OXYFUEL CLINKER PRODUCTION WITHOUT RECIRCULATION OF THE PREHEATER EXHAUST GASES

Abstract

Processes and plants for producing cement clinker, wherein no recirculation of preheater exhaust gases occurs and the ratio of solid fed in to exhaust gas in the preheater is set to greater than 1.0 kg of solid to gas.

Claims

1.-19. (canceled)

20. A process for producing cement clinker, comprising: preheating of a starting material to a calcination temperature, performing calcination of the preheated starting material in a calciner, firing of the calcined starting material in a rotary furnace to produce cement clinker, cooling of the cement clinker, introducing an oxygen-containing gas having a proportion of 15% by volume or less of nitrogen and a proportion of 50% by volume or more of oxygen into the calciner, wherein no gases from the rotary furnace are fed to the calciner, providing at least a first and a second cyclone preheater configured for preheating and connected to one another in a cascade-like manner, material transfer means and/or gas transfer means for transferring material between the cyclone preheaters, and wherein recirculation of the preheater exhaust gases does not occur, and wherein the ratio of starting material fed in relative to exhaust gas in said preheating step is set to greater than 1.3 kg of starting material to 1.0 kg of exhaust gas.

21. The process of claim 20 further comprising introducing oxygen-containing gas into the rotary furnace.

22. The process of claim 20 wherein the cyclone preheaters are multistage one-train or multitrain cyclone preheaters.

23. The process of claim 20 wherein the cyclone preheaters are two-train cyclone preheaters having from two to six stages.

24. The process of claim 20 wherein crossing of meal streams but no crossing of the gas streams occurs after each stage between the cyclone preheaters of a multitrain cyclone preheater.

25. The process of claim 20 wherein preheating occurs with involvement of at least one carbonator.

26. The process of claim 20 wherein a cyclone preheater having a carbonator of a second preheater train is supplied with exhaust gases coming from the rotary furnace, where the exhaust gases have a proportion of CO.sub.2 of less than 35% in the dry reference state.

27. The process of claim 25 wherein a carbonatization temperature is set via the carbonator having a cooler.

28. The process of claim 20 wherein the ratio of solid material fed in relative to exhaust gas in said calcination step is set to greater than 1.0 kg of solid material to exhaust gas.

29. The process of claim 20 wherein coarse fuels having an edge length of 70 mm or more, preferably 100 mm or more, are introduced into the calcinerm wherein the calciner is an entrained flow calciner having a nonvertical section, such that the hot gases in the calciner flow over the coarse fuels.

30. The process of claim 20 wherein the oxygen-containing gas contains 75% by volume or more of oxygen or contains 10% by volume or less of nitrogen or contains 75% by volume or more of oxygen and 10% by volume or less of nitrogen.

31. The process of claim 20 wherein the amounts of oxygen-containing gas and fuel fed in to the calciner are regulated as a function of the calcination temperature and temperature in the preheater.

32. The process of claim 20 further comprising recirculating the calciner exhaust gases.

33. A plant for producing cement clinker, comprising: a preheater, a calciner, a rotary furnace, a clinker cooler, an apparatus for feeding gas into the calciner, wherein oxygen-containing gas fed in has a proportion of 15% by volume or less of nitrogen and a proportion of 50% by volume or more of oxygen, wherein no air from the rotary furnace is fed into the calciner, cyclone preheaters connected to one another in a cascade-like manner comprising at least a first preheater and a second preheater, and means for material transfer and/or gas transfer between the cyclone preheaters, and the plant is free of a recirculation apparatus for preheater exhaust gases, wherein the plant is configured to set the ratio of solid material fed in relative to exhaust gas in the cyclone preheaters to a ratio of greater than 1.0 kg of solid material to exhaust gas.

34. The plant of claim 33 wherein the plant is configured for setting the ratio of solid fed in relative to exhaust gas in the cyclone preheaters to a ratio greater than 1.3 kg of solid material per 1 kg of exhaust gas.

35. The plant of claim 33 further comprising an apparatus for feeding oxygen-containing gas into the rotary furnace.

Description

DESCRIPTION OF FIGURES

[0154] In the figures, broken lines (arrows) denote gas transfer and solid lines (arrows) denote material transfer or mass transfer.

[0155] FIG. 1 shows a flow chart of a process based on the oxyfuel technology, in which hot gas exiting from the furnace is fed into preheater 2 which also receives material from preheater 1.

[0156] FIG. 2 shows a flow chart of a process based on the oxyfuel technology, in which hot exhaust air from the furnace is fed into preheater 2, in a manner similar to FIG. 1. However, in contrast to FIG. 1, exchange of material takes place between preheater 1 and preheater 2. In particular, crossing of material streams analogous to the PASEC process takes place there. Although it is in principle equally possible to convey the furnace exhaust gases into preheater 1, introduction into preheater 2 has the advantage that drying can then be carried out at right, i.e. less energy is required for condensation of water in the CO.sub.2 treatment.

[0157] FIG. 3 shows a flow chart of a process based on the oxyfuel technology, in which the hot exhaust gases from the combustion furnace are supplied to the preheater 3 and then flow further through the carbonator to the preheater 2. In this way, a partial depletion of CO.sub.2 in the right-hand stream is achieved. In addition, a cooler is arranged in the carbonator region in the right-hand stream.

[0158] FIG. 4 shows a flow chart of a process based on the oxyfuel technology, in which the procedure is similar to the process shown in FIG. 3, but, in contrast thereto, no cooler is present in the carbonator region.

[0159] FIG. 5 shows an apparatus in which an oxygen-containing gas is fed into the rotary furnace; this apparatus can be combined with the present invention. FIG. 5 illustratively shows a cooler (clinker cooler) K which is divided into five different cooling zones K1 to K5. Here, gas is introduced appropriately via the various blowers G. The blowers G assigned to the zones K3 to K5 feed in cooling air for the clinker, but no combustion air into the furnace. The blower assigned to zone K1 feeds in the oxygen-containing gas A which is introduced as combustion air into the furnace. The blower assigned to the zone K2 supplies barrier gas B. This barrier gas can, for example, consist to an extent of 85 percent by volume or more of carbon oxide, with the balance being inert gas, or, for example, consist to an extent of 85 percent by volume or more of oxygen, with the balance being inert gas. The term inert gas here preferably refers to components such as water vapor, argon, etc. In both cases, the gas B serves as barrier gas for sealing off the oxygen region from the air region of the cooler. Furthermore, a CO.sub.2 divider Ta is depicted in FIG. 1: this functions as a result of the introduction of the barrier gas or is configured in the form of a mechanical gas divider.

LIST OF REFERENCE SYMBOLS

[0160] K Cooler (clinker cooler) [0161] Ta Gas separation device with barrier gas (CO.sub.2 divider (barrier gas)) or mechanical gas separation device or mechanical gas separation device in combination with barrier gas (CO.sub.2 divider (mechanical or combination of mechanical/barrier gas)) [0162] G Blower [0163] K1 Cooling zone 1 (first cooling zone) [0164] K2 Cooling zone 2 (second cooling zone) [0165] K3 Cooling zone 3 (third cooling zone) [0166] K4 Cooling zone 4 (fourth cooling zone) [0167] K5 Cooling zone 5 (fifth cooling zone) [0168] A Oxygen-containing gas [0169] B Barrier gas [0170] hV Hot combustion air [0171] Al Exhaust air [0172] 1 Stack/atmosphere (residual gas) [0173] 2 CO.sub.2 transport/storage/further use [0174] 3 CO.sub.2 removal and compression [0175] 4 Exhaust gas treatment (from preheaters) [0176] 5 Exhaust gas treatment (from cooler) [0177] 6 Waste heat utilization/conversion into electric power [0178] 7 Preheater 1 (preheating of material) [0179] 8 Preheater 2 (preheating of material) [0180] 9 Preheater 3 (preheating of material) [0181] 10 Carbonator (with cooling) [0182] 11 Carbonator (without cooling) [0183] 12 Oxyfuel calciner (calcination of material) [0184] 13 Fuel store (for calciner) [0185] 14 Fuel store (for furnace) [0186] 15 Oxygen-containing gas/oxygen [0187] 16 Raw meal silo [0188] 17 Clinker silo [0189] 18 Heat utilization/exhaust gas treatment (from preheater 2) [0190] 19 Furnace (rotary tube furnace) [0191] 20 Cooler (clinker cooler) [0192] 21 Waste heat utilization/exhaust gas treatment (from preheater 1 or preheater 1 and preheating of oxygen-containing gas/oxygen) [0193] 22 Preheating of oxygen-containing gas/oxygen [0194] 23 Waste heat utilization/exhaust gas treatment (from cooler (clinker cooler))