JPS6033238A - Vertical jet stream layer calcining apparatus for cement rawmaterial - 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 an improvement in a vertical spouted bed calcination device for cement raw materials.

Vertical spouted bed calcining furnaces for cement raw materials have been gaining popularity in recent years because they have a simple structure, have little pressure loss, and have a longer raw material residence time of approximately 10 seconds, compared to 1 to 15 seconds for air flow type plate calciners. It has been widely used.

However, the residence time of the raw material in the jet calciner is still shorter than that in the fluidized bed calciner, and there is still room for improvement.

Although the fluidized bed calciner has the advantage of a long residence time for raw materials in the furnace, the amount of cold air used as fluidizing air is less than 20% of the theoretical combustion air amount in the calciner, resulting in poor thermal efficiency. Moreover, it has the disadvantage that the pressure loss in the fluidized bed is about 1000 izAH.

On the other hand, when we compare the combustion performance of calciners against solid fuels such as coal, we find that airflow type plate firing furnaces have inferior combustion performance due to the short residence time of solid particles in the furnace, and fluidized bed calciners have inferior combustion performance. Although the solid fuel has the advantage of a long residence time in the furnace, it does not form a high-temperature region in the furnace (the time to complete combustion of solid particles decreases exponentially as the combustion temperature increases). The combustion performance was relatively poor. In addition, although a conventional vertical spouted bed calciner forms a high-temperature flame inside the furnace, the residence time of coarse coal particles in the flame-forming area is short, and although it maintains relatively good combustion performance, it is still improving. leaving room for.

Generally, the decarboxylation reaction is a function of temperature and time, and if the residence time in the furnace is long, the gas temperature at the outlet of the calciner can be lowered, making it possible to reduce the unit heat consumption.

The present inventors have conducted extensive research in order to provide a calciner that can increase the residence time of raw materials and solid fuel in the vertical spouted bed calciner and is suitable for burning solid fuels such as coal. However, the present invention was achieved.

That is, the gist of the present invention is that in a cement raw material calcination device having multiple spouted bed calcination chambers, the cross section of the lowest stage spouted bed calcination chamber is made larger than the cross section of the upper stage spouted bed calcination chamber. A vertical spouted bed calcination device for cement raw materials is characterized by:

The invention will now be described with reference to illustrated embodiments.

Figure 1 shows a conventional vertical spouted bed calciner, where 1 is the furnace body, 2
is the lowest spouted bed calcining chamber, which consists of a combination of a cylindrical body part 2' and an inverted conical part 2. A kiln exhaust gas inlet 3 is provided at the lower end of the inverted conical portion 2''.

Reference numeral 4 designates an upper spouted bed calcination chamber, which is composed of a cylindrical body part 4' and an inverted conical part 4. is connected to. 6 is the cylindrical body part 4'
This is an outlet for calcined raw materials and exhaust gas.

7 is a secondary air introduction duct provided in the cylindrical body portion 2', 8 is a fuel supply pipe provided adjacent to the duct 7, and 9 is a raw material supply chute from the suspension preheater.

In FIG. 1, solid arrows indicate the flow of gas, and dashed arrows indicate the flow of raw materials.

In FIG. 2, the same symbols as in FIG. 1 indicate the same parts,
10 is a rotary kiln, 11 is a kiln butt, 12 is a cooler, and 13 is a suspension preheater.

Now, the kiln exhaust gas that has passed from the rotary kiln 10 through the kiln tail 11 and is supplied into the furnace body 1 from the kiln exhaust gas inlet 3 becomes a jet stream because the inlet 3 forms a throat part, and flows into the lowermost jet stream. It is introduced into the layer calcination chamber 2.

On the other hand, fuel is supplied from the fuel burner 8, combustion air is introduced through the secondary air introduction lower, and the chute 9
Powder and granule raw materials are supplied. Then, a spouted bed of the raw material is formed in the inverted conical part 2 and the cylindrical part 2', and the raw material is calcined by the combustion heat of the fuel. Next, the combustion exhaust gas containing unburned components from the spouted bed calcination chamber 2 passes through the throttle section 5 and enters the upper stage spouted bed calcination chamber 4, where the combustion exhaust gas flow undergoes speed changes of acceleration and deceleration. is given, and the unburned content and residual oxygen come into contact with each other due to the mixing effect due to the change in speed.
Unburned matter is thereby combusted in the chamber.

In this way, the calcined raw material passes through the discharge port 6 together with the firing gas and enters the cyclone at the lowermost stage of the suspension preheater 13.

In such a known calcination device, the present invention further includes:
The purpose is to increase the residence time of raw materials and solid fuel in the furnace, thereby lowering the gas temperature at the outlet of the calciner and reducing the unit heat consumption. Figure 3 shows the cement raw material calcining apparatus of the present invention. The same reference numerals as in FIG. 1 indicate the same parts. 14
is the ceiling.

In the apparatus of the present invention, the cylindrical body part 2 of the spouted bed calcining chamber 2 at the lowest stage
The cross-sectional area a of ' is 1.2 to 2.0 times larger than the cross-sectional area of the cylindrical body 4' of the upper spouted bed calcining chamber 4. If it is less than 1.2 times, the desired effect cannot be obtained, and if it is more than 20 times, the air velocity in the furnace decreases and the raw material stays in the furnace more than necessary, resulting in a large pressure loss. The relationship between the cross-sectional ratio and the residence time of the raw material in the furnace is shown, for example, in FIG.

In the apparatus of the present invention, the kiln exhaust gas entering the cylinder body 2' from the kiln exhaust gas inlet 3 forms a spouted bed, fuel is supplied from the fuel burner 8, and combustion air is supplied from the secondary air introduction lower. Along with the introduction, Shoot 9
The raw material is supplied and calcining is performed, but the cylindrical part 2'
Since the cross-sectional area of the calcining chamber 2 is larger than that of the cylindrical body portion 4', the raw material and solid fuel stay in the calcining chamber 2 for a much longer time than in the conventional apparatus.

After that, the combustion exhaust gas and raw materials that entered the upper spouted bed calcination chamber 4 through the constriction part 5 at the top of the calcination chamber 2 are
Shows similar behavior.

In the vertical spouted bed calcination device for cement raw materials of the present invention, the cross-sectional area of the cylindrical body of the spouted bed calcination chamber 2 at the lowermost stage is made larger than the cross-sectional area of the cylindrical body of the spouted bed calcination chamber 4 at the upper stage. In particular, the difference in the wind speed distribution in the spouted bed calcination chamber 2 at the lowest stage is large.
In particular, since the wind speed near the furnace wall is greatly reduced, the raw material holdup between the kiln exhaust gas injection part and the furnace wall increases, and the residence time of the raw material in the furnace increases.

Similarly, the residence time of the solid fuel coarse particles in the furnace increases, and the number of times the coarse particles come into contact with the burner flame increases, so that the coarse particles are exposed to high temperatures, improving combustion efficiency.

In the calcining furnace shown in FIG. 2, the cross-sectional area of the cylinder part 2' is 1.5 times the cross-sectional area of the cylinder part 4', and the cylinder part 2' and the cylinder part 4' shown in FIG. A comparative test was conducted with a conventional device in which both had the same cross-sectional area, and the results shown in the table below were obtained. In addition, in both Examples and Comparative Examples, the gas wind speed at the kiln exhaust gas inlet 3 was set to 30~
Selected from 4Q @ / Sec.

As is clear from the above table, according to the device of the present invention, ■ The raw material residence time was changed from about 10 seconds to about 15 seconds.

■ Therefore, the same decarboxylation rate can now be obtained at a lower calciner outlet gas temperature.

■ It appears that the solid fuel coarse particles are almost completely burned;
The combustion completion rate in the furnace has improved from 98 inches to 99.7'#.

The present invention provides a cement raw material calcination device having multi-stage spouted bed calcination chambers, in which the cross section of the lowest stage spouted bed calcination chamber is larger than the cross section of the upper stage spouted bed calcination chamber, resulting in high combustion efficiency. Therefore, even if the air ratio is lowered, combustion will be better and fuel efficiency will be reduced.

Also, since the residence time of the raw material is longer, it is necessary to use a lower temperature to obtain the same decarboxylation rate. Furthermore, the calcination efficiency and combustion efficiency can be greatly increased simply by increasing the cross section of the lower furnace body of the existing calcination furnace.

[Brief explanation of the drawing]

Figure 1 is a conceptual longitudinal sectional view showing a conventional vertical cement raw material calcination equipment, Figure 2 is a conceptual diagram showing the equipment shown in Figure 1 incorporated into a cement production equipment with a suspension breech heater, and Figure 3. 4 is a conceptual longitudinal cross-sectional view showing a vertical cement raw material calcination device according to the present invention, FIG. 4 is a view showing another embodiment of FIG. 3 except for the ceiling part 14, and FIG. It is a chart showing the relationship between the cross-sectional ratio and the residence time of the raw material in the furnace. 2.---Lowermost spouted bed calcining chamber, G...
Cylinder part, 4... Upper spouted bed calcining chamber, 4'.
...Cylinder part, 5...Aperture part, 6'...
...Discharge port, 7...Secondary air introduction duct,
8...Fuel supply pipe, 9... Raw material supply chute. Figure 4 Section ratio

Claims (3)

[Claims] (1) A cement raw material calcination device having a multi-stage spouted bed calcination chamber, characterized in that the cross section of the lowest stage spouted bed calcination chamber is larger than the cross section of the upper stage spouted bed calcination chamber. Vertical spouted bed calcination equipment. (2) A patent claim characterized in that the cross-sectional area of the cylindrical body of the lowermost spouted bed calcination chamber is formed to be 1.2 to 20 times the cross-sectional area of the cylindrical body of the upper spouted bed calcination chamber. A vertical spouted bed calcination device for cement raw materials according to scope (1). (3) A cement material having a multistage spouted bed calcining chamber. The calcination device consists of a multi-stage spouted bed calcination chamber consisting of a cylindrical body or a combination of a cylindrical body and an inverted cone, and a calcination furnace connected to the end of the rotary kill and installed upright. The lower part of the chamber has an inverted conical shape, and the kiln exhaust gas inlet is installed at the lower end.
A secondary air duct and a fuel supply pipe are provided on the side wall and a fuel supply pipe close to the duct, a raw material supply chute from a suspension preheater is provided near the furnace wall, the top of the furnace is narrowed, and an upper spouted bed calcination chamber is installed at the top of the furnace. A vertical spouted bed calcination device for cement raw materials according to claim 1 or 2, characterized in that the device is a cement raw material calcination device which is formed by serially arranging a cement raw material calcination device.