JPS609975B2 - Calcining device for cement raw material powder, etc. in floating preheating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a floatation device with a temporary combustion furnace that uses solid fuel such as pulverized coal.

Cement manufacturing technology has made remarkable progress in recent years, with kilns equipped with floating child heating devices with temporary combustion furnaces becoming the mainstay of calcination methods, and the conversion of fuel from heavy oil to coal is also a major issue in terms of oil conservation. It is being taken up. The following describes a method of calcination of cement raw materials using a calcination device using solid fuel, using pulverized coal as an example.

In the calcining furnace, the coal content is from a few percent to more than 10 percent.
It is used as pulverized coal, and when using this pulverized coal,
The combustion time is longer than that of heavy oil, and the combustion takes place at a relatively low temperature, so considerations such as making the shape and dimensions of the temporary combustion furnace larger than those using heavy oil were required.

On the other hand, it was necessary to pay attention to the following points in order to make the pulverized coal burner itself in the temporary combustion furnace similar to the characteristics of heavy oil fuel.

In other words, "{1) Choose a place with a high oxygen concentration as much as possible.

[2-Choose a high-efficiency burner that mixes well with oxygen. [3' In order to equalize the temperature distribution in a wide cross section,
Use as many burners as possible. etc. In addition, since a location with a high oxygen concentration was selected, the burner was located in the temporary combustion furnace in a location where it was easy to utilize the hot air from the clinker cooler.

However, at this position, regarding the combustion of pulverized coal itself,
Although this is advantageous, the jet stream formed by the kiln exhaust gas containing high-concentration raw materials discharged from the cyclone heat exchanger and the fuel gas riding on the swirl flow from the burner placed in the high-temperature bleed section do not mix sufficiently, resulting in uneven flow. As a result, the distribution of temperature and gas concentration inside the temporary combustion furnace becomes uneven, and the original size of the temporary combustion furnace cannot be used effectively. Therefore, the thermal efficiency of the temporary combustion furnace, that is, the temporary combustion efficiency If the swirling flow is bad and the swirling flow is strong, uneven combustion near the furnace wall in the temporary combustion furnace tends to cause problems such as furnace wall loss.
In order to eliminate the above-mentioned drawbacks of the secondary calcining furnace, the present invention is a cement raw material that is configured to change the mounting position of the burner so that the decarboxylation reaction can be carried out extremely efficiently in the calcining furnace. The present invention provides an apparatus for calcining powder, etc.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 illustrates a schematic configuration using a calcining apparatus according to the present invention.

In the figure, numerals 1 to 4 indicate cyclone heat exchangers, each of which is arranged in multiple stages and connected to each other through piping.

The fourth heat exchanger 4 at the top stage is connected to an exhaust fan 5, and the raw material is introduced into the acid pipe on the exhaust gas discharge side of the third heat exchanger 3. The raw material introduced into the exhaust gas of the third heat exchanger 3 is blown up by the rising high-temperature exhaust gas, as shown by the dotted arrow in FIG. 1, and is sent to the fourth heat exchanger 4 together with the exhaust gas. . In this fourth heat exchanger 4, the raw material is subjected to a cyclone action, and the raw material separated from the exhaust gas falls from below toward the second heat exchanger 2 through the piping. However, the raw material is heated by the exhaust gas rising from the second heat exchanger 2, and is led together with the exhaust gas to the third heat exchanger 3, where the raw material is separated and heated. The exhaust gas is discharged toward the first heat exchanger 1, but is raised again by the exhaust gas discharged from the first heat exchanger 1, and is discharged toward the second heat exchanger 1.
It is guided to the heat exchanger 2.

The raw material heated and separated in the second heat exchanger 2 is guided through a pipe 6 to a riser pipe 9 that connects the gas discharge side of the rotary kiln 7 and a temporary furnace 8. The exhaust gas from the calcination furnace 8 together with the exhaust gas
be led to. The lower part of the calcining furnace 8 also has a cyclone-type conical structure, and a pulverized coal burner 0 is installed at its base. This is a position where you can use your energy.

Here, pulverized coal is combusted and the raw material is calcined. In addition, the above-mentioned yuzu gas is used in the clinker cooler 11 of the rotary kiln 7.
It is guided by the Yuzu trachea 12, which is a pipe from the trachea. Conventionally, the riser pipe that guides the exhaust gas from the rotary kiln 7 to the calciner 8 has its inner diameter expanded in an upwardly tapered shape and connected to the calciner 8, as shown in FIG.
2 are connected to each other, and a pulverized coal burner 10 is further provided above it.

Furthermore, the citrus trachea 12 and the pulverized coal burner 0 are arranged at a certain inclination in the horizontal direction in order to swirl and mix the raw material and the pulverized coal in the calcining furnace 8, as shown in FIG. In contrast to the structure of the above-mentioned subordinate structure, in the present invention, as shown in FIGS. 5 and 6, the pulverized coal burner 10 is positioned lower than the trachea 12, and one or more pulverized coal burners 10 are installed. This structure is provided toward the center of the riser pipe 9.

Furthermore, the pulverized coal burner used in the present invention may have a simple cylindrical structure, as shown enlarged in FIG. 2, and simply pumps pulverized coal using air.

This is because the purpose of combustion in a calcining furnace is to decarboxylate the raw materials, so a relatively low temperature atmosphere of around 850°C is sufficient. Based on the idea that it is preferable to mix the raw material and combustion gas as much as possible, various tests using actual equipment have shown that in the decarboxylation reaction in the temporary combustion furnace, pulverized coal burns all at once and forms a flame. This is because it has been found that the original combustion of solid fuel, in which pulverized coal is dispersed along with the flow of raw materials and burns slowly, is more advantageous than combustion.

Based on these findings, we developed a calcining method using a floating child heating device with a calcining furnace, in which raw materials are introduced into the kiln exhaust gas passing through a general riser pipe, and a jet stream is formed in the calcining furnace.
This is a calcination method in which pulverized coal is ejected by placing a pulverized coal burner in the spouting flow of the high-concentration raw material and kiln exhaust gas mixture, and then mixed with citron air from the clinker cooler to calcinate the raw material. At the base of the temporary furnace,
One or several simple pulverized coal burners are installed toward the center of the riser at the upper end of the upper tapered enlarged part of the riser that leads the exhaust gas of the rotary kiln to the calciner, and at a position lower than the position of the trachea. We decided to set up a.

That is, in the present invention, the cement raw material is supplied to the rotary kiln 7 while being heated through a plurality of stages of cyclone type heat exchangers, and a calcining furnace 8 is provided between the cyclone type heat exchangers 1 to 4. In a temporary oxidation device for powder, etc., the rotary kiln exhaust gas is directed to the center of the riser 9 at the upper end of the upwardly tapered enlarged part of the riser 9 that leads to the calcination furnace 8, and at a position lower than the extraction pipe 12. This apparatus is characterized in that a solid fuel burner 10 having a simple tubular structure is provided so that the tip thereof is located in the jet stream generated by rotary kiln exhaust gas. According to this device, the high-concentration raw material mixture introduced into the middle of the riser pipe 9 flows from a relatively narrow cross section 8'' up to the connection position of the trachea pipe 12, to a wide cross section 8'' which is the connection position of the extraction pipe in the riser pipe. Before the high-concentration raw material moves to the wide cross-sectional area 8', it is mixed with the coal flow from the pulverized coal burner 10, and is mixed with the primary air supplied from the pulverized coal burner 10 and the combustion exhaust gas. Because the jet stream is struck by the action of the hot air, the hot air, raw materials, and pulverized coal are effectively mixed together.

Therefore, the disadvantage that conventionally the size of the calciner body could not be used effectively due to the drifting of these currents can be corrected. Also, since the atmosphere is not high in oxygen as in the installation position of a conventional pulverized coal burner, it does not burn all at once like in conventional pulverized coal burner combustion, and because the pulverized coal burner is facing the center, the jet stream is crushed. This, combined with the resulting extended residence time of the mixed raw materials, takes advantage of the inherent properties of solid fuels, such as slow combustion of fine coal grains that are uniformly dispersed between each raw material particle.

Therefore, an atmosphere is created in which there are no unburned remains and no temperature differences, so the heat of coal combustion can be effectively used as a temporary source of raw materials.

As mentioned above, not only is the heat unit improved by improving the calcining efficiency, but the mechanism is completely different from that of conventional coal combustion, and as a result, the pulverized coal burner also uses only cylindrical tubes. In addition, the primary air sent to the fine coal burner may be sufficient to flow the fine coal.

Therefore, by supplying pulverized coal, the burner pressure loss can be reduced.
Electric power consumption due to reduced air volume, wear inside the burner due to the complicated shape of the burner due to increased efficiency, burner unit cost,
Handling, furnace life, etc. are improved.

Note that the solid fuel is not limited to pulverized coal, and other fuels such as petroleum and coke may be used.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the entire calcining apparatus for cement powder, etc., and FIG. 2 is a longitudinal sectional view of a pulverized coal burner. 3 and 4 are longitudinal sectional views and cross sectional views of essential parts of a temporary furnace showing the installation of conventional burners, and FIGS. 5 and 6 are longitudinal sectional views and lateral sectional views showing the installation of burners according to the present invention. It is a front view. 1 to 4 = first to fourth heat exchangers, 5 = exhaust fan, 6
= Piping, 7 = Rotary kiln, 8 = Calciner, 9 = Standpipe, 10 = Pulverized coal burner, 11 = Clinker cooler
, 12 = Yuzu trachea. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. The raw material is preheated and supplied to the rotary kiln via a multi-stage cyclone heat exchanger, and in a calcination device for cement raw material powder, etc., which has a calcination furnace between the cyclone heat exchangers, the rotary kiln exhaust gas is at the upper end of the upwardly tapered enlargement of the riser leading to the calciner, and lower than the bleed pipe, towards the center of the riser, with its tip positioned in the jet flow generated by the rotary kiln exhaust gas. A calcining device for cement raw material powder, etc., characterized in that it is equipped with a solid fuel burner having a simple tubular structure.