US2169160A - Method for destroying sewage - Google Patents

Description

Aug. 8, 1939. MORETON 2,169,160

METHOD FOR DESTROYING SEWAGE Filed Feb. 20, 1955 Patented Aug. 8, 1939 UNITED STATES PATENT OFFICE Henry H. Moreton,

Laguna Beach, Calif.

Application February 20, 1936, Serial No. 64,981

6 Claims.

This invention is a method for destroying sewage and similar refuse material.

Sanitary engineers have long recognized that effective sewage disposal and destruction cannot be satisfactorily accomplished unless water and/ or soil pollution is completely avoided. In fact, attempts heretofore made to physically destroy sewage have met with indiiferent success from the standpoint of practical economy, convenience in handling, and complete sanitary safety, so that at the present time, the so-called bacterial systems are considered the safest and most desirable methods for municipal installations. Systems of the bacterial type however, involve the installation of apparatus which must be spread over a considerable area, require very large investments to meet the initial costs of installation, and they are more or less expensive to operate.

One of the objects of the present invention is to effect complete and economical physical destruction of sewage by incineration, whereby practically no residue is left, so that the possibility of either soil or water pollution is reduced to the absolute minimum. A further object is to provide for complete incineration of sewage in such manner that the discharge of objectionable and offensive odors, smokes and gases into the surrounding atmosphere is prevented. A further object is to provide a system of low installation cost and highly economic operation, capable of providing for complete incineration of the sewage in a continuous process, and to employ the caloric values inherent to the sewage being treated to assist in the incineration of the organic constituents.

The invention will be hereinafter fuly set forth and particularly pointed out in the claims.

In the accompanying drawing:

Figure 1 is a vertical elevation more or less diagrammatic in character, illustrating an apparatus constructed in accordance with the invention, certain parts being shown in section. Figure 2 is a detail sectional view of the dewatering device D taken at right angles to the showing of said device in Figure 1.

Referring to the drawing, I designates a combined dehydrator and incinerator which consists of a relatively long cylindrical chamber Ill, rotatively supported in a longitudinally inclined position, in a well known manner, by suitable bearings l l. Rotation of the cylindrical chamber may be effected by any suitable means, such as by a power-actuated gear l2 engaging a gear ring l3, which encircles the chamber ID. The cylinder is provided with an internal annular baffle B. The

higher end of said incinerator projects into a receiving chamber 14, which in turn extends to a stack S. An inlet chute I5 extends through the top of said chamber Ill.

The open lower end of the chamber In extends into a burner box 20, into which is projected one or more burners 2| for gas, oil, or the like, the delivery ends of the burners being directed axially toward the chamber lll, in such manner as to project the flame into the lower open end of the latter. The fuel for the burners may be brought from any suitable source of supply (not shown). For instance, gas from septic tanks is usually available for this purpose. The burner casing is provided with an outlet chute 22, through which the material previously deposited in the incinerator is discharged in a heated state. Located below the plane of the burner box 22 is a mixing chamber M, provided with an inlet chute 23 which directs material discharged from the chute 22 into said mixing chamber. The mixing apparatus may be of any suitable or desired construction, the tank M being shown for purposes of illustration. Any gases which may accumulate in the top of the mixer M are drawn out through exhaust pipe 24 by blower 25 and discharged into the burner box through a pipe 26, so that they will be burned in the chamber Ill.

Sewage, preferably in the form of sludge, is supplied to the mixer M by means of a pump P, connected with any desired source, and delivering through a pipe 28. The flow to pipe 28 is controlled by a suitable valve 29. A by-pass 3|] around said valve is provided, the by-pass being controlled by a valve 3|, so that the supply of sewage to the mixer may be controlled.

The mixer M is provided with an outlet pipe 32 communicating with the intake end of a sand pump SP, the discharge pipe 33 of said pump delivering into the top end of a dewatering chamber D. Said dewatering chamber is preferably of conical shape and provided with an upstanding wall or weir 34, so arranged as to provide an overflow chamber 35 for liquids, said liquids being free to flow back to the mixer M through pipe 35 It will be noted that the outlet end of the pipe 33 is well below the normal liquid level within the chamber D. Leading from a position below the normal liquid level is a pipe 36 forming the inlet of a pump P, the outlet of which dis- F charges through pipe 31 to a filter F. Sand which settles to the bottom of the chamber D is withdrawn by a suitable elevator E, which raises said material and discharges it into the chute I 5, for a purpose to be later described.

The filter F may be of any suitable or desired structure, preferably using granular inorganic material which may pass from the dewatering chamber D to the filter. Filtration is effected through the granular material and screens 39, the efiluent being discharged through the opening 40 in the bottom of the filter. The sand, as it accumulates within the filter chamber may be withdrawn by means of a suitable conveyor C, which will convey it to any desired location. It is preferred, however, to return it to the incinerating chamber.

In operation, assuming that the burners 2| have been lighted and are in operation, an initial charge of sand or similar inorganic granular material, capable of withstanding high temperature without fusing, is introduced into the incinerator through chute iii, the material being supplied by a suitable conveyor C leading from any suitable source of supply. It is preferred to use good sharp silica sand, and a sufficient quantity must be initially introduced to provide a charge of granular material sufficient to be continuously passing through the incinerator and to be thereafter returned to the incinerator for recycling. Passage of the material through the incinerator is effected by rotating the cylinder, and maintaining initial supply until the sand has travelled slowly downwardly through the chamber iii and is being discharged through the chute 22 in suificient quantity to prime the mixer M. The initial supply of sand is then shut off. During the initial charging the incinerator I is intermittently rotated for short periods of time sufficiently to agitate the material, and to thoroughly heat it. When the sand has acquired a sufliciently high temperature, the calciner I is continuously rotated and as the sand is discharged from the lower end thereof into the mixing tank M, sewage preferably in the form of sludge is also pumped into said mixing tank, by means of the pump P, and kept more or less at a predetermined level by any one of many available and well known means. For instance, for purposes of illustration, this function may be obtained by opening the valve 3% of by-pass 30, so that the supply may be lay-passed any time the supply of sewage exceeds the demands of this apparatus.

As the hot sand contacts with the sewage ma-- terial, gases are generated by the heat and then liberated from the mixture, and the colloidal characteristics of the sludge are also changed. That is to say, the colloidal constituents are coagulated and form coatings of sewage material upon the particles of granular material, to such an extent as to make it possible to effect a more eiiicien't filtration of the material delivered to filter F. The gases and steam which may generate, by reason of the contacting of the hot sand with the sewage are withdrawn through the pipe 24 and delivered into the chamber 25, so that said gases are ignited by the flame from the burners 2|.

The mixed sand and sewage is withdrawn from the lower end of the mixer M by means of the sand pump SP, and delivered into the top of the dewatering chamber D, the superfluous liquids floating to the top and overflowing into chamber 35, from which they are returned tothe mixer M by the pipe 35 Water is also withdrawn from the chamber D by means of the pump P and delivered to the filter F, the effluent passing out of the discharge opening The residual mixture of sewage and sand remaining in the chamber D is then elevated by the conveyor E, and discharged into the chamber l0 through the chute 15.

During the travel of the mixed sewage and sand through the incinerator I, the sewage will first be thoroughly dehydrated in the upper part of chamber 30, leaving the same coated with colloidal portions of dehydrated sewage material. As the mass of coated refractory particles continues its travel toward the lower end of the chamber l0, said mass passes through a heated space within which it is subjected to a gradually increasing temperature as it approaches the discharge end of said chamber. Therefore, near the upper end of the chamber l3 and immediately after dehydration of the material, the temperature is sufficiently high to ignite the dehydrated organic material, but without fusing the refractory material, and said organic material is completely incinerated by the time that the granular material reaches the discharge end of the chamber and passes out of the discharge chute 22. Incineration is effected by the burning off of the surface coatings carried by the refractory material as they travel through the chamber. The baflie B is located near the lower end of the cylinder l8, and so interrupts the flow of material as to provide a constantly changing bed of sewage and sand, against which the flames from the burner are directed, so as to insure tion of odors and smoke, as well as in the combustion of the organic constituents, the gases of combustion which are carried to the stack being without noticeable odors, so that they may be discharged into the surrounding atmosphere without offense or nuisance of any character. As the hot sand is discharged from the chute 22, it is practically free of all of the sewage constitu nts, and is ready for recycling. That is to say, as the hot sand is discharged through the chute 22 it is again delivered in a continuous operation to the mixer M, and mixed with new sewage supplied by the pump [8, after which the cycles are continuously maintained as long as desired.

The advantages of the invention will be readily apparent to those skilled in the art to which it belongs. An important advantage is that owing to the fact that the sand particles are provided with coatings of sewage material during the passage of the mixture through the incinerator, it is easy to so control its passage that even dehydration is effected, and this is particularly true after the initial dewatering of the mixture before it is introduced into the incinerator. Therefore, after the apparatus has once been placed in operation, less heat is required at the burner than would otherwise needed, thereby preventing fusing of the sand, and yet maintaining a sufficiently high temperature thereof, so that the practically clean sand leaves the incinerator it may be immediately mixed with more sewage and then returned to the incinerator for a new dehydrating and incinerating cycle. Another advantage is that as the mixture of sewage and sand is subjected to the heat, it will first give off its moisture, and later will be completely dehydrated and incinerated, the combustible gases given off during these stages being capable of developing suflicient B. t. u.s to very materiaily aid in the destruction 7 of following sewage. Another advantage is that during the incinerating stage the mixture of sand and sewage travels in a general longitudinal path, and that the burners project their flames in lines parallel with said path and at the terminal end thereof, so that the hottest Zone in the incinerator is adjacent the lower end thereof.

Having thus explained the nature of the invention and described an operative manner of constructing and using the same, although without attempting to set forth all of the forms of its use, What is claimed is:

1. A method of treating sewage comprising mixing sewage sludge with a heated mass of inorganic granular material, removing excess liquid from the mixture, and effecting complete dehydration and incineration by causing the mixture to travel through a heated space capable of imparting a temperature to the mixture which. will. efiect incineration of the organic constituents.

2. A method of destroying sewage comprising mixing heated sand and sewage, removing excess liquid from the mixture, causing the dewatered mixture of sand and sewage to travel from one location to another in a general longitudinal direction, heating the mixture during such travel until the mixture acquires a temperature capable of incinerating the organic constituents, and agitating the mixture during its said travel.

3. A method of treating sewage comprising ooagulating the colloids of the sewage material by mixing said material with heated inorganic granular material, removing excess liquid from the mixture, and incinerating the residual colloidal constituents by causing the dewatered mixture to travel through a heated space capable of imparting a temperature to the mixture which will be suificiently high to effect combustion of the colloidal constituents of the mixture.

4. A method of destroying sewage consisting of coagulating sewage solids by mixing hot inorganic granular material with sewage and in such manner as to provide the particles of granular material with coatings of the coagulated sewage solids, removing water from the mixture, and completely incinerating the coagulated coatings by passing the dewatered mixture through a space maintained at a temperature sufficiently high to burn off of said coatings while the mixture is travelling through said space.

5. A method of destroying sewage consisting of mixing hot inorganic granular material with sewage, so as to provide the particles of granular material with coatings of coagulated sewage solids, dewatering the mixture, dehydrating the coagulated coatings of the dewatered mixture, and subsequently completely incinerating the residual portions of said coatings by subjecting the mixture to a high temperature while travelling through a heated space.

6. A method of destroying sewage consisting of mixing sewage with hot inorganic granular material in such manner as to provide the particles of said granular material with coatings of coagulated sewage solids, conducting off vapors produced at the time of such mixing, removing excess water from the mixture, passing the dewatered mixture through a space maintained at a temperature suiiiciently high to burn oiT said coatings during the travel of the mixture through said space, and utilizing the said vapors to aid in maintaining said space at the desired temperature.

HENRY H. MORETON.

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