US2015052A - Process for treating sewage or similar material - Google Patents

Description

.Se t. 17,-1935. H. J. HARTLEY 2,015,052

PROCESS FOR TREATING SEWAGE OR SIMILAR MATERIAL Filed. Aug 17, 1934 Air INVENTOR 6 x I 6 BY l v ATTORNEYJ Patented Sept. 17, 1935 PATENT OFFICE PROCESS FOR TREATING SEWAGE OR SIIVIILAR. MATERIAL Henry J. Hartley, Hastings upon Hudson, N. Y., assignor to Nichols Engineering andResearch Corporation, New York, N. Y., a corporation of Delaware Application-August 17, 1934, Serial No. 740,250

Russet!) 2 Claims. (01. 110-15) after passage through the combustion zone thereof to thereby greatly decrease'or substantially eliminate the noxious or objectionable odors in said gaseous products 'of combustion.

Various other objects, advantages and characteristics of my invention will become apparent from the following description.

My invention. resides in the process, process steps, system, and features of the character hereinafter described and claimed.

For an understanding of my invention'and for an illustration of one of the forms my apparatus may take, for carrying out the invention, refer ence is to be had to the accompanying drawing, in which:

The figure is a vertical sectional view, partly in elevation, of a furnace arrangement as constructed and arranged in accordance with my invention. I

As shown on the drawing, F represents any suitable furnace or combustion chamber such, for example, as a multiple'hearth furnace of the Herreshoff type. As is well understood, a furnace of this character comprises a plurality ofsuperposed hearths surrounded and supported by the usual furnace wall structure. As illustrated, the hearth arrangement is such that a plurality of hearths I and 2 are .provided, a hearth 2 being disposed between each pair of hearths I, each hearth I being provided with a central opening la, each hearth 2 being provided with one or more outer openings 2a, and all of the hearths being secured in and supported by the furnace wall structure 3.

Extending axially through the center of the wall structure 3 is a suitably journalled, vertical rotatable shaft 4 which may be provided with radially extending rabblearms 5 utilizable for rabbling the material over each of the hearths in succession down through the furnace. As disclosed in Herreshofi U.-S. Letters Patent No. 976.175, November 22, 1910, the central shaft 4 and the rabble arms 5 may define conduits through which a cooling medium is adapted to circulate. In other respects, 'the usual design of furnaces of this general type may be followed and if desired, .the furnace arrangement may be manner.

' beneath.

of the general type disclosed in U. S. Patent No. 1,669,925, May 15, 1928.

Preferably, the material to be treated is ground in suitable manner to break up the large pieces and then filtered to remove such quantities of 5 moisture as may readily be disposed of in that Upon completion of this operation, the material may be fed into a hopper 6 fromwhich a screw conveyor 1, or equivalent, serves to transport the material so that it drops down through 10 a conduit 8 which terminates interiorly of the furnace F. From the conduit '8, the material falls uponthe uppermost hearth I and is rabbled inwardly by the teeth on the upper rabble arm 5 so that said material passes downwardly through the opening la of the upper hearth l and thereby reaches the uppermost hearth 2. On the hearth last named, the material is rabbled outwardly by the rabble arm which coacts therewith, the material eventually dropping from said hearth 2 through the openings Za-at the edge thereof. In this manner, the material to be treated or incinerated is rabbled alternately inwardly and outwardly across the superposed hearths of the Letters furnace, the material dropping through the inner opening of one hearth to 'the next lower hearth and, after passage thereacross, dropping through the openings at the periphery thereof so as to reach the periphery of the hearth there- The material, as it passes downwardly through the furnace, is first dried and then incinerated, the operation last noted occurring principally in the lower area of the furnace. It' will be understood that air is necessarily supplied .to the interior of the furnace for the purpose of supporting combustion. In accordance with my invention, such air is admitted into the furnace at or adjacent the top thereof and withdrawn from said furnace in the region of the bottom thereof, the air, therefore, passing downwardly through the furnace in the same general direction as is taken by the descending sewage material under treatment.

The arrangement for causing the air to move downwardly through the furnace'in the manner last described may be of any suitable character. To this end and as herein shown, a pipe or conduit 9 is so positioned that it opens into the top of the furnace chamber F. A second pipe or conduit Ill opens into the bottom of said furnace chamber F and has an exhaust fan II, or equivalent device, connected thereto. When the exhaust fan I I is operated by a suitable motor, not 55 shown, the products of combustion are withdrawn from the bottom of .the furnace F and caused to pass upwardlythrough said conduit Ill, and to be discharged to the atmosphere, if desired. The products of combustion which are thus withdrawn from the furnace are replaced by air which enters the top thereof through the conduit 9 which, preferably, communicates with the atmosphere as shown. Accordingly, in accordance with the invention, a down-draft stream of air and gases is established within the furnace chamber and this is maintained during continued operation of the fan i I.

With the furnace in operation, combustion of the descending sewage material proceeds on one or more of the lower furnace hearths. Ordinarily, the gases evolved from the material under treatment wouldrise through the furnace but, as stated above, the fan II establishes a downdraft stream of air. .Therefore, this air stream together-with the evolved gases necessarily passes through the above noted combustion zone and it is in this zone that the temperature is at a maximum interiorly of the furnace chamber.

'It results, therefore, due to the high tempera-- the gaseous material which passes to the atmosphere through the conduit II is largely or substantially free from noxious gases which, if present, would cause annoyance to persons in the vicinity.

From the viewpoint of emciency and economy, itis desirable for-the hot gases passing from the furnace chamber tobe brought into heat-eichanging relation with respect to the stream of air passing toward and into said furnace. This feature of the invention is illustrated on the drawing which shows a long section of the inlet pipe I as disposed interiorly of a corresponding section of the outlet pipe II. By virtue of this relation, it is obvious that the gases passing to the top of the furnace chamber by way of the pipe l are pre-heated by the hot gases passing through the pipe II. In lieu of a heat-exchange arrangement of the character shown, it is to be understood that any other suitable type of arrangement may be utilized for accomplishing this purpose. I

As stated, an important feature of the invention relates to the passage or withdrawal of the hydrocarbon vapors through the hottest zone 'of the furnace chamber, 1. e., the lower hearth or hearths on which occurs the principal combustion of the sewage material. Under such conditions, it will be understood that the invention is not to be limited to the passage of atmospheric air-from the pipe 9, or equivalent, into the top of the furnace chamber. As well, under some circumstances, this air may be introduced into said furnace chamber nearer the middle thereof although it will be understood that it is advantageous for such air to pass along a path of extendedlength while in contact with the sewage material so as to more effectively dry the same. As shown on the drawing, one or more gas or oil nozzles l2, or equivalent, may be associated with the furnace chamber so as to supply additional heat above the lower hearthor hearths.

' The heat obtained from these sources may be utilized at any time when the furnace is to be placed in operation and, under some circumstances, it may be desirable to utilize such heat sources intermittently or continuously so as to obtain such number of heat units in the combustion zone as may be required to emciently 5 ,posed either interiorly orexteriorly of the furnace chamber as desired.

As shown, the shaft 4 carries a lower gear I! with which meshes a second gear it operated by a suitable motor i5 or other equivalent device. With the motor I5 operating, the sewage material descending through the pipe 8 passes along a 20 circuitous path downward through the furnace chamber. Such materialis temporarily retained on each of the hearths while being advanced thereacross, the material, on each hearth i being moved toward the shaft 4 and, on each hearth 2, 25 being moved outwardly from said shaft 4.

' The air which is admitted into the furnace chamber through the pipe 0, or equivalent, likewise passes along a circuitous descending path while contacting with. the descending sewage material. It will be understood that such air passes inwardly toward the shaft 4 above the hearths l and outwardly from said shaft above the hearths 2, the air passing downwardly through the inner passages la of the respective hearths i and the outer passages 2a. of the respective hearths 2. .As a result, the sewage material is dried in an eifective manner in the upper furnace regions and as such material descends through the furnace, it becomes progressively 4o dryer. On one or more of the lower hearths, combustion of the dried material is completed and, under proper operating conditions, it results that such material becomes principally an ash by the time it reaches the lower hearth from which it maybe removed through a suitable conduit it or the like.

Under some circumstances, it may be desirable to treat the moist material on the upper hearth or hearths with one stream of air, pre- .heated or otherwise, and to treat the dry and burning material on the lower hearths with another stream of air. Due to the moist condition of the material, the first named stream of air remains substantially odorless and hence may 65 be passed to the atmosphere without objection. The second named stream of air becomes odorladen, however, and it is this air stream which is passed down-draftthrough the combustion zone or otherwise treated to deodorize the same, i. e., effect the removal of noxious odors. By proceeding in the manner just described, it is obvious that there is a substantial decrease in the volume of air which is subjected to heat treatment. This, of course, is decidedly advantageous. In view of all the foregoing, it becomes obvious that my novel process is especially advantageous, useful and efllcient because depending principally or entirely upon the heat generated by combustion of the sewage material for the elimina- 7 tion of noxious odors from the hydrocarbon gases. The expense of the complete operation is substantially decreased while, at the same time, the amount of equipment is decreased in comparison with the equipment required by prior art 76 arrangements for accomplishing the same end.

While the invention has been described with respect to certain particular preferred examples which give satisfactory results, 'it will be understood by those skilled in the art after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention and itis intended therefore in the appended claims to cover all such changes and modifications.

What is claimed as new and desired to be securedby Letters Patent is:

1. The process of treating sewage or similar material, which comprises passing said material downwardly through a plurality of superposed zones while first drying and then burning the same, temporarily retaining said material in each of a plurality of said zones, moving said material horizontally through each of said zones by the application of a series of successive rabbling impulses thereto, passing a stream of air downwardly through said zones along the path of travel of the material at each'of said zones successively, whereby the gaseous products of combustion produced with said air are made substantially free of noxious odors in passing through the lower of said zones where burning occurs,

discharging said products of combustion from the lowermost zone by suction, and subjecting said air prior to its introduction to-the uppermost zone to heat interchanging relationship with the exit gases from said lowermost zone.

2. The process of incinerating sewage material to form an ash and evolved gases free of noxious odor, which comprises first treating the material to remove therefrom a substantial portion of the moisture content thereof, then passing said material downwardly through a plurality of superposed zones while first drying and then burning the same, temporarily retaining said material in horizontal layers at each of said zones while periodically agitating and advancing it through each zone and gradually from zone to zone, said drying being effected by introducing a stream of preheated air into contact with the material at the zones of drying, and passing said stream of air downwardly from said drying zones along the path of travel of the material through the zones of burning, whereby the gases evolved from the drying material and the gaseousprodnets of combustion are heated at the zones of burning, to a high temperature for the substantial elimination of noxious odors therefrom.

a HENRY-J. HARTLEY.

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