JPS63259379A - Rotary kiln for baking powder raw material - 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 Technical Field of the Invention The present invention relates to a firing device for powder raw materials such as cement raw materials, alumina raw materials, or limestone powder, and particularly improves the quality of the fired raw materials and improves fuel efficiency. This is related to a baking device that can be used.

Conventional (support 4 rli' = tecement Typical examples of devices for generating talin power by firing powder raw materials include a so-called suspension-type raw material preheating device, a calcination device with an independent combustion device, and a single unit for firing. A combination of a rotary kiln and a talin force cooling system is used.

Figure 5 is a diagrammatic system diagram of the firing process for cement raw material powder, which includes such steps as calcination, firing, cooling, etc. The solid arrows in the figure indicate the flow of hot air exhaust gas, and the dashed arrows indicate the flow of the raw material powder. Shows the flow of powder.

This device mainly consists of a preheating device 1. A separation cyclone C1 connected to the inlet end layer 12 of the kiln 3 with a raw material discharge port 1 and a rotary kiln for clinker kiln 3. and a talin force cooling device 4.

In such a cement raw material firing device, the input chute 5
The raw material powder introduced from
It descends sequentially passing through 3.

On the other hand, the firing furnace 3 and the inlet end f of this firing furnace 3
The high temperature exhaust gas supplied from the calcining furnace 2 which is connected to the duct 7 is sucked by the induced air fan 8 and rises inside the raw material preheating device 1. Therefore, the duct 7
In the cyclones C3 to C1, mixing, heat exchange, and separation of the raw material powder and the high-temperature exhaust gas are repeated.

The raw material powder thus preheated is introduced into the calciner 2 from the raw material preheating device 1 through the preheated raw material chute 14.

In addition, an air bleed duct 13 extending from the talin cooling device 4 is connected to the calcining furnace 2, and the high temperature secondary air for firing generated in the talin cooling device 54 is transferred to the calcining furnace 2.
has been introduced. Therefore, in the calciner 2, combustion occurs with this high-temperature secondary combustion air and the fuel supplied together with the secondary combustion air from the unique burner 6, and the combustion heat is combined with the combustion furnace exhaust gas. The raw material powder is calcined by receiving the heat.

The calcined raw material powder enters the separation cyclone C4 as a powder separator connected to the combustion gas outlet 2I side of the calciner 2 together with the combustion gas and is separated, and then is transferred to the calcined raw material sheet L5. The raw material powder is sent to the rotary kiln 30 inlet end cover 12 via the Due to the combustion heat of the fuel,
After being subjected to the necessary heat treatment in the firing furnace 3 and becoming a talin force, it is cooled in the cooling device 4.

Note that air for clinker cooling is supplied by a forced air blower lO, and a part of the air heated by heat exchange with the talin force is distributed and introduced into the calciner 2 and rotary kiln 3 as described above. Excess air is exhausted by the induced draft fan 9. Then, the talin force output from the talin force cooling device rI14 is carried out to the next process by the conveyor 11.

Problems with the Prior Art In such a conventional apparatus, the raw material fed into the rotary kiln 3 is heated to 840 ml in the calcining furnace 2 installed at the inlet I11 of the rotary kiln 3 (upstream in the flow direction of the raw material).
Heated to ~900 degrees Celsius and calcined to over 80% (a carbonic acid)
However, the rotation speed of the rotary kiln 3 and the installation slope of the rotary kiln 3 determine the moving speed of the raw material in the rotary kiln 3.
It is slow and gentle as necessary to ensure the residence time necessary for the granulation and calcination that mainly takes place in the rear half of the rotary kiln 3, and also to supply the heat necessary for calcination within the rotary kiln 3. Since the fuel combustion device is located at the outlet end of the rotary kiln 3 when viewed in the flow direction of the raw material, the raw material fed into the rotary kiln 3 after decarboxylation is heated to the melt production temperature (approximately 1300°C). The rate of temperature rise is relatively slow.

As a result, the activity of the calcined raw material decreased significantly, and in that state it was sent to the second half of the rotary kiln to undergo the talin force generation reaction, which slowed down the firing reaction rate and required a lot of energy to generate clinker. .

Furthermore, since the clinker production reaction progresses slowly, firing takes a long time or requires higher temperatures, resulting in the production of clinker that is partially overfired, and requires a lot of energy to crush the clinker.

This phenomenon is due to the fact that clinker was produced in the same rotary kiln 3 under the same operating conditions, despite the fact that the first half and the second half of the rotary kiln 3 have different effects on the raw materials. However, simply adjusting the operating conditions of rotary kiln 3 (rotation speed, firing temperature, etc.) will not work.
Either the first half or the second half of rotary kiln 3 must be sacrificed.

One possible solution to this problem is to shorten the length of the rotary kiln 3 to shorten the residence time of the raw material in the rotary kiln 3, but this increases the temperature of the kiln exhaust gas, There is a problem in that the temperature of the raw materials to be input is also raised, and the raw materials are fused at the connection end cover with the calciner 2 on the inlet side of the rotary kiln 3 or inside the calciner 2, and there is still no adequate solution. I can't say that.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to shorten the transfer time of the powder raw material in the first half of the rotary kiln, thereby promoting the clinker production reaction of the raw material by rapidly heating the raw material.

To provide a rotary kiln for firing powder raw materials, which can reduce fuel consumption in the kiln, reduce clinker crushing power, and improve clinker quality by preventing clinker from overfiring.

Structure of the Invention In order to achieve the above object, the first means adopted by the present invention is to provide a powder raw material having a device for preheating the powder raw material or for preheating and calcining the powder raw material in the upstream part as seen in the flow direction of the powder raw material. In a rotary kiln for firing, the rotary kiln is divided into a first rotary kiln on the upstream side when viewed in the flow direction of the powder raw material, and a second rotary kiln connected to the first rotary kiln. This rotary kiln for firing powder raw materials is characterized in that the raw material movement speed within the second rotary kiln is faster than that within the second rotary kiln.

The second means is a rotary kiln for firing powder raw materials which has a device for preheating the powder raw materials or preheating and calcining the powder raw materials at the upstream side as seen in the flow direction of the powder raw materials. It is divided into a first rotary kiln on the upstream side and a second rotary kiln connected to the first rotary kiln, and the material movement speed in the first rotary kiln is set higher than that in the second rotary kiln. This rotary kiln for firing powder raw materials is characterized in that it is faster and that the first and second rotary kilns are each provided with independent combustion devices.

The preheated or calcined raw material is subjected to rotational motion and heated in the rotary kiln, so it is fired into clinker while undergoing granulation action, but the particle size distribution of the raw material in the longitudinal direction inside the rotary kiln is As shown in Figure 6, the particle size suddenly increases from about 1/3 of the way from the raw material outlet side, so the remaining 1/3 of the length of the conventional rotary kiln.
It can be seen that it is mainly granulated.

Therefore, the front 2/3 of the conventional rotary kiln! The c1 degree region is mainly due to the movement of raw materials and the calcination temperature of raw materials 84
This contributes to raising the temperature from 0 to 900°C to the melt production temperature (approximately 1300°C).

The raw material fed into the first rotary kiln of the present invention moves quickly through the kiln at a speed (V) expressed by the relationship of the following equation due to a relatively high rotational speed and/or a large gradient. No where: kiln rotation speed, θ, I: kiln slope As a result, the raw material is rapidly heated and immersed into the subsequent second rotary kiln. In the second rotary kiln, the first
The kiln rotation speed and slope are adjusted so that the clinker production reaction and granulation action take longer than in a rotary kiln.

In this way, the raw material is rapidly heated and raised in temperature in the first rotary kiln, so it is calcined or preheated at the inlet side of the first rotary kiln, and the raw material that has become highly active can be processed without reducing its activity. It can be sent to a temperature range where the talin force reaction occurs quickly, and the talin force reaction is promoted.

In addition, unlike conventional kilns that fire raw materials with reduced activity, there is no need to raise the raw material temperature higher than necessary or to fire the raw materials for a long time. Therefore, over-firing of the tarinka can be prevented. .

Furthermore, if a combustion device is installed in both the first and second rotary kilns to supply heat, the temperature gradient in the longitudinal direction within the rotary kilns can be set even larger and more appropriately.

Next, embodiments embodying the present invention will be described with reference to FIGS. 1 to 4 to provide an understanding of the present invention. However, the illustrated embodiments are merely examples of the present invention, and do not limit the technical scope of the present invention.

Here, FIGS. 1 and 2 show the case where the first rotary kiln is not equipped with a combustion device, and FIGS. 3 and 4 show the case where the first rotary kiln is not equipped with a combustion device. FIG. 6 is a schematic system diagram of an embodiment in which both second rotary kilns are equipped with a combustion device.

In the following embodiments, the same reference numerals are used for elements common to those of the conventional device shown in FIG.

The preheating section of the embodiment shown in FIG. 1 is the same as the configuration shown in FIG. 5, so illustration thereof is omitted.

In FIG. 1, the first rotary kiln 30a has an inlet end connected to the calciner 2 through an inlet end 1m12 and an outlet end connected to the second rotary kiln 2 through a connection 4 cover 22 for the flow of raw materials. It is connected to the inlet end of kiln 30I.

Therefore, from the connection end V3222 to the first rotary kiln 30
Next, the high-temperature combustion exhaust gas from the second rotary kiln 30b is introduced, and the raw material rapidly heated by the first rotary kiln 30a is transferred to the second rotary kiln 301. It will be discharged towards.

2nd rotary kiln 301. The exit end of is the exit end ri3
2, cooling bag r! 14.

When the high-temperature exhaust gas from the cooling device 4 is introduced to the outlet 4V232, at jt', the calcined talin powder granulated in the second rotary kiln 30 is discharged toward the cooling device 4.

Incidentally, a burner 6L that supplies heat for firing is provided at the outlet end fi32. Further, the first rotary kiln 30 & and the second rotary kiln 30 may be rotationally driven by independent rotational drive devices, respectively, and the second rotary kiln 30 and the first rotary kiln 30 . and are connected via an appropriate transmission mechanism to create a single drive! It may be rotationally driven by a JI source.

The operating conditions and installation conditions for each of the rotary kilns 30a and 30 are such that the moving speed of the raw material in the first rotary kiln 30a is higher than that in the second rotary kiln 30i.

It is set to be faster than that within.

For example, the first rotary kiln 30□ is replaced by the second rotary kiln 301. The equipment should be installed so that the installation slope is greater than that of the previous model, or the rotation speed should be set to be higher.

Of course, the movement speed of the raw material within the first rotary kiln 30□ is the second in terms of both the installation slope and the rotation speed.
It may be set to be faster than that in the rotary kiln 30b.

As a result, the first rotary kiln 30. The moving speed of the raw material can be set faster than the speed in a conventional rotary kiln, and the installation slope and rotation speed of the second rotary kiln can be set to the same level as the conventional rotary kiln. .

Therefore, in the raw material preheating device 1, calcination is almost completed, and the raw material passes through the calcination shade 15 to the first rotary kiln 30. The raw material powder that enters the inlet 4 cover 12 is
First, within the first rotary kiln 30□, it quickly moves toward the connection end ff122 while receiving a cascade movement due to the rotation of the first rotary kiln 30 on the cross section of the kiln.

During this time, the raw material is heated by the high temperature combustion exhaust gas from the second rotary kiln 30, and the raw material temperature before and after melt production (approximately 1
The temperature is rapidly raised to 300'C).

The raw material input into the connection 4 cover 22 is transferred to the second rotary kiln 301. Inside, the melt is subjected to cascade movement on the cross section of the kiln due to the rotation of the kiln, and the generated melt becomes a binder and moves toward the kiln outlet end 32 while being granulated.

During this time, the raw material is supplied with heat for calcination by the JIA calcination burner 6 provided at the outlet end 32, and the calcination reaction (
clinker formation reaction) occurs and calcining talin force is generated.

As mentioned above, the installation slope and rotation speed of the second rotary kiln 30b can be set to suitably low values, as in the past, so that there is enough space inside the kiln to generate the talin force and for granulation. Residence time can be secured.

As described above, in this example, the highly active calcined raw material, which has been mostly calcined, is rapidly heated in the first rotary kiln 30□ to around the melt generation temperature (approximately 1300°C). The clinker production reaction that occurs in the second rotary kiln 30I is promoted, and compared to the case of using only the conventional rotary kiln, firing is possible at a lower firing temperature, and fuel consumption in the rotary kiln can be reduced. In addition, the oxidation of fine clinker at high firing temperatures is suppressed, and a talin force of uniform quality is generated.

Furthermore, rapid heating also promotes granulation, which reduces the amount of fine clinker, improves pulverization, and reduces the pulverizing power used in talin force pulverization in the post-calcination step.

Next, a modification of the above embodiment will be described with reference to FIG.

In this example, the first rotary kiln 30& and the second rotary kiln 30t are installed so that the deviation in the height direction is suppressed to about 1/2 of the inner diameter of the first rotary kiln 30.0.
This was designed to make the device more compact.

Further, the second rotary kiln 30 can also be arranged diagonally below the first rotary kiln 30 □ instead of directly below it.

Note that in any of the above embodiments, the first rotary kiln 30. The installation slope of the second rotary kiln 30. is set to be the same as the installation slope of the second rotary kiln 30. The rotation speed may be increased.

Next, other embodiments will be described with reference to FIGS. 3 and 4.

The apparatus shown in FIG. 3 differs from the apparatus shown in FIG. ．． From the cooling device 4 to the calcining furnace 2
Combustion device 6. A part of the high temperature air supplied to the secondary air duct 23 is supplied through the secondary air duct 23.

Therefore, in this device, the amount of heat supplied to the first rotary kiln 30c can be obtained separately from the amount of heat supplied by the combustion device 716F, and
The rate of heating of the raw material in c can be adjusted. That is, the temperature gradient in the longitudinal direction within the first rotary kiln 30a can be further increased and appropriately set according to the properties of the raw material.

In the embodiment shown in FIG. 3, the secondary air duct 23 is branched from the high-temperature air duct leading from the cooling device 4 to the calciner 2. For example, as shown in FIG. It is directly connected to the cooling device 4, and the high temperature air from the combustion device 6b is directly connected to the combustion device 6. It may also be supplied to the vicinity of.

Effects of the Invention According to this invention, the temperature of the calcined raw material input into the first rotary kiln is rapidly raised without reducing its activity, so that the clinker production reaction in the second rotary kiln is promoted. This makes firing easier, and the overall fuel consumption of the rotary kiln can be significantly reduced.

In addition, since the clinker production reaction is promoted, the maximum firing temperature in the rotary kiln can be kept lower than in conventional kilns, and the firing time can also be shortened, preventing the talin force from leaking out. , the talin force strength does not become too large, and fine clinker is reduced.

Therefore, it is possible to improve the cooling performance in the talinka cooling device, improve the pulverization performance in the talinka crushing process, improve the quality of the talinka power, and reduce the crushing power.

If an independent combustion device is installed not only for the second rotary kiln but also for the first rotary kiln so that the temperature rise pattern unique to the first rotary kiln can be adjusted, it is possible to
Further increase the temperature gradient within the rotary kiln 30,
Further, it can be appropriately set depending on the raw material properties.

[Brief explanation of drawings]

1 to 4 are diagrammatic system diagrams showing the main parts of a firing apparatus according to an embodiment of the present invention, and FIG. 5 is a diagram showing a conventional firing apparatus for raw material powder, which is the background of the present invention. The diagrammatic system diagram shown in FIG. 6 is a graph showing the change in grain size in the longitudinal direction within the kiln. (Explanation of symbols) 30,. 30c...first rotary kiln 30b, 30
．． +...Second rotary kiln 2...Calcination furnace
22... Connection 4 cover 12... Inlet end rjI 32.
...Outlet end layer 4...Cooling device.

Claims (6)

[Claims] (1) In a rotary kiln for firing powder raw materials, which has a device for preheating the powder raw materials or preheating and calcining the powder raw materials at the upstream side when viewed in the flow direction of the powder raw materials, the rotary kiln is
It is divided into a first rotary kiln on the upstream side as seen in the flow direction of the powder raw material, and a second rotary kiln connected to the first rotary kiln, and the raw material movement speed in the first rotary kiln is controlled by the second rotary kiln. A rotary kiln for firing powdered raw materials, which is characterized by being faster than that in the interior. (2) The rotary kiln according to claim 1, wherein the first rotary kiln is driven to rotate at a higher speed than the second rotary kiln. (3) The rotary kiln according to claim 1 or 2, wherein the slope of the first rotary kiln is larger than that of the second rotary kiln. (4) In a rotary kiln for firing powder raw materials, which has a device for preheating the powder raw materials or preheating and calcining the powder raw materials at the upstream side when viewed in the flow direction of the powder raw materials, the rotary kiln is
It is divided into a first rotary kiln on the upstream side as seen in the flow direction of the powder raw material, and a second rotary kiln connected to the first rotary kiln, and the raw material movement speed in the first rotary kiln is controlled by the second rotary kiln. 1. A rotary kiln for firing powder raw materials, characterized in that the first and second rotary kilns are each provided with independent combustion devices. (5) The rotary kiln according to claim 4, wherein the first rotary kiln is driven to rotate at a higher speed than the second rotary kiln. (6) The rotary kiln according to claim 4 or 5, wherein the slope of the first rotary kiln is larger than that of the second rotary kiln.