EP0013871B1 - Process and apparatus for cooling burnt material such as sinters or pellets - Google Patents

Description

The invention relates to a method for cooling fired material, such as sinter or pellets, which is broken after leaving a continuously operating furnace system and cooled in a separate cooler in counterflow with blown air, and to an apparatus for performing this method.

The increasing demand for crude steel and pig iron has to be met mainly by the purchase of processed, ie fine-grained iron ores. For the agglomeration of these fine-grained ores and concentrates, on the one hand the sintering process and on the other hand the pelleting has become established and both the sintering, especially the sintering of fine ores, and the firing of pellets is carried out almost exclusively in continuously operating furnace systems, i.e. traveling rust systems because this is the only way to achieve the required high throughput. The material leaves the furnace system after passing through an ignition zone and a heat treatment zone as a hot sinter cake or as a fired pellet layer and must subsequently be cooled in its own, also continuously operating coolers, for which purpose it is broken and subjected to cooling air. To cool this hot, lumpy material, it is already known from DE-B-1 039234 to push air blown into the cooler in countercurrent through the material passing through the cooler and at least some of the cooling heat by returning the cooling air to the heat treatment zone of the furnace system to recycle. However, since all of the material leaving the furnace system has previously been brought into the cooler regardless of temperature differences, the cooling air is not optimally heated, and the use of the cooling heat remains unsatisfactory, especially if the entire amount of cooling air is to be returned, for example as in DE-A-1 558 609 has been proposed.

The invention is therefore based on the object of specifying a cooling method of the type described at the outset, which enables the cooling heat to be returned to the combustion process with a high degree of utilization without any particular effort. In addition, a simple, appropriate device for performing this method is to be created.

Starting from a method in which the entire amount of air printed through the material passing through the cooler is fed to the heat treatment zone in the furnace system, the invention achieves this object in that the fired material layer emerging from the furnace system is vertically divided into a lower, hotter and an upper one cooler part is separated and only the hotter parts are forwarded to the cooler. As measurements have shown, the fired material layer coming out of the furnace has a temperature of approximately 1100 ° C. in its lower third, while its upper part, approximately two thirds of the layer height, has cooled almost to room temperature. The temperature does not change continuously, but in narrow thickness ranges. The material layer can therefore be split into a hot and a cold part, whereby only the hot material portion of approx. 900 ° C needs to be fed to the cooler and the cold portion of approx. 30 ° C can be directly conveyed to cold screening. Since material with a uniformly higher temperature thus gets into the cooler, the cooling air is also heated to a higher temperature, and because of this high temperature, particularly economical and extensive utilization of the cooling air is possible. In addition, the amount of material to be cooled becomes smaller and additional fuel is saved for the heat treatment zone of the furnace system, which not only improves the efficiency of the entire system, but also simplifies environmental protection measures, since pollutants are mainly come from the fuel.

In order to be able to carry out the method according to the invention in a simple manner that meets all requirements, the cooler is preceded by a separating device for dividing the burned material into a hotter and a cooler part, the separating device being a conveyor shaft for the hotter and one that leads to the filling shaft of the cooler has a feed shaft for the cooler parts leading to cold screening. Since the material layer coming from the kiln has very different temperatures in height, such a separating device makes it possible to split off the cooler material, which no longer has to be fed to the cooler and can immediately be subjected to cold screening. The remaining hotter portion of the material is supplied to the filler shaft of the cooler and cooled in the cooler, whereby on the one hand hotter air from the cooler enters the heat treatment zone and on the other hand only a smaller amount of material has to pass through the cooler.

It is also advantageous if, according to the invention, to separate the material layer into a hotter and a cooler part, the separating device consists of a wedge-shaped hammer tool, for example a pneumatic hammer, which strikes from the bottom up and a guide grate which brings the fired material from the furnace system into the effective range of the tool. The hot material coming from the furnace system is thus gripped by the guide grate, in its path accordingly deflected and fed to the tool from above, whereby it is split. The wedge-shaped tool not only separates the material pieces, but also forms sliding surfaces for the separated material parts.

If the guide grate also has end sections that are adjustable with respect to the tool center plane, it is possible to vary the ratio of the split material parts by this adjustment of the grate in relation to the direction of action of the tool and to influence the temperature or amount of the portion to be supplied to the cooler or the cold screening.

• Fig. 1 die gesamte Sinteranlage,
• Fig. 2 und 3 zwei Ausführungsbeispiele eines Kühlers und
• Fig. 4 eine erfindungsgemäße Trenneinrichtung.

In the drawing, the subject of the invention is shown purely schematically, namely shows

• 1 shows the entire sintering plant,
• 2 and 3 two embodiments of a cooler and
• Fig. 4 shows a separation device according to the invention.

In a continuously operating furnace system 1 for sintering fine ores or the like, the material to be sintered is applied to a traveling grate 3 via a feed device 2, which leads it through an ignition zone 4 and a heat treatment zone 5. An induced draft fan 6 directs the cooler exhaust gases resulting from the sintering process to the outside, while the hotter exhaust gases are conveyed back into the ignition zone 4 via a fan 7. The finished sintered sinter cake 8 falls off from the traveling grate 3 in larger pieces after leaving the furnace system and comes into a sting crusher 9, where it is broken up into small pieces. The broken sinter cake then passes through a filling shaft 10 into a shaft cooler 11, which it leaves cooled by an emptying shaft 12 and a discharge chute 13 (arrows 8 '). To cool the sintered material, cooling air is blown into the cooler 11 via a fan 14, where it penetrates the feed in counterflow. The heated cooling air is drawn off via a pipe 15, fed to a solids separator 16, which frees it from the hot return material, and then fed entirely through line 17 to the heat treatment zone 5, so that practically all of the cooling heat can be reused in the sintering process.

The shaft cooler 11, which can have a round or angular cross section, has an upwardly tapering upper part 11a, which connects to the pipeline 15, and a funnel-shaped lower part 11b, which merges into the emptying shaft 12. The shaft cooler 11 receives an annular push table 18, which is mounted so as to be movable transversely on a cross support 19 and can be set into eccentric or oscillating movement by means of a drive 20. At a distance above the sliding table 18, a conical or pyramid-shaped material slide 21, which interacts with the sliding table 18, is fixedly mounted on the cross support 19. The tip of the material slide 21 lies below the mouth area 22 of the filling shaft 10, so that the broken sintered material 8a to be cooled is applied to the slide table 18 evenly distributed through the material slide 21 and evenly on the outside of the slide table as well as through the gap between the slide table movement Drawer and material slide is carried out on the inside of the drawer. Baffles 23 rotating on the side of the shaft cooler serve to regulate the material flow and to direct the cooling air through the material flow. The cooling air is then blown into the shaft cooler 11 by the blower 14 in the area of the push table 18, that is to say between the already cooled material and the still hot material, through inlet openings 14 ′ and penetrates the material to be cooled in counterflow, as indicated by the arrows 24. The filling shaft 10 is now long enough so that the sintered material 8a introduced is self-sealing and only minimal amounts of cooling air can escape through the cooling shaft. The same applies to the emptying shaft 12 if it is long enough, but a known double flap system can also be used for sealing with a low overall height.

In order to achieve accelerated cooling, additional air passage openings 25 can be provided in the material chute 21, which is indicated in the exemplary embodiment according to FIG. 3. According to the invention, as illustrated in FIG. 4, the cooler 11 is preceded by a separating device 26 which divides the sinter cake 8 into two parts in terms of height. As measurements have shown, the sinter cake is namely much hotter on its side resting on the traveling grate 3 than on its free surface, so that only the hotter portion needs to be fed to the cooler 11 through this separating device 26 and the cooler portion immediately undergoes cold screening, for example can be. The separating device 26 now consists of a wedge-shaped pneumatic hammer 27 which strikes from below and which interacts with a guide grate 28. The sinter cake pieces 8b falling from the traveling grate are gripped by the guide grate 28 on both sides and brought into the effective area of the hammer 27, which divides them into a cooler portion 8b 'and a hotter portion 8b ", which portions are discharged via separate conveyor shafts 29a, 29b to be able to vary the ratio between the two parts, the guide grate 28 has adjustable end sections 30, as a result of which the action level of the hammer 27 can be adjusted relative to the height of the sinter cake pieces 8b and the part 8b "supplied to the cooler can be selected in terms of quantity and temperature.

Claims (4)

1. A process of cooling fired material, such as sinter or pellets, which after leaving a continuously operating furnace plant is crushed and is cooled with blown-in air in a separate cooler in countercurrent operation, wherein the entire quantity of air forced through the material moving through the cooler is supplied to the heattreating zone in the furnace plant, characterized in that the layer of fired material leaving the furnace plant is divided in height into a lower, hotter part and an upper, cooler part and only the hotter parts are forwarded to the cooler.

2. Apparatus for carrying out the process according to claim 1, comprising a cooler, characterized in that the cooler (11) is preceded by a dividing device (26) for dividing the fired material (8b) into a hotter part (8b") and a cooler part (8b') and the dividing device comprises a conveying shaft (29b) for the hotter parts, which leads to the filling shaft of the cooler, and a conveying shaft (29a) for the cooler parts, which leads to a cold-sieving device.

3. Apparatus according to claim 2, characterized in that the dividing device (26) consists of a wedge-shaped hammer tool, such as a pneumatic hammer (27), which blows from bottom to top, and a guiding grate (28), which brings the fired material (8b) from the furnace plant (1) into the range of action of the tool.

4. Apparatus according to claim 3, characterized in that the guiding grate (28) comprises end sections (30) which are adjustable relative to the center plane of the tool.

Images