JPS60112651A - Calciner for cement raw material and lime 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 The present invention relates to an improvement of a calciner in a firing apparatus for cement raw materials and lime raw materials.

More specifically, multiple burners are installed near the outlet of the bleed duct, rather than on the side wall of the calciner body in the case of conventional solid or liquid fuels, to improve the mixing of the fuel and the air from the bleed duct. The combustion performance was improved by making the mixture uniform within the cross section of the calciner 7 Lee board, and the installation position of the burner tip was adjusted to prevent the frame extending from the burner from coming into contact with the main furnace wall. This article relates to the characteristic calcining furnace for cement raw materials and lime raw materials.

FIG. 1 shows a conventionally commonly used cement firing apparatus. The cement firing device includes a suspension preheater 1, a calcining furnace 5, a rotary kiln 7, a cooler 9, a cooler air supply fan 10, a suspension preheater 1 exhaust waste guide qftl, Z v F (iI pull 77n) 1
2 YoF)m has been completed.

Suspension preheater 1ti, normal 4-stage O cyclones 2a, 2b, 2c, 2d'ft:, pipe lines 5a, 3b, 3c, 3d connecting the cyclones and raw material chute 4a
, 4b, 4c, and 4d are connected and arranged vertically, and the cement raw material is preheated using high-temperature exhaust gas of about 1100℃ (Cha degree 1 to 5) coming out of p10-tari kiln 7. do. In addition, all these systems are IDF1
It is sucked and operated by 2.

The calcining furnace 5 includes a fluidizing air supply blower 6c, a fluidizing air duct 6a, a bleed air duct 6b for supplying hot air of about 700°C from the cooler 9, a raw material chute 4b from the cyclone 2c, and normal pulverized coal. Alternatively, it is composed of a fuel supply pipe (burner) 6d into which heavy oil is blown and an exhaust gas duct 6e.

The device transfers fuel from the burner 6d to ducts 6a, 6b.
The cement raw material entering from the raw material chute 4d is heated to 800 to 850° C., and the limestone in the cement raw material is calcined (decarboxylated). The cement raw material and exhaust gas decarboxylated in the calcining furnace 5 pass through the exhaust gas duct 6e, join with the kiln exhaust gas in the pipe 5d, and are transported to the cyclone 2d, where they are separated into solid and gas, Only the cement raw material is supplied to the rotary kiln 7 through the chute 4e.

The rotary kiln 7 heats the cement raw material to about 51,450°C due to the combustion heat of the fuel supplied from the burner 8.
It is reacted and converted into clinker. Also, Ku2
9 is a cooling device for clinker discharged from the rotary kiln 7, which uses air from a fan 10 to cool clinker to 150
Cool to ~250°C. Note that a part of the air heated by the cooler 9 is supplied to the calcination furnace 5 through the bleed air duct 6b.

FIG. 2 shows a conventional calcining furnace 5. The bottom of the calciner body 5 has an air distribution plate 6f consisting of a large number of nozzles (openings), and the upper side wall thereof includes a raw material shoe 4d, a plurality of fuel supply pipes 6d, and an air distribution plate 6f above these. It has one to four bleed ducts 6b arranged in the circumferential direction of the furnace on the side wall. Below the air distribution plate 6f, there is a fluidizing air duct 6a, an air chamber 6g, a powder discharge pipe 6h near the center of the air distribution plate 6f, and a discharge pulp 61 at its lower end. Note that FIG. 3 shows the AA@ plane of FIG. 2.

Normally, in the calciner 5, the entire amount of air necessary for combustion of the fuel supplied from the fuel supply pipe 6d (approximately 10 to 20 cm) is removed from the fluidizing air duct 6a, and the remaining required air is transferred to the bleed duct 6b.
Supplied from. In addition, the temperature in the calciner 5 is kept at a low temperature of 800 to 850°C due to the decarboxylation reaction of the cement raw material, and NOx is generated in the calciner due to the catalytic action of the cement raw material itself. The amount is low and for coal fuel,
Its value is 100-500 ppm 8 degrees.

When the fuel in such a calciner is heavy oil or pulverized coal, even if a fuel supply pipe (burner) is installed on the side wall of the main body, the ignition temperature of the fuel is low, and the fuel adheres to the cement raw material and spreads. In other words, since the solid fuel itself is fluidized and diffused, even if the mixture with air is somewhat poor, it can be completely burned in the calciner, and no particular inconvenience occurs. However, when gas fuel, for example natural gas containing methane as a main component, is used as a fuel, the ignition temperature of methane is higher than that of coal or nitrogen oil, and it takes longer to burn. In addition, the mixing of the fuel and the combustion supporting gas (oxygen) is a gas-gas mixture, and unlike liquid or solid fuels, diffusion mixing in a fluidized bed is not good, so it is difficult to mix quickly and achieve a sufficient VC. . Therefore, complete combustion cannot occur in the calciner, and the cyclone 2 on the downstream side
There is a high possibility that the temperature of the exhaust gas from the suspension preheater 1 will increase, resulting in an increase in fuel consumption. In addition, since the combustion time is longer than heavy oil or pulverized coal, the flame from the burner may extend for a long time and come into contact with the main furnace wall, causing the inconvenience of causing damage to the furnace wall material due to local overheating of the furnace wall. expensive.

Therefore, the present inventors have developed a method of calcining that eliminates the drawbacks of the conventional methods described above and enables complete combustion when burning cement raw materials and lime raw materials using gaseous fuel such as natural gas. As a result of intensive research into the method, the present invention was completed.

That is, the present invention provides a calciner in which a gaseous fuel such as natural gas is blown into a cement raw material or a lime raw material that is at room temperature or preheated to cause a decarboxylation reaction, and the gaseous fuel is supplied to the calciner. A cement raw material characterized in that a plurality of burners are provided near the outlet of the bleed air duct so as to satisfy the following item (1) and further satisfy at least one of the items (2) to (4). Calcining furnace for lime raw materials (1) The burner is installed at a distance of (0,2 to 04)D along the bleed duct (where D is the diameter of the bleed duct) from the opening of the bleed duct when viewed from above. thing.

(2) Set the insertion depth from the furnace wall to 0 to 3 of the diameter of the bleed duct.
It should be 0chi.

(3) The mounting angle should be 0 to 20' upward.

(4) When viewed from the top of the main body, the burner tip should be oriented 10 to 20' into the tank from a direction perpendicular to the bleed air duct.

It is related to.

The invention will be explained below with reference to the drawings.

FIG. 4 shows a calcining furnace 5 to which the present invention is applied. The symbols used in the figures are the same as those in FIGS. 2 and 3. At the bottom of the calcining furnace 5, there is an air distribution plate 6f consisting of a large number of nozzles, and on the upper side wall of the air dispersion plate 6f, raw material shoes) 4d1 are disposed on the upper side wall of the air dispersion plate 6f.
It has four bleed air ducts 6b. A fluidizing air duct 6a is provided below the air distribution plate 6f.

A powder discharge pipe (Sh) is provided near the center of the air chamber 6g and the air distribution plate 6f, and a discharge pulp 61 is provided at its lower end.
The figure shows a cross section taken along line B'-B in FIG. Also, Figure 6 shows
FIG. 4 shows a cross section taken along line C-C in FIG. The outlet of the bleed air duct 6b (
A plurality of gaseous fuel supply pipes (burners) 6J are installed in the circumferential direction through the side wall (Sk'i) of each bleed duct (near the connecting part with the calciner main body).
As shown in FIG. 5, the tip of the burner 6J is directed into the tank by 10 to 20 degrees from the direction perpendicular to the bleed duct 6bK, and as shown in FIG. The installation angle is about 0 to 20 degrees upward. In addition, in FIG. 6, D indicates the inner diameter of the air bleed pipe 6b.

In order to complete the combustion of natural gas containing methane and the like in the calciner, it is most important to improve the mixing with air as much as possible below the calciner. This includes:
It is necessary to mix the gas ejected from the burner with air as quickly as possible, and to do so, the jet from the burner must
It is necessary to pass through a place where the relative speed is high. As in the present invention, near the outlet of the bleed air duct 6b.

If the burner 6J is installed on the adjacent side wall 6k, compared to the case where it is installed on the side wall of the calciner 5 main body, the burner 6J is mixed in the bleed duct and then inside the calciner 5 main body, so 2 is mixed in place. This allows for faster mixing with air. On the side 1!6 near the outlet of the bleed air duct 6b, the calciner 5
The data obtained by injecting the tracer gas from the position corresponding to the burner on the side wall of the main body and comparing the mixing state of the same cross section inside the main body is shown in the seventh table.
Shown in Figures (a) + (b).

FIG. 7(a) shows the tracer gas distribution in the lower part of the free board of the calciner 5 main body when the burner 6j is provided on the side wall 6k of the bleed duct 6b, and FIG. 7(b) shows the tracer gas distribution on the side wall of the calciner 5 main body. This figure shows the tracer gas concentration distribution when a burner is installed at each measurement location.The numerical values shown in both figures are the tracer gas concentration.1σ: Standard deviation (dispersion state of concentration distribution) Dimensional concentration (value obtained by making the concentration at each measurement location dimensionless using the arithmetic average concentration at all measurement locations) Arithmetic mean value of x+x n: Number of data Cross-sectional average of Figures 7 (a) and (b) [i.e., X The average value (average value of 14 measurement locations)] is 1 for each
．． It is 0.

As is clear from this result, the burner is connected to the bleed air duct 6.
It is clear that mixing is better when provided on the side wall 6k near the outlet of b.

Furthermore, as shown in FIGS. 5 to 6, the burner 6j is directed toward the inside of the tank by about 10 to 20 degrees from the direction perpendicular to the bleed air duct 6b. By inserting a hole and setting the mounting angle upward by about 0 to 20 degrees, damage to the side wall 6 due to overheating can be prevented due to direct contact of the frame to the bleed duct 6b facing the burner 6J. be able to.

Regarding the mounting direction, insertion depth, and mounting angle of the burner 6J, a visualization experiment was conducted by actually replacing the flow of the frame with a smoking incense. A part of the results are shown in FIG.

FIG. 8 (1) shows the experimental results regarding the burner installation direction, and FIG. b
) is the case where it is attached to the bleed air duct 6b at an angle of 20 degrees from the right angle direction. In the case of FIG. 8 (1>(a), the frame 100 has rotated around the main body of the calciner 5,
Such a phenomenon was not observed in the case of Figure 8 (1) (b).

Figure 8 (2) shows the experimental results regarding the burner insertion depth. ) (b) Fi,
s.

This is the case when it is set to In the case of Fig. 8 (2) (b), the frame 100 collided with the wall of the calciner 5 main body, but in Fig. 8 (2) (a), no such phenomenon was observed. Ta.

Figure 8 (3) shows the experimental results regarding the burner installation angle. is installed in the bleed air duct 6b at an upward angle of 10 degrees, as shown in Fig. 8 (
3) (C) is the case where it is attached to the bleed air duct 6b at a downward angle of 10 degrees. In the case of Fig. 8 (3) (C), the frame 100 collided with the wall of the calciner 5 main body;
No such phenomenon was observed in Figure (3) (a) t (b).

This result shows that the above numerical range is an acceptable range for the purposes of the present invention.

[Brief explanation of the drawing]

Diagram M1 shows a conventionally commonly used cement firing device. FIG. 2 shows a conventional calcining furnace, and FIG. 3 shows a cross section taken along line AA in FIG. FIG. 4 shows the calcining furnace of the present invention, and FIGS. 5 and 6 show the BB cross section and the CC cross section of FIG. 4, respectively. FIG. 7 shows data comparing the mixing states due to differences in burner mounting positions using tracer gas. FIG. 8 shows the flow of flame under various conditions. Sub-Agents 1) Meifu Agent Ryo Hagiwara - Figure 4 Figure 7

Claims (1)

[Claims] Cement raw materials or lime raw materials at room temperature or preheated,
In a calciner in which a gaseous fuel such as natural scum is injected to cause a decarboxylation reaction, the burner that supplies the gaseous fuel to the calciner satisfies the following (1) and further (2) to (2) A calcining furnace for cement raw materials and lime raw materials, characterized in that a plurality of calcining furnaces are provided near the outlet of a bleed air duct so as to satisfy at least one of item 4). (1) The burner is installed at a distance of (02-04) D (where D is the diameter of the bleed duct) along the bleed duct from the opening of the bleed duct when viewed from above. (2) Set the insertion depth from the furnace wall to 0-3 of the diameter of the bleed duct.
It should be 0chi. (3) The mounting angle should be 0 to 20 degrees upward. (4) When viewed from the top of the main body, place the burner tip at a angle of 10~b from the direction perpendicular to the bleed air duct.