LU103071B1 - Optimized heat management in a plant for the thermal treatment of mineral substances - Google Patents

Abstract

The present invention relates to a plant for the thermal treatment of a mineral material, wherein the plant has a preheater 10, a calciner 20 and a furnace 30, wherein the plant has a gas inlet 61 and a gas outlet 62 as well as a material inlet 51 and a material outlet 52, wherein the components for transferring a material flow from the material inlet 51 via the preheater 10, the calciner 20 and the furnace 30 to the material outlet 52 are connected, wherein the components for transferring a gas flow from the gas inlet 61 via the furnace 30, the calciner 20 and the preheater 10 to the gas outlet 62 are connected, wherein the preheater 10 is designed in several stages, characterized in that the calciner 20 for transferring the material flow leaving the calciner 20 or the preheater 10 for transferring the one stage 11, 12, 13 of the Preheater 10 leaving material flow is connected to a heat exchange device 70, wherein the heat exchange device 70 is connected to the preheater 10 for returning the material flow.

Description

thyssenkrupp Industrial Solutions AG 230063P00LU thyssenkrupp AG 02/13/2023 LU103071 1/12

Optimized heat management in a plant for the thermal treatment of mineral materials

The invention relates to increasing the heat discharge from a

Combustion process in order to avoid further firing and thus, for example and in particular, to be able to fully utilize the exhaust gas purification of the main process.

Cement plants are complex systems. The complexity is currently increasing, for example to make the plants more environmentally friendly. For example, substitute fuels are being used to save fossil fuels in particular.

to conserve resources. Devices are also integrated to separate the carbon dioxide produced and released and thus prevent the release of the greenhouse gas. However, this requires energy. At the same time, for example,

Clays are used and calcined to minimize the release of carbon dioxide from the reactant, but these clays must be dried regularly. For many

Processes therefore attempt to use energy from the main process, for example, heat exchangers are used intensively in the area of the gases leaving the process. However, the amount of heat available is limited.

At the same time, an additional combustion unit would increase the complexity, especially when it comes to carbon dioxide separation.

DE 10 2018 206 673 A1 describes an oxyfuel clinker production with special

Oxygen gassing is known.

From DE 10 2018 206 674 A1, an oxyfuel clinker production without recirculation of the preheater exhaust gases is known.

Therefore, there is a desire to provide thermal energy as integrated as possible.

The object of the invention is to extract sufficient thermal energy from the actual

Main process also for all upstream, downstream or secondary processes.

thyssenkrupp Industrial Solutions AG 230063P00LU thyssenkrupp AG 02/13/2023 LU103071 2/12

This object is achieved by a system having the features specified in claim 1.

Advantageous further developments result from the subclaims, the following

Description and drawings.

The plant according to the invention is used for the thermal treatment of a mineral

Materials. In particular, the plant is a plant for the production of cement clinker.

The plant has a preheater, a calciner and a furnace. The plant has a gas inlet and a gas outlet as well as a material inlet and a

The components (preheater, calciner and furnace) are designed for

Transfer of a material flow from the material inlet via the preheater, the

Calciner and the furnace to the material outlet. The components are further connected to transfer a gas flow from the gas inlet via the furnace, the calciner and the preheater to the gas outlet. Thus, the plant is basically in

Countercurrent is constructed, although in some sections, for example in the calciner, the currents can still flow locally in cocurrent. The preheater is designed in several stages. This represents a conventional thermal treatment device, for example for the production of cement clinker, reduced to the most important basic components and is well known from the state of the art and in many different forms.

Usually, the system also has a material cooler, which is usually arranged between the furnace and the gas inlet, in which the product is cooled and the gas supplied to the furnace is heated. The material cooler can also be designed in such a way that only a partial gas flow is transferred into the furnace, another part of the material cooler is cooled with another gas flow (usually the colder

area) and the heated gas stream at another location, for example at a

drying device. For example, the system can be used for the oxyfuel

operation, so (idealized) pure oxygen is used at the beginning, which is converted by combustion processes to (idealized) pure carbon dioxide at the end (plus water, which is easily separated) (additional carbon dioxide is usually released from the mineral material). This (idealized) pure

Carbon dioxide can then be used elsewhere without complex gas separation, thus avoiding emissions. One of the challenges in the oxyfuel process is to avoid false air, especially nitrogen from the ambient air, for which all possible gas leakage points must be sealed as far as possible. For example, the amount of false air can be 5% to 10% over the entire process. Any reduction in false air therefore leads directly to an increase in the purity of the carbon dioxide and thus to a reduction in the effort required for the necessary purification. It is therefore critical that if ambient air and thus nitrogen penetrates the gas stream, gas escapes into the environment to at least

With regard to the aspect of necessary cleaning, this is not relevant. Although the invention is particularly suitable for the oxyfuel process, it is not limited to it.

According to the invention, the calciner is designed to transfer the slurry leaving the calciner

Material flow or the preheater for transferring the material flow leaving a stage of the preheater is connected to a heat exchanger. The

Heat exchanger is connected to the preheater to return the material flow. According to the invention, a warm solid flow and not a gas flow is discharged from the process. This has a number of advantages. Firstly, the discharge of a solid material flow can be easily secured against the ingress of false air and is therefore particularly suitable for the oxyfuel

process. On the other hand, it is also possible to use the

The energy required for this can be provided in a simple manner in the main process, which means that all additional measures (use of alternative fuels, exhaust gas purification, carbon dioxide separation and the like) can be fully utilized and do not have to be kept in reserve multiple times, which would be the case if another combustion device were to be used elsewhere for

The generation of heat would be the case. Also, especially when using

Substitute fuels thus achieve the required temperature and residence time for the safe

Combustion can be ensured in a simple manner. The heat exchange device therefore serves in particular to provide further heat generation devices, in particular

To avoid combustion devices in the entire complex. Further advantages are explained below.

In a further embodiment of the invention, the heat exchange device is a

Cocurrent heat exchanger with separation cyclone or a fluidized bed heat exchanger.

Both variants have advantages, especially depending on the way in which the heat is to be transferred. A direct current heat exchanger with a separation cyclone enables extremely fast heat transfer through the direct contact between the gas and the solid material that is transported by the gas stream. Air or a circulating process gas are particularly suitable as gases. A

Fluidized bed heat exchangers, on the other hand, have mostly tubular guides for a heat transfer medium arranged in a fluidized bed.

Heat transfer than through a wall, which makes the process significantly slower.

On the other hand, this creates a separation between material and

Heat transfer medium is achieved, so that Thermodle and especially

Steam is particularly suitable for very high steam temperatures, which in turn increases the efficiency, for example in a turbine for

Driving a compressor or a generator. The

Fluidized bed heat exchangers are preferably fluidized with a small amount of fluidizing gas, whereby the fluidizing gas is preferably circulated. This can safely exclude, for example, the entry of false air into the system.

In a further embodiment of the invention, the heat exchange device is connected to a grinding device or a drying device. Preferably, the

Heat exchange device in this case a direct current heat exchanger with

Separation cyclone, in which a gas stream is heated, which is then heated again into the

grinding device. In this case, the connection between the

heat exchange device and the grinding device or the drying device.

Gas line for this heated gas.

In a further embodiment of the invention, the gas outlet of the system is provided with a

Carbon dioxide separation device. The cement industry in particular is a

Carbon dioxide-intensive industry. Separation therefore has a very big effect.

Currently, several alternative processes are available for separating carbon dioxide from an exhaust gas stream. Two examples are amine scrubbing and

Carbonate looping process (also calcium looping process). Here, the

Carbonate looping process, however, required significantly higher temperatures. In both

In these cases, the carbon dioxide from the exhaust gas stream is first chemically bound, once to an amine, once to CaO. This takes place in the absorber part of the thyssenkrupp Industrial Solutions AG 230063P00LU thyssenkrupp AG 13.02.2023 LU103071 5/12

Carbon dioxide separation device. The medium loaded with carbon dioxide is then transferred to another area of the carbon dioxide separation device and regenerated there, i.e. the carbon dioxide is released again. This means that the carbon dioxide stream is free of nitrogen or argon, for example. For the regeneration,

Energy is required. For example and preferably, the carbon dioxide separation device is an amine washer. The amine washer has an amine regeneration device in which the carbon dioxide bound to the amine is released again. The amine

Regeneration device is connected to the heat exchange device for transferring the medium heated in the heat exchange device. Here, the

The heat exchange device can be designed, for example, as a fluidized bed heat exchanger for generating steam.

In a further embodiment of the invention, the first adjacent to the calciner

Stage of the preheater for transferring the material flow leaving the first stage of the preheater to the heat exchanger. Adjacent here means that the material flow or the gas flow is led from one adjacent component to the other adjacent component, here as the material flow from the first stage of the preheater adjacent to the calciner into the calciner and the gas flow from the calciner into the first stage of the preheater adjacent to the calciner. The heat exchanger is for returning the

material flow to the second stage of the preheater. The second stage is the stage following the first stage in the material flow direction and preceding the first stage in the gas flow direction. This has proven to be an ideal temperature window for producing, for example, high-quality steam for efficient further

to gain use.

In a further embodiment of the invention, the system is designed for operation with a

Gas containing less than 50 vol.%, preferably less than 10 vol.%, nitrogen in the

gas flow supplied to the gas inlet. It is therefore an oxyfuel

The aim is to avoid any secondary air or other air entering the system in order to obtain the purest possible air at the end of the process.

Carbon dioxide. The process according to the invention enables the

Removing only the solid mineral material in a simple manner.

thyssenkrupp Industrial Solutions AG 230063P00LU thyssenkrupp AG 02/13/2023 LU103071 6/12

In a further embodiment of the invention, the heat exchange device

Ambient air as a heat exchange medium. The heat exchange medium air is brought into direct contact with the material flow. This results in a special

Advantage if the plant is connected to a carbon dioxide separation device and/or is operated according to the oxyfuel process. In both cases, the

Carbon dioxide from the main process does not enter the environment. But through the contact of the

Ambient air, which also contains carbon dioxide, even if only in small quantities, comes into contact with the hot, at least partially decarbonated, material and the decarbonated material absorbs carbon dioxide again (particularly optimal at around 650 °C).

This carbon dioxide is released again in the calciner at the latest and is thus separated with the other carbon dioxide and not released into the environment. This not only prevents the emission of new carbon dioxide, but also removes it (albeit to a small extent) from the atmosphere and then

Carbon dioxide is separated from the furnace process and subsequently sequestered.

The effort involved is minimal, so that compared to conventional CO,-

Separation and subsequent sequestration costs and energy expenditure are minimal.

In a further embodiment of the invention, the furnace and/or the calciner has a substitute fuel supply device. Substitute fuels must be burned at a minimum temperature and for a minimum period of time (also prescribed by law). This is easily possible in the main process. For small combustion plants, for example in a drying device, where much lower temperatures are required, this would be uneconomical. By using the heat exchange device according to the invention, however, the required

Heat can be provided in the simplest way using alternative fuels.

In a further embodiment of the invention, the heat exchange device is connected to a turbine. The turbine is connected to a carbon dioxide compressor.

When carbon dioxide is separated, for example using the oxyfuel process or by separation in an amine scrubber, the carbon dioxide is compressed.

This step is comparatively energy-intensive in the process. Alternatively, the thyssenkrupp Industrial Solutions AG 230063P00LU thyssenkrupp AG 13.02.2023 LU103071 7/12

Turbine can also be connected to a generator to produce electricity, for example to make the system self-sufficient from an external power grid.

In a further embodiment of the invention, the heat exchange device is designed in two stages. The first heat exchange stage is designed to transfer the heat from the material flow to a gas flow. The second heat exchange stage is designed to indirectly transfer the heat from the material heated in the first heat exchange stage.

gas flow to a steam flow. Therefore, the second heat exchange stage can be designed as a plate heat exchanger or as a tube bundle heat exchanger. In this case, the gas is preferably circulated between the first heat exchange stage and the second heat exchange stage.

In a further embodiment of the invention, the system has a further

Heat exchange device. For example, a first heat exchange device is arranged between the first stage of the preheater and the second stage of the preheater and a second heat exchange device is arranged between the second stage of the

preheater and the third stage of the preheater. The first

Heat exchanger and the second heat exchanger can be used independently of each other, for example to provide heat for two

To provide different processes. Alternatively, these can also be used for the

Heat exchange medium can be connected in series. For example, water vapor is first heated in the second heat exchange device and then in the first

Heat exchanger device heats up even further. This allows the steam to reach a higher temperature level overall and thus a higher efficiency.

In a further embodiment of the invention, the heat exchange device has a

Cold material feed. A cold solid material is fed to the heat exchanger via the cold material feed. In the heat exchanger, the

material flow and the cold material flow, which is fed through the cold material feed, are mixed. In the heat exchanger device, the two

Solid streams, hot and cold, are mixed directly and the heat is transferred directly. The heat exchanger is connected to the preheater via the material inlet to return the material flow. In particular and preferably, the combined gas flow (hot and cold) is introduced together again at the beginning of the process. This is done, for example and preferably, by heating the

Cold material flow drying of the cold material flow. This is done by the

The mixture is heated in the heat exchanger to 90 °C, for example, and thus dried. The escaping moisture is preferably removed via the gas phase. For example, fine-grained

Materials such as raw meal, limestone, fly ash, slag,

Used sand and/or residues from concrete demolition, such as crushed sand or

Cement stone.

In a further embodiment of the invention, the system is a system for

Production of cement clinker.

In a further embodiment of the invention, the plant is operated according to a method in which the combustion processes are carried out exclusively within the plant. Further combustion processes, for example in a dryer or an amine scrubber, are therefore dispensed with or at least reduced to a high degree.

As already mentioned, this significantly facilitates exhaust gas purification and in particular carbon dioxide separation. It also facilitates the use of substitute fuels for all thermal processes.

In a further embodiment of the invention, the amount of heat discharged in the heat exchange device is determined as a function of the temperature of the gas stream at the

Gas outlet or a point of the gas flow downstream of the gas outlet. The control can be achieved, for example, by controlling the flow rate of the

Heat exchange fluids through the heat exchange device. There are exhaust gas purification processes downstream of the processes, for example special dust separators, which must not exceed a certain temperature. This control makes it possible to maintain the outlet temperature of the exhaust gas even when there are temperature fluctuations in the process.

gas flow in a simple manner without directly interfering with the main process.

thyssenkrupp Industrial Solutions AG 230063P00LU thyssenkrupp AG 02/13/2023 LU103071 9/12

The system according to the invention is explained in more detail below with reference to embodiments shown in the drawings.

Fig. 1 State of the art

Fig. 2 first example

Fig. 3 second example

Fig. 4 third example

Fig. 5 fourth example

Fig. 6 fifth example

Fig. 1 shows a system according to the state of the art. Material to be thermally treated is introduced into the preheater 10 via the material inlet 51 and is gradually heated in the third stage 13, the second stage 12 and the first

Stage 11 is preheated. Stages 11, 12, 13 are designed as co-current heat exchangers with a separating cyclone. The preheated material is transferred to the calciner 20, then to the furnace 30 and finally to a material cooler 40 and from there to the material outlet 52. The gas flow is added to the overall material flow in the

The gas is fed through the gas inlet 61 into the material cooler 40, preheated there and transferred to the furnace 30. In the furnace 30, combustion usually takes place for heating/energy provision. The gas is then transferred to the calciner 20, where further combustion usually takes place. The

Gas is transferred from the calciner 20 to the preheater 10 and then to the gas outlet 62.

In this case, all other modifications or variations known to the person skilled in the art that are customary and known for such systems are possible, for example and in particular a gas bypass between the material cooler 40 and the calciner 20.

Likewise, the material cooler 40 can, for example, have a further gas flow, for example in particular in the end region (at low material temperature).

Fig. 2 now shows, in addition to the prior art, a heat exchange device 70 in a first example. The material flow after the separation cyclone of the second

Stage is partially transferred to the heat exchanger device 70. This allows the thyssenkrupp Industrial Solutions AG 230063P00LU thyssenkrupp AG 13.02.2023 LU103071 10/12

Material can be easily removed without any problems when reinserting

Secondary air is introduced into the system. In the example shown, the material flow is brought into contact with a medium, for example air, which is supplied through the medium inlet 71, in a direct current heat exchanger and then separated again in a separating cyclone. The heated medium, for example air, can thus be discharged through the medium outlet 72 and fed to another

process.

The second example shown in Fig. 3 has, in addition to the example shown in Fig. 2, an additional grinding device 80. The heated in the heat exchange device 70

Medium is transferred to the grinding device 80. The unground material is fed to the grinding device 80 via the grinding material inlet 81, ground there and then transferred to the preheater 10 via the material inlet 51. The material does not have to be transferred directly and immediately, but rather a

Intermediate storage in a silo. For example, another

Mixing, also with other solids, can take place. The medium cooled in the grinding device 80 is discharged via the cold medium outlet 73 and could be at least partially returned to the medium inlet 71.

The third example shown in Fig. 4 has, in addition to the example shown in Fig. 2, a carbon dioxide separation device 90, for example an amine scrubber. The

Exhaust gas from the plant is transferred from the gas outlet 62 into the carbon dioxide separation device 90, more precisely into the absorber 91. In the absorber 91, in particular, a large

A portion, for example 90%, of the carbon dioxide is bound, for example in a

Amin. The exhaust gas cleaned in this way is then discharged via the exhaust outlet 63. The scrubbing system loaded with bound carbon dioxide, for example amine, is

Absorber 91 is transferred to a regenerator 92 in order to release the carbon dioxide there again and thus the washing system is not transferred back to the absorber 91. The energy required for the regeneration is provided by the

Heat exchange device 70 heated medium from the medium outlet 72 of the

Carbon dioxide separation device 90 and, after the necessary energy has been released, is released again via the cold medium outlet 73. The medium usually runs in a separate system, for example heat exchanger tubes, so that there is no direct contact between the amine and the medium.

This also enables subsequent separation of the medium from the amine or

Avoid carbon dioxide. The medium can be returned to the cold medium outlet 73

Medium inlet 71. After the carbon dioxide has been released again, it is discharged via the carbon dioxide outlet 93 and can be reused.

Fig. 5 shows a fourth example. In this case, the plant is operated in the oxyfuel process, so that the exhaust gas at the gas outlet 62 (after a not shown

dehumidification) to an extremely high proportion of carbon dioxide, so that this

compressor 100 and discharged via a carbon dioxide outlet 102. The

Compressor 100 is driven by a turbine 101. In order to drive the turbine 101, the heat exchanger device 70 is designed in two stages. In a first

In the first heat exchange stage, the heat is transferred to a gas that is circulated and in the second heat exchange stage 74, it is transferred to a steam that is fed in via the steam inlet 75 and is transferred to the turbine 101 as hot steam 76. The steam cooled down after the turbine 101 is released again via the steam outlet 77 and can be returned to the steam inlet 75.

Fig. 6 shows a fifth example, which differs in the type of heat exchange device 70 from the second example in Fig. 3. The heat exchange device 70 in the fifth example shown is a fluidized bed heat exchanger 78, which has a

Fluidization air circuit 79 creates a fluidized bed inside. Within the

Heat exchanger tubes are arranged in the fluidized bed, which are supplied with a medium via a medium inlet 71 and this medium is heated and passed on to the grinding device 80 via the media outlet 72.

Reference numerals 10 Preheater 11 First stage 12 Second stage 12 Third stage 20 Calciner thyssenkrupp Industrial Solutions AG 230063P00LU thyssenkrupp AG 13.02.2023 LU103071 12/12 30 Furnace 40 Material cooler 51 Material inlet 52 Material outlet 61 Gas inlet 62 Gas outlet 63 Exhaust gas outlet 70 Heat exchange device 71 Medium inlet 72 Medium outlet 73 Cold medium outlet 74 Second heat exchange stage 75 Steam inlet 76 Heating steam 77 Steam outlet 78 Fluidized bed heat exchanger 79 Fluidization air circuit 80 Grinding device 81 Grinding material inlet 82 Cold medium outlet 90 Carbon dioxide separation device 91 Absorber 92 Regenerator 93 Carbon dioxide outlet 100 Compressor 101 Turbine 102 Carbon dioxide outlet

Claims (16)

thyssenkrupp Industrial Solutions AG 230063P00LU thyssenkrupp AG February 13, 2023 LU103071 1/3 patent claims 1. Plant for the thermal treatment of a mineral material, the plant having a preheater (10), a calciner (20) and a furnace (30), the plant having a gas inlet (61) and a gas outlet (62) as well as a material inlet (51) and a material outlet (52), the components for transferring a material flow from the material inlet (51) via the preheater (10), the calciner (20) and the furnace (30) to the material outlet (52) being connected, the components for transferring a gas flow from the gas inlet (61) via the furnace (30), the calciner (20) and the preheater (10) to the gas outlet (62) being connected, the preheater (10) being designed in several stages, characterized in that the calciner (20) for transferring the material flow leaving the calciner (20) or the preheater (10) for Transfer of the material flow leaving a stage (11, 12, 13) of the preheater (10) is connected to a heat exchange device (70), wherein the heat exchange device (70) is connected to the preheater (10) for returning the material flow. 2. Plant according to claim 1, characterized in that the heat exchange device (70) is a direct current heat exchanger with a separation cyclone or a fluidized bed heat exchanger (78). 3. Plant according to one of the preceding claims, characterized in that the heat exchange device (70) is connected to a grinding device (80) or a drying device. 4. Plant according to one of the preceding claims, characterized in that the gas outlet (62) of the plant is connected to a carbon dioxide separation device (90). 5. Plant according to claim 4, characterized in that the carbon dioxide separation device (90) is an amine scrubber, the amine scrubber having an amine regeneration device, the amine thyssenkrupp Industrial Solutions AG 230063P00LU thyssenkrupp AG 13.02.2023 LU103071 2/3 regeneration device is connected to the heat exchange device (70) for transferring the medium heated in the heat exchange device (70). 6. Plant according to one of the preceding claims, characterized in that the first stage (11) of the preheater (10) adjacent to the calciner (20) is connected to the heat exchange device (70) for transferring the material flow leaving the first stage (11) of the preheater (10), and the heat exchange device (70) is connected to the second stage (12) of the preheater (10) for returning the material flow, wherein the second stage (12) is the stage of the first stage (11) following the first stage (11) in the direction of the material flow and preceding it in the direction of the gas flow. 7. Plant according to one of the preceding claims, characterized in that the plant is designed for operation with a gas with less than 50 vol.%, preferably less than 10 vol.%, nitrogen in the gas stream supplied to the gas inlet (61). 8. Plant according to one of the preceding claims, characterized in that the heat exchange device (70) has ambient air as heat exchange medium, wherein the heat exchange medium air is brought into direct contact with the material flow. 9. Plant according to one of the preceding claims, characterized in that the furnace (30) and/or the calciner (20) has a substitute fuel supply device. 10. Plant according to one of the preceding claims, characterized in that the heat exchange device (70) is connected to a turbine, wherein the turbine is connected to a carbon dioxide compressor. 11. Plant according to one of the preceding claims, characterized in that the heat exchange device (70) is designed in two stages, wherein the first heat exchange stage is designed to transfer the heat to a gas stream, wherein the second heat exchange stage (74) is designed to indirectly transfer the heat thyssenkrupp Industrial Solutions AG 230063P00LU thyssenkrupp AG 13.02.2023 LU103071 3/3 from the gas stream heated in the first heat exchange stage to a steam stream. 12.System according to one of the preceding claims, characterized in that the system has a further heat exchange device (70). 13. Plant according to one of the preceding claims, characterized in that the heat exchange device (70) has a cold material feed, wherein in the heat exchange device (70) the material flow and the cold material flow which is fed through the cold material feed are mixed, wherein the heat exchange device (70) is connected to the preheater (10) via the material inlet (51) for returning the material flow. 14. Plant according to one of the preceding claims, characterized in that the plant is a plant for producing cement clinker. 15. Method for operating a plant according to one of the preceding claims, characterized in that combustion processes are carried out exclusively within the plant. 16. Method according to claim 15, characterized in that the amount of heat discharged in the heat exchange device (70) is regulated as a function of the temperature of the gas flow at the gas outlet (62) or at a point of the gas flow downstream of the gas outlet (62).