DE2444641C3 - Drying and incineration furnace for solids-containing materials such as sludge and the like - Google Patents

Description

To create incineration furnace of the type mentioned, in which a technically simple means Even distribution of the material to be treated in both single and multi-floor ovens whose hearth floors are ensured

This object is achieved according to the invention by the features specified in claim 1

By arranging a chain in the manner according to the invention between the agitator arms is not only one that is extraordinarily effective in terms of even distribution, but goes beyond that Technically surprisingly simple construction also made available. The chains thus create dams or in the case of uneven loading, heaps in the area for good combustion or treatment required leveled so that there is an even distribution over the Stove floors result in demixing effects occur due to the arrangement according to the invention did not cause permanent circulation of the material to be treated.

Due to the uniform distribution on the hearth floors, a uniform flow of material can also be achieved through the furnace, with the flow component in the radial direction due to the lack of dead zones can be set smaller than before. This leads to better utilization of the! Capacity of the Furnace.

The solution according to the invention is also advantageous from a technical point of view because it takes into account the operating conditions of such ovens. So can the aggressive atmosphere inside the stove due to the lack of sensitive bearing points in the construction according to the invention does not lead to an increased Wear and thus lead to a shortening of the service life. The technical structure is also - compared to known constructions - amazingly simple, which makes maintenance problem-free and becomes inexpensive.

It is true that rotary drum furnaces are used to treat muddy or other lumps material with a tendency already known to arrange chains in the furnace interior (cf. DE-PS 8 81 927). However, these chains are only used to break up and break up the lumps and not to Achieving an even distribution and circulation of the material to be treated on a level Hearth base.

In the case of an oven with a plurality of stoves arranged vertically at a distance from one another according to the The preamble of claim 2 is proposed according to an advantageous development of the invention, that the agitator chains are arranged in at least one of the upper hearths.

This measure is based on the knowledge that a uniform distribution of the to be treated Material must be made primarily in the top flocks because of unevenness in Experience has shown that the material distribution is essentially retained when passing through all hearth levels will.

It is already known for such ovens (cf. for example US-PS 21 17 487), in the two upper cookers in addition to the agitator arms further agitating elements in Provide the form of spaced on a shaft rotating disks opposite their Direction of movement are inclined so that they the material to be treated in a predetermined direction overturn. However, these agitating elements also throw up dams and also lend to the treating material has a flow component in the radial direction. They have a leveling function Disk-shaped stirring elements therefore not work. In addition, the bearings of the disk-shaped stirring elements work bearing waves under the influence of the aggressive atmosphere in the furnace interior, so that only with a technically very complex bearing construction for a function of the disk-shaped Stirring elements also ensure that the shaft can rotate over a longer period of time Maintenance of such rotatable stirring elements is very complex and therefore only at high cost accomplish.

Further advantageous refinements of the invention emerge from patent claims 3 to 6.

Exemplary embodiments of the invention are described below with reference to FIG Drawings described in more detail. It shows

F i g. 1 is an axially sectioned view of a furnace with a plurality of cookers,

FIG. 2 is a cross-sectional view of an upper inflow cooker showing the distribution of material in FIG known procedure,

Figure 3 is a cross-sectional view of an upper inflow cooker with representation of the material distribution when using the concept according to the invention,

Figure 4 is a cross-sectional view of an upper outflow cooker with representation of the material distribution according to the conventional procedure,

F i g. Figure 5 is a cross-sectional view of an upper outflow cooker showing the distribution of material using the inventive concept,

F i g. 6 is a sectional view of the upper part of a furnace provided with the invention;

F i g. 7 shows a section along the line 7-7 according to FIG. 6,

F i g. 8 is an enlarged view of a chain according to the invention arranged between agitator arms;

Fig. 9 is a perspective view of an upper range of an oven showing the operative ones Position of the chain,

Fig. 10 is a perspective view of an upper one Cooker similar to Fig. 9 showing a way of attaching the agitator chains.

In the drawing and in particular in FIG. 1 is the top of a furnace 10 with a plurality of cookers shown, wherein the furnace has a generally cylindrical shape. The furnace consists of one tubular outer steel jacket 12, which, as indicated at 14, with firebricks or the like heat-resistant material is lined. Although with some systems burner nozzles only in one or two lower cookers are provided, in the present embodiment, each cooker is provided with a plurality of Equipped burner nozzles 16 which extend both axially and tangentially into the hearth. With connected to the outlets of various individually controlled burner assemblies, not shown Burner nozzles are distributed across the furnace 10 and are more useful for generating and / or maintaining Temperature and atmospheric conditions in the different zones of the furnace to meet the specific needs take desired treatment. Furthermore, special work doors and windows 18 are provided, to monitor the operation of the oven at each hearth level.

The interior of the furnace 10 is by means of hearth floors 20 and

22 divided into a plurality of vertically oriented flocks, only the top four flocks being shown are. Each hearth base consists of a refractory material and is preferably slightly curved, so that the floor is given a self-supporting property in the oven. Near the outer shell 12 of the furnace are provided outer, circumferentially extending drop bores 24, while near the Central drop bores 26 are formed in the center of the furnace in alternating hearth bottoms 22. Although in F i g. 1, the top or first hearth is shown as an outflow hearth, it goes without saying that the inventive Concept in the same way on an oven with a first single-flow oven or a lower oven Oven can be applied to a wide variety of cookers.

1, a rotatable vertical central shaft 28 extends axially through the furnace 10. The shaft 28 is, as indicated at 30, held by an upper bearing and a lower bearing, not shown. she will rotated by a suitable drive device of known type, not shown. A variety of at a distance mutually arranged agitator arms 32 is attached to the central shaft 28, as indicated at 34, the paddle arms in each hearth extending outwardly above the hearth floor. At the Rühramien stirring teeth are formed which extend down to near the bottom of the stove. The stirring teeth are inclined to the longitudinal axis of their associated agitator arms so that upon movement of the agitator arms 32 as a result of Rotation of the central shaft 28 causes the stirring teeth 36 to continuously move through on the relevant hearth base to be treated material and this gradually to the drop bores 24 and 26 in the Force hearth bottoms.

The material to be treated is fed into the furnace at its upper end by means of a belt conveyor 38 and a fill inlet 40. When the top hearth, as in Fig. 1 shown a discharge hearth is the fill inlet 40 is near the furnace center. However, the top stove is a Single-flow stove, the filling capacity is relocated to the perimeter of the furnace. The material moves through the Furnace basically serpentine downwards and is drained from the bottom of the furnace. At the A gas outlet port 42 is provided at the top of the furnace through which gases and others during the Combustion products formed during operation in the furnace can be carried out.

F i g. Fig. 2 shows the flow of the material to be treated according to the prior art, being at The first hearth is a single flow hearth 22. The material generally designated 44 enters the hearth from above through a feed inlet 46 and is according to the arrow 48 partially around the hearth as a result of the The stirring teeth move in the direction of arrow 49 so that the material finally passes through the central drop hole 26 falls The agitator teeth are inclined to the longitudinal axis of the agitator arm in question so that material movement has a relatively large radially inward flow component 50 and a relatively has small circumferential flux component 52 making a substantial portion or portion of the Cooker remains uncovered or only very thinly coated with material, as indicated by the reference number 54 is indicated

In contrast to FIG. 2 shows F i g. 3 the material flow according to the invention, wherein the first hearth a Single-flow hearth 22 represents. The material, generally designated 56, enters the hearth from above the feed inlet 46 and is moved completely over the hearth according to the arrow 58 and falls through the central drop hole 26 substantially along its entire circumference. According to the invention is thus a Measure taken to the radial flow sector or the material component 60 and further are separate and independent means provided to control the circumferential flow sector or material component 62. In this way, the two river sections can be selected individually so that the material to an even distribution over the entire stove without creating dead zones, whereby this takes place by means of the independent selection of the two components. In addition, the material residence time in the hearth between entry and exit according to the material and the treatment concerned influence in a targeted manner.

In Fi g. 4, an outflow hearth 20 is shown, the flow of material being indicated in accordance with known techniques is. The material 64 enters the hearth from above through an inlet 66 and disperses as through the Arrow 68 indicated by means of the stirring teeth rotating in the direction of arrow 70 only partially over the Hearth before it falls through the circumferentially arranged drop bores 24. It should be noted that that the agitator teeth are inclined to the longitudinal axis of the agitator arm in question, so that a relatively large radial outward material flow component or vector 72 and a relatively small circumferential Flux component or a vector 74 is created, and thus a substantial part 76 of the hearth remains uncovered or only thinly covered with the material to be treated

In contrast to the known carbon black configuration according to FIG. 4 shows Fig. 5 soot formation in one Ausstromherd 20 with material treatment according to the invention. The material generally designated 78 enters the hearth from above through feed inlet 66 and rotates completely as indicated by arrow 80 the hearth and falls essentially along the entire circumference through the circumferential bores 24. How Will be explained in more detail below, means are provided to the radial soot vector or the To control material component 82 and further separate or independent means are provided to the Circumferential flow vector or material component 84 control. It follows that the circumferential component 84 according to the invention is substantially larger than the peripheral component 74 in the prior art so that a uniform flow distribution without dead zones is present over the entire hearth ensures that the control of the circumferential component 84 is independent of the control of the radial component 82 is In addition, the material dwell time on the stove can be targeted according to the Material and the process in use can be controlled.

The in the F i g. 2 and 4, in contrast to that shown in FIGS. 3 and 5 shown technology according to the invention to diverse problems. For example, there is a waste Oven zone, which reduces the effective oven area. Due to the uneven combustion further shortens the life of the furnace lining material. It has been found that an one side of the stove has a tendency to ignite

or burning occurred while the other side was in a smoldering or smoldering state, ie on one side of the furnace the material being treated is on a stove in a burning state, while on the other side of the furnace it is burning State not reached until it moved to a lower hearth. Thus there was a burn on one side of the stove, while the other side of the stove was still drying out. This created difficulties in controlling the residence time on the various cookers and made it practically impossible to control the burners and the atmospheric conditions, including the turbulence, in each cooker so that a clean distribution r i of the gas occurred over the cooker. This consequently led to overheating of the material in some areas of the oven and excessive heating in other areas, which in some treatments resulted in a poor product. An attempt to roast zinc sulfide for the purpose of adding zinc oxide resulted, for example, in zinc sullai. which is difficult to remove from the oven. In addition, it turns out that a clean combustion over the entire hearth zone provides better heat transfer and therefore a more economical use of the 2 ^r > fuel. In conjunction with the treatment of waste or sewage sludge, clean burn over the entire stove prevents the emission of smokers and the formation of blue smoke or tar fumes too fine to be removed by currently operating daily scrubbers which had reduced the need of providing Nachbrernern or even eliminated previously necessary to the statutory provisions, such as y> the Environmental Protection Agencv's Visual appea rance code to meet.

In order to create an even distribution of the material to be treated over the hearth according to FIGS. 3 and 5, a device is provided to separately control the circumferential vector or the initial movement component of the material with respect to the radial vector or the radial movement component. g in the F i. 6 to 9, the two upper foci of the furnace are shown, wherein the Rührzähne 36? ur longitudinal axis are inclined with their 4 ^r> at reffenden stirring arms so as to the radial component 60. F '1 g of a substantial part 3. or 82. Fig. 4. The movement of the material to be treated on the herds. As can best be seen from Figures 7 and 9, adjacent paddle arms 32-0 are connected with paddles 86 around a substantial part of the Circumferential component 6Z Fig. 3. or 84. T i g. 5. The hciSi. Uil · Rühivähne serve to. Means to control the radial movement and the chains as a means to control the peripheral movement of the material on the stove ge serves the careful coordination of the inclination of the stirring teeth and the arrangement of the stirring chains to distribute the material evenly over the stove without dead zones when the central shaft 28 in the direction of the arrow 88 according to FIG. 7 and 9 is rotated. Each end of a Rührkcttc 86 is thereby attached to a stirring tooth 36 in which a shackle 90. Γ i g. 8. Is passed through a ring multicore 92, which is connected to the stirring tooth by a nut 94 and screw%. bS The Celts are laid in such a way that one end extends from near the circumference of the agitator arm and the other end is attached to the inner part of the next adjacent agitator arm. The chain slackens a little, but not enough to drag on the floor of the stove. When installing the chain, a gap on the order of about 2.54 cm is left on screw 96 so that adjustment is possible by turning the screw. A 6.25 mm ketle with an overall length of about 3.2 m is suitable for a furnace with an outside diameter in the range of about 6.7 m the central shaft is rotated, but the combination of the two components acting on the material to be treated sweeps it evenly over a hearth to an F-'allbohrung, where the material falls through to the nearest hearth and then again evenly over this hearth to whose Faiibbohrung is touched and this process continues successively from the upper to the lower end of the furnace.

In the embodiment of the invention according to FIG. 10, a stirring chain 98 is provided, one of which End at the agitator arm 36 arranged on the outer circumference of the agitator arm 32, as indicated by the reference number 100, while the other end of the chain is attached to the central shaft 28 at 102 connected. The chain 98 is also arranged with some slack, but not so is great. that the chain grinds on the hearth base 22. If accordingly, as indicated by arrow 104, As the central shaft 28 is rotated, the agitation chains provide essentially a circumferential flow component and the stirring teeth, which are inclined to the longitudinal axis of their respective stirring arms, essentially a radial flow component of the material, creating a smooth and uniform one Material distribution over the hearth base 22 without the formation of dead zones. Although Fig. 10 shows a single flow hearth shows, the inventive concept of this embodiment is in the same way on one Outside applicable.

Furthermore, it goes without saying that the first or topmost hearth of the oven is either an inflow or can be an outflow focus. In the treatment of certain materials it may be necessary that only the means for separately controlling the radial and circumferential flow components for the movement of the Material to be placed on the first or top hearth or the first and second top hearth., there. once the material has been evenly distributed over an upper hearth. it in this uniform distribution also remains in the following lower-lying herds. In the treatment äiidi-ici Materιαίίνη however it can gcgcbcncnfa !! ·, not be necessary to such means to control the To provide material flow components on the first hearth, but these means for controlling the flow components at one or more subordinate ones to order other flocks. The principles of the invention are also applicable to an oven Applicable to a single stove with either one radial kin or outflow of the material to be treated is present.

The device described for controlling the radial and circumferential material flow components separately is particularly suitable for treating waste material such as sewage sludge.

In some urban communities, the drying of the mud is done during part of the year

required, the remaining components being used as fertilizers. Is the fertilizer utilization not in question, at other times of the year the mud is dried, incinerated, or burned. The principles of the present invention apply to both drying and drying Ashing method applicable. According to the invention, the wet sewage sludge is used continuously for this purpose Entered into the top of the furnace, the sludge is fed to a first zone in the top of the furnace Drying fed by the sludge over one of the top hearths with a radial flow component and is forced simultaneously over this hearth with an independent circumferential flow component, so that the sludge in a uniform and evenly distributed manner in the direction of the relevant Downhole according to Fig. 3 and 5 flows. After that, will the sludge successively passed over each stove and

through the associated drop hole to the next below lying hearth in the first zone, the sludge being in essentially the same drying state is kept above each stove. If only the drying of the sewage sludge is in question, will the sludge so dried is removed from the lower end of the first zone of the furnace. In the process which includes both ashing and drying, the sludge dried in the above manner becomes one second zone in the lower part of the furnace is fed to incineration, placing the sludge successively over each Hearth and through the relevant drop hole to the next hearth below in this zone with the sludge in substantially the same ashing state over each hearth in the Zone remains and a controlled amount of heat is supplied to more than one stove for drying and To incinerate the sludge.

In addition 6 sheets of drawings

Claims (6)

Patent claims: 1. Drying and incinerator for solids Materials such as slurries and the like having at least one substantially horizontal Hearth, a central rotatable one extending upward through the center of the hearth Shaft on which a plurality of agitating arms extending radially outward over the hearth is attached, of which stirring teeth extend almost to the hearth bottom and, relatively to the longitudinal axis of their associated agitator arms, are arranged obliquely to the material to be treated to push over the hearth with a radial flow component and a circumferential flow component, furthermore with a self between two agitator arms from one agitator arm to the agitator arm following in the direction of rotation occupied extending with a plurality of spaced apart stirring elements compliant organ, characterized in that the compliant organ along a line from a point near the outer end of each agitator arm (32) to a point near the inner end of the agitator arm following in the direction of rotation and each from a slightly sagging chain (86,98) that does not drag on the bottom of the stove. 2. Oven according to claim 1, with a plurality of vertically spaced apart cookers and several at a distance from one another, running through the center of the oven and through each hearth extending rotatable central shaft attached to agitator arms that extend radially over each hearth extend outside, with alternating foci in the area of the central shaft arranged drop bores and the intermediate foci arranged in the area of their outer circumference have and the inclined arrangement of the stirring teeth with respect to the longitudinal axis of the Agitator arms is chosen so that the radial flow component of successive flocks alternately inwards or outwards, d. H. is directed in the direction of the relevant drop bores, thereby characterized in that the agitator chains (86, 98) in at least one of the upper hearths (20, 22) are arranged. 3. Oven according to claim 1 or 2, characterized in that devices (90, 92, 94, 96) to adjust the tension of the agitator chains (86,98) are provided. 4. Oven according to claim 1 or 2, characterized in that each agitator chain (86) between the outer agitator tooth of one agitator arm (32) and the inner agitator tooth of the following Stretcher arm extends. 5. Oven according to claim 1 or 2, characterized in that one end of each agitator chain (98) attached to the central shaft (28) and its other end to the agitator arm (32) off-center is. 6. Oven according to claim 5, characterized in that the agitator chain (98) between the outermost Agitator tooth (36) of the agitator arm (32) and the central shaft (28) is arranged. The invention relates to a drying and incineration furnace for solid-containing materials according to the preamble of claim 1. Ovens of this type are used in a wide variety of areas. They are used, for example, for Treatment of waste or sewage sludge or for the roasting of ores. With ovens of this type there is always the problem that the Exhaust gases contain unwanted solid and ίο gaseous impurities. These impurities are mostly the result of complete combustion. It is therefore already in the most varied of ways Attempts have been made to take precautions to ensure more complete combustion than before, especially for reasons of environmental protection ever higher demands on the purity of the Atmosphere emitted exhaust gases. One reason for the incomplete combustion in such ovens is, among other things, the different layer thicknesses of the material to be treated on the hearth floors. The agitator teeth attached to the agitator arms, which dig their way through the material to be treated like a ploughshare, create dams that prevent uniform combustion or treatment of the material. Towing strips have already been placed behind the agitator arms to remove the raised dams, which level the material to be treated and thus an even coverage of the oven floors should ensure (see, for example, page 1 of DE-PS 4 80 147 or DE-PS 5 72 603). It has, however shown that the overturning effect caused by the stirring teeth is caused by the dragged rails is partially destroyed again, so that there is insufficient circulation of the material to be treated is ensured. In addition, segregation phenomena occurred, which led to the Deposit finer-grained components of the material to be treated on the base of the stove. , Attempts have been made to improve the inadequate circulation in such furnaces by arranging so-called turning strips. The desired effect was only partially achieved, however, as the spiral strips tended to push the material in front of them on the hearth floors. _χ In order to eliminate effects of this type, it has already been proposed for a furnace of the type mentioned at the beginning been (see. DE-PS 4 80 147), between the agitator arms articulated trapezoidal To arrange frames, which are used to form upward rakes on their underside with a multitude are equipped with prongs. This known construction prevents the damaging formation of pronounced dams and causes constant circulation of the material to be treated. However, the construction of the frame-like rake is very complex and therefore expensive. In addition, the frame-like rakes have a high weight, which is why a relatively high drive energy is necessary to drive the agitator arms. Because of the aggressive atmosphere in which the frame-like rakes move, the joints between the rakes are subject to high wear. The maintenance of such systems is also very expensive due to the bulkiness of the frame-like rakes and the large number of tines used, which means that long downtimes have to be accepted.
The object of the invention is to provide a drying and