Waste Burner

Abstract

A burner for disposing of waste materials by combustion including a housing defining a substantially closed combustion chamber, means for injecting at least one flame to the combustion chamber tangential thereto, means for discharging combusted materials from the combustion chamber and means for creating a static pressure in the combustion chamber to provide for a retention time of waste materials in the chamber to permit complete combustion.

Description

This invention relates to an apparatus for incinerating waste materials, and more particularly to a burner for disposing of waste solids and gases.

A wide variety of burners for disposing of waste effluents are known to the art. However, increased emphasis in recent years on the control of air pollution has led to the enactment of legislation restricting the quantity of pollutants which can be released into the atmosphere with the result that few afterburners heretofore known comply with the requirements of such stringent legislation.

It is accordingly an object of the present invention to provide a burner for incinerating waste solids and gases which produces an effluent which does not significantly contribute to pollution in the atmosphere.

It is another object of the present invention to provide a burner for incinerating wastes which is characterized by a high degree of efficiency in combustion of wastes.

These and other objects and advantages of the present invention will appear more fully hereinafter, and for purposes of illustration, not by way of limitation, reference is made to the drawing, in which:

FIG. 1 is a partially exposed perspective view of one embodiment of the present invention;

FIG. 2 is a sectional view of the embodiment shown in FIG. 1 taken along the line A--A.

FIG. 3 is a side view showing the interior of another embodiment embodying the features of the present invention; and,

FIG. 4 is a top view of the burner illustrated in FIG. 3.

The concepts of the present invention reside in a burner comprising a substantially cylindrical combustion chamber having means to introduce the influent waste material to be incinerated tangentially to the combustion chamber. Spaced vertically above the means for introducing the waste influent is at least one burner means which is positioned to inject a flame tangentially into the combustion chamber concurrently with the waste influent. In the preferred embodiment in which two burners are employed, the burners are positioned 180.degree. apart about the periphery of the combustion chamber housing at staggered elevations.

Another feature of the present invention resides in means provided at the discharge outlet of the combustion chamber which operate to create a static pressure in the combustion chamber to provide for sufficient retention time of the waste material within the combustion chamber to permit complete combustion of the waste materials. In accordance with one embodiment, the discharge outlet is arranged tangentially to the combustion chamber, but in a direction opposite to the flow of materials in the combustion chamber whereby the effluent is forced to reverse its direction of flow in order to exit from the chamber to thereby create sufficient static pressure to provide the desired retention time. In an alternative embodiment, the discharge means is an orifice positioned at the top of the combustion chamber and is partially obstructed by means of a baffle or retention plate to create the desired pressure differential over the vertical dimension of the combustion chamber.

Referring now to the drawings, there is shown in FIG. 1 a preferred embodiment of the invention wherein the burner 10 comprises a housing 12 defining a generally cylindrical combustion chamber 14. As shown in the drawing, housing 12 comprises a metal skin 16 to impart increased structural strength to the device and a refractory lining 18, such as a firebrick lining. It will be appreciated by those skilled in the art that, instead of firebrick, a variety of other refractory materials may be employed. Similarly, the metal skin may be omitted if desired. Combustion chamber 14 is provided with a top 20, which may be, if desired, integral with sidewalls 12, comprising a metal skin 22 and a refractory lining 24.

Provided on housing 12 near the bottom thereof is inlet means 26 for feeding the waste material to be incinerated tangentially to the interior of combustion chamber 14. As shown, means 26 comprises an opening in housing 12 through which solid and gaseous waste material is injected while suspended in an air stream. For this purpose, use may be made of a blower (not illustrated in the drawing) which is capable of operating at elevated temperatures to inject a preheated feed stream comprising the waste material suspended in an air stream to be burned in combustion chamber 14.

Spaced above and circumferentially from inlet means 26 on housing 12 is means 28 to inject a flame into combustion chamber 14 tangential to the inner wall thereof in a direction which is the same as the direction of flow of the influent feed stream. Means 28 comprises at least one, but preferably at least two burners positioned on housing 12. In accordance with the preferred embodiment two burners are employed, and are positioned 180.degree. apart about the circumference of combustion chamber 14 on housing 12 and at staggered elevations to inject flames tangentially to combustion chamber 14 whereby the refractory material is preheated in order to aid in the combustion of the waste materials. It will be appreciated that with larger combustion chambers, it may be advantageous to utilize more than two burners.

Any of a wide variety of burners may be used in the burner of the present invention. Particularly preferred are natural or manufactured gas-fired burners capable of temperatures within the range of 800.degree. to 2,200.degree. F., such as type WR-D-FR manufactured by the Maxon Premix Burner Company, Inc. of Muncie, Indiana. The burners are preferably provided with automatic controls for the gas and secondary air supplies to control the temperature in the burner.

There is provided near the top of housing 12 discharge means 30 which operate to create a static pressure of the gases within combustion chamber 14 to provide sufficient retention time in chamber 14 for all the waste materials to be completely burned. In the embodiment shown in FIG. 1, discharge means 30 is positioned so that the flow of effluent from combustion chamber 14 is tangential to the interior wall thereof, but in a direction opposite to the direction in which the flames and the influent feed are injected. In this way, the effluent gases are forced to change their direction of flow in order to be discharged from combustion chamber 14, thereby creating the desired static pressure within the combustion chamber. Tangential discharge means 30 may be provided with a stack 32, if desired, to carry the combusted materials away from the apparatus. It is frequently advantageous to provide vent means 34 on the top 22 of housing 12 to permit escape of minor amounts of gases which may become trapped in the upper portion of the combustion chamber 14. It will be appreciated that vent means 34 has a cross-sectional area sufficiently less than that of discharge means 30 to retain the static pressure created by discharge means 30. It is also possible to provide vent means 34 with a safety valve assembly whereby the vent is operative only if the pressure in combustion chamber 14 reaches a predetermined level.

FIG. 2 illustrates the arrangement of the burners on the burner housing. As can be seen from this figure, burners 28 and 29 are spaced from each other 180.degree. about the circumference of housing 12, and are positioned so that the flame from each is injected into combustion chamber 14 tangential to the walls in a generally clockwise direction. Waste influent is injected tangentially through inlet means 26 in the same direction as the burner flames whereby the waste material is caused to swirl centrifically around the interior wall of combustion chamber in the same direction as the burner flame so as to be heated by the burner flame to the combustion temperature to thereby burn out all combustible materials in the feed stream.

As is shown by the arrows in FIG. 2, the stream of swirling gases and solids is forced to change its direction of flow in order to exit through tangential discharge means 30 to thereby create sufficient static pressure for the desired retention time in combustion chamber 14 to permit complete combustion of the waste materials.

An alternative embodiment of the present invention is illustrated in FIG. 3, wherein the burner comprises a housing 40, formed of an outer layer or skin 42 of metal which is lined with a refractory material 44, defining a substantially cylindrical combustion chamber 46. Chamber 46 is closed at its top by an inverted conical member having a discharge opening 50 therein, which communicates with a stack 52 which is adapted to discharge gases resulting from combustion in combustion chamber 46.

Near its base housing 40 is provided with inlet means 54 through which waste material may be injected in an air stream tangentially to the cylindrical wall of combustion chamber 46. Spaced above and circumferentially from inlet means 54 are burners 55 and 56 positioned on housing 40 at staggered elevations to inject flames tangentially into combustion chamber 46.

In the embodiment of FIG. 3, there is provided means 58 in the form of a baffle plate spaced below discharge opening 50 to create a static pressure within combustion chamber to thereby provide for sufficient retention time of waste materials in the combustion chamber for proper combustion. Baffle plate 58 serves to partially obstruct the flow of gases and solids, thereby creating the desired pressure differential within the combustion chamber.

It is frequently advantageous to provide a plurality of baffle means 60 projecting from the wall of combustion chamber 46 to insure sufficient turbulence therein for complete intermixing of the influent feed stream and flames from burners 55 and 56. Baffles 60 may conveniently be formed of the refractory material constituting the lining 44.

FIG. 4 illustrates a top view of the embodiment shown in FIG. 3. As can be seen in this figure, burners 55 and 56 are spaced 180.degree. about the circumference of housing 40, and are positioned to inject flames tangential to the wall of the housing. Positioned between the burners is inlet means 54 through which waste materials to be burned may be injected tangentially to the walls of combustion chamber 46.

In the operation of the burner of the present invention, the burners are ignited and are allowed to preheat the interior walls of the combustion chamber. Thereafter, the waste solids and gases are conveyed to a fan or blower capable of operating at high temperatures where the waste materials are preheated, if necessary, and injected tangentially into the combustion chamber where all combustibles are substantially completely burned.

The apparatus of the present invention has been found especially well-suited for use as an afterburner for burning out solids and gases present in the effluent from furnace dewaxing operations. Such effluent is produced from a dewaxing furnace at a temperature of 450.degree. to 650.degree. F. so that it is not necessary to preheat the effluent before feeding to the afterburner. It is generally advantageous to provide a blower which is capable of operating in the temperature range of 200.degree. to 800.degree. F. to accommodate variations in temperature of the dewax furnace effluent. For this particular application, it is preferred that the combustion chamber be dimensioned such that the apparatus can accommodate the desired volume of influent feed at a linear velocity no greater than 500 feet per minute, thereby providing for a retention time of at least 1.25 seconds, preferably at a temperature within the range of 1,900.degree. to 2,200.degree. F.

Operated in this manner the burner of the present invention operates at maximum efficiency, and complies with stringent air pollution control standards. It will be appreciated that the parameters noted above will vary with the particular feed to the burner, but their determination can readily be made by those skilled in the art.

It will be apparent from the foregoing that I have invented a new and improved burner for disposing of waste solids and gases, which is characterized by efficient and economical operation, and yet satisfies current regulatory controls for prevention of air pollution.

It will be understood that various changes may be made in the details of construction and operation without departing from the spirit of the invention, especially as defined in the following claims.

Claims

I claim:

1. A burner for disposing of waste materials by combustion comprising a housing defining a substantially closed combustion chamber, means for supplying influent feed to said chamber, means for injecting at least one flame to said chamber tangential to said housing and means for discharging combusted gases including a discharge opening extending into said chamber tangential to said housing in a direction opposite to the direction in which said flame is injected whereby said combusted materials are caused to reverse their direction of flow to pass through said discharge opening thereby creating a static pressure in said chamber to provide a retention time of said waste materials in said chamber to permit complete combustion.

2. A burner as defined in claim 1 wherein said combustion chamber is substantially cylindrical.

3. A burner as defined in claim 1 wherein said housing includes an outer metal skin and a refractory liner.

4. A burner as defined in claim 1 wherein said means for supplying influent feed includes a feed opening communicating with said chamber, said feed opening extending tangentially into said chamber to permit said influent feed to be injected into said chamber tangential to said housing in the same direction in which said flame is injected.

5. A burner as defined in claim 1 wherein said means for injecting at least one flame in said chamber includes at least two burners, said burners being adapted to inject flames into said chamber.

6. A burner as defined in claim 5 wherein said burners are spaced above said means for supplying influent feed.

7. A burner as defined in claim 5 wherein said burners are positioned at staggered elevations on said housing.

8. A burner as defined in claim 5 wherein said burners are spaced 180.degree. from each other about the periphery of said housing.

9. A burner as defined in claim 1 wherein said burner includes vent means, said vent means communicating with said discharge opening.

10. A burner as defined in claim 1 wherein said burner includes a plurality of baffles positioned on said housing in said chamber.