RU137292U1 - FIRING UNIT WITH A PRELIMINARY COOLING AREA - Google Patents

Abstract

1. A calcining plant for iron ore pellets, comprising a drying zone and a heating zone, a calcination zone, a recovery zone and a cooling zone following each other in the direction of transporting the iron ore pellets, wherein a first exhaust line (12) is provided that exhausts warm air (14) from the drying zone and the heating zone, and a second exhaust line (16) that removes hot air (18) from the combustion zone and the recovery zone, characterized in that a pre-cooling zone is provided located between the recovery zone and the zone o a supply line (22) having an inlet (8) for the supply air (10), which leads to the pre-cooling zone the air mixture (26) from the supply air (10), warm air (14) and hot air ( 18), and a connecting line (28) is provided leading from the first outlet line (12) and the second outlet line to the inlet line (22) .2. Firing plant (2) according to claim 1, characterized in that the supply line (22) contains a compressor (F6). 3. The calcining plant (2) according to claim 2, characterized in that the connecting line (28) is connected to the section (30a) of the suction side of the supply line (22) .4. Firing plant (2) according to claim 1 or 2, characterized in that the first (12) and / or second outlet line (16) comprises a compressor (F3, F5) and a connecting line (28) on the pressure side section (30b) connected to the first (12) and / or second supply line (16) .5. Firing plant (2) according to claim 1 or 2, characterized in that it is equipped with a control device (32) that controls the shares of warm air (14), hot air (18) and supply air (10) in the air mixture (26) .6 . Firing unit (2) according to claim 5, characterized in that

Description

The utility model relates to a calcining plant, in particular to that for iron ore pellets.

Raw materials are often granulated. For example, it is known that in the processing of iron ore it is granulated. For example, from documents: Pelletizing, Lurgi Metallurgie GmbH, Frankfurt aM, 1589e / 6.97 / 20 or Innovation: SIMINE PELLET / Higher Productivity, Lower Costs an New Generation Pellet Plant, Andreas Lekscha, metals & miming, 2 may 2006, www.siemens /com./mining the so-called Lurgi-Davy-Traveling-Grate process is known as the classic method with a mechanical chain grate (agglomeration belt): spherical raw pellets are formed or rolled in a drum pelletizer or plate pelletizer. In an agglomeration belt or roasting plant, the raw pellets are dried and then calcined at high temperatures to produce finished pellets, i.e., calcined pellets.

FIG. 2 shows a known calcination plant 2. In the known sintering method, raw GR pellets — here the iron ore pellets are placed on the protective layer HL, which is formed from already fired (iron ore) pellets FP. There is an AZ suction (exhaust) zone or an AWk suction air box after feeding pellets at the end upstream of the installation, that is, the head of the installation. In the direction of flow, the pellets are transported one after another through the drying zone TRZ, the heating zone WZ, the calcining and curing zone BRZ, the recovery zone REZ and the cooling zone KZ of the calcining plant. In the BRZ firing zone, raw GP pellets are converted to fired FP pellets. At the end of the installation, they fall onto the conveyor belt of CO haulage.

The respective zones are separated from each other by stationary dividing walls 4. The cooling zone KZ has two regions KZ1 and KZ2 of the cooling zone with which the common collector E of the air box is associated. On it through the supply line 6, which has an input 8 for the supply air 10, the supply air 10 is supplied through the compressor (fan) F1. The supply air 10 is blown in the direction of the flow arrows shown in FIG. 2 (this is also true for the following description) through the fired pellets FP in the horizontal cooling zone from the bottom up. In this case, the fired pellets FP are cooled, and the supply air 10 is heated. The perceived heat with air as a coolant from the KZ1 region of the cooling zone through the central main collector NK from above to the heating zone WZ and the firing zone BRZ is transported and used to support the operation of the BR burners in the firing zone BRZ and in the heating zone WZ. This warm air supports a combustion process in which fuel, such as natural gas, is burned in BR burners. The warm air in the recovery zone REZ and the burnt gas in the burning zone BRZ through the pellet layer and then through the collector C are sucked off by the compressor F3 through the second exhaust line 16. The heat of this gas is directly used to dry the raw GR pellets in the TRZ 2 region of the drying zone, i.e. without application of an additional compressor. In the drying zone region TRZ1, this gas is used for the same purpose by means of compressor F2. Gas, here warm air 14 from the heating zone WZ and region TRZ2 of the drying zone, is sucked out through a layer of raw pellets GR by a compressor F5 through a collector B and an electric filter ESP1 and through a gas exhaust pipe (fireplace) K through the first exhaust line 12.

Hot air 18 has a higher temperature than warm air 14, and the latter has a higher temperature than supply air 10.

The described curing method or kiln 2 according to the prior art only to a limited extent corresponds to modern technical, economic and environmental requirements. It is problematic that part of the calcined pellets breaks, or that the pellets at the end, that is, after passing through the calciner, are not sufficiently cooled and therefore damage the subsequent conveyor belt of CO rollbacks.

The use of only one compressor for several technological purposes, such as cooling hot pellets in KZ1 and KZ2, regulating the pressure in the upper part of the kiln, leads to technological conflicts and complicates the stable process control.

Known kiln 2 contains additional components that are not essential for the proposed utility model and therefore are not considered in detail.

The task of the utility model is solved by the calcining plant according to paragraph 1 of the formula of the utility model, especially for iron ore pellets, which has a drying zone. The drying zone downstream is followed by a heating zone adjacent to it. A firing zone follows downstream; behind it, again, the recovery zone adjoins downstream again. Downstream of the recovery zone is a cooling zone. The first exhaust line discharges warm air from the drying and heating zone, the second exhaust line discharges hot air from the firing zone and the recovery zone. Between the recovery zone and the existing cooling zone, consisting of areas KZ1 and KZ2, there is a pre-cooling zone. The calcining plant also has a supply line, which in turn has an inlet for the supply air. The supply line leads to the pre-cooling zone air mixture of supply air, warm air and hot air. The calcining unit also has a connecting line leading from the first and second outlet lines to the inlet line. The connecting line thus directs warm air from the first exhaust line and hot air from the second exhaust line to the supply line so that warm air and hot air are mixed there with the supply air.

The position of the pre-cooling zone “between” the recovery zone and the actual cooling zone, consisting of areas KZ1 and KZ2, can be implemented in two alternatives, depending on the definition of the corresponding utility model of the cooling zone: the known cooling zone is actually shortened and follows its own areas KZ1 and KZ2 behind the pre-cooling zone.

Strictly speaking, also the connecting line may contain an inlet for supply air. The supply line then degenerates into part of the connecting line. It is only essential to mix the supply, warm and hot air and supply them to the pre-cooling zone by means of an appropriate piping system.

The utility model is based on the knowledge that between the firing zone and the recovery zone, on the one hand, and the cooling zone, on the other hand, there is a significant temperature difference, and the fired pellets, when passed through the temperature drop zone accordingly, are affected by a temperature difference, which can often lead to their breaking. The utility model is based on the fundamental knowledge that a huge amount of heat in the form of warm air from the second section TRZ2 of the drying zone and the heating zone WZ by means of the compressor F5 and chimney K is usually uselessly emitted into the atmosphere, and the coolant temperature here is about 160 ° FROM.

Therefore, according to the utility model, a pre-cooling zone is established between the recovery zone and the cooling zone. This happens, for example, in such a way that the known collector E of the air box is separated (part E, part D), and a supply line extends to part D. Thus, the pre-cooling zone can be adjusted independently of the cooling zone in relation to the temperature of the mixture for the air mixture and the flowing amount of air. Thus, it is possible to provide better selectivity of the entire cooling process. The temperature difference for the pellets is reduced due to the more uniform or stepwise cooling of the pellets over time, i.e. during passage through the calcining unit, if the temperature of the cooling air in the pre-cooling zone lies between the temperatures of the calcining, recovery and cooling zones. At the same time, through the connecting line from both outlet lines to the inlet line, part of the heat from the drying heat and the firing zone is used productively.

The result is less bursting or broken pellets, and, therefore, provides improved quality of the finished pellets and the specific productivity of the manufacturing method. It provides greater technological flexibility of the cooling process in the kiln, as well as improved use of the residual heat already existing in the process and, thereby, reducing fuel consumption due to the rational use of this heat. Therefore, it provides increased productivity, reduced production costs and reduced environmental pollution.

In a preferred embodiment of the utility model, the supply line comprises a compressor. By controlling it, it is then possible in the pre-cooling zone to influence the actual amount of the supplied air mixture. The degrees of freedom for controlling the kiln are increased. In the kiln, this creates a new compressor circuit in the pre-cooling zone.

By introducing an additional compressor in the cooling zone of the installation, on the one hand, the cooling zone and the pre-cooling zone can be independently controlled with respect to their air flow. Since both the compressor of the pre-cooling zone and the compressor of the cooling zone supply air to the main manifold and thereby affect the pressure above the burners, it is also possible, by means of two compressors, to perform more efficient pressure control above the burners in the heating zone WZ, firing zone BRZ and cooling zone KZ1.

In a preferred embodiment of this embodiment of the utility model, the connecting line with respect to the position of the compressor in the discharge line is connected to a portion of the suction side of the supply line. The suction power of the compressor in the supply line is used to draw in warm and hot air through the connecting line.

Typically, also the first and / or second outlet lines comprise a compressor. The connecting line is then connected in a preferred embodiment, respectively, to a portion of the pressure side of the first and / or second discharge line, that is, to the compressor blast side.

In another preferred embodiment, the calcining plant comprises a control device that controls the proportions of warm, hot and supply air in the air mixture. This is most often the valve, which can be located in the connecting line or supply line. In this way, the desired temperature of the air mixture can be set between the temperatures of the supply air and the hot air.

In an embodiment of this embodiment, the calcining plant furthermore comprises a control device, which thus acts on the control device, so that the temperature of the air mixture is usually regulated almost always at a predetermined nominal value. This provides the opportunity to achieve a uniform temperature of the mixture and, thus, maintaining a constant product quality or production conditions. A suitable mixture temperature may be, for example, about 100 ° C.

In a preferred embodiment of the utility model, an additional additional aspiration (exhaust) cooling zone of the AC with an associated air box in the firing unit is created further downstream of the cooling zone. A third exhaust line is associated with the suction cooling zone, which removes dusty air from the suction cooling zone.

In the cooling zone, as a rule, the lower pellets are sufficiently cooled, so here the cooling air flows from below. In this case, the upper pellets are cooled to a lesser extent. Due to the creation of an additional aspiration cooling zone for the speakers, it becomes possible there to pour air pellets from above and simultaneously suck off the existing dust. So the hotter upper pellets available so far are better cooled. The temperature differences in the layer of pellets in the vertical direction are reduced, so that, in particular, the temperature is balanced between the upper and lower pellets. In general, in this way, the pellets exit the unit at substantially the same temperature. Destruction of the conveyor belt by hauling separate too hot pellets is prevented.

In a preferred embodiment of this embodiment, a third discharge line is connected to the exhaust compressor, the exhaust compressor, in addition to the aspiration cooling zone, being further associated with a different calcination zone. A similar exhaust compressor, for example, at the end of the belt, is already associated with an aspiration zone in the cooling hopper. In other words, this existing compressor is then also used for the aspiration cooling zone.

In a preferred embodiment, the ratio of the areas of the aspiration zone AZ at the end upstream of the kiln to the drying zone (TRZ) adjacent to it in the downstream direction has a certain value. In other words, the drying zone at the end upstream in the direction of transporting the pellets of the plant is lengthened at the cost of the aspiration zone there. Thus, an increase in the drying area in the drying zone is obtained. This option is based on the knowledge that in known installations there is still enough spare space that has not been used until now to remove dust from there and create an aspiration (exhaust) zone there. The hood used for this (AWk exhaust air box) can be connected to the corresponding compressor. The area that is newly obtained by reducing and / or shifting the suction area is thus connected in the upstream direction to the existing drying area, and therefore the latter is increased in accordance with the utility model in comparison with known installations. Both regions TRZ1 and TRZ2 of the drying zone are changed in a different suitable relation to each other, in particular, both increase. The pellets dry more evenly and better and are thus better suited for the subsequent process.

The above-described properties, features and advantages of the present utility model, as well as the method by which this is achieved, are explained in the following description of exemplary embodiments with reference to the drawings, where, in a schematic representation, the following is shown:

Figure 1 corresponding to the utility model of the expanded firing plant according to figure 2,

Figure 2 roasting apparatus according to the prior art.

Figure 1 shows the corresponding utility model extension 20 of the known kiln 2 in figure 2. For this, the known collector of the air box E is shortened at its end upstream. An additional collector of the air box D is installed there, because of which the first area KZ1 of the cooling zone KZ is also shortened. In its place, therefore, the VKZ pre-cooling zone arises. Depending on the method of consideration, the cooling zone KZ, consisting of the areas KZ1 and KZ2, is shortened, and a pre-cooling zone VKZ is introduced between it and the recovery zone REZ. In another, equivalent way of consideration, the cooling zone KZ adjoins in an unchanged form to the recovery zone REZ. The KZ1 region of the cooling zone is then shortened, and the VKZ pre-cooling zone is introduced as the region for the KZ cooling zone. 1, this is indicated by a bracketed dividing line between the recovery zone REZ and the cooling zone KZ.

The pre-cooling zone through the collector of the air box D and the supply line 22 leads the air mixture 26 in the direction of the arrow 24. The supply line 22 has an inlet 8 for the supply air 10. Through the connecting line 28, the supply line 22 is also connected to the first exhaust line 12 and the second discharge line 16. The connecting line 28 is made of two parts and, thus, goes in two different places in the supply line 22.

Warm air 14 and hot air 18 through the connecting line 28 from the first exhaust line 12 and the second exhaust line 16 is supplied in the direction of arrow 24 to the supply line 22 and there is mixed with the supply air 10 to obtain an air mixture 26.

With respect to the first discharge line 12 and the second discharge line 16, the connecting line 28 or its corresponding partial branches extend into their pressure side portions 30b, i.e., respectively, on the pressure sides of the compressors F3, F5. Thus, their injection action is used to direct the warm air 14 and the hot air 18 through the connecting line 28.

In a preferred embodiment, the supply line 22 comprises a compressor F6 and, therefore, a suction side portion 30a and a pressure side portion 30b relative thereto. The connecting line 28 then exits to the first suction side portion 30a of the supply line 22. Thus, the suction action of the compressor F6 is used not only to draw in the supply air 10 through the supply line 22, but also warm air 14 and hot air 18 through the connecting line 28.

In preferred embodiments, the connecting line 28 and / or the supply line 22 comprise respective control devices 32, in this case valves, which control the respective amounts of supply air 10, warm air 14 and hot air 18, which, on the one hand, are sucked in or transported through the inlet 8 or the connecting line 28. Thus, it is possible to adjust their respective shares in the air mixture 26.

In a preferred embodiment, a control device is associated with one or more control devices 32. It controls the corresponding control devices 32 in such a way that the temperature TM of the air mixture 26 is regulated to be set to a predetermined value S. Moreover, the temperature of the mixture TM is in the temperature range TF of the supply air 10, TW of warm air 15 and the temperature of hot air 18. Since the operation of the kiln is true: TF <TW <TH, then it is true: TF≤TW≤TH.

In a preferred embodiment, the extension 20 of the known calciner 2 in FIG. 2 also includes the introduction of an aspiration (exhaust) cooling zone AC according to FIG. It is turned on after the well-known cooling zone KZ. This is accomplished by creating a third exhaust line 36 that removes dusty air 38 in the direction of arrow 24 from the aspiration cooling zone AC. The flow around the fired pellets FP is carried out in the aspiration cooling zone of the AC (see flow arrows in FIG. 1) in a vertical direction from top to bottom, that is, opposite to the direction of flow in the cooling zone KZ. Due to this, the temperature profile of the fired pellets FP arranged in layers on top of one another is equalized when cooled in the vertical direction.

In a preferred embodiment, the third discharge line 36 is connected to an exhaust compressor FA, which in a known installation is associated with a rear exhaust air box AWh. Initially, therefore, other than the aspiration cooling zone of the AC, the zone is associated with the calcining plant and is now simply shared for the aspiration cooling zone of the AC.

In a preferred embodiment, the exhaust air box AWk located at the end upstream of the installation and thus the aspiration zone AZ is reduced compared to the known installation, and the drying zone TRZ, on the contrary, is increased. In an embodiment not shown, the aspiration zone AZ is also shifted only upstream to the installation zone not yet used. The drying zone TRZ is increased in the longitudinal direction of the installation, and therefore its area FT is increased. The resulting ratio of the areas, the area FA of the aspiration zone FA to the area FT of the drying zone TRZ, is the ratio F of the areas, which takes on a certain value here. In this case, the regions TRZ1 and TRZ2 of the drying zone themselves, as a rule, increase. So for drying raw pellets, GP is given more space in the drying zone TRZ, and they are better and more uniformly dried.

Although the utility model is illustrated in detail and described by means of a preferred embodiment, the utility model is not limited to the disclosed examples, and other options may be derived by a person skilled in the art without deviating from the scope of protection of the utility model.

Claims (9)

1. A calcining plant for iron ore pellets, comprising a drying zone and a heating zone, a calcination zone, a recovery zone and a cooling zone following each other in the direction of transporting the iron ore pellets, wherein a first exhaust line (12) is provided that exhausts warm air (14) from the drying zone and the heating zone, and a second exhaust line (16) that removes hot air (18) from the combustion zone and the recovery zone, characterized in that a pre-cooling zone is provided located between the recovery zone and the zone o a supply line (22) having an inlet (8) for the supply air (10), which leads to the pre-cooling zone the air mixture (26) from the supply air (10), warm air (14) and hot air ( 18), moreover, a connecting line (28) is provided leading from the first outlet line (12) and the second outlet line to the inlet line (22). 2. Firing plant (2) according to claim 1, characterized in that the supply line (22) contains a compressor (F6). 3. Firing plant (2) according to claim 2, characterized in that the connecting line (28) is connected to the section (30a) of the suction side of the supply line (22). 4. Firing plant (2) according to claim 1 or 2, characterized in that the first (12) and / or second outlet line (16) contains a compressor (F3, F5), and a connecting line (28) in the area (30b) the pressure side is connected to the first (12) and / or second supply line (16). 5. Firing plant (2) according to claim 1 or 2, characterized in that it is equipped with a control device (32) controlling the shares of warm air (14), hot air (18) and supply air (10) in the air mixture (26) . 6. The kiln (2) according to claim 5, characterized in that it is equipped with a control device (34), which, by acting on the control device (32), regulates the temperature of the air mixture (26). 7. Annealing plant (2) according to claim 1 or 2, characterized in that it comprises an aspiration cooling zone located after the cooling zone in the direction of transporting iron ore pellets with a third exhaust line (36) that exhausts dusty air from it (38). 8. The calcining plant (2) according to claim 7, characterized in that the third discharge line (36) is connected to an exhaust compressor, additionally associated with the zone of the calcining plant (2), which differs from the aspiration cooling zone (AC). 9. The calcining plant (2) according to claim 1 or 2, characterized in that the ratio of the areas of the aspiration zone of the calcining plant (2) to the drying zone located behind it in the direction of transporting iron ore pellets is set to increase the drying zone while decreasing and / or shifting the zone aspiration.

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