Abstract:
A compact, self-contained apparatus for treating wastewater containing as impurities and pollutants various non-volatile (at water boiling points) fluids such as greases, oils and soaps. The apparatus includes a vessel for collecting the wastewater and a heating chamber including waste oil burners and a heat transfer liquid such as mineral oil to heat the wastewater mixture to boil off the water and to reduce the volume of liquid for disposal. A wastewater supply tank may be positioned under the apparatus.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from U.S. Provisional Patent Application Ser. No. 60/887,222, filed Jan. 30, 2007, which is herein incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention relates to apparatus for the treatment of wastewater resulting from cleaning of, for example, buildings, vehicles and machinery by reducing the volume of wastewater required for disposal by an efficient water evaporation utilizing a waste oil burner as a heat source. 
       BACKGROUND OF THE INVENTION 
       [0003]    As explained in my U.S. Pat. No. 6,887,344, No. 5,582,680, and No. 6,200,428, the entire disclosures of which are incorporated by reference into this application, good manufacturing processes, concern for the environment, and changes in environmental practices and regulations all have created additional needs in handling waste fluids after manufacturing and cleaning operations, especially in disposing of water based mixtures containing pollutants such as greases, oils, soaps, heavy metals, road film and carcinogens. Whereas in the past it was acceptable merely to dump such waste liquids in the ground or in sewer systems, current good practices and environmental laws and regulations now severely discourage and/or prohibit such practices. Although very laudable in intent, the result can be very costly, especially to businesses who must use substantial quantities of water in their operations, as for example to clean buildings, vehicles and other machines, which will result in wastewater containing greases, oils, minute metallic and other particles, and detergents. Additionally, there are many wastewater sources for which mass reduction by evaporation is useful. 
         [0004]    Each of the aforementioned patents describes and claims an apparatus operated on the evaporation principle and which is relatively inexpensive to manufacture, simple and safe to operate, and relatively more efficient in the active removal of non-volatile fluids and contaminants from wastewater. What is needed is an improvement to such apparatus that is compact and useful in the myriad operations that produce wastewater, such as in the treatment and reduction of wash and rinse water resulting from the cleaning and or mopping of buildings, vehicles and machinery, including especially the large amounts of wastewater generated by cleaning large areas of high trafficked floors in commercial and industrial facilities using power scrubbing equipment. 
         [0005]    The waste left after water has been removed from a waste stream may comprise a dry powder of solids in certain cases or, potentially, a waste oil. Such a waste oil may come from petroleum products in the wastewater or many businesses may have waste oil from other sources. While this oil is considered a waste, the oil may still be used as an energy source, such as by burning the waste oil as a fuel source in a heating apparatus. It would be a benefit to a business to use this waste as a fuel source; however, waste oil tends to leave a significant residue when combusting with numerous contaminants. Cleaning the equipment that burns waste oil is needed to extend the life of the equipment. 
         [0006]    Thus, an apparatus that is compact and easily moved within a facility, and uses an environmentally safe heat transfer fluid and an optional disposable liner to contain the wastes remaining after evaporation is needed. Further, a waste oil heating system that provides heat to a wastewater evaporator to utilize an energy source that may otherwise be wasted is needed. 
       SUMMARY OF THE INVENTION 
       [0007]    In accordance with this invention, there is provided a novel wastewater treatment apparatus that treats wastewater containing, as impurities and pollutants, various non-volatile (at water boiling points) fluids such as greases, oils, carcinogens and detergents, by vaporizing the water using a waste oil heating system and a heat transferring mineral oil by which heat transfer is effected. 
         [0008]    An advantage of the present invention is that the apparatus offers significant savings in labor, reduction of contamination risk, and energy savings. Further, the invention provides an easily cleaned waste oil heating system that allows an increased use of resources as the waste oil may come from the wastewater stream treated by the apparatus or other sources. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The present invention is disclosed with reference to the accompanying drawings, wherein: 
           [0010]      FIG. 1  is a partial isometric view of a first embodiment of this invention, taken on line  1 - 1  of  FIG. 2  and showing the essential structure of a wastewater treatment apparatus according to the invention; 
           [0011]      FIG. 2  is a side view of the first embodiment of the apparatus as shown in  FIG. 1 , with the wastewater tray shown in partial cross section; 
           [0012]      FIG. 3  is a cross-sectional view taken on line  3 - 3  of  FIG. 2 ; 
           [0013]      FIG. 4  is a top view of the embodiment of  FIGS. 1 and 2  with the waste oil burners shown in phantom; 
           [0014]      FIG. 5  is a partial sectional view of one end of a heat tube of  FIG. 1 ; 
           [0015]      FIG. 6  illustrates the liner of the present invention; 
           [0016]      FIG. 7  is a partial isometric view of the preferred embodiment of this invention, taken on line  7 - 7  of  FIG. 8  and showing the essential structure of a wastewater treatment apparatus according to the invention; 
           [0017]      FIG. 8  is a side view of the preferred embodiment of the apparatus as shown in  FIG. 7 ; 
           [0018]      FIG. 9  is a cross-sectional view taken on line  9 - 9  of  FIG. 8 ; 
           [0019]      FIG. 10  is a top view of the embodiment of  FIGS. 7 and 8 ; 
           [0020]      FIG. 11  is a sectional view of the reentrant tubes of  FIG. 7  with one turbulator in place one turbulator partially inserted; and 
           [0021]      FIG. 12  is an end view of the heat tube and reentrant tubes of  FIG. 7 . 
       
    
    
       [0022]    Corresponding reference characters indicate corresponding parts throughout the several views. The examples set out herein illustrate several embodiments of the invention but should not be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION 
       [0023]    Referring to  FIG. 1 , an embodiment of the present invention comprises a wastewater treatment apparatus  10  and an optional separate wastewater receiving tank  12 . Apparatus  10  includes an external jacket  14  substantially cubic in shape, though other shapes may be used. Contained inside and spaced from jacket  14  is an interior heat generating chamber  16  which is defined at its outside by a heating vessel  18  (e.g., 10 gauge steel) having side walls and a bottom wall as shown, and on the inside by a fluid (e.g., wastewater) receiving vessel  20  with a V-shaped bottom wall and preferably being titanium or stainless steel (e.g., having an internal volume of about 60 gallons, 160 gallons, or 200 gallons and being 151/gauge). Heating vessel  18  in turn is spaced from outer jacket  14  by an air space  22  (e.g., about 2 inches in width on all four sides). Although not shown, heating vessel  18  may be supported at its bottom by jacket  14  using vertical posts or the like. 
         [0024]    Fluid receiving vessel  20  as shown includes side walls, a V-shaped bottom wall and at least a partially open top. Similarly to my previous U.S. Pat. No. 6,887,344, fluid vessel  20  in turn is supported by heating vessel  18  by outwardly extending (e.g., 4 inch) flanges  24  at the top of all four sides sitting atop similar, inwardly extending flanges  26  at the top of all four sides of heating vessel  18 . As thus shown in  FIGS. 1 and 3 , heating chamber  16  extends across the bottom wall and the height of the side walls of fluid vessel  20 . Vessels  18  and  20  may be welded together by their respective flanges, but preferably are held together by detachable means such as stainless steel bolts to enable vessel  20  to be readily removed for maintenance of heating chamber  16  and the heating elements to be described. 
         [0025]    Within heating chamber  16  and below vessel  20  as shown in  FIGS. 1 ,  3 , and  5  are two heat tubes  29   a  and  29   b  (e.g., 10 inches in diameter) each in respective communication with a waste oil burner  30   a  and  30   b  that blows ignited waste oil through the heat tube. Turbulators  33  installed at the ends of heat tubes  29   a ,  29   b  are vanes having a shape and an orientation appropriate to provide an even distribution of the heat within the heat tubes  29   a ,  29   b . The heat tubes output the exhaust into the flue pipe  37 , which is separate from the steam exhaust pipe  40  described below to keep the typically dirty waste oil exhaust separate from the evaporated water. A waste oil reservoir  31 , which may include a filtered input, supplies waste oil to the waste oil burners  30   a  and  30   b  via hoses or pipes. In a particular embodiment, the waste oil may be mixed with a fuel oil. The waste oil heaters  30   a,b  are preferably equipped with high performance air filters in order to supply clean air with the waste oil for improved combustion. 
         [0026]    The heat tubes  29   a,b  are preferably straight tubes because burning waste oil will tend to leave a significant amount of residue in the tubes. Straight tubes can be easily cleaned on a regular basis. To facilitate this, waste oil burners  30   a,b  are at least partly supported by a door  70  in the external jacket  14  that may be removed or swung open to expose the open ends of the heat tubes  29   a,b  so that they may be cleaned. Further, since waste oil may have various contaminants that may be unknown depending on the source of the waste oil, it may be necessary to filter or scrub the exhaust. In this regard, removable filters or a scrubber system may be placed in communication with the flue pipe  37  or the output of the heat tubes  29   a,b.    
         [0027]    In addition, heating chamber  16  is substantially filled (e.g., about one half the depth of chamber  16 ) with a non-toxic, heat transfer liquid mineral oil  32  such as PARATHERM NF Heat Transfer Fluid supplied by Paratherm Corporation of Conshocken, Pa., to evenly distribute to vessel  20  the heat transferred from the heat tubes  29   a,b  and causing the wastewater contained in the fluid vessel to boil and evaporate while enabling the contaminates in the wastewater to settle in vessel  20  in concentrated form for later disposal. Also, as shown in  FIGS. 1 and 3 , heat transfer oil  32  fills at least the entire bottom and a substantial portion of the sides of heating chamber  16 . Such a mineral oil can be heated up to 600° F., which on being so heated begins to circulate convectively to carry the heat to the fluid receiving vessel. In order to ensure efficient heat transfer from the heat tubes  29   a,b  to the heat transfer oil  32 , the waste oil heaters  30   a,b  run at no more than a combined 500,000 BTU. In a particular embodiment, the waste oil heaters  30   a,b  run at 230,000 BTU each. 
         [0028]    As described in my previous U.S. Pat. No. 6,887,344, the wastewater is delivered to vessel  20  by an inlet  34  connected by a pipeline or flexible hose  35  and self priming pump means  36  to a suitable supply tank, such as tank  12 , as shown in  FIGS. 2 and 4 . Of course, alternative wastewater delivery systems may be used including batch and continuous delivery systems as well as automatic and manual delivery systems. Water vapor, as it is generated, escapes from vessel  20  in the apparatus from space  22  by exhaust pipe  40  that preferably includes an exhaust blower fan  42  to facilitate the air flow and exhaust. In a preferred embodiment, the blower  42  is a draft induction blower. There also is provided on the top of the jacket  14  a removable access cover  44  that may be lifted off by handles  45  as shown to expose the inside of vessel  20  through at least a partially open top for inspection and routine maintenance, and may also be available for hand filling of wastewater from pails and the like. 
         [0029]    At the rear of vessel  20  is an access pipe  46  extending through both jacket  14  and vessel  18  and opening into vessel  20  to enable the insertion of a hose to pump out any contaminate-concentrated water remaining in the apparatus for suitable disposal. Pipe  46  ( FIGS. 1 ,  2 , and  4 ), which may include a removable cap on its outer side, is preferably angled, for example at 45 degrees, to enable the inserted hose to be extended to the bottom of vessel  20 . Alternatively, the pipe  46  may be a drain located at the bottom of the “V” formed by the bottom wall of the vessel  20 . Further, the bottom of the “V” may be sloped with the pipe  46  being located at the nadir of the vessel  20 . 
         [0030]    Similarly to my previous U.S. Pat. No. 6,887,344, power to operate apparatus  10  is supplied to the control panel  28  mounted at the side of jacket  14  as shown, with the electrical power delivered through a suitable 3-prong plug from any 110 volt receptacle. The control features may include those described in my patent, U.S. Pat. No. 5,582,680, but may also simply comprise a “dead man” switch  52  to power supply pump  36  only while switch  52  is actively held in its closed position by the operator, an optional combined start-stop 24-hour timer control  54  to start and shut off the electrical power at selectable times, and a “HI-LO” switch  56  to select alternative high and low heat settings of, for example, 350° F. and 150° F., respectively. 
         [0031]    Further as shown, apparatus  10  is supported by suitable legs  59 , which preferably are adjustable in height and may include lockable casters for easy movement. 
         [0032]    As described in my previous U.S. Pat. No. 6,887,344, the removable wastewater supply tank  12  (e.g., about 24 inches wide and 4 inches high) preferably extends beyond apparatus  10  (e.g., 10 inches at each end) to enable a direct fill from the drain of a power scrubber and is mounted on casters  60  to enable the tank  12  to be moved out from under apparatus  10 . The top wall  62  of tank  12  includes an access opening through which wastewater is dumped into a removable filter tray  65  placed in tank  12 , and supply pump  36  which is mounted on a bracket detachable from top wall  62  (to enable pump  36  to be used with other wastewater supply means) connected by the flexible, detachable hose  35  to inlet  34 . The example size of tank  12  is sufficient to hold wastewater from a 50-gallon power scrubber. The power cord  57  ( FIG. 4 ) for pump  36  may conveniently be plugged into a twist lock receptacle  58  in control panel  28  to operate the pump from the control panel. Filter tray  65  is removable and may include a disposable filter bag into which the waste water is poured to filter out larger particles in the wastewater. Filter tray  65  may be made of any suitable close mesh material such as a polyester that, when full, can be removed and incinerated or otherwise properly disposed along with its filtered contents. 
         [0033]    Pump  36  may alternatively be mounted directly on the back wall of jacket  14 . If desired, or if necessary because of local environmental regulations, the evaporating discharge pipe  40  can be connected to a conventional water condenser coil (not shown) to collect distilled water for reclaiming and reuse as washwater. 
         [0034]    In operation, the apparatus is first filled with wastewater generated by a floor scrubber or the like, either by hand or through supply tank  12  by holding pump switch  52  closed until vessel  20  is filled to an appropriate level. The preferred heating level is then set on HI-LO switch  56  and the timer control  54  is then set both to close the heating circuit for the selected time and to actuate blower fan  42  causing the wastewater to reach its boiling temperature, evaporate the water and expel the water vapor from the apparatus. When the water is substantially evaporated, the remaining waste is then removed from vessel  20  through pipe  46  or cover  44 . 
         [0035]    Referring now to  FIG. 6  and as described in my previous U.S. Pat. No. 6,887,344, an alternate embodiment of the present invention comprises a disposable liner  75 , made of a material that is waterproof and both nonporous and impervious with respect to the expected content of contaminants in the wastewater, and which is further capable of withstanding heat up to about 450° F., for example a 32 oz. silicone rubber coated, fiberglass woven fabric identified as G32SIL and manufactured by Amatex Corporation of Norristown, Pa. 
         [0036]    Liner  75  is fabricated so as to prevent the through-passage of water and waste, the sides and bottom of liner  75  conforming in its outer shape to the contours of the fluid receiving vessel  20  of the wastewater treating apparatus. Liner  75  has at least one closeable opening  76  at its top to admit unprocessed wastewater from any source and vent evaporating water during operation to reduce the nonvolatile contaminates to their dry state. Liner  75  is formed of sufficient material at its top to be capable of being sealed shut and removed from fluid receiving vessel  10  and disposed, for example by incineration, along with the residue. The closure may consist of draw string  78  as shown or other suitable means such as adhesive tape. 
         [0037]    If the temperature difference between the heat tubes and the oil exceeds certain limits, the efficiency of the heat transfer from heat tubes to oil is reduced, due in part to radiative and conductive cooling through the external walls of the heating chamber containing the oil and the heat tubes, and due in part to variations in convective behavior of the oil at different temperature ranges and viscosities. Consequently, a means is described whereby the relative differences between the oil temperature, the heating vessel temperature, and the ambient temperature may be held within such limits as will promote a maximally efficient transfer of heat to the oil and energy savings. This means is similar to the means described in my previous U.S. Pat. No. 6,887,344 and contributes to the useful life of the heat tubes and the heat transfer fluid. 
         [0038]    To accomplish the foregoing, an alternate embodiment of the invention includes the incorporation of several thermally-activated sensors, two immersed in the oil in the heating vessel and not touching other surfaces or substances, another attached directly to the surface of the heating vessel, and the fourth located in the control box. The sensors are interconnected in the electrical circuit so that when the temperature differences between the sensors exceed a certain preset limit, the waste oil burners are turned off. 
         [0039]    To control the heating circuit as described and as shown in  FIG. 3 , thermally-activated sensors or thermocouples  80 ,  81 ,  82  and  83 , for example sensor type Rapidship MI manufactured by Watlow-Gordon of Richmond, Ill., are connected to the waste oil burner activation circuit. The thermal sensor elements of sensors  80  and  81  are suspended in oil  32  in heating vessel  18 , the thermal sensor element of sensor  82  is mounted against the surface of the heating vessel  18 , and the thermal sensor element of sensor  83  is located within the control box  28 . 
         [0040]    Thermally-activated sensors  80 ,  81 ,  82  and  83  are connected to a heating control circuit of any type that detects differences in temperature between two or more sensors and changes the state of a power-circuit switching means depending on the relationship between those differences and a set value, e.g.: 
         [0000]    
       
         
               
               
             
           
               
                   
               
               
                 Condition 
                 Action 
               
               
                   
               
             
             
               
                 Differences between respective 
                 Close switching means to waste oil 
               
               
                 sensors less than set value 
                 burners 30a, b 
               
               
                 Differences between any two 
                 Open switching means to open circuit 
               
               
                 sensors exceeds respective set 
                 to waste oil burners 30a, b 
               
               
                 value 
               
               
                   
               
             
          
         
       
     
         [0041]    A suitable preset value may be about 30° F. such that the switching means is closed if the temperature differences are less than that amount and open if more than that amount. The waste oil burners  30   a,b  are actuated and deactuated through a circuit switching means as described above. When the starter button of apparatus  10  is first closed, the switching means is closed to activate the waste oil burners  30   a,b  to blow ignited waste oil through the heat tubes  29   a,b , respectively, and raise the temperature of the heat transfer fluid  32  sufficiently to cause wastewater in vessel  20  to be evaporated. However, as the transfer fluid  32  is being heated, the temperature of the heat tubes  30   a,b  will continue to rise even faster and cause temperature gradients to occur within the transfer fluid  32 . 
         [0042]    The temperature probes  80 ,  81 ,  82 ,  83  are provided to limit the temperature differential. Consequently, when a difference in temperature between two of the thermally-activated sensors exceeds a set value, the heating circuit will deactivate the waste oil burners  30   a,b  until the temperature of the heat tubes  29   a,b  drops to a level at which the temperature differential is less than the set value. At that time, the differences in temperature between thermally-activated sensors does not exceed the set value and the waste oil burners  30   a,b  continue heating the heat transfer fluid  32 . In a particular embodiment, the waste oil burners are actuated and deactuated individually so that the control circuit may run the waste oil burners individually to reduce a horizontal temperature differential if needed. This more energy efficient cycle continues until the heat transfer fluid  32  reaches and is maintained at its preset operating temperature to cause evaporation of the wastewater. The operation may continue by adding more wastewater as desired. When a sufficient amount of contaminants has been collected, the apparatus  10  preferably is operated until all of the remaining wastewater is evaporated leaving a residue that is free of water in the contaminants in liner  75  for disposal by an environmentally safe means. 
         [0043]    In a more preferred embodiment shown in  FIGS. 7-12 , the wastewater treatment apparatus  110  includes a fluid receiving vessel  120  having a substantially flat bottom, and one or more heat tubes  129  with reentrant tubes  184 . The same reference numbers are used for elements that correspond to the elements described in the previous embodiments. 
         [0044]    The vessel  120  simplifies the construction and maintenance of the apparatus  110  because one may use a standard vessel that may be used with other wastewater treatment apparatus. While not shown in the figures, a jacket or similar structure as described in the previous embodiments may be used in the preferred embodiment. The vessel  120  is contained within the heating vessel  18  forming the heating chamber  16 . The heat transfer fluid  32  is contained in the heating chamber  16  in contact with the outer surface of the heat tube  129  and the reentrant tubes  184 . 
         [0045]    The heat tube  129  and reentrant tubes  184  are best shown in  FIGS. 9 and 11 . While only a single heat unit (burner, heat tube, and two reentrant tubes) is shown in the figures, two or more units may be used. In a particular embodiment, the heat tube  129  is a 10-in diameter tube, the reentrant tubes  184  are 4-in diameter tubes, and the reentrant tubes  184  extend about 4-in into the heat tube  129 . The tubes comprise a heat-conducting metal. The heat tube  129  and reentrant tubes  184  are straight for easy cleaning of the residue left by the combusting waste oil. The heat tube  129  is in communication with the waste oil burner  30  and the reentrant tubes  184  exhaust into a flue pipe  137 . The heat tube  129  includes an end wall  190  ( FIG. 12 ) that closes the end of the heat tube  129  around the reentrant tubes  184  to prevent the combusting gasses from escaping into the heating chamber  16 . 
         [0046]    The preferred turbulators  133  are best shown in  FIGS. 11 and 12 . A turbulator  133  according to the preferred embodiment is a plate of metal that slides into the reentrant tube and is shaped to provide a tortuous path for the combusting waste oil in the reentrant tube. This improves the heat transfer of the hot gasses to the fluid  32 . Further, the inlets  185   a  of the reentrant tubes  184  are located some distance (e.g., 4-in) within the heat tube  129 . This slows the exit of the hot gasses from the heat tube  129  into the reentrant tubes  184 . 
         [0047]    The preferred placement of the turbulators  133  within the reentrant tubes  184  is so that the turbulator extends from the inlet  185   a  of the reentrant tube to the edge of the heating chamber  16  as shown in  FIG. 9 . The placement may be made using a tool  186  shown in  FIG. 11 . The tool  186  includes an insertion plate  187  and a stop plate  188 . The insertion plate is the length from the outlet  185   b  of the reentrant tube  184  to the edge of the heating vessel  18 . The insertion plate  187  pushes the turbulator  133  into the reentrant tube  184  until the stop plate  188  contacts the outlet  185   b . The tool  186  is removed from the reentrant tube  184  and the turbulator  133  is left in the preferred position. Alternatively stops may be welded or otherwise fastened into the reentrant tubes  184  to aid in placing and retaining the turbulators  133 . 
         [0048]    The features and operation of the previous embodiments may be incorporated into the preferred embodiment as desired. For example, a liner similar to the liner  75  may be used in conjunction with the fluid vessel  120 . In a further example, the supply tank  12  may be used with the preferred embodiment. In an even further example, a heating control circuit and thermocouples are used in the preferred embodiment. 
         [0049]    From the description above, it should be clear that the present invention offers significant savings in labor, reduction of contamination risk, and energy savings. The use of waste oil as the fuel source in the heating portion of the apparatus allows an increased use of resources as the waste oil may come from the wastewater stream treated by the apparatus or other sources. This waste oil might normally be thrown away or incinerated; however, the configuration of the apparatus described above allows additional energy to be put to use from this waste. The use of a removable liner which may either be cleaned or disposed of substantially reduces the cleaning effort required for the apparatus. The use of the described temperature-difference control for the heating vessel reduces the waste of energy used in heating, and further adds to the useful life of the heat transfer fluid  32 . It also may provide a degree of safety in case of heating vessel leakage or other abnormal condition. 
         [0050]    It is to be understood that the aforementioned description is illustrative only and that changes can be made in the apparatus, in its components and their functions, without departing from the scope of the invention as defined in the following claims.