CEMENT-MANUFACTURING PLANT AND PROCESS FOR PRODUCING CEMENT CLINKER

Abstract

A cement production plant may include a preheater for preheating raw meal, a calciner for calcining the preheated raw meal, and a furnace with a furnace burner for firing the raw meal to form cement clinker. The furnace has a combustion gas inlet for admitting a combustion gas with an oxygen content of 30% to 75% into the furnace. The cement production plant may also include a cooler for cooling the cement clinker. The calciner and the furnace each have at least one respective fuel inlet for admitting at least one fuel into the calciner and the furnace. The calciner and the furnace each have at least one respective inert gas inlet for respectively admitting inert gas into the calciner and the furnace.

Claims

1.-16. (canceled)

17. A cement production plant comprising: a preheater configured to preheat raw meal; a calciner configured to calcine the raw meal that has been preheated; a furnace with a furnace burner configured to fire the raw meal to form cement clinker, wherein the furnace has a combustion gas inlet configured to admit a combustion gas with an oxygen content of 30% to 100% into the furnace; and a cooler configured to cool the cement clinker; wherein the calciner and the furnace have a respective fuel inlet configured to admit fuel into the calciner and the furnace, wherein the calciner and the furnace have a respective inert gas inlet for respectively admitting inert gas into the calciner and the furnace.

18. The cement production plant of claim 17 wherein the fuel inlet and the inert gas inlet are arranged separately from one another and each forms an inlet.

19. The cement production plant of claim 17 wherein the fuel inlet and the inert gas inlet together form an inlet.

20. The cement production plant of claim 17 wherein at least one of the calciner or the furnace has multiple inert gas inlets.

21. The cement production plant of claim 17 wherein the calciner has a raw meal inlet configured to admit raw meal into the calciner, wherein the raw meal inlet is arranged upstream of the fuel inlet and the inert gas inlet in a direction of flow of gas within the calciner.

22. The cement production plant of claim 17 wherein the calciner has a raw meal inlet configured to admit raw meal into the calciner, wherein the raw meal inlet is arranged downstream of the fuel inlet and the inert gas inlet in a direction of flow of gas within the calciner.

23. The cement production plant of claim 17 wherein the calciner has at least two raw meal inlets configured to admit raw meal into the calciner, wherein at least one of the at least two raw meal inlets is arranged upstream of the fuel inlet in a direction of flow of gas within the calciner.

24. The cement production plant of claim 17 comprising a control device that is connected to a temperature measuring device within the calciner and that is configured to regulate a quantity of at least one of raw meal, inert gas, or fuel in the calciner based on a temperature ascertained by the temperature measuring device.

25. The cement production plant of claim 17 wherein at least one cross-sectional constriction of a calciner cross section is configured within the calciner.

26. The cement production plant of claim 17 comprising a guide element for guiding at least one of gas flow or fuel within the calciner.

27. The cement production plant of claim 27 comprising multiple of the guide element, wherein the calciner includes fuel charging apparatuses that each comprises a fuel inlet and an inert gas inlet, wherein one of the guide elements is assigned to each fuel charging apparatus.

28. The cement production plant of claim 17 comprising a combustion chamber disposed between the furnace and the calciner, the combustion chamber having a raw material inlet, a fuel inlet, and an inert gas inlet.

29. A method for producing cement clinker, the method comprising: preheating raw meal in a preheater; calcining in a calciner the raw meal that has been preheated; firing in a furnace with a furnace burner the raw meal that has been preheated and calcined to form cement clinker, wherein a combustion gas with an oxygen content of 30% to 100% is supplied to the furnace; and cooling the cement clinker in a cooler; and supplying a fuel and an inert gas to the furnace and to the calciner.

30. The method of claim 29 comprising supplying the inert gas to the calciner and/or to the furnace together with the fuel.

31. The method of claim 29 comprising supplying the inert gas to the calciner and/or to the furnace separately from the fuel.

32. The method of claim 29 comprising admitting the raw meal into the calciner in a direction of flow of gas within the calciner prior to the fuel and the inert gas.

33. The method of claim 29 comprising: ascertaining a temperature within the calciner; and regulating a quantity of at least one of raw meal, inert gas, or fuel that is supplied to the calciner based on the temperature.

34. The method of claim 29 wherein a flow-calmed region is configured within the calciner by way of a guide element or a cross-sectional constriction of a cross section of the calciner.

Description

Description of the drawings

[0045] The invention is explained in more detail below by means of several exemplary embodiments with reference to the accompanying figures.

[0046] FIG. 1 shows a schematic representation of a cement production plant with a calciner and a furnace according to an exemplary embodiment.

[0047] FIG. 2 shows a schematic representation of a calciner with an inert gas inlet according to a further exemplary embodiment.

[0048] FIG. 3 shows a schematic representation of a calciner with an inert gas inlet according to a further exemplary embodiment.

[0049] FIG. 4 shows a schematic representation of a calciner with a guide element according to two further exemplary embodiments.

[0050] FIG. 1 shows a cement production plant 10 with a single-line preheater 12 for preheating raw meal, a calciner 14 for calcining the raw meal, a furnace 16, in particular a rotary furnace for firing the raw meal to form clinker, and a cooler 18 for cooling the clinker fired in the furnace 16.

[0051] The preheater 12 comprises a plurality of cyclones 20 for separating the raw meal from the raw meal gas flow. By way of example, the preheater 12 has five cyclones 20 arranged in four cyclone stages one below the other. The preheater 12 has a material inlet, not shown, for admitting raw meal into the uppermost cyclone stage of the preheater 12 comprising two cyclones 20. The raw meal successively flows through the cyclones 20 of the cyclone stages in counterflow to the furnace and/or calciner exhaust gas and is thereby heated. The calciner 14 is arranged between the last and the penultimate cyclone stage. The calciner 14 has a riser, in particular a riser pipe, with at least one calciner firing for heating the raw meal, so that calcination of the raw meal takes place in the calciner 14. Furthermore, the calciner 14 comprises a fuel inlet for admitting fuel and an inert gas inlet for admitting an inert gas into the riser. The calciner 14 further comprises a combustion gas inlet 26 for admitting oxygen-containing combustion gas into the riser of the calciner 14. The combustion gas is in particular the furnace exhaust gas enriched with oxygen. The oxygen content of the combustion gas is at most 85% between the furnace 16 and the calciner 14. The calciner exhaust gas is introduced into the preheater 12, preferably into the penultimate cyclone stage, and leaves the preheater 12 downstream of the uppermost cyclone stage as preheater exhaust gas 22.

[0052] The furnace 16 is connected downstream of the preheater 12 in the direction of flow of the raw meal, so that the raw meal preheated in the preheater 12 and calcined in the calciner 14 flows into the furnace 16. The material inlet/gas outlet 25 of the furnace 16 is directly connected to the riser of the calciner 14, so that the furnace exhaust gas flows into the calciner 14 and then into the preheater 12. The furnace 16 is, by way of example, a rotary furnace with a rotary tube rotatable about its longitudinal axis and arranged at a slight downward angle. The furnace 12 has a furnace burner 28 and an assigned fuel inlet 30 at the material outlet end within the rotary furnace tube. The material outlet of the furnace 16 is located at the opposite end of the rotary tube from the material inlet 25, such that the raw meal is conveyed within the rotary tube by rotation of the rotary tube towards the furnace burner 28 and the material outlet. The raw meal is fired within the furnace 16 to form cement clinker. The sintering zone 32 comprises the rear region of the rotary tube on the material outlet side, preferably the rear third in the direction of material flow.

[0053] The cooler 18 for cooling the clinker is connected to the material outlet of the furnace 16. The cooler 18 has a cooling gas chamber 34 in which the clinker is cooled by a cooling gas flow. The clinker is conveyed in a direction of conveyance F through the cooling gas chamber 34. The cooling gas chamber 34 has a first cooling gas chamber portion 36 and a second cooling gas chamber portion 38, which adjoins the first cooling gas chamber portion 36 in the direction of conveyance F. The furnace 16 is connected to the cooler 18 via the material outlet of the furnace 16, so that the clinker fired in the rotary furnace 20 falls into the cooler 18.

[0054] The first cooling gas chamber portion 36 is arranged below the material outlet of the furnace 16, so that the clinker from the furnace 16 falls into the first cooling gas chamber portion 36. The first cooling gas chamber portion 36 constitutes an inflow region of the cooler 18 and preferably comprises a static grate 40 which receives the clinker exiting the furnace 16. In particular, the static grate 40 is completely arranged in the first cooling gas chamber portion 36 of the cooler 10. Preferably, the clinker from the furnace 16 falls directly onto the static grate 40. The static grate 40 preferably extends completely at an angle of 10° to 35°, preferably 14° to 33°, in particular 21 ° to 25° to the horizontal, so that the clinker slides along the static grate 40 in the direction of conveyance.

[0055] The first cooling gas chamber portion 36 is adjoined by the second cooling gas chamber portion 38 of the cooler 18. In the first cooling gas chamber portion 36 of the cooler 18, the clinker is cooled in particular to a temperature of less than 1000° C., wherein the cooling is performed in such a way that a complete solidification of liquid phases present in the clinker into solid phases takes place. When leaving the first cooling gas chamber portion 36 of the cooler 18, the clinker is preferably completely in the solid phase and at a temperature of 1000° C. or less. In the second cooling gas chamber portion 38 of the cooler 18, the clinker is further cooled, preferably to a temperature of less than 100° C. Preferably, the second cooling gas flow can be divided into a plurality of partial gas flows which have different temperatures.

[0056] The static grate of the first cooling gas chamber portion 36 has, for example, passages through which a cooling gas enters the cooler 18 and the clinker. The cooling gas is generated, for example, by at least one fan, blower or pressure vessel arranged below the static grate 40, so that a first cooling gas flow 42 flows from below through the static grate into the first cooling gas chamber portion 36. The first cooling gas flow 42 is, for example, pure oxygen or a gas containing 15 vol % or less of nitrogen and 30 vol % or more of oxygen. The first cooling gas flow 42 flows through the clinker and then flows into the furnace 16. The first cooling gas flow forms, for example, part or all of the combustion gas of the furnace 16. The high proportion of oxygen in the combustion gas results in a preheater exhaust gas consisting substantially of CO2 and water vapour, and has the advantage of eliminating the need for costly downstream purification processes for exhaust gas purification. Furthermore, a reduction of the process gas quantities is achieved, so that the plant can be dimensioned considerably smaller.

[0057] Inside the cooler 18, the clinker to be cooled is moved in the direction of conveyance F. The second cooling gas chamber portion 38 preferably has a dynamic, in particular movable, grate 44, which adjoins the static grate 40 in the direction of conveyance F. Below the dynamic grate 44, a plurality of fans are arranged by way of example, by means of which the second cooling gas flow 46 is blown from below through the dynamic grate 44. The second cooling gas flow 46 is, for example, air.

[0058] In FIG. 1, a comminution device 48 is connected to the dynamic grate 44 of the second cooling gas chamber portion 38 by way of example. A further dynamic grate 50 is connected to the comminution device 48 below the comminution device 48. Preferably, the cold clinker 52 has a temperature of 100° C. or less when leaving the cooler 18.

[0059] For example, cooler exhaust air 54 is discharged from the second cooling gas chamber portion 38 and fed into a separator 56, such as a cyclone, for separating solids. The solids are fed back to the cooler 18, for example. An air-to-air heat exchanger 58 is connected downstream of the separator 56, so that the cooler exhaust air preheats air within the heat exchanger 58, which is fed to a raw mill, for example.

[0060] FIG. 2 shows a detail of a cement production plant 10 according to FIG. 1, wherein the regions not shown correspond, for example, to those of FIG. 1 and like reference signs represent like elements. The calciner 14 shown in FIG. 2 has two fuel charging apparatuses 60 by way of example. R is also conceivable that the calciner 14 has only exactly one fuel charging apparatus 60 or more than two fuel charging apparatuses 60. The two fuel charging apparatuses 60 are mounted at a distance from each other on the riser 62 of the calciner 14. By way of example, the fuel delivery devices 60 are mounted at different height levels on the riser 62. Each fuel charging apparatus 60 is assigned a fuel inlet 24 and an inert gas inlet 64, such that fuel and inert gas are directed into the fuel charging apparatus 60. The fuel charging apparatuses 60 are arranged offset from each other by 180°, by way of example. For example, the fuel charging apparatus comprises a means for transporting the fuel, such as a screw conveyor or a chute. The fuel or fuels can also be fed in pneumatically, for example, by conveying with the aid of an inert gas.

[0061] FIG. 2 further shows that a fuel inlet 30 and an inert gas inlet 68 are assigned to the furnace burner 28 so that fuel and inert gas are supplied to the furnace burner 28. The fuel inlet 24, 30 and the inert gas inlet 64, 68 are formed, for example, separately from each other or as a common inlet into the calciner 14 or the furnace 16. The inert gas is, for example, CO2 or water vapour. The inert gas may serve both as a conveying agent and to influence the ignition or control of the combustion process,

[0062] In FIG. 2, the raw meal inlet 70 in the calciner 14 is formed by way of example by the solids outlet of the penultimate cyclone stage. The raw meal inlet 70 is arranged, for example, between the two calciner burners 60. Alternatively, the raw meal can preferably be fed below each of the individual combustion zones downstream of the fuel inlets 30. Another possibility for feeding raw meal and fuel is to use a combustion chamber arranged parallel to the riser of the calciner to feed fuel and meal simultaneously in a low-oxygen zone. Preferably, the fuel is fed centrally into a downwardly directed combustion chamber. Around the fuel feed, the raw meal is fed on a radial circumference or on the circumference of the cylindrical combustion chamber in such a way that the fuel is surrounded by a curtain of meal. At the lower end of the combustion chamber, this connects to the upwardly directed riser of the calciner. The fuel encased by the meal is introduced into the oxygen-rich calciner flow, where it is ignited. The heat is directly consumed by the calcining reaction of the raw meal.

[0063] The calciner 14 has, by way of example, a temperature measuring device 66 for ascertaining the temperature inside the calciner 14. The cement plant 10 further comprises a control device 72 which is connected to the temperature measuring device in such a way that the temperature measuring device 66 transmits the ascertained temperature to the control device 72. The control device 72 is connected to the fuel inlet 24, the raw meal inlet 70 and/or the inert gas inlet 64 and is designed in such a way that it controls/regulates the quantity of fuel, raw meal and/or inert gas in the calciner 14 in dependence on the ascertained temperature.

[0064] FIG. 3 shows a further example of a calciner 14 of FIGS. 1 and 2, wherein like reference signs represent like elements. The riser 62 of the calciner 14 has a plurality of different cross-sectional areas. The fuel charging apparatuses 60 of the calciner 14 are attached to the same side of the riser 62, for example without angular offset, but at different height levels. In the direction of flow of the gas within the riser 62, each fuel charging apparatus 60 has a respective raw meal inlet 70 directly upstream and/or downstream. The fuel inlet 24 and the inert gas inlet 64 are each arranged at the fuel charging apparatus 60 of the calciner 14, in particular at the same level as the respective fuel charging apparatus 60.

[0065] The cross-sectional constrictions ensure balanced mixing within the riser and thus lead to even combustion and temperature distribution in the longitudinal and transverse directions of the riser of the calciner.

[0066] In FIG. 4 is a detail of a calciner 14, wherein like reference signs represent like elements. The calciner 14 has a guide element 73, which in the left-hand illustration is attached by way of example within the riser 62 and in the right-hand illustration is attached by way of example to the fuel charging apparatus 60 in the specific form of a flue.

[0067] In the left-hand illustration, the guide element 73 is arranged in such a way that it causes a constriction of the cross section of the riser 62. The guide element 73 is in particular in plate form, chamber form or box form and is attached to the inner wall of the riser 62, moreover, by way of example, at the same height and opposite the fuel charging apparatus 60.

[0068] In the right-hand illustration, the guide element 73 has the exemplary form of a diffuser, wherein the cross section of the guide element 73 increases in the direction of flow of the fuel. The guide element 73 is attached to the fuel charging apparatus 60, in particular at the mouth of the fuel charging apparatus 60 into the riser 62, and in particular allows a targeted introduction of the fuel into the riser 62. It is also conceivable that the guide element 73 is flush with the riser and does not project into it, so that a uniform inlet of the fuel into the riser 62 is allowed.

[0069] The guide element 73 is formed, for example, from a high-temperature-resistant ceramic or a fibre composite material.

LIST OF REFERENCE SIGNS

[0070] 10 cement production plant

[0071] 12 preheater

[0072] 14 calciner

[0073] 16 furnace

[0074] 18 cooler

[0075] 20 cyclone

[0076] 22 preheater exhaust gas

[0077] 24 fuel inlet of the calciner

[0078] 25 material inlet into the furnace

[0079] 26 combustion gas inlet of the calciner

[0080] 28 burner or burner lance of the furnace

[0081] 30 fuel inlet of the furnace

[0082] 32 sintering zone

[0083] 34 cooling gas chamber

[0084] 36 first cooling gas chamber portion

[0085] 38 second cooling gas chamber portion

[0086] 40 static grate

[0087] 42 first cooling gas flow

[0088] 44 dynamic grate

[0089] 46 second cooling gas flow

[0090] 48 comminution device

[0091] 50 dynamic grate 50

[0092] 52 cold clinker

[0093] 54 cooler exhaust air

[0094] 56 separator

[0095] 58 heat exchanger

[0096] 60 fuel charging apparatus

[0097] 62 riser of the calciner

[0098] 66 temperature measuring device

[0099] 64 inert gas inlet

[0100] 68 inert gas inlet into the furnace

[0101] 70 raw meal inlet into the calciner

[0102] 72 control device

[0103] 73 guide element