Cement plant

Abstract

There is provided a cement plant including a chlorine bypass apparatus capable of efficiently reducing the chlorine concentration in a cement kiln due to exhaust gas extraction by a small amount, by preventing calciner exhaust gas low in chlorine concentration from contamination and extracting a part of kiln exhaust gas high in chlorine concentration. In the invention, a baffle wall 20 which protrudes, on a lower face 16a of an exhaust duct 16 of a calciner connected to the pipe inclination part 14 of an exhaust gas pipe 9 rising from a kiln inlet part 2 of a cement kiln 1, toward a pipe inclination part 14 side at an inclination angle within a range of 20 to 60 relative to the horizontal plane, and a spacing between a lower end edge 20a of the baffle wall and an opposite wall plane 14a of the pipe inclination part is configured such that an average flow rate of the exhaust gas between the both falls within a range of 15 to 35 m/s.

Claims

1. A cement plant comprising: a calciner which calcines the cement raw material preheated by a preheater; a cement kiln which burns the cement raw material calcined by the calciner; an exhaust gas pipe which feeds exhaust gas discharged from a kiln inlet part of the cement kiln to the preheater; and a chlorine bypass apparatus which is connected to the exhaust gas pipe and picks out a part of the exhaust gas, wherein the exhaust gas pipe comprises: a pipe inclination part which gradually inclines upward toward a downstream side of the exhaust gas from the kiln inlet part; and a rising duct which is connected to an upper end part of the pipe inclination part and introduces the exhaust gas to the preheater, wherein an exhaust duct of the calciner is connected to an upside face of the pipe inclination part, and a gas extracting pipe of the chlorine bypass apparatus is connected to the pipe inclination part between the exhaust duct and the kiln inlet part, wherein a baffle wall protruding toward the pipe inclination part side on a lower face of the exhaust duct of the calciner at an inclination angle within a range of 20 to 60 with respect to a horizontal plane is formed, and a spacing between a lower end edge of the baffle wall and an opposite wall plane of the pipe inclination part is configured such that an average flow rate of the exhaust gas between the lower end edge and an opposite wall plane falls within a range of 15 to 35 m/s, and wherein both the inclination angle of the baffle wall and the average flow rate of the exhaust gas prevent gas passing through the exhaust duct of the calciner from entering the chlorine bypass apparatus.

2. The cement plant of claim 1, wherein the gas extracting pipe is connected to the upside face of the pipe inclination part.

3. The cement plant of claim 1, wherein the gas extracting pipe is connected to a side face between and the upside face of the pipe inclination part and a downside face of the pipe inclination part.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a vertical cross-sectional view of the essential portion showing one embodiment according to the present invention.

(2) FIG. 2 is a diagram showing flow lines of exhaust gas as analysis results in Examples under usage of the embodiment in FIG. 1.

(3) FIG. 3 is a graph obtained by plotting the results in Table 1.

(4) FIG. 4 is a schematic configuration diagram showing a general cement plant.

(5) FIG. 5 is an enlarged view showing the essential portion of FIG. 4 along with a flow of exhaust gas.

(6) FIG. 6 is a diagram showing flow lines of exhaust gas as analysis results in Examples mentioned above under usage of the conventional cement plant.

DESCRIPTION OF EMBODIMENTS

(7) FIG. 1 shows the essential portion of one embodiment of a cement plant according to the present invention. The other constituent portions are similar to those shown in FIG. 4 and, hereafter, their description is simplified using the same reference signs for those.

(8) As shown in FIG. 1, in this cement plant, in a lower part of a lower face 16a of the exhaust duct 16 for the calciner 10 (joint part with the pipe inclination part 14), a baffle wall 20 is formed such that its inclination angle with respect to the horizontal plane is gentler than that of the relevant lower face 16a. The baffle wall 20 is a flat plane with an inclination angle within a range of =20 to 60 with respect to the horizontal plane, and is formed so as to protrude toward the pipe inclination part 14 side.

(9) Furthermore, a spacing between a lower end edge 20a of the baffle wall 20 and an opposite wall plane 14a as the inner wall of the downside face of the pipe inclination part 14 is configured such that an average flow rate of the exhaust gas passing through between the lower end edge 20a and the opposite wall plane 14a falls within a range of 15 to 35 m/s.

EXAMPLES

(10) The inventors analyzed the change in pressure loss and the like in the exhaust gas flow from the cement kiln 1 to the pipe inclination part 14 regarding Examples 1 to 11 and Comparative Examples 1 to 6 in the case that the inclination angle of the baffle wall 20 shown in FIG. 1 and the average flow rate of the exhaust gas passing through between the lower end edge 20a thereof and the opposite wall plane 14a of the pipe inclination part 14 were changed.

(11) TABLE-US-00001 TABLE 1 Average Gas Rate across Closest Cross- Closest Pressure Loss between Sectional Plane Inclination Distance Kiln and Rising Duct (m/s) Angle () (mm) (mmAg) Example 1 16.7 30 2343 21.54 Example 2 15.2 20 2832 19.64 Example 3 15.5 30 2343 21.87 Example 4 34.2 20 1200 26.23 Example 5 24.8 45 1800 25.28 Example 6 28.1 50 1500 25.56 Example 7 21.5 35 1992 24.21 Example 8 17.1 60 2350 21.76 Example 9 24.9 20 2380 20.44 Example 10 33.8 25 2340 28.28 Example 11 25.4 40 2413 21.08 Comparative Example 1 40.8 30 1000 41.73 Comparative Example 2 37.0 35 1100 36.51 Comparative Example 3 34.9 70 1400 39.30 Comparative Example 4 15.9 70 2785 33.67 Comparative Example 5 25.3 70 2207 40.01 Comparative Example 6 34.9 70 2170 41.96

(12) Table 1 is a chart showing the analysis results in the case that the inclination angle and the average flow rate of the exhaust gas were changed in Examples mentioned above and presents the dimensions and results.

(13) FIG. 3 showing the above-mentioned results as a plot in which the average flow rates (m/s) of the exhaust gas passing through between the lower end edge 20a and the opposite plane 14a of the pipe inclination part 14 are on the horizontal axis and the pressure losses (mmAq) in the exhaust gas flow from the cement kiln 1 to the pipe inclination part 14 are on the vertical axis.

(14) Furthermore, the flows of the calciner exhaust gas discharged from the exhaust duct 16 were analyzed regarding the cement plant shown in FIG. 2 and the conventional cement plant shown in FIG. 6.

(15) From the analysis results shown in Table 1, FIG. 2, FIG. 3 and FIG. 6 as above, in Examples 1 to 11, it is apparent that the flow of the exhaust gas does not suffer large pressure loss, and in addition, the calciner exhaust gas from the exhaust duct 16 is prevented from falling down toward the kiln inlet part 2 side of the cement kiln 1 and being picked out from the gas extracting pipe 11, and thus that the exhaust gas from the cement kiln 1 which gas is high in chlorine concentration can exclusively be sent to the chlorine bypass apparatus from the gas extracting pipe 11, this enabling the chlorine concentration in the cement kiln 1 to be efficiently reduced due to the exhaust gas extraction by a small amount, as a consequence of configurations in which the inclination angle of the above-mentioned baffle wall 20 with respect to the horizontal plane falls within a range of 20 to 60 and the spacing between the lower end edge 20a of the baffle wall 20 and the opposite wall plane 14a of the pipe inclination part 14 is set such that the average flow rate of the exhaust gas therebetween falls within a range of 15 to 35 m/s.

(16) On the contrary, when the above-mentioned average flow rate of the exhaust gas exceeds 35 m/s as in Comparative Examples 1 and 2, it is apparent that the above-mentioned pressure loss drastically elevates and that the spacing between the above-mentioned lower end edge 20a and opposite wall plane 14a is too narrow, this causing the pressure loss in the pipe inclination part 14 to increase and causing the risk of the operation to be affected.

(17) Moreover, when the above-mentioned inclination angle exceeds 60 even in case that the above-mentioned average flow rate of the exhaust gas falls within the range of 15 to 35 m/s as in Comparative Examples 3 to 6, it is apparent that the flow of the calciner exhaust gas disturbs the flow of the kiln exhaust gas from the pipe inclination part 14 toward the rising duct 15, this similarly causing the pressure loss in the pipe inclination part 14 to become increased.

(18) Incidentally, in above-mentioned embodiment, only the case that the gas extracting pipe 11 of the chlorine bypass apparatus is connected to the upside face of the pipe inclination part 14 is described, whereas the present invention is not limited to this but can be similarly applied to a case where the gas extracting pipe of the chlorine bypass apparatus is connected to a side face between the above-mentioned upside face and a downside face of the pipe inclination part 14.

INDUSTRIAL APPLICABILITY

(19) By preventing calciner exhaust gas low in chlorine concentration from contamination and extracting a part of kiln exhaust gas high in chlorine concentration, there can be provided a cement plant including a chlorine bypass apparatus capable of efficiently reducing the chlorine concentration in a cement kiln due to exhaust gas extraction by a small amount.

REFERENCE SIGNS LIST

(20) 1 Cement kiln 2 Kiln inlet part 4 Preheater 9 Exhaust gas pipe 10 Calciner 11 Gas extracting pipe of chlorine bypass apparatus 12 Cyclone of the same 13 Bag filter of the same 14 Pipe inclination part 14a Opposite wall plane 15 Rising duct 16 Exhaust duct from calciner 16a Lower face 20 Baffle wall 20a Lower end edge Inclination angle of baffle wall 20