JPS642875B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a powder preheating device. More specifically, the present invention relates to a suspension preheater type powder preheating device that efficiently preheats powder such as cement raw materials. Conventionally, when preheating cement raw materials in a rotary kiln, as shown in FIG. Raw materials are fired in kiln 1. In such a conventional preheating device, the cement raw material is supplied into the connecting duct 4 by the feeding rotary feeder 3, and in the duct 4 comes into countercurrent contact with the high-temperature gas flowing from the two-stage cyclone 5, and exchanges heat. It flows into the first-stage cyclone 6 together with the high-temperature gas, and is supplied to the connecting duct 7 from the bottom of the first-stage cyclone 6 . Similarly, from the connecting duct 7 to the two-stage cyclone 5, the second-stage cyclone 5
to connecting duct 8, from connecting duct 8 to three-stage cyclone 9, from three-stage cyclone 9 to connecting duct 1
0, from the connecting duct 10 to the 4-stage cyclone 11
From 4-stage cyclone 11 to rotary kiln 1
supplied to In addition, in the figure, 12 is an exhaust fan,
13 is a connection duct, 14 is a burner, and 15 is a clinker cooler. That is, in the conventional suspension preheater type powder and granular material preheating device shown in the figure, most of the heat exchange between the powder and granular material and the high-temperature gas occurs through the connection ducts 4, 7, and 8 between the cyclones, the rotary kiln, and the four-stage cyclone. This is carried out within the connecting duct 10 between the connecting ducts 4, 7, and 11.
Most of the heat exchange occurs in the section from when the granular material and the high-temperature gas are connected in countercurrent in 8 and 10 until they ride the flow of the high-temperature gas, that is, the run-up section. In other words, once the granular material has been carried by the flow of high-temperature gas, almost no heat exchange is performed thereafter. Therefore, in the conventional suspension preheater type powder preheating device as described above, countercurrent contact between the powder and the high temperature gas for efficient heat exchange occurs in each of the connecting ducts 4, 7, 8, and 10. This occurs only once each time, and the countercurrent contact time is very short, and the raw materials are not completely dispersed, so the overall heat exchange rate is low. In order to improve this heat exchange rate, it is necessary to The drawback was that a cyclone had to be attached. In view of the above circumstances, an object of the present invention is to provide a spouted layer forming section in at least one of the connecting ducts between each cyclone or the connecting duct between a kiln and a cyclone, and to create a spouted layer of high temperature gas within the spouted layer forming section. By forming
The object of the present invention is to provide a powder preheating device that can improve the heat exchange rate and reduce the amount of heat used. Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings. FIG. 2 is a conceptual diagram showing an embodiment of a powder preheating device according to the present invention, which is basically the same as the device shown in FIG. This is a suspension preheater type powder preheating device comprising two cyclones, and among the numbered numbers in the figure, the same numbered parts as in FIG. 1 indicate the same ones as in FIG. The difference between this device and the device shown in Figure 1 is the kiln 1 and the 4-stage cyclone 1.
The spouted bed forming portions 8a and 10a are provided in the connecting duct 10 between the three-stage cyclone 9 and the four-stage cyclone 11, and in the connecting duct 8 between the three-stage cyclone 9 and the four-stage cyclone 11.
The spouted bed forming portions 8a, 10a in this embodiment are formed to inflate the respective connecting ducts 8, 10 and expand the passage cross-sectional area of the high temperature gas midway. In order for the high temperature gas to become a spouted layer in the spouted layer forming sections 8a and 10a, the radius of the maximum part of the spouted layer forming sections 8a and 10a is r ₂ , the radius of the high temperature gas introduction section is r ₁ ,
When the height is l, it is preferable that the following relationships are satisfied: cross-sectional area of the maximum part πr ² / ₂ / cross-sectional area of the introduction part πr ² / ₁ ≧2 height l / diameter of the introduction part 2r ₁ ≧1.5. Note that both of the above equations limit the lower limit value, and do not limit the upper limit value, but the upper limit value is automatically limited by the length of the connecting duct. In short, the shape of the spouted layer forming portions 8a, 10a is suitable as long as it expands the cross-sectional area of the high-temperature gas passage midway in order to form a spouted layer of high-temperature gas, and satisfies both of the above equations. , its mode is not limited to that shown in FIG. 2, for example, FIG.
It may be as shown in b, c, and d. In the granular material preheating device configured as described above, the granular material is heated in the same way as in the device shown in FIG.
The high-temperature gas is supplied into the kiln 1 from the feeding rotary feeder 3 through the suspension preheater 2.
Since a spouted bed is formed in the spouted bed forming portions 8a and 10a, the high-temperature gas and the powder come into contact with each other in countercurrent flow within the spouted bed forming portions 8a and 10a.
And the powder particles are dispersed. Therefore, compared to the case where the spouted bed forming section is not provided as shown in Fig. 1, in this device, the number and time of countercurrent contact between the high temperature gas and the granular material are longer, and the granular material is dispersed. Therefore, sufficient heat exchange is carried out, and it is possible to improve the heat exchange rate and reduce the amount of heat used, for example, the amount of heat used for firing cement clinker. The spouted bed forming section may be arbitrarily provided in any or all of the connection duct 10 between the kiln and the cyclone, or the connection ducts 4, 7, and 8 between the cyclones, as required. In addition, the spouted layer forming section in the present invention may be any unit as long as it forms a spouted layer of high-temperature gas within the connection duct, and may include, for example, a separate spouted layer forming means other than those shown in the above embodiments. It may be something like that. Next, the results of the cement raw material preheating comparison test between the conventional device shown in Fig. 1 and the present device shown in Fig.
It is shown in the figure and Table 1. FIG. 4 shows the relationship between the outlet temperature of the high-temperature gas of the four-stage cyclone 11 and the decarboxylation rate of the cement raw material in the kiln in both of the above devices. As can be seen from this figure, according to this apparatus, the outlet temperature of high-temperature gas is lower than that of the conventional apparatus, and the decarboxylation rate is improved. In addition, Table 1 below shows the gas temperature at each cyclone outlet in both devices and the clinker 1Kg.
As can be seen from this table, with this device, the gas temperature at the outlet of each cyclone is lower than with conventional devices, and the unit heat consumption for clinker baking is 40Kg/Kcal. It is declining. 【table】

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram showing a conventional powder preheating device.
Fig. 2 is a conceptual diagram showing an example of a powder preheating device according to the present invention, Fig. 3 a, b, c, and d are cross-sectional conceptual diagrams showing an example of a spouted bed forming section, and Fig. 4 is a conventional device. It is a figure showing the comparative test result of this device. 1... Kiln, 2... Suspension preheater, 4, 7, 8... Connection duct between each cyclone, 10... Connection duct between kiln and cyclone, 8a, 10a... Spouted bed forming section.

Claims (1)

[Claims] 1. In a suspension preheater type powder preheating device comprising one or more cyclones attached to a kiln, a connection duct between the kiln and the cyclone or a connection duct between each cyclone is provided. A powder preheating device characterized in that at least one of the ducts is provided with a spouted bed forming section. 2 The spouted bed forming section substantially satisfies the following: Maximum cross-sectional area of the spouted bed forming section/cross-sectional area of the introduction section of the spouted bed forming section≧2 Height of the spouted bed forming section/diameter of the introduction section of the spouted bed forming section≧
1.5. The granular material preheating device according to claim 1, wherein the spouted bed forming section is formed by enlarging the passage cross-sectional area of the high-temperature gas midway in order to satisfy the condition 1.5.