METHOD AND PLANT FOR PRODUCING CEMENT CLINKER

Abstract

The invention relates to a method and plant for producing cement clinker, comprising the steps of: burning raw materials to form cement clinker in a furnace, preheating the raw materials with flue gases of the furnace, and dehumidifying and cooling flue gases of the furnace by means of a condensation heat exchanger.

Claims

1. A method for producing cement clinker, comprising the steps of: burning raw materials to form cement clinker in a furnace, preheating the raw materials with flue gases from the furnace, and dehumidifying and cooling flue gases from the furnace by means of a condensing heat exchanger.

2. The method according to claim 1, wherein the flue gases are cooled by means of the condensing heat exchanger to a temperature of less than 50 C.

3. The method according to claim 1, further comprising cleaning the flue gases with a Regenerative Thermal Oxidation (RTO) and/or with a flue gas desulphurisation (DeSOx) before dehumidifying and cooling the flue gases by means of the condensing heat exchanger.

4. The method according to claim 1, wherein the flue gases are recycled into the furnace after dehumidifying and cooling by means of the condensing heat exchanger.

5. The method according to claim 1, wherein the flue gases, after dehumidifying and cooling by means of the condensing heat exchanger, are supplied to a Carbon Capture and Utilisation (CCU) or Carbon Capture and Storage (CCS) unit for separating carbon dioxide.

6. The method according to claim 5, wherein the CCU or CCS unit is configured for absorption of carbon dioxide in a scrubbing liquid.

7. The method according to claim 6, wherein the CCU or CCS unit comprises an amine scrubber.

8. The method according to claim 5, wherein the CCU or CCS unit is configured for adsorption of carbon dioxide on a solid.

9. The method according to claim 5, wherein heat obtained during dehumidifying and cooling of the flue gases by means of the condensing heat exchanger is used for desorption of the carbon dioxide.

10. The method according to claim 7, wherein heat obtained during dehumidifying and cooling of the flue gases by means of the condensing heat exchanger is used for desorption of the carbon dioxide in the amine scrubber.

11. The method according to claim 1, wherein heat obtained during dehumidifying and cooling of the flue gases by means of the condensing heat exchanger is used to dry the raw materials and/or a fuel of the furnace.

12. A plant for producing cement clinker, comprising: a furnace for burning raw materials to form cement clinker, a preheater for preheating the raw materials with flue gases from the furnace, and a dehumidifying and cooling stage comprising a condensing heat exchanger for dehumidifying and cooling flue gases of the furnace.

13. The plant for producing cement clinker according to claim 12, comprising a flue gas cleanup stage interposed between the preheater and the dehumidifying and cooling stage.

14. The plant for producing cement clinker according to claim 12, wherein the condensing heat exchanger comprises a feed line and a discharge line for a cooling liquid.

15. The method according to claim 2, wherein the flue gases are cooled to a temperature of less than 45 C.

16. The method according to claim 2, wherein the flue gases are cooled to a temperature of less than substantially 40 C.

17. The plant for producing cement clinker according to claim 13, wherein the flue gas cleanup stage is an RTO and/or a desulphurisation stage.

18. The plant for producing cement clinker according to claim 14, wherein the discharge line is connected to a CCU or CCS unit.

19. The plant for producing cement clinker according to claim 18, wherein the discharge line is connected to an amine scrubber of the CCU or the CCS unit.

20. The plant for producing cement clinker according to claim 19, wherein the discharge line is connected to an evaporator of a desorber of the amine scrubber.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0036] FIG. 1 shows a functional diagram of an embodiment according to the invention, in which the flue gases are dehumidified and cooled by means of a condensing heat exchanger after a flue gas cleanup before the flue gases are used to dry the raw materials or the fuel or are recycled into the rotary kiln.

[0037] FIG. 2 shows a functional diagram of a further embodiment according to the invention, in which the dehumidified and cooled flue gases are fed to a CCU/CCS unit for separating the carbon dioxide.

DETAILED DESCRIPTION

[0038] FIG. 1 shows a plant 1 for producing cement clinker, which is part of a cement plant. The plant 1 comprises a furnace 2, in particular a rotary kiln, in which raw material, in particular raw meal, is sintered to form cement clinker. In addition, a preheater 3, in particular a preheating tower, is provided, preferably having a cyclone cascade with a plurality of cyclones (not shown) connected in series. In the preheater 3, the raw material is preheated with the aid of flue gases from the furnace 2 before entering the furnace 2. At the upper end of the preheater 3, the flue gases are drawn off. As usual, the plant 1 comprises a cleanup stage 4 with which the flue gases drawn off from the preheater 3 can be cleaned. An RTO (Regenerative Thermal Oxidation) stage, for example, may be provided as cleanup stage 4. The flue gases leave the cleanup stage 4 at temperatures of, for example, approx. 200 C. (cf. arrow 5).

[0039] In the embodiment shown, the flue gases are fed after the cleanup stage 4 to a condensing heat exchanger 6, which comprises a feed line 7 for a cooling liquid, preferably at a temperature of less than 20 C., and a discharge line 8 for the heated cooling liquid, preferably at a temperature of more than 40 C. In addition, the condensing heat exchanger 6 comprises an outlet 9 for the condensate that is produced during the condensation of the flue gases in the condensing heat exchanger 6. The outlet 9 can be connected to a water treatment stage. The flue gases coming from the cleanup stage 4 are dehumidified and cooled by means of the condensing heat exchanger 6. The temperature of the flue gases at the exit of the condensing heat exchanger 6 is preferably less than 40 C. (cf. arrow 10). The heat content of the cleaned, dehumidified and cooled flue gases can be used with the aid of a drying stage 11 to dry, for example, the raw materials or a fuel.

[0040] Additionally or alternatively, the flue gases can be recycled downstream of the condensing heat exchanger 6 into the cement clinker production, in particular into the rotary kiln (cf. dashed line 12). This embodiment is particularly suitable for the so-called oxyfuel process, in which the flue gases are returned to the furnace and, at the same time, pure oxygen is supplied in order to maintain combustion. In this way, the proportion of CO2 in the flue gases increases, which significantly increases the CO2 separation potential. The recirculation of the flue gases is also used to transport the heat in the cementing process.

[0041] In a further embodiment variant, the condensing heat exchanger 6 may be interposed between the preheater 3 and the flue gas cleanup stage 4, so that the flue gases are dehumidified and cooled downstream of the preheater 3 by means of the condensing heat exchanger 6 before the flue gases enter the cleanup stage 4.

[0042] In a further embodiment variant, two condensing heat exchangers 6 are provided, wherein one condensing heat exchanger 6 is arranged between the preheater 3 and the cleanup stage 4 and the other condensing heat exchanger 6 is arranged downstream of the cleanup stage 4.

[0043] FIG. 2 shows an alternative embodiment wherein the flue gases, after dehumidifying and cooling by means of the condensing heat exchanger, are supplied to a Carbon Capture and Utilisation (CCU) or Carbon Capture and Storage (CCS) unit 13. This CCU/CCS unit 13 is configured to separate the carbon dioxide in the flue gases. In a favourable embodiment variant, the CCU/CCS unit 13 comprises an amine scrubber. The amine scrubber comprises an absorber and a desorber, which may be connected to the discharge line 8 for the heated cooling liquid of the condensing heat exchanger 6 to provide heat for desorption of the carbon dioxide from the amine solution.