DE102021201730A1 - Height-optimized device for the heat treatment of mineral substances - Google Patents

Abstract

The present invention relates to a device for the heat treatment of mineral substances, the device having a preheater 10, a calciner 20 and a cooler 30, characterized in that at least two of the structural units (preheater 10, calciner 20 and cooler 30) are arranged next to one another.

Description

The invention relates to a device for the heat treatment of fine-grained mineral substances, for example mineral carbonates, clays or metallic ores.

Such devices include a preheater, a calciner and a cooler. In principle, the material flow of the solids and the gas flow run in countercurrent, with sections usually being cocurrent with interposed separators, in particular cyclone separators. While the gas flows through the plant from the bottom up, the feed material flows through the plant from the top down by gravity. For this reason, the preheater, calciner and cooler are usually arranged one above the other. Since the preheater and cooler in particular are usually multi-stage, the overall height is high, which corresponds to the sum of the height of the individual assemblies or process stages. However, it is precisely this construction height that poses a problem in implementation in many places due to earthquake risks, strong winds or local regulations, which in some cases makes it impossible to use this technology.

Another weak point of the entrained flow technology, in addition to the overall height, is the very short residence time in the calciner. It is known that by extending the process time, the product properties can be further adapted to later requirements. If a corresponding device, for example a dwelling tank or material return system, is integrated to extend the dwelling time, the overall height increases further.

From the EP 0 125 973 B1 a device for the thermal treatment of minerals in powder form with gases is known.

From the US 6,574,885 B1 a cyclone heat exchanger is known.

From the WO 98/55418 A1 a device for heat treatment of powder is known.

From the EP 1 060 146 B1 a kiln plant and a method for cement production is known.

Due to the comparatively high overall height, the load-bearing steel structure is very complex and expensive for static reasons. In some places, the construction of such a system is completely unthinkable due to local height restrictions or due to the dangers of earthquakes or strong winds.

The object of the invention is to create a device that can also be implemented under these boundary conditions.

This problem is solved by the device with the features specified in claim 1 . Advantageous developments result from the dependent claims, the following description and the drawings.

The device according to the invention is used for heat treatment such as, for example and in particular, roasting, calcination, dehydration or phase changes of mineral substances, in particular fine-grained mineral substances. For example and in particular, the mineral substances are selected from the group comprising mineral carbonates, gypsum, limestone, magnesite, dolomite, phosphate ore, clays, metal ores or a mixture thereof. The apparatus has three assemblies, a first assembly being a preheater, a second assembly being a calciner, and a third assembly being a cooler. These are usually arranged one above the other so that the material passes through the device from top to bottom. In individual sections of the device, the material is lifted by the gas flow against the force of gravity, but overall the material passes through the system from top to bottom, driven by gravity. In order to reduce the resulting large overall height, according to the invention two of the three assemblies are arranged next to one another. For example, the calciner and the cooler are arranged one above the other and thus next to the preheater. Alternatively and preferably, the preheater and the calciner are arranged one above the other and thus next to the cooler.

In a further embodiment of the invention, all three assemblies are arranged side by side. Thus, both preheater and calciner as well as cooler are arranged side by side.

On the one hand, the side-by-side arrangement increases the required floor space, but on the other hand, the height is reduced. If the floor space is limited, for example when expanding existing systems, the placement of two assemblies next to each other, for example the cooler and the calciner, can already have an advantage in terms of height construction. It has been shown to be advantageous that in one embodiment in which the cooler and calciner are arranged next to one another, a combustion device arranged at the lower end of the calciner and consisting of a burner chamber and at least one burner, which accounts for a comparatively high proportion of the total system weight, is at a lower height can be mounted. As a result, a lighter steel construction can be used. In addition, assembly and subsequent maintenance work on the burner chamber and burner is made easier by the low arrangement. It can also be advantageous to arrange the preheater next to the calciner. For systems where the floor area is not structurally limited, placing all three assemblies next to each other shows that the reduction in height compared to the increase in floor area has a positive influence on the supporting steel structure, and that a simpler and cheaper construction can be selected as a result can.

Another advantage of this design is that the assembly time of the entire system can be significantly reduced, since several prefabricated cyclone units for the different process stages can be installed on one platform level. In addition, the crane units for assembly and later revisions can be selected to be significantly smaller.

In a device in which the preheater is arranged next to the calciner, it has proven to be advantageous that the discharge point of the calciner product can be shifted upwards without the absolute height of the preheater above the ground being correspondingly shifted upwards. As a result, the discharge point of the calciner can be optimally positioned to meet the further requirements of the system design, without increasing the overall height of the device. For example, by moving the discharge point of the calciner upwards, additional components, such as residence reactors or material flow dividers with returns to the calciner, can be installed in the material path between the calciner and the cooler without increasing the overall height.

In a further embodiment of the invention, the preheater has a first material inlet and a first material outlet. The first material outlet is also called the discharge point of the preheater. The calciner also has a second material inlet and a second material outlet. The second material outlet is also called the discharge point of the calciner. The cooler also has a third material inlet and a third material outlet. The third material outlet is also called the discharge point of the cooler. The first material outlet is advantageously arranged above the second material inlet and the second material outlet is arranged above the third material inlet. In this way, a low overall height is achieved, but at the same time material is prevented from being conveyed against the force of gravity.

In a further embodiment of the invention, the preheater has a first gas inlet and a first gas outlet. The calciner also has a second gas inlet and a second gas outlet. The cooler also has a third gas inlet and a third gas outlet. The second gas outlet is advantageously connected to the first gas inlet via a first gas line and the third gas outlet is connected to the second gas inlet via a second gas line. The first gas line and the second gas line each have a falling gas line part and a lower deflection on the underside. Optionally and preferably, the first gas line and the second gas line each have an upper deflection. Since the components are no longer arranged one above the other as usual, the hot gas must now be deflected and guided to a lower level so that the gas flow enters the subsequent assembly from below again. Although this lengthens the path of the gas flow and at the same time more surface is created, which leads to heat loss, but this is compensated by the lower height of the overall construction. Optionally, these connecting gas lines can be used as a process space for conditioning the gas flow. For example, additional energy can be added to the first gas line between the cooler and the calciner by adding hot gas by means of a hot gas supply from other processes or a hot gas generator, or by directly supplying fuel or electrical energy. The route of the second gas line favors the mixing of the gas flows. In a further embodiment, additives, for example and in particular to minimize NO _x , can be introduced into the first gas line between the calciner and the preheater. The length of the gas line increases the residence time for the reaction between the additive, for example ammonia and _NOx .

In a further embodiment of the invention, at least one lower deflection is designed as a U-shaped deflection.

In a further embodiment of the invention, at least one lower deflection is designed as a U-shaped deflection with a tapering course. This results in a nozzle effect and an acceleration of the gas at the end, which is advantageous for reducing deposits in the lower deflection.

In a further embodiment of the invention, the lower deflection has an inflow pot, a settling chamber or a vortex pot. The first gas line and the second gas line are in this case via the lower deflection laterally connected to the inflow pot, the settling chamber or the vortex pot. The inflow pot, the settling chamber and the vortex pot preferably have a material discharge for removing deposits.

In a further embodiment of the invention, the second lower deflection of the second gas line has a second removal point for solids. The solids discharged here are preferably returned via the third material inlet of the cooler. Otherwise, the solid can also be discharged directly and, depending on its composition, added to the product or discarded.

In a further embodiment, the first lower deflection of the first gas line has a first removal point for a solid. The solids discharged here are preferably returned via the third material inlet of the cooler. Otherwise, the solid can also be discharged directly and, depending on its composition, added to the product or discarded.

In a further embodiment of the invention, a fan is arranged in at least one descending part of the gas line.

In a further embodiment of the invention, a dwelling time container is arranged between the second material outlet and the third material inlet. The second material outlet is located above the dwell tank and the third material inlet is located below the dwell tank. The dwell tank serves to keep the temperature to be treated at the elevated temperature for a certain period of time in order to allow further reactions over time. The dwell tank can already be a tube with a low slope, but can also, for example, according to the DE 10 2019 201 763 A1 be executed.

In a further embodiment of the invention, a material flow divider is arranged between the second material outlet and the third material inlet. The material flow divider has a first partial flow outlet and a second partial flow outlet. The first partial flow output is connected to the third material input and the second partial flow output is connected to the calciner. Thus, part of the material flow is fed back into the calciner. This increases the stochastic residence time of the material in the calciner. The material can be fed into the calciner via the second material inlet or alternatively via a further optional separate material inlet, which can be located at a higher position in the riser pipe depending on the temperature profile of the calciner.

In a further embodiment of the invention, the calciner has at least one ascending calciner section. Optionally, the calciner can have a falling calciner section. If the calciner has a falling calciner section, the falling calciner section is shorter than the rising calciner section. Due to the falling calciner section, the height of the second material outlet can be optimally adapted to the requirements of the device.

In a further embodiment of the invention, further additives for conditioning the gas flow are fed into the first gas line and/or the second gas line.

In a further embodiment of the invention, thermal energy is supplied in the first gas line and/or the second gas line.

Due to this arrangement of the assemblies, different burner chamber geometries or burner installations can be installed in the lower area of the calciner without affecting the height of the inlets and outlets of the material and gas flows of the device.

• 1 Ausführungsbeispiel ohne Verweilzeitbehälter
• 2 Ausführungsbeispiel mit Verweilzeitbehälter
• 3 detaillierte Darstellung

The device according to the invention is explained in more detail below with reference to an exemplary embodiment illustrated in the drawings.

• 1 Embodiment without residence time tank
• 2 Embodiment with dwell tank
• 3 detailed representation

In 1 a first device according to the invention for heat treatment is shown schematically. The device has a preheater 10, a calciner 20 and a cooler 30, which are arranged side by side, whereby more space is required, but the height can be reduced.

The material to be processed enters the preheater through an educt feed 60 into the first material inlet 12 , is heated by the exhaust gas stream of the calciner and exits again heated through a first material outlet 14 . From here the material enters the second material inlet 22 of the calciner 20 and is thermally converted here. The material leaves the calciner via a second material outlet 24 and reaches the cooler 30 via the third material inlet 32. Here the material is cooled and leaves the cooler through the material outlet 34 via the product discharge 70.

Viewed as a whole, the gas flow is in the opposite direction. Cool gas reaches the third gas inlet 36 in the cooler 30 via the gas supply line 80 and is heated there by the material. The heated gas leaves the cooler 30 through the third gas outlet 38. Since the second gas inlet 26 of the calciner 20 is located significantly lower due to the adjacent construction, the device has a second gas line 50, which has a second lower deflection 52 at the lower end .

A burner space for supplying the necessary thermal energy is usually located in the direct vicinity of the second gas inlet 26 . The preheated gas stream of the cooler 30 entering here from below serves as the main combustion air. The gas flows through the calciner 20 which, for example and preferably, has a separating cyclone at the end to separate gas and material. The gas is then fed through the second gas outlet 28 into the first gas line 40 in order to be fed again to a lower level of the first gas inlet 16 of the preheater 10 . For this purpose, the first gas line also has a first lower deflection 42 at the bottom. In the preheater 10, the hot gas entering from below heats the cold material entering from above and is itself cooled in the process. The cool gas is then routed through the first gas outlet 18 to the gas outlet 90 . The gas discharge 90 can have a dust separator, for example.

In the 2 shown second inventive device for heat treatment differs from that in 1 shown first device according to the invention for heat treatment in that it additionally has a dwell time container 100 between the second material outlet 24 and the third material inlet 32 .

In 3 A more exemplary embodiment of the second heat treatment device according to the invention is shown in more detail. It can be seen that in the in 3 shown embodiment, both the preheater 10 and the cooler 30 are each formed by three cyclone stages, each cyclone stage having a riser pipe and a cyclone separator connected thereto, as well as a material chute with a gas shut-off element and a dispersing element. In addition to the educt feed 60, a further material feed 110 is shown, for example for the return of filter dust. Within the risers of the individual cyclone stages, the material flow and the gas flow move in parallel, but overall the gas and material flow pass through the device in countercurrent. The individual assemblies, calciner 20, preheater 10 and cooler 30 are connected to gas lines 40, 50, the lower connection being a U-shaped lower deflection 42, 52 in the embodiment shown. The material outlets 14, 24 of the individual assemblies are connected to the material inlets 22, 32 in such a way that material is supplied by means of chutes without further conveying elements (vertical or horizontal). In addition, an additional holding tank 100 is provided here in order to increase the time of the material at the process temperature. The advantage of the embodiment shown here is that a clever height orientation of the lower deflectors 42, 52 allows the solid material flows exiting here to be fed back to the cooler 30.

In this exemplary embodiment, the advantages according to the invention can also be seen that, in a device according to the invention, compared to a device according to the prior art, in which all cyclone stages are arranged one above the other, the overall height can be significantly reduced. As a result, for example, a shorter conveying element can be used for the material supply 60 to the preheater stage compared to the prior art. Due to the arrangement of the assemblies according to the invention next to one another, the focus of the individual assemblies is in each case at a significantly lower level in comparison to the prior art. A modification of the arrangement, sizes, number of cyclone stages, lengths of risers and the installation of other assemblies, such as a holding tank 100 shown here, only affect the height of a single assembly, here the calciner, and not the height and design of the other two assemblies

Reference List

10

preheater

12

first incoming material

14

first material exit

16

first gas inlet

18

first gas outlet

20

calciner

22

second material input

24

second material exit

26

second gas inlet

28

second gas outlet

30

cooler

32

third material input

34

third material exit

36

third gas inlet

38

third gas outlet

40

first gas line

42

first lower deflection

50

second gas line

52

second lower deflection

60

educt feed

70

product discharge

80

gas supply

90

gas evacuation

100

residence time tank

110

further material feed

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 0125973 B1 [0004]
• US 6574885 B1 [0005]
• WO 9855418 A1 [0006]
• EP 1060146 B1 [0007]
• DE 102019201763 A1 [0024]

Claims (15)

Device for the thermal treatment of mineral substances, the device having three assemblies, the first assembly being a preheater (10), the second assembly being a calciner (20) and the third assembly being a cooler (30), characterized in that that at least two of the three assemblies are arranged side by side. device after claim 1 , characterized in that the three assemblies are arranged side by side. Device according to one of the preceding claims, characterized in that the preheater (10) has a first material inlet (12) and a first material outlet (14), the calciner (20) having a second material inlet (22) and a second material outlet (24) wherein the cooler (30) has a third material inlet (32) and a third material outlet (34), the first material outlet (14) being arranged above the second material inlet (22), the second material outlet (24) being arranged above the third Material input (32) is arranged. Device according to one of the preceding claims, characterized in that the preheater (10) has a first gas inlet (16) and a first gas outlet (18), the calciner (20) having a second gas inlet (26) and a second gas outlet (28) wherein the cooler (30) has a third gas inlet (36) and a third gas outlet (38), the second gas outlet (28) being connected to the first gas inlet (16) via a first gas line (40), the third Gas outlet (38) is connected to the second gas inlet (26) via a second gas line (50), the first gas line (40) and the second gas line (50) each having a falling gas line part and a lower deflection (42, 52 ) exhibit. device after claim 4 , characterized in that at least one lower deflection (42, 52) is designed as a U-shaped deflection with a tapering course. device after claim 4 , characterized in that the at least one lower deflection (42, 52) has an inflow chamber or a settling chamber below the subsequent riser. device after claim 4 , characterized in that at least one lower deflection (42, 52) has a vortex pot below the subsequent riser. Device according to one of Claims 4 until 7 , characterized in that the second lower deflection (52) of the second gas line (50) has a second removal for solids, the solids removed from the second removal being fed to the product flow which comes from the third material outlet (34). Device according to one of Claims 4 until 8th , characterized in that the first lower deflection (42) of the first gas line (40) has a first removal for solids, the first removal being arranged above the third material inlet (32), the solids removed from the first removal being fed to the third material inlet ( 32) is supplied. Device according to one of Claims 4 until 9 , characterized in that a fan is arranged in at least one falling part of the gas line. Device according to one of the preceding claims, characterized in that between the second material outlet (24) and the third material inlet (32) a dwell time container (100) is arranged, wherein the second material outlet (24) is arranged above the dwell time container (100), wherein the third material inlet (32) is arranged below the delay tank (100). Device according to one of the preceding claims, characterized in that a material flow divider is arranged between the second material outlet (24) and the third material inlet (32), the material flow divider having a first partial flow outlet and a second partial flow outlet, the first partial flow outlet being connected to the third material inlet (32) is connected, the second partial stream output being connected to the calciner (20). Device according to one of the preceding claims, characterized in that the calciner (20) has at least one rising calciner section, wherein the calciner (20) can have a falling calciner section, the falling calciner section being shorter than the rising calciner section section is. Device according to one of the preceding claims, characterized in that further additives for conditioning the gas flow are fed into the first gas line (40) and/or the second gas line (50). Device according to one of the preceding claims, characterized in that thermal energy is supplied in the first gas line (40) and/or the second gas line (50).

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