US 3748081 A
Disposal apparatus for burning liquid fuel waste comprises a vaporizing surface disposed below a combustion zone and adapted to receive the liquid fuel. The vaporizing surface can be a movable channel extending outside of the apparatus. In operation, the fuel is introduced into the apparatus in liquid form and then vaporized and burned.
Description (OCR text may contain errors)
United States Patent 1191 Hummell 45] July 24, 1973 METHOD AND APPARATUS FOR DISPOSAL OF LIQUID WASTE John D. Hummell, Brice, Ohio PPG Industries, Inc., Pittsburgh, Pa.
Filed: May 20, 1971 Appl. No.: 145,342
Related US. Application Data Continuation-impart of Ser. No. 19,833, March 16, 1970, abandoned.
US. or. 431/7, 110/7 R, 110/8 R 1111.01. F23g 7/04 Field of Search 110/7 R, s R, 9 R; 431/2, 11, 37, s, 214, 242,v 190, 285, 336, 337, DIG. 70
References Cited UNITED STATES PATENTS 2,014,714 9/1936 Bauer 431/285 X 2,537,467 l/195l Komline 110/8 R X 3,483,832 12/1969 Boll et a1 110/7 R 2,564,384 8/1951 Wales, Jr. 43l/D1G. 70 1,978,054 10/1934 McDonnell 431/238 Primary Examiner-Meyer Perlin Assistant ExaminerWilliam C. Anderson Attorney-Chisholm & Spencer  ABSTRACT Disposal apparatus for burning liquid fuel waste comprises a vaporizing surface disposed below a combustion zone and adapted to receive the liquid fuel. The vaporizing surface can be a movable channel extending outside of the apparatus. In operation, the fuel is introduced into the apparatus in liquid form and then vaporized and burned.
10 Claims, 8 Drawing Figures FIG. I
4 Sheets-Sheet 1 Patented July 24 1973 MUS INVENTOR I JOHN HUMMELL BY (3| 1 e TTQRNEYS FIG. 2
Patented July 24, 1973 4 Sheets-Sheet 2 INVENTOR ATTORNEY Joy 0. HUMNELL uA .H nnlvv El qoll I H w i W $2 m m 5 6 7 nul finia E F m m 29 254 v u 7 n b 2 DwVo m m E w 9/ m r 1 0 5??? V ///////Wm HmW//////4/////// v. .W L
as w 4 Patented July 24; 1973 4 Sheets-Sheet :5
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INVENTOR J /I/V 0. II'UMMELL M WW ATTORNEY6 Patented July 24, 1973 4 Sheets-Sheet 4 aY-i i U FIG. 7
INVENTOR JOHN D HUMMELL BY W w ATTORN E Y5 1 METHOD AND APPARATUS FOR DISPOSAL OF LIQUID WASTE CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of copending application Ser. No. 19,833, filed Mar. 16, 1970 and now abandoned.
DESCRIPTION OF THE INVENTION The present invention relates generally to liquid waste disposal systems and particularly to an improved method and apparatus which requires substantially no pre-treatment of the liquid waste before introduction into the incinerator and which results in essentially solids-free exhaust gases, so that no elaborate air pollution control equipment need be associated with the exhaust gases to remove particulate matter. The invention is adapted to efficiently dispose of combustible liquid wastes of various types, particularly liquid organic wastes containing solvents, resins, paint sludges, chemical residues, or the like. It is useful with essentially any liquid containing appreciable proportions of combustible organic materials, including aqueous wastes containing up to 70 percent or more of water.
The method of the present invention permits the introduction of liquid waste at ambient temperatures and at a pressure not substantially higher than atmospheric pressure into a combustion chamber. The waste liquid flows freely, without atomization and generally at a metered rate, into the apparatus where it vaporizes and is then mixed with a proper proportion of combustion air to ensure substantially complete smoke-free combustion. With liquid wastes which contain a relatively large percentage of non-combustibles, a further step is desirable where the non-combustible solids in the liquid waste are collected on the vaporizing surface and periodically removed therefrom to prevent excessive buildup and the possibility of the solid particles being picked up and blown out with the exhaust gases.
in general, the apparatus for practicing the novel method of the present invention comprises a housing which defines a chamber having a combustion zone which includes means for introducing air, these usually including a plurality of air inlet ports and an exhaust port. The air inlet ports communicate with a source of combustion air. The lower portion of the chamber is provided with fuel inlet. passage means which communicate with a source of liquid waste fuel and which may include means for shielding the incoming fuel from the heat generated in the combustion chamber. The fuel enters below the combustion zone into the lower portion of the chamber, which serves as a vaporizing zone.
The apparatus also includes a vaporizing surface or hearth disposed below the fuel inlet passage means for receiving the flow of liquid fuel and forming a thin layer thereof, and for vaporization of the volatile combustibles contained therein. An auxiliary burner is disposed in the chamber adjacent to the vaporizing surface for initial heating of the vaporizing surface, if needed, and for initial ignition of the combustibles vaporized from said hearth.
Another preferred embodiment of the present invention includes a movable vaporizing surface and means for removing any solids collecting on the surface, as when the waste contains inorganic materials.
It is therefore an object of the present invention to provide a method of liquid waste disposal and an apparatus for practicing the same which permits liquid fuel wastes to be burned in a simple, efficient manner and which substantially eliminates solids from being introduced into the surrounding atmosphere with the exhaust gases.
It is another object of the present invention to provide a method and apparatus of the type described which permits the liquid wastes to be introduced without pre-heating or high pressure pumping or the like to condition the liquid for intimate mixing with combustion air.
It is another object of the present invention to provide a method and apparatus of the type described which provides for removal of any solids after the volatile constituents have been burned, in a relatively simple manner without polluting the surrounding atmosphere or employing conventional expensive air pollution control equipment.
It is a further object of the present invention to provide a method and apparatus of the type described which is of relatively simple, inexpensive construction and still very efficient and economical in operation with a minimum of maintenance required.
Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the invention are clearly shown.
IN THE DRAWINGS FIG. 1 is a top plan view in section of a liquid waste incinerator in accordance with the present invention, the section being taken through one of the air inlet ports;
FIG. 2 is a front elevational view in section of the incinerator shown in FIG. 1, the section being taken along the centerline of the apparatus;
FIG. 3 is a top plan view in section of another preferred embodiment of a liquid waste incinerator constructed in accordance with the present invention, the section being taken along line 4--4 in FIG. 4;
FIG. 4 is a front elevational view in section of the incinerator shown in FIG. 3, the section being taken along line 3-3 in FIG. 3;
FIG. 5 is a partial front elevational view in section illustrating the fuel inlet port and theair seal which cornprises a portion of the incinerator shown in FIG. 3;
FIG. 6 is a partial front elevational view in section illustrating a hearth cleaning station which comprises a portion of the apparatus shown in FIG. 3;
FIG. 7 is a partial front elevational view of an idler assembly as shown in FIG. 3, and
FIG. 8 is a partial front elevational view of the drive assembly shown in FIG. 3.
Referring specifically to the drawings, an apparatus for the disposal of liquid wastes constructed in accordance with the present invention is shown in FIGS. 1 and 2 and includes a housing, indicated generally at 20, which forms a chamber 22 having an upper combustion zone 25 generally defined by the upper portion of housing 20.
A plurality of air inlet ports 24 are provided in the side walls of housing 20, in the combustion zone, and are communicated via air duct 28 to a regulated source of combustion air, such as a conventional blower diagrammatically illustrated at 26.
A pair of fuel inlet passage means 30 are provided in the lower portion of housing and are communicated via pipe lines 34 and valve means 36 to a conventional pump 38 which in turn is communicated with a storage tank or source of liquid wastes, not shown.
Pump 38 and valve means 36 mainly function to meter the flow of liquid wastes into the incinerator as the liquid wastes are not required to be pre-heated nor are high pumping pressures required.
The dimensions of inlet passages 30 although not critical are relatively large as compared to restricted orifices or the like which function to divide the inlet fluid into a spray as employed in prior liquid waste disposal apparatus.
Generally substantially all liquid wastes commonly incurred could function with merely a gravity feed and pump 38 is used primarily to control the flow rate of liquid entering the housing.
Inlet passages 30 are preferably protected from the heat generated in the combustion chamber by a surrounding insulating material 40 to maintain the temperature of passages 30 low enough to prevent reaction of any of the materials or premature vaporization of the volatile constituents in the liquid waste being fed into housing 20. Suitable insulating materials include water, air, ceramics, etc.
Fuel ignition means, such as auxiliary burner 42, is provided adjacent to the vaporizing surface 44, which is in the bottom portion of chamber 22. The vaporizing surface is usually the bottom of the housing along with the lowermost portion of the sidewalls. This area of the chamber 20, having the fuel inlets and the vaporizing surface, forms vaporizing zone 27.
Vaporizing surface 44 is preferably heated initially by burner 42 to cause an increased rate of vaporization of the volatile constituents present in the thin liquid layer of fuel on the vaporizing surface. The combustible vapors are then ignited by the burner 42 as they become mixed with the combustion air entering inlet ports 24. This permits rapid and smoke-free start-up even with liquid waste fuels having relatively low volatility. After the start of theoperation, the heat generated in the upper portion of housing 20 by the burning fuels and radiated down to the surface of the liquid waste and the vaporizing surface is generally sufficient to provide rapid enough vaporization of the volatile constituents to maintain efficient smoke-free combustion. Then auxiliary burner 42 is no longer needed.
The above described arrangement provides ease of control because only a small volume of liquid fuel is present on the vaporizing surface at any time. This also permits the vaporizing surface to be heated by radiant energy, so as to provide a rapid rate of vaporization of the volatile constituents in the waste fuel, to obtain a maximum rate of complete combustion of the combustible constituents, but not so rapid as to cause any solids that might be suspended in the liquid waste to be carried out with the exhaust vapors. The heat energy supplied to the vaporizing surface should not be sufficient to cause substantial film boiling of the liquid wherein a thin layer of vapor actually forms between the hot vaporizing surface and the liquid being introduced. This is particularly true when the waste fuel contains appreciable solids. However nucleate boiling of the liquid layer is desirable wherein the liquid layer actually lies on the vaporizing surface and the vapors bubble through the liquid to escape and any solids suspended in the liquid remain on the vaporizing surface.
The liquid waste is usually metered into the chamber through passages 30 at a rate consistent with the combustion air flow, which may be regulated with conventional controls, and the burning capacity of the structure. The volatile constituents vaporize in the vaporizing zone and burn in the combustion zone where by appropriate arrangement of the air pattern and control of the fuel vaporization, as described above, the air-vapor mixture is maintained in the proper proportions to provide continuous smoke-free combustion. The mixture within the chamber ranges from vapor-rich in the vaporizing zone, near vaporizing surface 44, to ideal combustion proportions near air ports 24, to air-rich near the exhaust outlet or flue 23.
Now referring to FIGS. 3-8, another embodiment of the present invention is illustrated, which differs from the first described embodiment mainly in the provision of a movable vaporizing surface for continuously removing the solid residue collecting thereon from a liquid waste bearing a substantial percentage of solids, such as for example, various types of paint sludges.
Referring specifically to FIGS. 3 and 4, a housing, generally indicated at 50, forms a combustion zone 52 generally defined in the upper portion of chamber 51. A plurality of air inlet ports 54 are provided in the combustion zone and are communicated to a regualted source of combustion air, such as for example, a con ventional blower diagrammatically illustrated at 56, via duct 58 similarly to the embodiment shown in FIGS. 1 and 2.
The lower portion of chamber 51 is the vaporizing zone 53, and in this area a movable vaporizing surface in the form of a rotating circular channel 60 is provided. A portion of this channel extends through side wall openings 62; the portion of channel 60 extending through housing 50 is disposed in the lower portion or vaporizing zone of chamber 51, below air inlet ports 54 and above auxiliary burner 64. Alternatively, burner 64 can be located above channel 60.
Channel 60 may be driven by any conventional drive means, and is shown by way of example as supported on roller-like rotatable friction drive gear assembly, indicated generally at 70.
Each drive assembly is illustrated by FIG. 8 and includes a supporting base 68 for a plurality of rods 69 which in turn are connected to bearing members 71. A shaft 73 is rotatably mounted in bearing members 71 and operatively connected to a conventional hydraulic drive motor 75. A pair of drive gears 77 and 79 are mounted on shaft 73 and frictionally engage the bottom surface of channel 60. The inner gear 77 is of smaller dimensions than the outer gear 79 since the inner portion of channel 60 will travel a lesser distance than the outer portion.
A pair of idler assemblies, indicated generally at 81, are included to aid in maintaining channel 60 in the same horizontal plane of travel. FIG. 7 illustrates such an idler assembly, each of which includes a support base 83, to which a frame is fixedly mounted by means of rods 87. A pair of shafts 89 are mounted in brackets 91 which are mounted on frame 85. An idler gear 93 is rotatably mounted on each shaft 89 and enporizing surface may be employed without departing from the spirit of the present invention.
The liquid waste is preferably metered to the moving vaporizing surface through an inlet passage and air'seal illustrated in FIG. 5. lnlet means in the form of an open pipe 72 is disposed adjacent to one of the side wall opening 62 on the outside of housing 50, and forms a liquid layer on the vaporizing surface (channel 60). As the liquid waste enters the chamber 51, it vaporizes at a relatively rapid rate due first to the heated surface of the channel 60, which is heated initially by auxiliary burner 64, if necessary, and then by the heat radiated from the burning fuel in chamber 51 after initial ignition of the combustible vapors.
Pipe 72 communicates with a source of liquid waste, not shown, and the flow is controlled by a conventional valve means 74 and a conventional pump, not shown, which meters the flow at low pressure into pipe 72.
An air sea] 76 with regulated purge air supplied through a pipe 78 which may be connected to blower 56, if desired, surrounds inlet pipe 72 and functions to prevent a back flow of vapors or liquids from inside chamber 51 through side wall opening 62. Air seal 76 includes a housing 100 fixed to the side wall of housing 50 and side wall opening 99 to permit the passage of channel 60. A similarly constructed air seal 82 without an inlet pipe 72, is provided for the other side wall opening 62.
As the volatile constituents in the liquid waste vaporize from that portion of channel 60 inside chamber 51, any solids suspended in the waste remain in channel 60 are carried .out-of the chamber as the channel rotates. A typical rate of rotation for channel60 with most materials varies from about.0.5 to about three revolutions per minute.
The solid residue is removed in a continuous manner at'a cleaning station indicated generally at 84. Many means for continuously removing the solid residue from channel 60 may be employed without departing from the spirit of the present invention. However, by way of illustration, a typical example is shown in FIG. 6 and includes a housing 86 provided with side wall openings 88 to permit channel 60 to pass through housing '86.
" A rotating brush 90 is mounted inhousing86 to contact the surface of channel 60 and may be driven by any conventional means to loosen any solid particles carried on the channel and sweep them towards a collector 92. Collector 92 can be, for example, the inlet portion of a vacuum dust collection system. The solids are thereby pneumatically conveyedto a storage vessel or the like, not shown, for independent disposal.
Basically, the twoembodiments described operate in similar manner. The liquid waste is introduced into the vaporizing zone within the chambenusually by metering at low pressure through an open pipeor the like. The vaporizing surface is preferably pre-heated to ensure rapid smoke-free start-up'by vaporizing the volatile constituents rapidly forintimate mixingwith combustion air, which is fed through inlet ports disposed above the vaporizing zone and regulated to provide the proper vapor-air mixture to ensure continuous complete smoke-free combustion.
ln-one example of operation-of-thc apparatus of this invention, there is employed apparatus, as illustrated in FIGS. 1 and 2herein, with refractory-lined chamber 4% feet square and 12 feet high. The fuel inlet passages are two one-half inch diameter pipes, through which liquid waste fuel is introduced. The exhaust gases are vented through a breeching and stack.
The liquid fuel is organic solvent, mainly aliphatic and aromatic hydrocarbons, containing about 20-25 percent dissolved organic solids and 15-20 percent suspended organic solids.
To initiate operation, an auxiliary burner is fired at about 3,000,000 Btu per hour for about 4 hours to preheat the refractories to a temperature of l600-l800F. The liquid fuel is then fed at a rate of up to gal./hr., which combustion air is introduced from the blowers at 6000 to 8000 cubic feet per minute. After the liquid fuel ignites the auxiliary burner is turned off.
Stable, self-sustaining and virtually complete combustion is achieved in this manner, with no flames visible in the stack and fully transparent exhaust gases. The rate of liquid fuel feed is varied (depending on heating value and viscosity) so as to maintain the temperature of the combustion gases entering the stack at the desired temperature, usually between l700 and 2000F., while maintaining the flow of combustion air constant. In other modes of operation the rate of flow of air is also varied.
Operation of the apparatus illustrated in FIGS. 3 and 4 is carried out similarly. The major difference in operation between the two embodiments lies in the movable vaporizing surface which is moved at a controlled rate (for example, about one revolution per minute). Any solid residue collected on the hearth is continuously removed at a cleaning station located outside the housing as the volatiles in the liquid waste are continuously burned in the combustion chamber.
An optional component which can be incorporated into the apparatus as described comprises means for recovering heat from the exhaust gases. A conventional heat exchanger or boiler is effectively employed for this purpose, and not only provides economic advantages but also reducesemission of heat to the atmosphere, i.e., so-called thermal pollution. Other optional equipment can include scrubbers or the like to remove undesirable gases from the exhaust stream.
From the foregoing description it should be readily apparent thatthe method and apparatus of the present invention provide a simple, efficient system for burning liquid waste materials. By vaporizing the volatile constituents in the vaporizing zone, intimate mixing with the combustion air is achieved without the need for high pressure pumping of the inlet fuelto transform'the incoming liquid into spray. Also solids which may be suspended in the liquid waste are left on the hearth to prevent them from being entrained in the exhaust gases and carried into the atmosphere. in prior methods wherein the liquid feed is atomized under high pressure, non-combustible solids can be carried off with the exhaust vapors to contribute to air pollution unless the exhaust is associated with relatively complicated and expensive air pollution control apparatus.
While the forms of embodiments of the present invention asherein disclosed constitutes preferred forms, it is to be understood that other forms might be adopted.
1. An apparatus for burning liquid fuel comprising, in combination, a housing means defining a chamberrhaving a combustion zone; means for deliveringa liquid fuel into said chamber; a vaporizing surface disposd below said combustion chamber and adapted to receive said liquid fuel, said vaporizing surface comprising a circular channel-like member disposed through said housing such that a portion thereof extends through said chamber and a portion is outside of said housing, said channel-like member being rotatable about a generally vertical axis; and fuel ignition means in said chamber and adjacent to said vaporizing surface.
2. The apparatus of claim 1 in which said means for delivering said liquid fuel includes low pressure metering means.
3. The apparatus of claim 1 in which said vaporizing surface is configured to receive said liquid fuel and to form a layer of said liquid fuel on said vaporizing surface.
4. The apparatus of claim 1 including mechanized cleaning means in adjacent relationship to said vaporizing means and disposed outside of said housing for automatic removal of solids residue collecting on said-vaporizing surface.
5. The apparatus of claim 1 including sealing means for preventing the escape of liquid and vapor from said chamber.
6. The apparatus of claim 5 wherein said sealing means includes a source of pressurized air disposed outwardlyfrom said housing.
7. An apparatus for burning liquid waste fuels comprising, in combination, a housing means defining a combustion chamber including a plurality of air ports and two sidewall openings; means communicating with said air ports and with a source of air for introducing predetermined quantities of combustion air into said chamber; a vaporizing hearth means disposed adjacent to said housing and movably mounted for travel through said housing between said sidewall openings; waste fuel inlet passage means communicating with said hearth means; means for metering the flow of liquid waste fuel communicating with a source of liquid waste fuel and with said fuel inlet passage means; sealing means associated with said sidewall openings in said housing for preventing the flow of liquid and vapor from the interior of said housing outwardly through said sidewall openings; and means mounted in said housing for igniting the combustible constituents vaporizing from said hearth means.
8. A disposal apparatus for burning combustible organic liquid waste, which comprises:
a housing defining a generally vertical chamber having a lower vaporizing zone, an intermediate combustion zone means, and an upper exhaust zone, said zones being aligned and in fluid communication;
a stationary vaporizing surface disposed in and extending across said vaporizing zone, said vaporizing surface being aligned with said combustion zone means;
means for delivering a stream of combustible organic liquid waste onto'said vaporizing surface from at least one location above and adjacent the edge of said vaporizing surface so as to provide a thin' film of said liquid extending across said vaporizing surface;
a start-up burner means disposed in said vaporizing zone for initially heating said vaporizing surface to a temperature such that it vaporizes the thin film of liquid waste disposed thereon, said start-up burner means being adapted to initially ignite the vaporized liquid waste;
means for introducing combustion air into said combustion zone means at a location spaced above said vaporizing zone so that the combustion air mixes with the vaporized liquid waste from said vaporizing zone and maintains the combustion thereof;
said combustion zone means being disposed above said vaporizing zone so as to provide a substantially unobstructed fluid communication therebetween, said unobstructed fluid communication permitting a sufficient portion of the heat generated in said combustion zone means to radiate down to the surface of said liquid film and to said vaporizing surface so as to provide a rapid enough vaporization of said liquid film to maintain a continuous combustion of vaporized liquid waste in said combustion zone means without continued use of said start-up burner.
9. The apparatus of claim 8 wherein said means for delivering said organic liquid waste onto said vaporizing surface is insulated from the heat radiated from said combustion zone means down to said vaporizing zone.
10. The apparatus of claim 9 wherein said means for delivering said liquid fuel includes low pressure metering means.
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