water while the gas stream continues flowing in the scrubber and exits therefrom. In some scrubbers perforated plates are used to enhance particulate transfer. A filter media may be used to remove remaining moisture from the gas stream and additionally filter the gas stream before discharge to the atmosphere. The settled particulates are removed from the scrubber. 
     Venturi wet scrubbers are one type of wet scrubbers. Venturi wet scrubbers force a particle-laden gas stream to pass over the surface of a pool of scrubbing liquid as it enters an orifice. With the high gas velocities typical of this type of scrubber, the liquid from the pool becomes entrained in the gas stream as droplets. As the gas velocity and turbulence increases with the passing of the gas through the narrow orifice, the interaction between the particulate matter and liquid droplets also increases. Particulate matter and droplets are then removed from the gas stream by impingement on a series of baffles that the gas encounters after the orifice. The collected liquid and particulate matter drain from the baffles back into the liquid pool below the orifice and are removed from the scrubber. 
     One wet scrubber application involves removal of aluminum dust particles in auto body repair facilities. With the increased use of aluminum body parts in motor vehicles, the repair of damaged vehicles requires safe and effective removal of aluminum dust created by sanding. Aluminum dust or particulates are highly explosive. When repairing a vehicle having aluminum components, it is also important to capture all the particulates at the source to prevent cross metal contamination. If cold steel particles come in contact with bare aluminum, even in microscopic levels, it can lead to a reaction called “galvanic corrosion”. This reaction can corrode the metal or cause blistering or bubbling on the painted surface. 
     SUMMARY OF THE INVENTION 
     Explosive dust from the exhaust hose of an orbital sander or the like is drawn into the wet scrubber unit and forced down through a venturi channel deep into a water reservoir. The water acts as a separator, and a majority of the dust particles fall to the bottom of the unit immediately. Those particles that manage to escape the first stage of cleansing, are forced through thick curtains of water, and are deflected by a series of baffles into the water turbulence, separating the remaining dust from the air. The moist clean air is drawn up through the unit by an internally fitted fan blower, passes through a stainless steel mist eliminator, where the moisture is removed from the clean air before discharge from the scrubber. The particulates which have settled to the bottom of the water reservoir are removed through a sludge drain valve. 
     In one embodiment, the disclosure provides a portable wet scrubber having a main housing having a closed first end wall and an open second end wall and a detachable top mounted motor housing including a fan blower adapted to draw gas from said main housing and to discharge the gas from the motor housing. The main housing has upper, middle and lower sections. The upper section includes a filtering element, the middle section includes a fluid reservoir and a scrubbing module disposed therein. The scrubbing module cooperates with the upper and lower sections. A contaminated gas inlet port is arranged in the side wall of the main housing and adjoins an inlet duct of the scrubbing module. The lower section includes the lower portion of the fluid reservoir and means for removal of particulates extracted from the contaminated gas. 
     The scrubbing module has a plurality of baffles disposed longitudinally between a pair of end walls of the scrubbing module. The baffles are arranged to define a plurality of associated channels therethrough. The channels comprise a first inner channel cooperating with the inlet duct, a pair of second inner channels adjacent the end section of the first inner channel and a pair of third channels. The second channels converge into an associated chamber in communication with the first and third channels. The third channels are disposed adjacent the first channel in cooperation with the second channels. 
     In a further embodiment, the closed end wall of the portable wet scrubber is affixed to a cart having a platform, a plurality of wheels affixed to the platform, a pair of members extending from the platform means and conjoining with a cross member at the opposite ends thereof. 
     In another embodiment the first channel in the scrubber module comprises an angled top wall plate and a pair of inner baffles each extending generally orthogonally from each side of the top wall. 
     In another embodiment a pair of spaced apart longitudinal baffle plates are disposed parallel to each inner baffle to form a pair of second channels adjacent each side of first channel. Each longitudinal baffle plate has an angled end section extending towards said inner baffle. 
     In another embodiment the second channels converge into a single open lower chamber. 
     In another embodiment the third channels are generally arcuate in shape and are disposed in spaced relationship from the angled end of each longitudinal baffle plate. 
     In another embodiment each inner baffle includes a flat section proximate the top wall and an opposing bulbous like end section. 
     In another embodiment the bulbous ends of the inner baffles comprise a plurality of plate segments formed into a diamond shape. 
     In another embodiment the bulbous ends comprise a generally spherical shape. 
     In another embodiment the fluid reservoir has a generally conical shaped bottom wall having a valved drain. 
     In another embodiment there is a fluid inlet port communicating with the reservoir. 
     In another embodiment there are means for controlling the fluid level in the reservoir. 
     In another embodiment there is a controller for selective operation of the fan. 
     In another embodiment the filter element comprises a filter frame and filer media. 
     In another embodiment there are included a pair of opposed angled baffles disposed between the scrubbing module and the filter element. The baffles extend inwardly from the side wall of the main housing to form an opening between the baffle ends. 
     In another embodiment there is provided an outlet port in the side wall of the main housing at the filter element section. The outlet port has means for discharging built up gas from the filter element section. 
     In another embodiment the main housing is generally cylindrical in shape. 
     The features and advantages described herein are not all-inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and not to limit the scope of the inventive subject matter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An embodiment will now be described in detail by way of example, with reference to the accompanying drawings. 
         FIG. 1  is a front view of a wet scrubber of the present disclosure mounted on a cart. 
         FIG. 2  is rear side view of the scrubber of  FIG. 1   
         FIG. 3  is side view of the scrubber of  FIG. 1 . 
         FIG. 4  is a front view of the scrubber showing certain internal elements in dashed lines. 
         FIG. 5  is side view of the scrubber from showing certain internal elements in dashed lines. 
         FIG. 6  is a top view of the scrubber of  FIG. 1 . 
         FIG. 7A  is a top view of the motor fan housing with the top removed. 
         FIG. 7B  is a side view of the motor fan blower unit within the motor housing. 
         FIG. 8A  is an enlarged top view of the bottom support plate for the motor fan blower unit. 
         FIG. 8B  is an enlarged side cross section view of the bottom support plate of  FIG. 8A . 
         FIG. 9  is a side view of the filter media assembly within the scrubber of  FIG. 1 . 
         FIG. 10  is a side view of the filer media frame. 
         FIG. 10A  is a top view of the filter media frame with the filter media. 
         FIG. 11  is the top view of the filter media assembly in the scrubber unit when the top motor housing is removed. 
         FIG. 12A  is a top view of the filter frame bottom annular support plate. 
         FIG. 12B  is a top view of the filter frame top annular hold down plate. 
         FIG. 13  is an enlarged perspective view of the scrubber module. 
         FIG. 14A  is an end view of the scrubber module showing the internal baffles in dashed lines. 
         FIG. 14B  is a cross section view of scrubber module of  FIG. 10  at section B-B. 
         FIG. 15A  is a side view of scrubber module within the scrubber housing showing the flow direction of the incoming gas stream. 
         FIG. 15B  is a cross section view of scrubber module within the scrubber showing flow directions of the gas streams, the water level before operation and for comparison the water level during operation. 
     
    
    
     DETAILED DESCRIPTION 
     The description, which follows, and the embodiments described therein, is provided by way of illustration of an example, or examples of particular embodiments of principles and aspects of the present invention. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the invention. In the description that follows, like parts are marked throughout the specification and the drawings with the same respective reference numerals. The terms top, bottom, upper, lower, upwardly, downwardly, and the like, as used herein, are applied only for convenience in description and should not be taken as limiting the scope of this invention. 
     Referring now to  FIGS. 1 to 6 , there is shown a portable wet scrubber, generally designated  10 , constructed in accordance with the principles of this disclosure and comprising a housing  15  having a cylindrical side wall  20  and a bottom end wall  25 , an open top end and a contaminated or dirty gas inlet port  27 . Although housing  15  preferably has a circular cross section, any suitable cross-sectional configuration can be employed within the purview of the present invention. 
     A motor housing  30  is removably mounted to the top of housing  15  by a pair of latches  40 . Handles  50  on the side wall  32  of motor housing  30  provide for easier removal of motor housing  30 . A series of elongated openings  60  are provided around the circumference of side wall  32 . Openings  60  dissipate heat buildup within the motor housing  30 . Foam sound attenuation material may additionally be provided in the motor housing  30  to reduce noise levels during operation. An inlet port  70  on side wall  32  is adapted for attachment of a compressed air hose for admitting compressed air into a controller assembly (as later described) within motor housing  30 . Two outlet ports  80 A and  80 B are provided on side wall  32  on the opposite side of inlet port  70  for discharging compressed air from controller assembly. 
     For portability, bottom wall  25  of scrubber  10  is bolted to a cart comprising a flat support plate  11 , two swivel wheels  12 A, two fixed wheels  12 B, vertical members  13 A and  13 B and handle  14  linking members  13 A and  13 B. 
     Referring to  FIGS. 7A, 7B, 8A, and 8B , motor fan blower unit  115  having bearings for handling moist air is mounted within motor housing  30 . “Motor fan blower unit” will be hereinafter referenced as motor. Motor  115  has a 1560 watt blower capable of producing 145 inches of water column and 140 free flow cubic feet per minute (CFM). The motor is bolted via bolts  143  to annular bottom support plate  120 . Bottom support plate  120  may optionally be provided with stiffener bars  125  for added strength. An outlet pipe  130  for discharging air from motor housing  30  extends from the motor blower  115  through side wall  32 . Outlet pipe  130  includes a silencer to reduce the noise level of the discharging air. A series of openings  35  in the top wall of motor housing  30  provide air intake for the motor. 
     Compressed air is provided through inlet port  70  to a tee  135 . Tee  135  diverts the incoming compressed air into hoses  141  and  142  which extend circumferentially around motor  115  to outlet ports  80 A and  80 B in side wall  32 . Each hose is provided with an air flow switch  145 . When a pneumatic tool is attached to contaminated gas inlet duct  27  of scrubber  10 , motor  115  is automatically turned on by air switches  145 . A motor starter controller  150  is also provided on side wall  32  for setting the operation of motor  115 . The motor starter controller has three operational settings, namely on, off and auto. The ‘on’ setting allows the scrubber unit to continuously run without shutting off. The ‘off’ setting turns off the unit. The ‘auto’ setting allows the compressed air to turn on the scrubber unit. The auto setting has a 10 second off delay. The delay allows a user to temporarily release the pneumatic tool without shutting off the scrubber. A rack  55  is optionally mounted to side wall  32  of motor housing for storing hoses. 
     Referring to  FIGS. 4, 5 and 6 , housing  15  includes a middle compartment having a fluid reservoir  155  and a venturi scrubbing module  160  (also called a scrubbing module) mounted to the inside wall of housing  15 , a lower compartment containing the lower section of fluid reservoir  155  and a waste effluent drain assembly  165  for draining fluid reservoir  155 , and, an upper compartment containing filter media assembly  170 . 
     The bottom portion of fluid reservoir  155  has a conically shaped bottom wall  175  having a drain outlet  180 . A shut-off valve  185  is fitted to drain outlet  180  for controlling the removal of waste effluent from the fluid reservoir bottom. A hose [not shown] may be affixed to valve  185  to direct the waste effluent to an area remote from scrubber  10 . The lower compartment of housing  15  is accessible by a hinged door  190  in side wall  20 . 
     Contaminated gas inlet duct  27  on side wall  20  is adapted to receive a dirty gas stream from the exhaust hose of a connected pneumatic tool, such as an orbital sander. Inlet duct  27  may comprise a single hose adapter for receiving one pneumatic tool hose or a Y-shaped fitting  28  with two hose adapters for simultaneous connection of two pneumatic tool hoses. 
     Water, or any other suitable liquid, from an external water supply via a hose (not shown) is introduced into water inlet port  195  and flows into fluid reservoir  155 . Water inlet port  195  is provided with a shut off valve  200 . The water level in fluid reservoir  155  is monitored by a water level gauge such as a sight glass  205  disposed between two valved ports  210  and  215  in housing side wall  20 . Sight glass  205  is marked with low and high water levels. When the desired water level is shown on sight glass  205  shut off valve  200  is closed and the external water supply is turned off. 
     Referring to  FIGS. 13, 14, 15A and 15B , venturi scrubbing module  160  is mounted above the lower conical portion of fluid reservoir  155 . The venturi scrubbing module  160  comprises a first end wall  220  having a quadrangular notch  225  at its top centre and a spaced apart second end wall  230  having an identical sized quadrangular notch  235  at its top centre. Each end wall has outward facing flanges  240  and  245  extending from the vertical edges of end walls  220  and  230 . The flanges provide surfaces for affixing the venturi scrubbing module  160  to the inner side wall of housing  15 , such as by welding. End walls  220  and  230  have the same configurations and dimensions. A quadrangular duct  250  projects from notch  225 . The duct  250  abuts the interior side wall of housing  15  at gas inlet duct  27 . An adapter from rectangular to circular (not shown) is fitted to duct  250  for connection to inlet duct  27 . Duct  250  may be cylindrically shaped in which case an adapter is not required. 
     The venturi scrubbing module  160  further comprises a plurality of baffles forming a plurality of channels. An elongate plate having a width equal to the width of notches  225  and  235  is affixed to the top of end wall notch  225  and to the bottom of end wall notch  235 , to form an angled top wall  260  of an inner channel  265 . Elongate baffles  270  and  275  are arranged to extend downwardly from the top edges of end walls  220  and  230  and longitudinally from end wall  220  to end wall  230  at the side edges of notches  225  and  235 . Baffles  270  and  275  form the side walls of inner channel  265 . Baffles  270  and  275  extend approximately three quarters of the distance between the top and bottom edges of end walls  220  and  230 . Baffles  270  and  275  have flat sections  280  and  285  respectively and lower bulbous like sections  290  and  300 . Lower sections  290  and  330  may comprise a combination of angled flat surfaced plate segments formed into a generally tear drop or diamond shape at the opposite end. Lower sections  290  and  300  may alternatively have curved surfaces to from a rounded shape. Sections  290  and  300  intensify turbulence of the gas stream during the scrubbing process. 
     Baffle plates  305  and  310  extend upwardly from the bottom edges of end walls  220  and  230  and longitudinally between end walls  220  and  230 . Baffle plates  305  and  310  have inwardly angled top ends  315  and  320  respectively. Baffle plates  305  and  310  are arranged approximately equidistant between notches  225  and  235  and the side edges of end walls  220  and  230 . Baffle plates  305  and  310  extend upwardly to approximately the same height as the bottom of duct  250 , thereby forming channel  325  between baffle  270  and baffle  265  and channel  330  between baffle  275  and baffle  275 . Since baffles  270  and  275  do not extend the entire height of the end walls, channels  325  and  330  open into a single open lower chamber  332 . 
     Upper baffles plates  345  and  350  comprise plate segments formed into a substantially arcuate shape. Baffles plates  345  and  350  extend longitudinally between end walls  220  and  230  are arranged above baffle plates  305  and  310 , thereby forming upper channels  355  and  360 . Alternatively, upper baffles plates  345  and  350  may consist of single rounded plates. 
     Filter media assembly  170  is located in the upper compartment of housing  15  below motor housing  30 . Filter media assembly  170  comprises a filter media frame  365  supported by an annular bottom support plate  370 , an annular top plate  375 , filter media  380  arranged within frame  365  between bottom plate  370  and top plate  375 , threaded rods  385  between bottom and top plates and removable threaded knobs  390  at top end of rods. Knobs  390  are used to tighten top plate  375  against bottom plate  370  to hold down filter frame  365 . Removal of knobs  390 , permits removal of top plate  375  for replacing filter media  380 . Filter media  380  removes entrained moisture in the cleansed gas stream before it exits scrubber  10 . Filter media  380  may consist of stainless steel mesh or other suitable media material or mist eliminators designed for removal of entrained moisture for the specific type of gas stream being cleansed. 
     Arranged below filter media assembly  170  and above the venturi scrubber module  60  are a pair half-moon shaped baffles  400  and  405  extending inwards from side wall  20  of housing  15 . Baffles  400  and  405  only extend partly into the interior of housing  15  thereby forming an opening  410 . Baffles  400  and  405  remove entrained water in the gas stream before entry into filter media assembly  170 . The downward angle of the baffles cause water captured by baffles  400  and  405  to drip downwards in the housing. 
     The cleansing of a gas stream contaminated with aluminum particulates generates hydrogen gas which is discharged through relief valve  415  arranged through side wall  20  in the upper section of housing  15 . Relief valve  415  is normally in a shut off position during operation of the scrubber and automatically opens to discharge any built up hydrogen gas when the scrubber unit is turned off. 
     In operation, a water supply hose is connected to water inlet valve  200  is opened. Water fills fluid reservoir  155  until the desired water level  420  is shown on sight glass  205 . Water supply valve  200  is then turned off. A compressed air hose is connected to inlet port  70 . A pneumatic tool exhaust hose with a particle entrained gas stream (such as dust from a sander) is connected to inlet port  28  causing air flow switches  145  to turn on motor  115 . As illustrated in  FIGS. 14A, 14B, 15A and 15B , the gas stream enters through duct  250  of venturi scrubbing module  160  and is forced down through inner channel  265 . The velocity of the gas stream causes turbulence in the water shown as  425 . Some water becomes entrained in the gas stream as droplets. The water acts as a separator, and a majority of particulates in the contaminated gas stream fall to the bottom of reservoir  155  immediately. Those entrained particles that manage to escape the first stage of cleansing in inner channel  265 , are forced through thick curtains of water, and are deflected by baffles into the water turbulence through several channels, separating the remaining particulates from the gas stream. In particular, the gas stream is directed towards channel  332  and around the bottom of baffles  270  and  275 , into channels  325  and  330 . The angled ends  315  and  320  of baffles  305  and  310  direct the gas stream towards surfaces  280  and  285  of baffles  270  and  275  and upwardly towards upper channels  345  and  350 . Arcuate upper channels  345  and  350  direct the cleansed gas stream in a generally curved outward flow direction exiting the venturi scrubbing module. The moist cleansed gas is drawn up through scrubber  10  by motor  115  and passes through the stainless steel media assembly  170 , where remaining moisture is removed from the cleansed gas. The particulate matter which has settled to the conical bottom of reservoir  155  may be removed through drain valve  185 . 
     While the principles of the invention have been shown and described in connection with specific embodiments, it is to be understood that such embodiments are by way of example and are not limiting As is evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the mobile stand illustrated in the drawings. Other modifications and applications, or equivalents, will occur to those skilled in the art. The terms “having”, “comprising” and “including” and similar terms as used in the foregoing specification are used in the sense of “optional” or “may include” and not as “required”. Many changes, modifications, variations and other uses and applications of the present construction will, however, become apparent to those skilled in the art after considering the specification and attached drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims that follow. The scope of the disclosure is not intended to be limited to the embodiments shown herein, but is to be accorded the full scope consistent with the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated , but rather one or more.