Fume recovery methods

Information

  • Patent Grant
  • 6534020
  • Patent Number
    6,534,020
  • Date Filed
    Wednesday, July 9, 1997
    27 years ago
  • Date Issued
    Tuesday, March 18, 2003
    21 years ago
Abstract
Apparatus (10) for recovering fumes from a roofing kettle (12) includes a fan (72) for drawing air from the hollow interior of a housing (20). A conduit (34) extends through the housing front wall (22) and terminates in the hollow interior. A burner assembly (44) is disposed within the conduit (34) for providing a flame within the conduit (34). The housing side wall (30) includes a fresh air intake (78). A flexible metal hose (80) extends between the outer free end of the conduit (34) and the roofing kettle (12). Rotation of the fan (72) causes air to be drawn from the interior of the housing (20) and in turn through the fresh air intake (78), through the conduit (34) and the hose (80) from the interior of the kettle (12), and through the duct (46) and tube (58) of the burner assembly (44). Fumes are thereby drawn from the kettle (12) through the conduit (34) and are burned or otherwise consumed in the conduit (34) so that the emissions from the outlet (76) of the fan (72) are clear and generally free of odor.
Description




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


, is 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 engages 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.



Claims
  • 1. Method for recovering fumes from a container of roofing material comprising rotating a fan to draw air from the inside of the container of roofing material for passing through a conduit in fluid communication with the container of roofing material; and providing a flame within the conduit, with the fumes passing through the conduit with the air drawn from inside of the container of roofing material being burned or consumed by the flame.
  • 2. The fume recovery method of claim 1 further comprising: providing a housing having a hollow interior, with the conduit extending into the hollow interior and having a first free end located in and in fluid communication with the hollow interior of the housing.
  • 3. The fume recovery method of claim 2 further comprising: providing a fresh air intake into the hollow interior of the housing, wherein a first portion of a volume of the air within the hollow interior of the housing has passed through the conduit and a second portion of the volume of the air within the hollow interior of the housing has passed through the fresh air intake.
  • 4. The fume recovery method of claim 2 wherein the flame is provided within the conduit which is horizontally arranged.
  • 5. The fume recovery method of claim 2 wherein the fan is located outside of the hollow interior of the draws air from the hollow interior of the housing and having an inlet in communication with the hollow interior of the housing.
  • 6. The fume recovery method of claim 2 wherein the flame is provided by providing a fuel to a burner assembly disposed within the conduit; igniting the fuel while the air is passing through the conduit; and continuing to provide fuel to the burner assembly after the fuel is ignited and while the air is passing through the conduit.
  • 7. The fume recovery method of claim 2 further comprising: providing a flexible metal hose, with the conduit having a second free end located outside of the hollow interior of the housing, with the metal hose being secured to the second free end of the conduit; and removably connecting the metal hose to and in fluid communication with the container of roofing material.
  • 8. The fume recovery method of claim 1 wherein the rotation of the fan draws air from inside of the conduit in fluid communication with the container of roofing material.
  • 9. The fume recovery method of claim 1 recovery wherein the fan is rotated by a gasoline engine.
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Entry
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