JPS6080075A - Method of fluidizing fluidizing baking furnace - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluidization method for a fluidized furnace for firing powder raw materials such as cement and alumina.

In this type of conventional spouted bed fluidized fluidized firing furnace for powder raw materials, for example, as shown in FIG. There was a disadvantage that a stagnation area C of the medium was formed and the flow became stagnant, resulting in worsening of the flow (1). In order to prevent this, that is, to prevent the formation of the stagnation zone C, the inclination angle θ of the conical portion should be made considerably larger than the angle of repose of the fluid medium. However, this is not preferable because the height of the entire fluidized firing furnace becomes too high. Moreover, since the amount of retention in the furnace is increased in the height direction, the layer thickness of the fluidized bed becomes large, and therefore the air pressure of the fluidizing air must be set to high pressure, which has the disadvantage of increasing running costs.

The present invention was made in order to eliminate the above-mentioned drawbacks of the conventional fluidized fluidized kiln. , and by limiting the flow rate of fluidization to a specific range when forming the fluidized bed, it is possible to increase the residence time of the fluidized material in the furnace without increasing the overall height of the fluidized firing furnace. In addition, it is possible to process a stable fluidized bed by reducing the thickness of the fluidized bed and lowering the pressure of the fluidizing air, thereby reducing power consumption.(2) It is an object of the present invention to provide a method for fluidizing a fluidized fluidized kiln that can be formed.

For this reason, the configuration of the present invention is based on a method of forming a spouted bed in the center of the furnace interior of a fluidized fluidized firing furnace for powder raw materials, and forming a fluidized bed around the spouted bed. The method is characterized in that the fluid is fluidized at a flow rate that is 2.5 to 3 times the fluidization start speed of the average particle diameter of the fluid.

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3.

In Fig. 2, 1 is a fluidized firing furnace for powder raw materials, 2 is a central high-speed wind pipe, 3 is an aeration pipe as an aeration mechanism, 4 is a raw material input pipe, 5 is an aerodynamic valve, 6 is a burner, and 7 is a freewheel. 8 is a gas discharge duct, 9 is a low-speed wind pipe attached to the lower end of the central high-speed wind pipe 2, 10 is a lower hopper installed in its place, and 11 is the primary classification performed in the central high-speed wind pipe 2. As shown, a primary classification air supply pipe 12 supplies high-speed air to the middle of the high-speed wind pipe 2, and 12 is the low-speed wind pipe 9.
This is an air supply pipe for secondary classification that supplies air to the lower hopper 10 so that secondary classification is carried out. Note that the air diffuser pipe as the air diffuser mechanism 3 has a large number of air diffuser holes drilled laterally, and air is blown into each air diffuser pipe from a blower (not shown) via a flow rate adjustment valve. There is.

That is, the fluidized fluidized firing furnace 1 includes a central high-speed wind pipe 2 that blows out a high-speed airflow upward from the center of the lower part of the furnace 1 to form a spouted layer 13 in the center of the furnace, and this high-speed wind pipe 2. A large number of diffuser pipes are installed horizontally around the vicinity of the upper end level to form a fluidized bed 14 around the spouted bed 13. Therefore, the fluidized firing furnace 1 has a structure that combines the two functions of a spouted bed 13 and a fluidized bed 14.The arrow 15 indicates the powder raw material, the arrow 16 indicates the exhaust gas, and the arrows 17 and 18 indicate the It shows air.

In the fluidized firing furnace l for powder raw materials shown in FIG. 2, the classification mechanism includes a low-speed wind pipe 9, a primary classification air supply pipe 11, a secondary classification air supply pipe 12, etc. under the central high-speed wind pipe 2. Therefore, the primary classification is performed by the high-speed upward air flow supplied from the air supply pipe 11 for secondary classification, and the secondary classification is performed by the low-speed wind pipe 9 using the air supplied from the air supply pipe 12 for secondary classification, Also, both air supply pipes 11 and 1
The air supplied from the central high-speed wind pipe 2 merges with the high-speed rising air and is ejected in one direction from the upper end of the central high-speed wind pipe 2, so that a spouted bed 13 is formed in the center of the furnace. Further, the air supplied into the furnace from the aeration holes of the aeration pipe, which is an aeration mechanism, becomes fluidized gas, and a fluidized bed 14 is formed around the spouted bed 13 .

Here, when forming the fluidized bed 14, the in-furnace superficial velocity of air from the aeration pipe as the aeration mechanism 3 is set to 2.5 to 3 times the fluidization start velocity Utnf of the average particle diameter of the fluid. A stable fluidized bed 1 can be achieved by
4 and the running cost can be reduced.

That is, as a result of the experiment, the above-mentioned superficial velocity in the furnace was 2.5.
When the temperature was less than Umf, the fluidity state was slow, and the movement of particles near the furnace wall was particularly poor, which was not appropriate. In addition, if it exceeds 3 Umt, the fluidity becomes too intense, the bubbles grow large, and the heat transfer efficiency deteriorates, and the amount of scattering increases, resulting in a decrease in efficiency due to an increase in the load on the precipitator. The dog was affected by wear and tear, so it was still not suitable.

Although FIG. 2 shows the case where the air diffuser 3 is a diffuser pipe, FIG. 3 shows the case where the air diffuser 3 is a perforated plate. Therefore, in FIG. 3, fluidizing air is supplied from the fluidizing gas supply pipe 19 to the lower part of the perforated plate as shown by the arrow 20, but the amount of air supplied is blown upward from the perforated plate. The superficial velocity of the air in the furnace is determined by the above-mentioned 2.
Set so that 5 Umt to 3 Umt.

In addition, as the aeration mechanism 3, the injection nozzle type % formula % As mentioned above, the present invention uses a fluidized firing furnace that has both the functions of a spouted bed and a fluidized bed, and when forming the fluidized bed, 2 of the flow start speed of the average particle diameter of the fluid.
Since the fluid is fluidized at a flow rate range of 5 to 3 times, stable flow can be obtained even in a large fluidized bed, making it easy to increase the size of the fluidized kiln, and moreover, compared to a single spouted bed, Capacity can be increased simply by increasing the cross-sectional area while keeping the thickness of the fluidized bed constant, making it possible to lower the pressure of fluidizing air and significantly reducing power costs.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional spouted bed type fluidized kiln, Fig. 2 is a vertical cross-sectional elevation view showing one example of the apparatus for carrying out the present invention, and Fig. 3 is a longitudinal cross-sectional view showing another example. It is an elevational view. ■...Fluidized firing furnace, 2...Central high-speed wind pipe, 3...
Aeration mechanism, 4... Powder raw material input pipe, 13... Spouted bed, 14... Fluidized bed. (7) Figure 1 2nd eye

Claims (1)

[Claims] 1. A method in which a spouted bed is formed in the center of the furnace interior of a fluidized firing furnace for powder raw materials, and a fluidized bed is formed around the spouted bed, and when forming the fluidized bed, the average 1. A method for fluidizing a fluidized kiln, characterized by fluidizing the fluid at a flow rate ranging from 2.5 times to 3 times the fluidization start speed of the particle size.