Patent Publication Number: US-6709637-B2

Title: Fume recovery apparatus and methods

Description:
CROSS REFERENCE 
     The present application is a division of U.S. application Ser. No. 08/890,471 filed Jul. 9, 1997 now U.S. Pat. No. 6,534,020 B1. 
    
    
     BACKGROUND 
     The present invention generally relates to apparatus and methods for recovering fumes, particularly to apparatus and methods for recovering fumes during the application of a heated, waterproofing material to a roof, and specifically to apparatus and methods for recovering and burning fumes from a heated, waterproofing material. 
     During the installation of many flat roofs, waterproofing material is heated such as in a roofing kettle or like tanker and pumped therefrom onto a roof. To avoid pressure build-up as the result of heating the material and to prevent the creation of a vacuum during pumping, the kettle is vented to the atmosphere. Unfortunately, such venting also allows the escape of fumes to the atmosphere, which fumes are extremely repugnant to many. In fact, many roofing contracts, especially for schools, hospitals, residential areas and the like, require that the fumes from at least the roofing kettle be recovered and not be allowed to escape to the atmosphere. 
     Prior attempts to solve this problem in the field of roofing material application included the use of filtration units such as disclosed in U.S. Pat. No. 5,591,244. Such units are undesirable for several reasons. First, such filter units require a large initial capital investment. Further, operation of such units causes the filters thereof to become plugged requiring replacement. In addition to the cost of the filters and their installation, disposal costs can be large as often such plugged filters are classified as hazardous waste. Additionally, air is required to be drawn through the filters even as material filtered from the air collects on the filter. Thus, large fans are required, which require considerable energy input and are quite noisy. Also, considerable heat is withdrawn from the kettle with the air and thereby increasing the amount of heat which must be supplied to the material by the kettle. Additionally, such filter units are quite large and often are required to be transported to the job site by a flat bed truck. 
     Another attempt to solve this problem has been the use of an afterburner such as manufactured by Reeves Roofing Equipment Co., Inc. of Helotes, Tex. 78023. Generally, such an afterburner includes a vertical chimney upstanding from a roofing kettle lid or cover. A burner was positioned in the chimney. The heat from the burner causes air to rise in the chimney and be drawn from the interior of the roofing kettle. The fumes passing through the chimney and past the burner are burned to eliminate visible smoke and odor. Although fire screens are provided, fire and explosions are of concern because the burner in the afterburner is in close proximity to the material in the roofing kettle and there is no provision for stopping gas flow to the burner in the afterburner in the event that the burner flame does not start or goes out. Also, as air flow is dependent solely upon the chimney effect of the afterburner, fumes tend to escape from the kettle around the lid cover and other locations even when the afterburner is operational. Additionally, operation of afterburners is limited to roofing kettles and the like and generally is not applicable for use at other locations such as on the roof itself. 
     Thus, a need continues to exist for apparatus for recovering fumes from a roofing kettle or the like which overcomes the disadvantages and deficiencies of prior approaches at solving this problem. 
     SUMMARY 
     The present invention solves this need and other problems in the field of fume recovery especially for the roofing industry by providing, in the preferred form, apparatus and methods for drawing air in fluid communication with the fumes of a container of heated material through a conduit and past a burner assembly in the conduit, with the flame of the burner burning or otherwise consuming the fumes of the container. 
     In most preferred aspects, the conduit is horizontally arranged and terminates in the hollow interior of a housing so that fresh air can also be drawn from the hollow interior in addition to the air drawn through the conduit, with fresh air also being provided to the burner assembly inside of the conduit. 
     It is thus an object of the present invention to provide novel methods and apparatus for recovering fumes. 
     It is further an object of the present invention to provide such novel fume recovery methods and apparatus especially adapted for mobile applications between various job sites and especially in the roofing industry. 
     It is further an object of the present invention to provide such novel fume recovery methods and apparatus having relatively low air flow rates while preventing the tendency of fumes to escape from the source during operation. 
     It is further an object of the present invention to provide such novel fume recovery methods and apparatus having reduced capital costs. 
     It is further an object of the present invention to provide such novel fume recovery methods and apparatus having reduced operational costs. 
     It is further an object of the present invention to provide such novel fume recovery methods and apparatus which do not require disposal of collected material. 
     It is further an object of the present invention to provide such novel fume recovery methods and apparatus having reduced operational noise. 
     It is further an object of the present invention to provide such novel fume recovery methods and apparatus having reduced risk of igniting the fumes or the material source of the fumes. 
     It is further an object of the present invention to provide such novel fume recovery methods and apparatus of a minimal size which is easy to handle and transport. 
    
    
     These and further objects and advantages of the present invention will become clearer in light of the following detailed description of an illustrative embodiment of this invention described in connection with the drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The illustrative embodiment may best be described by reference to the accompanying drawings where: 
     FIG. 1 shows a diagrammatic, top plan view of a fume recovery apparatus according to the preferred teachings of the present invention. 
    
    
     The FIGURE is drawn for ease of explanation of the basic teachings of the present invention only; the extensions of the figure with respect to number, position, relationship, and dimensions of the parts to form the preferred embodiment will be explained or will be within the skill of the art after the following description has been read and understood. Further, the exact dimensions and dimensional proportions to conform to specific force, weight, strength, and similar requirements will likewise be within the skill of the art after the following description has been read and understood. 
     Where used in the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms “top”, “bottom”, “first”, “second”, “inside”, “outside”, “front”, “back”, “outer”, “inner”, “upper”, “length”, “end”, “side”, “horizontal”, “vertical”, and similar terms are used herein, it should be understood that these terms have reference only to the structure shown in the drawings as it would appear to a person viewing the drawings and are utilized only to facilitate describing the illustrative embodiment. 
     Description 
     An apparatus for recovering fumes according to the preferred teachings of the present invention is shown in the drawings and generally designated  10 . In the most preferred form shown, apparatus  10  is utilized to recover fumes from a roofing kettle  12 . Kettle  12  can be of any design such as of the type disclosed in U.S. Pat. No. 5,575,272. Generally, kettle  12  includes a vat or similar container  14  in which asphalt or other similar water-proofing roofing material is heated by any suitable means. A vat cover  16  encloses the open top of vat  14  and can include one or more vat lids  18  which can be raised and lowered for the introduction of hard kegs of asphalt for melting. After melting, the liquid asphalt can be pumped from vat  14  to the roof by suitable pumping mechanisms. 
     Generally, apparatus  10  includes an insulated housing  20  having a front wall  22 , a back wall  24 , a bottom wall  26 , a top wall  28 , and first and second side walls  30  defining a hollow interior. In the most preferred form, access is provided to the hollow interior of housing  20  by hinging top wall  28  to second side wall  30 . Housing  20  in the preferred form is movably supported such as by wheels  32 . 
     A conduit  34  extends generally horizontally through front wall  22  into the hollow interior of housing  20  and towards but spaced from back wall  24  parallel to and intermediate bottom and top walls  26  and  28  and parallel to and intermediate side walls  30 . Thus, the free, downstream end of conduit  34  is located in and in fluid communication with the hollow interior of housing  20 . In the most preferred form, conduit  34  includes a first inlet portion  34   a  integrally formed with front wall  22 , a second, interconnection portion  34   b , and a third, combustion chamber portion  34   c . Interconnection portion  34   b  is located intermediate and is removably connected to portions  34   a  and  34   c  such as by mounting flanges. The outer surface of combustion chamber portion  34   c  in the preferred form includes suitable insulation  36 . 
     A circular baffle plate  38  having a diameter slightly larger than the diameter of conduit  34  and considerably smaller than the spacing between walls  26  and  28  and between walls  30  is supported in a spaced relation from the free, downstream end of conduit  34 . Specifically, in the preferred form, first and second legs  40  are provided having first ends suitably secured such as by welding to baffle plate  38  and opposite, second ends suitably secured to a collar  42  which is removably secured to conduit  34 . 
     Apparatus  10  further includes a burner assembly  44  disposed within conduit  34  for providing a flame in conduit  34 . Generally, burner assembly  44  includes an L-shaped duct  46  mounted to interconnection portion  34   b . In particular, duct  46  includes a first leg  50  integrally formed and extending generally horizontally through interconnection portion  34   b . Duct  46  further includes a second leg  48  extending generally perpendicular to first leg  50  and generally horizontally and concentrically inside conduit  34 . In particular, leg  48  extends beyond the downstream end of portion  34   b  and into portion  34   c , with the free end of leg  48  located spaced from the downstream end of portion  34   c  and adjacent the upstream end of portion  34   c . The diameter of duct  46  is considerably less than the diameter of conduit  34  and in the preferred form is less than one-half of the diameter of conduit  34 . 
     A circular baffle plate  52  having a diameter slightly less than the diameter of conduit  34  and larger than the diameter of duct  46  is supported in conduit  34  in a spaced relation from the free, downstream end of duct  46 . Specifically, in the preferred form, first and second legs  54  are provided having first ends suitably secured such as by welding to baffle plate  52  and opposite ends suitably secured to a collar  56  which is removably secured to duct  46 . 
     Burner assembly  44  further includes a tube  58  integrally formed with and extending generally horizontally through first side wall  30 . Tube  58  has a diameter slightly greater than the diameter of duct  46 . The free, upstream end of leg  50  extends into tube  58  and beyond the inner, free end of tube  58 . 
     Burner assembly  44  further includes a source  60  of fuel such as LP gas (liquid propane) in fluid communication with a control box  62  by a fuel line  64 . A fuel line  66  extends from control box  62  into and through tube  58  and terminates in a nozzle located in leg  50  of duct  46 . It should be noted that air is allowed to communicate inside of burner assembly  44  through tube  58  and into duct  46  and around fuel line  66  and the nozzle thereof. A spark igniter or spark plug  68  or similar ignition device is positioned in leg  50  of duct  46  upstream of the nozzle of fuel line  66  for igniting the fuel exiting from the nozzle of fuel line  66 . A flame sensor  70  or similar device for detecting that the fuel exiting the nozzle of fuel line  66  is burning is positioned in leg  50  of duct  46  upstream of spark plug  68 . It should be appreciated that a source of power such as a battery or provisions for plugging into an electrical outlet, not shown, may be necessary for operation of control box  62 , spark plug  68 , and flame sensor  70 . 
     In the preferred form, control box  62 , spark plug  68  and flame sensor  70  are of the form disclosed in U.S. Pat. No. 5,941,236 which is hereby incorporated herein by reference. In particular, control box  62  includes suitable circuitry to open a solenoid valve to an open condition to allow flow of fuel from source  60  and through fuel lines  64  and  66  to the nozzle in duct  46 . After a time delay of a few seconds, for example about four seconds, for fuel gas to flow to duct  46 , a current is applied to spark plug  68  to produce a spark which ignites the fuel gas mixture. The flame extends through duct  46  and engaged baffle plate  52 . Flame thus passes flame sensor  70  which senses the flame. If a flame is sensed by flame sensor  70 , control box  62  maintains the solenoid valve open allowing communication between fuel lines  64  and  66 . If a flame is not sensed by flame sensor  70 , control box  62  de-energizes the solenoid valve preventing communication between fuel lines  64  and  66 . It should be noted that the circuitry of control box  62  includes suitable provisions for allowing the initial communication of fuel lines  64  and  66  and the production of a spark by plug  68  even though flame is not sensed by sensor  70  to start operation and for performing further attempts to initiate ignition if not occurring after the first and second attempts when the on-off switch is initially turned to its “on” position. It should be noted that spark plug  68  is not continually activated during operation of apparatus  10 , but is only activated during attempts to initiate ignition. 
     Apparatus  10  further includes provisions for drawing air from the hollow interior of housing  20 . In the preferred form, a fan  72  is provided having an inlet  74  integrally formed with and extending through back wall  24  and an outlet  76  located outside of housing  20 . Fan  72  is suitably powered such as by a gasoline engine or an electric motor. In addition, housing  20  includes a fresh air intake  78  allowing air communication from outside of housing  20  to the hollow interior thereof. In the preferred form, intake  78  is integrally formed in and extends through first side wall  30  and spaced upstream of the free, downstream end of conduit  34  and can include an adjustable valve plate for adjusting flow rates therethrough. 
     Apparatus  10  is removably attached to kettle  12  in the form shown by a flexible metal hose  80  extending from the free, upstream end of conduit  34  positioned outside of the hollow interior of housing  20  to a suitable plenum  82  positioned in cover  16  of kettle  12 . Thus, the interior of vat  14  is in removable fluid communication with the interior of housing  20  by hose  80 . 
     Now that the basic construction of apparatus  10  according to the preferred teachings of the present invention has been set forth, the operation and some of the advantages of apparatus  10  can be explained and appreciated. Specifically, after hose  80  is attached between kettle  12  and apparatus  10 , the source of power for fan  72  is started to rotate fan  72 . Rotation of fan  72  creates suction in the hollow interior of housing  20  drawing air from the interior of vat  14  through conduit  34  and hose  80  creating negative pressure in kettle  12 , drawing air through duct  46  and tube  58 , and also drawing air through intake  78 . The on-off switch of control box  62  is manually moved to its “on” position to supply and ignite the fuel in a manner as previously set forth. The resulting flame extends from duct  46  and against baffle plate  52 . Due to the negative pressure inside of kettle  12 , fumes are drawn from kettle  12 , through hose  80 , and into conduit  34  where they are drawn across the flame at baffle plate  52  and downstream of baffle plate  52 . A combustion chamber is formed in conduit  34  downstream of baffle plate  52  which is typically at a temperature of about 1400-1500° F. (760°-815° C.). Thus, as the fumes from kettle  12  are drawn into conduit  34  and pass through the flames and into the combustion chamber of conduit  34 , they are burned or otherwise consumed so that the emissions from outlet  76  of fan  72  are clear and generally free of odor. It can be appreciated that baffle plate  38  helps to control flame spread and to control the temperature in the combustion chamber of conduit  34 . In this regard, maximum efficiency of operation of apparatus  10  occurs when the combustion chamber of conduit  34  reaches its desired operating temperature after start-up. 
     It should then be appreciated that fan  72  according to the teachings of the present invention has relatively low air flow rates. Specifically, as the air is not drawn through filters, air flow rates can be relatively low. Specifically, the capital costs are reduced for smaller size fans  72 , and the operational costs and noise are similarly reduced for smaller fans  72 . Additionally, less heat is drawn from the material of kettle  12  at reduced air flow rates so that the operational heating costs of kettle  12  are not significantly increased. Further, intake  78  allows for fresh air to be drawn into the hollow interior of housing  20  by fan  72  in a mixture of about 2½ parts of fresh air to about one part air drawn from kettle  12  so that the air drawn from kettle  12  is minimized. However, it should be appreciated that the air drawn from kettle  12  should be sufficient so that fumes do not have a tendency to escape from kettle  12  around cover  16 , lids  18  and other locations. In the preferred form, air drawn through hose  80  and conduit  34  is in the order of 150 cubic feet (4¼ cubic meters) per minute whereas the air drawn through intake  78  is in the order of 360 cubic feet (10.2 cubic meters) per minute. 
     Additionally, the risk of burner assembly  44  igniting the fumes or the material inside kettle  12  is clearly minimized specifically, the flame produced by burner assembly  44  is at a remote location from the interior of kettle  12  and the flame is directed away from the interior of kettle  12  by leg  48  of duct  46  and is drawn away from the interior of kettle  12  by operation of fan  72 . Also, the fumes of kettle  12  are drawn away from the interior of kettle  12  and are combusted at a remote location from the interior of kettle  12 . 
     The only consumable of apparatus  10  is the fuel of source  60  which in the most preferred form is of the same type utilized for heating the material in kettle  12  and which is supplied at 10 psi (0.7 kilograms per square centimeter) (aside from the energy requirements for operation of control box  62  and fan  72 ). The cost of the fuel is considerably less than the cost of filters, and there are no disposal problems such as arise in disposing of used filters. Additionally, the labor required in removing and replacing filters is completely eliminated. 
     Additionally, the size of apparatus  10  according to the teachings of the present invention is relatively small and considerably smaller than prior filter units. In particular, apparatus  10  in the preferred form is of a size to fit in the box of the pick-up or similar truck utilized to pull kettle  12 . Thus, it is easily transported to the desired sites separate from kettle  12  and can be operated with different kettles  12  where and when necessary. In this regard, due to its relatively small size, apparatus  10  could be lifted up to the roof surface or repair site for recovering fumes as the material is being pumped from kettle  12  into mobile carriers on the roof. It can be appreciated that apparatus  10  can be sized according to the desired air flow from the source of fumes such that for roof top operation, the size of apparatus  10  can be further minimized for ease of handling. 
     Thus since the invention disclosed herein may be embodied in other specific forms without departing from the spirit or general characteristics thereof, some of which forms have been indicated, the embodiments described herein are to be considered in all respects illustrative and not restrictive. The scope of the invention is to be indicated by the appended claims, rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.