US3417717A - Furnace for the combustion of waste materials, particularly refuse - Google Patents

Description

Dec. 24, 1968 T. JACOBOVICI 3,417,717

FURNACE FOR THE COMBUSTION OF WASTE MATERIALS, PARTICULARLY REFUSE Original Filed July 2, 1965 9 2 V///// k 2 i o q} a g g 77450002 JA C050 V/C/ INVENTOR Arron/m Mann:

3,417,717 FURNACE FOR THE COMBUSTION OF WASTE MATERIALS, PARTHCULARLY REFUSE Theodor Jacohovici, Zurich, Switzerland, assignor to Von Roll AG, Gerlafingen, Switzerland, :1 Swiss corporation Original application July 2, 1965, Ser. No. 469,104. Di-

vided and this application July 24, 1967, Ser. No. 655,629 tliaims priority, application Switzerland, July 8, 1964, 8,954/64 5 Claims. (Cl. 110-7) ABSTRACT OF THE DISCLOSURE Background of the invention The present application is a divisional of my co-pending United States application, Ser. No. 469,104, filed July 2, 1965 and commonly assigned.

The present invention relates to an improved combustion furnace for the combustion of waste materials of all types containing combustible and normally non-combusible components, particularly refuse.

It is generally known to those versed in the art that the combustion of wastes of all types containing combustible and normally non-combustible components brings with it considerable difficulties. Thus, research for many years has been extremely active in this field of endeavor, particularly since it is desired to bring about destruction of the waste materials under the best possible hygienic and economical conditions.

Now, it is already known to the art that combustion at temperatures above the slag melting limit in so-called high-temperature furnaces brings with it quite considerable advantages over combustion techniques performed at lower combustion temperatures. Thus, with such high temperature furnaces there is first of all obtained a simpler, practically constant firing schedule. Furthermore, the permissible thermal load in the combustion compartment is higher and, therefore, a larger specific throughput is also possible. Moreover, the over-all combustion process is improved and it is thus possible to make removal and after-treating of the products or residues of combustion simpler. Additionally, these residues from combustion with appropriate after-treatment, for instance by granulation of the liquid slag, can be possibly commercially utilized as construction materials. Finally, dust formation is considerably smaller so that regulations or ordinances concerning cleanliness of the flue gases conducted into the open atmosphere, and which regulations are becoming nowadays more and more exacting, can be more easily complied with.

However, up to the present it has not been possible to utilize such high temperature furnaces in a simple and operationally satisfactory manner for the destruction of wastes, for instance refuse. Previously known methods and furnaces for the combustion of such wastes, apart from the disadvantage of a difiicult, and during operation,

- ire States Patent 3,417,? l 7 Patented Dec. 24, .1968

quite considerable unstable firing, possessed a relatively low thermal load for the combustion compartment, generally incomplete combustion, and thus hygienic unsatisfactory and economically unusuable residues of combustion, as well as also considerable dust formation.

Summary of the invention Accordingly, it is a primary object of the present invention to provide an improved furnace for the combustion of waste materials of all types containing combustible and normally non-combustible components, particularly refuse, in which the previously mentioned disadvantages of the prior known furnaces can be overcome in a very simple and reliable manner.

A further considerable object of this invention is directed to an improved furnace construction for the effective combustion of waste materials of all types containing combustible and normally non-combustible components, in which the line gases resulting from combustion are relatively dust-free, and the waste materials undergoing combustion are considerably completely burned, so that the resulting residues from combustion have economic value and can be employed as a useful product.

Another object of this invention relates to an improved furnace construction for the very effective and reliable combustion of waste materials of all types containing combustible and normally non-combustible components, wherein the furnace possesses increased thermal efficiency, the throughput of materials through the furnace is considerably improved, the combustion process results in a more complete combustion of the materials, and a cleaner flue gas is ejected into the atmosphere.

As pointed out above, the present invention relates to an improved combustion furnace for the reliable combustion of waste materials of all types containing combustible and normally non-combustible components, but particularly refuse, which is characterized by the features that, in the combustion compartment or chamber of the furnace there is located a support, or receptacle, for the material to be burned and which is of substantially pocket-like construction, i.e. possesses a substantially bowlor trough-shaped configuration and provided with an overflow edge for the removal of liquid slag.

Brief description of the drawing Other features, objects and advantages of the present invention will become apparent by referring to the following detailed description and drawing in which the single figure schematically illustrates a preferred embodiment of inventive furnace for the combustion of waste materials, such furnace being generally depicted in longitudinal section and illustrating certain accessory equipment.

Description of the preferred embodiments Turning attention now to the drawing, it will be recognized that a suitable apparatus 1 for comminution of the waste material e.g. refuse is provided with an infeed or filling funnel 1a. This comminuting apparatus 1 communicates via a delivery device 2 with a waste materialsupport means, or receptacle, here shown as a pan 3 stationarily arranged in the forward portion 12a of a combustion furnace 12. In the exemplary embodiment illustrated this delivery device 2 is constructed as an infeed chute 2a. The supporting pan or vat 3 is provided with a pocket-like construction, here shown as a trough 3a formed by a lining of refractory material, and serving as gas impervious support means for the material to be burned. Additionally, the trough 3a incorporates an overflow edge 3b for the removal of the liquid slag collecting in trough 311. Of course, the trough So could also have a substantially bowl-shaped configuration as schematically indicated by reference numeral 3a. Hence, it should be understood that the term pocket-like construction as applied to the support means for the waste material is employed in its broader sense to include substantially trough-shaped and bowl-shaped construction, as well as variations thereof.

In a rear flue 13 of the furnace 12 there is arranged an air pre-heater 5. The air heated in this .air pre-heater 5 and servingas combustion air for combustion of the refuse in the furnace 12, is delivered via a conduit 14 to the forward region 12a of the furnace 12. Before this heated air is delivered to the forward furnace region 12a it is enriched with oxygen obtained in a suitable oxygen generating installation 4 and delivered via a short conduit into the hot-air conduit 14. The hot combustion air enriched with oxygen is blown into the combustion chamber or compartment of the furnace 12 through the agency of injection nozzles 6 mounted to a nozzle box or housing 16. Specifically, the injected air is introduced at sufliciently high pressure so that the air jets emanating from these nozzles 6 reach the pan 3 and the material to be burned located in the trough 3a thereof and, thus, impinge such material. In order to generate the necessary air pressure, for this purpose there is provided a high-pressure blower 11. The latter is conveniently connected to the conduit 14 for the combustion air in front of the nozzle housing 16 in the flow direction of such air and behind the point of connection of the oxygen conduit 15 with the hot-air conduit 14.

It will also be observed that a discharge shaft 7 cornmunicates with the pan or vat 3 and delivers the liquid slag, overflowing the molten bath in the trough 3a and over-running the overflow edge 3b, into a granulation vessel 8 filled with water. An immersion tube or stud 17 is arranged at the lower end of the discharge shaft 7 and immerses somewhat into the water bath of the granulation vessel 8, thus insuring that no cold air can infiltrate in undesired manner from beneath via the discharge shaft 7 into the interior of the furnace 12. The path of the flue gases resulting from combustion of the refuse or otherwise through the furnace 12 is indicated in the drawing by arrows A.

The combustion or flue gases generated in the combustion compartment or chamber 30 flow through the furnace 12 along the path represented by the arrows A, and initially flow through an uptake flue 18 and thereafter through the already mentioned rear flue 13, constructed as downstake flue. The downtake flue 13 is separated from the uptake fine 18 by a vertical, intermediate wall 19 which near its top 19a forms together with the housing of the furnace 12 a throughflow opening 20. Heating surfaces 9 and 9' of a waste-heat boiler are arranged in the uptake flue 18 and downtake flue 13, respectively. After passing the air pre-heater 5 the flue gases arrive via a waste-gas stud 21 into a combined de-dusting and suction device 10, then escape into the open or surrounding atmosphere via a pipe 10a which, as the case may be, can be constructed as a sheet metal chimney possessing appropriate height. At the lower end of the downtake flue 13 there is provided a funnel-shaped ash discharged 13a by means of which larger ash particles can be removed. Finer ash and dust particles are first separated from the flue gases in the de-dusting installation 10 and leave this de-duster 10 via an outlet stud 10b.

The previously described exemplary embodiment of inventive combustion furnace operates in the following manner:

The material to be burned introduced via the delivery device 2 into the furnace 12 arrives at the support pan 3 and in the trough 3a (or bowl 3a) where it ignites and burns. At the start of the combustion operation when the furnace is still cold, ignition of the eomminuted material is achieved by means of fuel-oil burned in one or more burners, conveniently located, so that their flames will impinge upon the material. For the sake of simplicity, these burners have not been represented in the drawing, considering that their role is only temporary. In fact, once the furnace is in operation at temperatures of 1500 C. and above-as considered hereinafter-its refractory lining is brought to incandescence and the intense heat radiation emanating herefrom will insure ignition and sustain combustion of the material. Furthermore, by contact with particles already burning, the material freshly brought-in will ignite and burn. Due to the combustion air enriched with oxygen and injected by means of the nozzles 6 there is obtained and maintained a combustion chamber temperature which is above the melting point of the residues of combustion, so that the resulting residues of combustion, i.e. slag, are melted and liquified and there forms in the trough 3a a molten bath 3d of higher temperature. This molten bath 3d replenishes itself continually, since the pan 3 at its forward region has delivered thereto new material to be burned whereas liquid slag is removed from this pan 3 at the rear via the overflow edge 3b. Due to these measures ignition and combustion of the subsequent delivered fuel is guaranteed. In order to start the combustion process when the furnace is cold there is provided for this purpose an oil burner 22. With refuse possessing a lower calorific value H =1800 kcal./kg. and a content of moisture, combustibles and ash in a ratio of 30% /44%/26%, it is possible to reach and maintain with an oxygen surplus of a combustion chamber temperature of approximately 1500 C. without supplementary fuel, with the aid of combustion air at 400 C. enriched to 35% 0 In fact, the combustion chamber temperature can be increased to approximately 1600 C. by enriching the combustion air to 40% oxygen content.

The flue gases resulting from combustion of the refuse possess a temperature of 1500 C. to 1600 C. and are guided through the heating surfaces 9, 9 of the wasteheat boiler and then through the air pre-heater 5, whereby they deliver with countercurrent flow their sensible heat while cooling down to about 350 C. The air pre-heater 5 must possess a suitable construction, i.e. possibly constructed as ceramic regenerative air pre-heater, in order to heat up the necessary combustion air from about 50 C. to about 500 C., so that after its admixing with the delivered oxygen an average temperature of the enriched combustion air of approximately 400 C. results. So as to make possible heating of the air to about 500 C., of course the temperature of the flue gases entering the pre-heater 5 must lie considerably above 500 C. and the terminal portion of the air pre-heater can be arranged in the flue gas stream at a location where such flue gases possess sufficiently high temperature.

It will further be appreciated that instead of the pan 3 with its trough 3a or bowl 3a stationarily mounted in the furnace 12 it would also be possible to pivotably mount such within the furnace, whereby there is achieved an intensive mixing and acceleration of the slag melting process.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. Accordingly, what is claimed is:

1. Furnace for the incineration of waste material of all types containing combustible and normally non-combustible components, and concomitant smelting of its residues, comprising means providing a combustion compartment internally of said furnace, receptacle means for the waste material which is to be burned located in said combustion compartment, said receptacle means possessing a substantially pocket-like construction and an overflow edge for removal of liquid slag, at least one nozzle member arranged above said receptacle means and directed towards the latter for injecting combustion air, means cooperating with said nozzle member for preheating the combustion air, and means cooperating with said nozzle member for introducing oxygen to enrich the combustion air.

2. Furnace for the incineration of waste material of all types containing combustible and normally non-combustible components, as defined in claim 1, wherein said receptacle means possesses a substantially trough-shaped configuration.

3. Furnace for the incineration of waste material of all types containing combustible and normally non-combustible components, as defined in claim 1, wherein said receptacle means possesses a substantially bowl-shaped configuration.

4, Furnace for the incineration of waste material of all types containing combustible and normally non-combustible components, as defined in claim 1, wherein said receptacle means is constructed from refractory material and is gas impervious.

5. Furnace for the incineration of waste material of all types containing combustible and normally non-combustible components, as defined in claim 1, further including blower means for pressurizing the combustion air prior to injecting the same through said nozzle member.

References Cited UNITED STATES PATENTS 1,580,656 4/1926 Coninck 110-24 2,764,109 9/1956 Grosse.

2,865,344 12/1958 Firl 110-1 X 2,961,977 11/1960 Coleman 110-8 3,344,758 10/1967 Wotschke 110-18 JAMES W. WESTHAVER, Primary Examiner.

US. Cl. X.R.

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