LU103158B1 - Simplifying carbon dioxide capture from exhaust gases of a cement plant - Google Patents

Abstract

The present invention relates to a device for the thermal treatment of a mineral material, wherein the device has a heat consumer, in particular a comminution device 10, and a treatment device 20, wherein the treatment device has a gas outlet, wherein the heat consumer, in particular the comminution device, has a gas inlet, characterized in that the device has a gas-gas heat exchanger 30, wherein the gas-gas heat exchanger 30 has a first side with a first inlet and a first outlet and a second side with a second inlet and a second outlet, wherein the gas outlet is connected to the first inlet and the second outlet is connected to the gas inlet, wherein the gas-gas heat exchanger 30 is a rotary heat exchanger.

Description

230045P00LU 1/6 LU103158

Simplifying carbon dioxide capture from exhaust gases of a cement plant

The invention relates to a plant for the thermal treatment of a mineral

Material, for example, for the production of clinker, in which the resulting

Carbon dioxide can be separated in a particularly efficient manner.

The cement sector in particular is comparatively heavily involved in carbon dioxide emissions, as in addition to the carbon dioxide produced from the fuel, further carbon dioxide is also released from the treated limestone, for example. Therefore, there are many

Approaches to separate the carbon dioxide produced in this way in order to prevent emissions.

WO 2011 / 029 690 A1 describes a process for producing cement with

Separation of CO, known.

The separation of carbon dioxide is easier the higher the initial

Carbon dioxide content is already present. Therefore, processes are known that use the purest possible oxygen during the thermal treatment and thus

Minimize contamination of the resulting carbon dioxide, especially with nitrogen.

Such procedures are known, for example, from DE 102018 206 673 A1 or the

DE 102018 206 674 A1. However, this only makes sense if the

Subsequently, the input of nitrogen is minimised as far as possible.

In order to use the heat efficiently in a thermal treatment plant, the exhaust gas from the preheater can be used, for example, in

The heat can be used to dry the incoming material stream during milling. The disadvantage here is that air is likely to enter and thus the

The concentration of carbon dioxide decreases, which in turn increases the effort required for separation.

The aim of the invention is to make optimal use of the heat and to prevent the entry of

To minimize secondary air in the main gas stream.

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

Features. Advantageous further developments emerge from the subclaims, the following description and the drawing.

The device according to the invention is used for the thermal treatment of a mineral material, for example for the production of clinker from limestone.

Device has a heat consumer, in particular a

shredding device, and a treatment device. The

Treatment device has a gas outlet. The gas outlet is the point at which the gas flow leaves the thermal treatment device, usually at the point of a preheater where the mineral material is applied. Material flow and gas flow are usually distributed over the entire

Device viewed in opposite directions, although often running parallel in places.

The heat consumer, in particular the shredding device, has a

Gas inlet. Warm gas is fed through the gas inlet, which in turn is able to remove moisture from the material, for example. Such systems are known to the expert in a wide variety of designs and are used, for example, to produce clinker from limestone or to produce artificial

Pozzolans from clays. The exact design of the thermal

treatment device or the heat consumer, in particular the

Crushing device is not essential for the invention and can be carried out according to the state of the art.

According to the invention, the device has a gas-gas heat exchanger. The gas

Gas heat exchanger has a first side with a first inlet and a first

outlet and a second side with a second inlet and a second outlet.

The gas outlet is connected to the first inlet. The warm exhaust gas from the thermal treatment device is thus fed into the first side of the gas-gas

heat exchanger to release its heat. The second outlet with the

Gas inlet, the gas heated in the second side of the gas-gas heat exchanger is thus supplied to the heat consumer, in particular the

shredding device. The gas-gas heat exchanger is a

Rotary heat exchanger, also called regenerator. In a

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In rotary heat exchangers, a mostly disc-shaped body with gas passages is rotated. A part of the rotating body is located in the first

side, the other part in the second side. The rotating body is flowed through in one direction on the first side and in the opposite direction on the second side. In fact, this results in a countercurrent heat exchanger, which enables the most complete possible transfer of heat. Such

Rotary heat exchangers are now often used in building

Air conditioning technology. The advantage of a rotary heat exchanger is its relatively compact design. In return, it is accepted that

Rotation of the rotating body always a certain, but comparatively small

Exchange of gas between the first side and the second side takes place through the gas channels of the rotating body. However, this is within an acceptably small range compared to the total volume flow. This means that the waste heat can be used efficiently, without high equipment costs and without contamination of the carbon dioxide-containing gas.

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

Carbon dioxide separation device. Preferably, the first outlet is connected via a

Dust removal device connected to a carbon dioxide separation device. This means that the carbon dioxide can be separated with only very little contamination from foreign gases, which minimizes the effort required for separation.

In a further embodiment of the invention, the treatment device comprises a

Preheater and a calciner. In addition, the treatment device can also have a rotary kiln. The gas outlet is at the gas flow end of the

preheater.

In a further embodiment of the invention, the heat consumer is a

Crushing device. In the crushing device, the mineral raw material, for example limestone, is usually crushed, in particular broken and/or ground. At the same time or afterwards, drying usually takes place in order to remove the water in order to later

Energy requirement for this is no longer available in the thermal treatment device.

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In a further embodiment of the invention, the shredding device is a

Mill. For example, the mill is a vertical roller mill.

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

Dust extraction device. By using the gas-gas

The gas flow can already be sufficiently cooled by means of a heat exchanger, so that a further cooling device, for example and in particular a

Evaporative cooler can be dispensed with.

In a further aspect, the invention relates to a method for operating a device according to the invention. The ratio of gas supplied into the first inlet to the second inlet is selected such that the gas stream exiting from the first outlet is available for further processing, in particular

Dust separation, no further cooling is necessary. Is used as gas for the second

If ambient air is used on the side (for example 20 °C), the

Cooling of the gas flow in the first side can be easily adjusted by the ratio of the gas flows.

In a further embodiment of the invention, the gas of the first side is not cooled below 100°C, preferably not below 120°C. In this way, a

Condensation of water in the rotating body is avoided. This has several

Advantages. Firstly, condensation on the first side and evaporation on the second side would require large amounts of heat. Secondly, the gas flow on the second side would be humidified, but would then be

The shredding device is also intended to serve the purpose of drying.

The device according to the invention is explained in more detail below using an embodiment shown in the drawing.

Fig. 1 schematic representation of the device

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In Fig. 1, the device according to the invention is shown highly schematically and not to scale.

The mineral material, for example limestone, is fed to the crushing device 10, for example a vertical roller mill, where it is crushed and

The material flow is then dried by the

treatment device 20, more precisely the preheater 21. The preheated

Material enters the calciner 22 and the rotary kiln 23 and then into the

Material cooler 24 and can then be removed as a product, for example clinker.

The gas stream is preheated via the material cooler 24 in the rotary kiln 23 and from there into the calciner 22. Typically, the rotary kiln 23 and the

Calciner 22 combustion reactions to generate the energy required for the thermal treatment. In the preheater 21 the gas flow then releases a large part of the

Heat to the material flow. The gas flow leaves the preheater at 300°C, for example. This gas flow is fed into the first side of the gas-gas heat exchanger 30 and passed through the rotating body 31. In the example shown, the rotating body 31 rotates around an axis of rotation which is arranged vertically in the image plane. In the rotating body 31, the gas flow gives off the heat to the rotating body 31, which is warmer on the top than on the

Bottom (in this illustration). The cooled gas stream is fed, for example, at 120°C into a dust removal device 40 and then into a

carbon dioxide separation device 50.

For example, ambient air at 20°C is supplied to the second side of the gas-gas heat exchanger 30. This gas flow is selected to be slightly smaller than the gas flow from the treatment device 20, so that the gas on the second side of the gas-gas heat exchanger 30

Gas heat exchanger 30 of the comminution device 10 is supplied, for example, at 275°C.

Reference numeral 10 Shredding device 20 Treatment device

230045P00LU 6/6 LU103158 21 Preheater 22 Calciner 23 Rotary kiln 24 Material cooler

Gas-gas heat exchanger 31 rotating body

dust extraction device

carbon dioxide capture device

Claims (7)

230045P00LU 1/1 LU103158 patent claims 1. Device for the thermal treatment of a mineral material, the device comprising a heat consumer and a treatment device (20), the treatment device having a gas outlet, the heat consumer having a gas inlet, characterized in that the device comprises a gas-gas heat exchanger (30), the gas-gas heat exchanger (30) having a first side with a first inlet and a first outlet and a second side with a second inlet and a second outlet, the gas outlet being connected to the first inlet and the second outlet being connected to the gas inlet, the gas-gas heat exchanger (30) being a rotary heat exchanger. 2. Device according to claim 1, characterized in that the first outlet is connected to a carbon dioxide separation device (50). 3. Device according to one of the preceding claims, characterized in that the treatment device (20) has a preheater (21) and a calciner (22), wherein the gas outlet is arranged at the gas flow end of the preheater. 4. Device according to one of the preceding claims, characterized in that the heat consumer is a comminution device (10). 5. Device according to claim 4, characterized in that the crushing device (10) is a mill. 6. Device according to one of the preceding claims, characterized in that the first outlet is connected to a dust removal device (40). 7. Method for operating a device according to one of the preceding claims, characterized in that the ratio of gas fed into the first inlet to gas fed into the second inlet is selected such that the gas stream exiting from the first outlet does not require further cooling for further processing.