JPS594633B2 - Firing equipment for powder and granular raw materials such as cement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for firing powdery raw materials such as cement in a rotary kiln.

In a rotary kiln for firing cement, alumina, lime, gypsum, etc., an inclined cylindrical drum rotates to transport raw material powder and granules, which are then heated by a burner from the bottom of the raw material flow and undergo countercurrent heat exchange. Ru.

In these conventional rotary kilns, the raw material is fed from the upper side and firing is performed while the raw material flows downward. Thermal efficiency is extremely poor. Therefore, in order to enhance the firing effect, large equipment is required, which has various drawbacks such as increased heat dissipation loss, increased driving power, and a larger installation space. The present invention is an improvement of a rotary kiln for eliminating the above-mentioned drawbacks and improving thermal efficiency.One embodiment will be described below in detail based on the drawings. The rotary kiln 11 is arranged so as to be inclined so that the other end thereof is lower, and from the collecting end Ild side to the other end side are a first large diameter part 11c, a first truncated conical boundary part 11f, and a small diameter part. portion 11b, second truncated conical boundary portion 11e, and second large diameter portion I
la are formed continuously in this order, and the second large diameter portion 11a
A sinker 6 is provided at the lower end, and the combustion gas is discharged to the outside from the urine collection 11d, and a plurality of sinkers are provided at intervals in the circumferential direction at a position near the second truncated conical boundary portion 11e in the small diameter portion 11b. A raw material supply hole 13 is bored to form an annular chamber surrounding the raw material supply hole 13 outside the small diameter portion 11b, and a raw material supply pipe 7 is connected to the upper part of the annular chamber, and the raw material supply hole 13lfC is individually connected to the raw material supply hole 13lfC. A granular raw material for cement, etc., characterized in that a corresponding pulp 12d is provided so that a raw material supply hole 13 can be opened and closed by a cylinder 12e, and only the raw material supply hole 13 located above is opened by a valve 12d. This is a firing device.

FIG. 1 is a system diagram of an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the main part thereof.

The granular raw material preheated and decarboxylated in the auxiliary combustion furnace 4 is collected by the cyclone type floating heat exchanger 1 and supplied to the rotary kiln 5 from the damper 9 via the raw material supply pipe 7.
The damper 9 prevents combustion gas from blowing up into the floating heat exchanger 1. The path of the combustion gas is shown by a broken line, and the path of the raw material supplied from the raw material supply pipe 7 and introduced into the rotary kiln 11 is shown by a chain line. The raw material fired in the rotary kiln 11 is led to the cooler 8, and the heated air from the cooler 8 is led to the auxiliary combustion furnace 4 as shown by the phantom line. Used for combustion in IC. The rotational axis of the rotary kiln 11 is inclined so that the kiln bottom 11d at one end thereof is raised and the other end is lowered.

This rotary kiln 11 has a first large diameter portion 11c1 a first truncated conical boundary portion 11f from the kiln bottom 11 side to the other end side.
1 small diameter portion 11b1 second truncated conical boundary portion 11e and second
The large diameter portion 11a is formed in this order. A burner 6 is provided at the lower end of the second large diameter section 11a as is known in the art, but in this example, the raw material is supplied by a raw material input device 12 provided at the lower end of the small diameter section 11b. . The raw material input device 12 is constructed as shown in FIG. That is, the fixed side plate 12 has the input port 7a of the raw material supply pipe 7 opened on the upper side.
A, a rotating side plate 12b attached to rotate integrally with the kiln 5, and a bellows peripheral plate 12c form a short annular chamber that is kept in an airtight state. A plurality of pulps 12d are fitted through the holes 13, and each valve 12d is connected to the hydraulic cylinder 1 so as to be pulled up and opened only when the kiln is above the kiln.
2e is assembled. A plurality of circular raw material supply holes 1 are provided at equal intervals in the circumferential direction on the side wall near the lower end of the small diameter portion 11b.
3 is bored, and all holes beyond the hole reaching the top of the kiln are closed by the valve 12d. Large diameter part 11
The combustion gas that has proceeded through the section a is accelerated at the small diameter section 11b, and the raw material supplied to the small diameter section 11b via the raw material supply pipe 7 and the upper supply hole 13 is transferred to the small diameter section 11b1 and the first truncated conical boundary section 11.
f and the first large diameter section 11c, then returns to the lower part, and is heated and fired again at the small diameter section 11b1, the second truncated conical boundary section 11e, and the second large diameter section, and is cooled as the product 10. Enter vessel 8. In this way, the raw material passes through the small diameter portion 11b twice, thereby further improving the heat exchange efficiency. In this way, the device of the present invention
The gas flow is made high speed in a small diameter part of an appropriate length from the raw material inlet installation part to the top to diffuse the raw material and exchange heat, and the mixed gas is decelerated in the large diameter part on the bottom side of the kiln to separate and settle the raw materials. It has good heat exchange properties. For example, when producing 8,000 tons of cement per day using a rotary kiln equipped with an auxiliary combustion furnace and a floating heat exchanger, the conventional rotary kiln method has a diameter of 6.0 m and a length of 100 m, whereas the kiln of the present invention has a diameter of 5.0 m and a length of 100 m. A diameter of 0 m and a length of 40 m was sufficient, and the throughput per kiln internal volume was increased by 3 to 4 times. As detailed above, in the present invention, raw material powder and granules are introduced into the small diameter section which is the middle section in the longitudinal direction of the kiln, and after being calcined by flame from the bottom, the material is fed into the first large diameter section. Since the sinter is separated and precipitated and then heated again in the small diameter portion, the calcination efficiency can be greatly increased.

Therefore, the throughput per unit volume within the kiln is greatly increased, so the kiln can be made smaller and shorter in length. Therefore, the clinker cooler can be placed in parallel with the kiln, so it does not take up much space, and the bleed air pipe from the cooler can be short.
Heat radiation loss is also reduced, heat consumption per unit of clinker is reduced, and equipment costs are significantly reduced. In addition, since the raw materials are mixed into the combustion gas, the gas temperature decreases, and especially when raw materials are introduced from the burner side, the temperature at the burning point (the highest temperature part) of the flame decreases, reducing wear on the kiln inner wall bricks. This reduces the gas temperature at the bottom of the kiln, reducing problems such as coating adhesion. In addition, from an environmental point of view, the amount of nitrogen oxides generated inside the kiln is reduced by lowering the burning point temperature. In particular, according to the present invention, the raw material supply hole 13 is the second one in the small diameter portion 11b.
Since the hole is drilled at a position close to the truncated conical boundary portion 11a, the raw material supplied from the raw material supply hole 13 is fed to the small diameter portion 11.
At b, it violently collides with the gas flow whose velocity has been increased, disperses in the combustion gas, floats, and is sent to the upper side of the kiln.

Therefore, the raw material is well dispersed in the combustion gas, and the heat transfer efficiency to the raw material is good. Moreover, by increasing the flow rate of the combustion gas in the small diameter portion 11b, the raw material can be reliably fed to the first large diameter portion 11c on the upper side of the kiln, where it can be separated and settled. This makes the residence time of the raw material in the kiln constant, eliminates variations in quality, and improves the quality of the product.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing one embodiment of the present invention, and FIG. 2 is an enlarged sectional view of the main part. 1...Cyclone type floating heat exchanger, 4...
... auxiliary combustion furnace, 6 ... burner, 7 ... raw material supply tube, 11 ... rotary kiln, 11a.
...Second large diameter part, 11b...Small diameter part, 1
1c...First large diameter part, 11d...Kiln end, 11e...Second conical boundary part, 11f...
...First truncated conical boundary part, 12... Raw material input device, 12d... Valve, 12e...
- Cylinder, 13... Raw material supply hole.

Claims (1)

[Claims] 1. The rotary kiln 11 is arranged so as to be inclined so that the kiln bottom 11d at one end of the rotation axis is raised and the other end is lowered,
The first large diameter portion 11 extends from the kiln bottom 11d side toward the other end side.
c, the first truncated conical boundary part 11f, the small diameter part 11b, the second truncated conical boundary part 11e, and the second large diameter part 11a are formed continuously in this order, and the lower part of the second large diameter part 11a is A burner 6 is provided, combustion gas is discharged to the outside from the kiln bottom 11d, and a second truncated conical boundary portion 11e in the small diameter portion 11b is provided.
A plurality of raw material supply holes 13 are bored at intervals in the circumferential direction at closer positions, and the raw material supply holes 1 are formed outside the small diameter portion 11b.
3, a raw material supply pipe 7 is connected to the upper part of the annular chamber, and valves 12d individually corresponding to the raw material supply holes 13 are provided so that the raw material supply holes 13 can be opened and closed by cylinders 12e. , by the valve 12d,
A firing device for granular raw materials such as cement, characterized in that only the raw material supply hole 13 located at the top is opened.