US3575119A - Electrical arc apparatus for disintegrating and incinerating a slurry organic material - Google Patents

Abstract

An apparatus for disintegrating and incinerating a concentrated slurry of solid organic material. The apparatus having an arcuate tunnel, a series of pairs of arc forming electrodes spaced along and mounted within said tunnel and electrical source means connected to each pair of said arc forming electrodes. Advancing means continuously to advance a layer of the organic material through the arcuate tunnel and consecutively into juxtaposition to the arcs formed between each of the pairs of arc electrodes wherein the temperature of that portion of said organic material in juxtaposition to each of said pairs of arc forming electrodes is abruptly raised to from about 2,000* F. to about 15,000* F., at which temperatures the bonds between the carbon and other atoms are dissolved, and means to maintain an oxidizing atmosphere within said tunnel.

Description

United States Patent Andrew W. Marl, Jr.

325 Wheeler S.W., Ardmore, Okla. 73401 [21 Appl. No. 742,804

[22] Filed July 5, 1968 [45] Patented Apr. 13, 1971 [72] Inventor [54] ELECTRICAL ARC APPARATUS FOR DISINTEGRATING AND INCINERATING A 70/4 53 5 00A Ci Primary Examiner- Volodymyr Y. Mayewsky Attorney-Berman, Davidson & Berr r an ABSTRACT: An apparatus for disintegrating and incinerating a concentrated slurry of solid organic material. The apparatus having an arcuate tunnel, a series of pairs of are forming electrodes spaced along and mounted within said tunnel and electrical source means connected to each pair of said are forming electrodes. Advancing means continuously to advance a layer of the organic material through the arcuate tunnel and consecutively into juxtaposition to the arcs formed between each of the pairs of arc electrodes wherein the temperature of that portion of said organic material in juxtaposition to each of said pairs of are forming electrodes is abruptly raised to from about 2,000 F. to about 15,000 E, at which temperatures the bonds between the carbon and other atoms are dissolved, and means to maintain an oxidizing atmosphere within said tunnel.

Patented April 13, 1971 2 Sheets-Sheet l 6 WW H m we 5 12 v M m w m w W Y T M M POWER v SOI/FCi Patented April 13, 1971 2 Shoots-Shoot 2 FIG. 2.

INVlLVI'U/r. 4/1 0054/ m filmy? ELECTRICAL ARC APPARATUS FOR DISINTEGRATING AND INCINERATING A SLURRY ORGANIC MATERIAL In the copending application of Andrew W. Marr and Dewey K. Wallace, Ser. No. MI ,557, filed May 26, 1967, now US. Pat. No. 3,503,347, dated Mar. 3l, 1970, there is disclosed a method and means for the Incineration of Garbage." Essentially, however, that process is a "batch" process which, however, recognizes that abruptly raising the temperature of organic material to the region of more than 2,000 F. largely will free the bonds of the carbon atoms from the remaining atoms in the compound (in the case of carbohydrates, hydrogen and oxygen in a water-forming ratio), thereby enormously reducing the bulk and weight of the original organic material, since the portions detached from the carbon atoms will be largely gaseous of vaporous in form.

The present invention improves on the Marr-Wallace disclosure by making the process continuous and in broadening its scope to include sewage sludge such as is developed in any modern sewage disposal plant. This is accomplished by continually advancing the largely organic material into the influence of consecutive plasma arcs and finally discarding a residue, the majority of which constitutes noncombustible material. No process yet known is 100 percent effective (under other than laboratory conditions) which will completely consume and/r disintegrate organic materials so as to leave only the ash or incombustible material. The ash as a practical matter will be found to comprise largely incombustible salts of calcium with, of course, a certain concomitant of the salts of lithium, sodium and magnesium, etc. Reduction of the original organic mass to such salts as just referred to, results in an enormous reduction both in weight and volume of the original organic material.

So far as applicant is aware, prior procedures in the disposal either of sewage sludge or raw garbage has been confined to dehydration of the same and its sale in the form of fertilizer. As a market, however, particularly as regards sewage, competition with fertilizer is not altogether satisfactory. The fertilizer market, for any particular section of any particular country is highly seasonal but the supply of'sewagc and consequently of sewage sludge is exceedingly regular. The same thing applies, of course, to garbage. Bear in mind that the residual salts (largely of calcium base) are essentially alkaline. The residual salts, then, subject perhaps to further treatment such as reheating, are available for use in a multitude of fields other than fertilizer.

The treatment of raw sewage, no matter what its ultimate disposal, is rather standardized. The raw sewage is given a rough straining to remove such obvious detriti as toilet paper, match hooks, etc., and then is passed over some form of screen, filter or thickener so as to remove in large part, the original water content (solids run usually from to 500 parts per million) of the raw sewage flow. By the nature of vacuum filters, the residue or sludge is reduced to from l0 to 20 percent solids. The residue or sludge may or may not be subjected to further treatment to reduce the water content. By any known mechanical means, the water content may not be reduced below 40 to 60 percent of the total weight. The present invention is concerned with reduction of the total mass, virtually regardless of its water content or how the water content was arrived at. Screens, presses and other dewatering steps are not of concern here. On the other hand, disposal of the gases and vapors produced by the hereinafter described disintegration and vaporization process and apparatus are not of concern here, nor is scrubbing" or precipitation or condensation of the various exhaust gases.

It is, accordingly, a primary object of this invention to provide a method and means of reducing the weight and bulk of waste organic material by the sudden raising of the temperature of such organic material to above, substantially 2,000 F.

It is a further object of this invention to provide a method and means aforesaid which will be continuous in operation.

It is a further object of this invention to provide a method and means aforesaid which will be carried out, preferably, within an oxidating atmosphere which will complete, by incineration or combustion, the reduction of the original material to a solid residue containing, substantially, only its inorganic or noncombustible components.

The above and other objects will be made clear from the following detailed description taken in connection with the annexed drawings, in which: 1

FIG. 1 is a plan view of one form of the apparatus forming part of this invention;

FIG. 2 is a side elevation taken from the left-hand side of FIG. 1;

FIG. 3 is a section on the line 3-3 of FIG. 2, showing a typical heating station of the plasma are type; and

FIG. 4 is a side elevation of a mobile unit embodying the general principles of the apparatus disclosed in FIGS. 1, 2 and 3.

Referring now to FIGS. 1 and 2, there is shown a volute casing 10 which increases in cross-sectional area from a starting point 12 to an ultimate discharge point 14, where gaseous products are discharged to a stack 16. The volute casing 10 constitutes an arcuate tunnel and will be referred to as such in certain of the claims. A pipeline l8 delivers the watered sludge to a vertical pipeline 20 which enters and proceeds through the gas discharge line 16 through a, preferably, vertical line 22. This, of course, represents a heat exchanger transferring heat from the discharge gases in the stack 16 to the incoming sludge in the pipe 22. The showing, of course, is simplified. Subdivision of the pipe 22 into multiple branches and the provision of such heat absorptive area increasing means as ribs or flanges are, of course, wholly within the purview of this invention.

At the center of the volute casing 10 is a rotatable shaft 24 which, as viewed in FIG. 1 and quite arbitrarily, rotates counterclockwise in the direction of the arrow 26. A disc 28 surrounds the shaft 24 and rotates therewith.

Peripherally arranged around the disc 28 but mounted in the volute casing 10, are a plurality of heating stations, mutually substantially identical, and generally designated in FIG. 1 by the reference numeral 30. These heating stations 30 may include a conventional electric are but preferably are of the Plasma Jet" type. A suitable discussion of this subject will be found in a bulletin entitled Plasma Jet Technology, available from the Superintendent of Documents, US. Government Printing Office, under the identification number NASA-SP-(BS and so far as the present disclosure is concerned, reference is hereby made to FIG. 1.1, appearing on page 5 of that publication.

The publication noted in the preceding paragraph, although relatively recent, may be considered as conventional. A further development of the plasma jet arc appears in the magazine Chemical Week," issue of Mar. 30, 1968, at page 56, which discusses a rotary or whirling type of plasma jet are well adaptable to use in connection with the present invention and the use of which definitely is contemplated.

FIG. 3 shows a cross section which includes part of the volute passageway 10 and cuts diametrically through one of the heating stations 30. Since conventional arcs are old and well known, it not not deemed necessary to provide here a detailed disclosure of such an arrangement. FIG. 3, therefore, discloses an adaptation of the showing above referred to appearing in the publication Plasma Jet Technology. In FIG. 3, the rotor or disc 28 is shown as having adjacent its periphery a series of ribs 32 which mate with grooves in the body portion 34 of a heating station 30. The grooves are defined by ribs 36 formed in the body portion 34 which, with the ribs 32, constitute a labyrinth seal against the egress of gases generated in the volute casing 10.

A cap 38 formed of refractory or at least insulating material is mounted in the body portion 34 and supports a preferably tungsten electrode 40 which has a conically tapered end 42. A copper electrode 44 also is mounted in the body portion 34 and mates with the refractory cap 38', as shown at 46 in FIG. 3.

The electrode 44 has a central bore 48 topped by a conical aperture 50 registering with but spaced from the conical end 42 of the tungsten electrode 40, An electric are forms in the gap between the conical end end, and the conical seat 50. An arcing potential across the gap is supplied to the tungsten electrode 40 by a insulated connection 52 and to the copper electrode 44 is a insulated connection 54.

In order to constitute the system of electrodes just described, a plasma jet arc" rather than a simple arc, the cap 38 is designed to provide a cavity 56 around the electrode 40 and above the electrode 44. The cavity 56 is supplied by a duct 58 with a constant stream of gas, usually air, which enters in the direction of the arrow 60 and is vented through the gap between the conical tip d2 of electrode at) and the conical seat 50 of the electrode 4%, thence through the passage 48. This flow of gas in addition to creating the plasma jet effect has the incidental effect of acting as a coolant for the electrode 40. The electrode 44 is cooled by the passage of a cooling medium through an intermediate duct 62 form in the electrode 44 and supplied with coolant through a duct 64.

Returning now to the rotating disc 28, it will be noted that the disc 28 has a'circumferential trough 66 which is lined with a refractory 68. At suitable intervals the trough 66 has formed thereon bosses 70 which support axles 72 on which are rotatably mounted a series of bearing wheels 74 which ride in a continuous track 76 provided in the body 34.

As best shown in FIG. 1, the vertical sludge pipe 22 terminates near the bottom of the stack 16 in a horizontal line 80 which joins an arcuate section 82 centered on the axis of the shaft 24 and overlying the various heating stations 30. The arcuate section 82 is provided at various points 84 with downwardly directed outlet pipes 86 which deposit sludge 88 in the trough 66 for which see FIG. 3.

In passing through the lines 18, 22 and 80, the sludge has become quite highly compressed and for this reason it is desirable to provide the section 82 at various points with a venturi section 90 into the throat of which is directed a jet 92. The venturis 90 and jets 92 preferably are placed slightly in advance of each heating station 30 so that sludge delivered through an outlet 86 will have its density reduced, making it more amenable to the rapid evolution of gases and steam. The increased volume of gas and steam generated by the heating stations 30 is accommodated by the volute form of the casing 10.

As best seen in FIG. 2, air is supplied to the line 82 by a header 94. A second header 96 provides air to the cavities 56 and hence to the arc. Coolant, however, is supplied to the copper electrode 44 through a header 93. If additional air is needed for the purpose of consuming carbon ,formed as a residue of the decomposition of the organic material, it may be added as desired at various points around the casing 10.

Referring now to FIG. 4, there is shown a truck 200 on which is mounted a rotary tank 202, the general design and construction being similar to that of the conventional concrete mixing truck. An arc electrode is provided within the tank adjacent each end and supplied with both the jet forming gas and with coolant by conventional means. From time to time, rotation of the tank 202 is stopped and an additional charge of sewage or garbage is deposited therein. The tank is then sealed, rotation is resumed and the arc is turned on. This, of course, is essentially a batch process. The tank is provided with conventional venting means and the gas as vented may be given any suitable scrubbing, filtering or cleaning operation.

While certain specific embodiments have been disclosed herein, it is not intended to limit this invention to the precise details disclosed. The application itself doubtless will suggest to those skilled in the art numerous modifications. The invention, therefore, is to be limited only as set forth in the subjoined claims.

Iclaim:

1. An apparatus for disintegrating and incinerating a concentrated slurry of solid organic material, said apparatus comprising: an arcuate tunnel, a series of pairs of are forming electrodes spaced along and mounted within said tunnel, electrical source means connected to each pair of said are forming electrodes, advancing means continuously to advance a layer of said material through said tunnel and consecutively into juxtaposition to the arcs formed between each of said pairs of arc electrodes wherein the temperature of that portion of said organic material in juxtaposition to each of said pairs of are forming electrodes is abruptly raised to from about 2,000 F. to about l5,000 F., at which temperatures the bonds between the carbon and other atoms are dissolved, and means to maintain an oxidizing atmosphere within said tunnel.

2. The apparatus of claim 1, in which said are is of the plasma jet type.

3. The apparatus of claim 1, in which said material advancing means comprises a rotary table and said arcs are arcuately arranged about a portion, at least, of its periphery.

4. The apparatus of claim 3, in which said arcuate tunnel comprises a volute casing surrounding the periphery of said table and receiving gases evolved from said organic material.

5. The apparatus of claim 4, including a conduit receiving said gases from said volute casing and a heat exchanger in said conduit, said material passing through said heat exchanger on its way to said table.

Claims (4)

1. 2. The apparatus of claim 1, in which said arc is of the plasma jet type.
2. 3. The apparatus of claim 1, in which said material advancing means comprises a rotary table and said arcs are arcuately arranged about a portion, at least, of its periphery.
3. 4. The apparatus of claim 3, in which said arcuate tunnel comprises a volute casing surrounding the periphery of said table and receiving gases evolved from said organic material.
4. 5. The apparatus of claim 4, including a conduit receiving said gases from said volute casing and a heat exchanger in said conduit, said material passing through said heat exchanger on its way to said table.

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