JPS5969450A - Method and device for calcining cement 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 a method for calcination of cement using a calcination device consisting of a suspension preheater, a calcination furnace, a converter, and a clinker cooler, and improvements to the device.

In the calcination process of cement raw materials, it is important to increase the thermal efficiency of the fuel used in this process, and at the same time to increase the thermal efficiency of the fuel used in this process.
1) Increasing thermal efficiency, including the obvious use of sensible heat from waste and clinker cooler exhaust; ,
Reduction of generated nitrogen oxides is required.

Although many calcining methods and devices for carrying out the calcining methods have been proposed and implemented to date, there is still a long way to go to meet the requirements set forth in I-1.

In response to the above-mentioned demands, the present inventor set the following conditions or problems and completed the following invention in order to create a calcining method and an apparatus for the same that satisfy these conditions.

l) The original l powder, which is the object to be calcined, is allowed to remain in the calcining process for as long as possible.

2) The fuel to be supplied to the calcination process is brought into contact with and mixed with high-temperature combustion air immediately after it is introduced into the calcination furnace, and is combusted.

3) The rotary furnace exhaust gas also makes effective use of its sensible heat during calcination-L.

An object of the present invention is to provide a method for calcining raw materials for cement and an apparatus therefor that solve the above-mentioned problems.

The present invention introduces air into the upper end of the calciner, immediately supplies fuel and raw material powder into this air, and creates a swirling flow inside the furnace like a cyclone, causing the air to flow inside the furnace while swirling. Move it downward. During this time, the fuel is burned to advance the heating and calcining of the original, or the flow of combustion residue quickly reverses and is extracted from the center of the furnace to the outside of the furnace. On the other hand, the rotary furnace υl waste is introduced from the center of the calcining furnace end in the -1- direction, and is caused to flow Jj7 to form a spouted bed. The raw material 1 calcined in the swirling flow of the combustion gas described above is separated from the gas by the time the combustion scum is reversed due to the centrifugal effect of the swirling flow, and falls into the direction of the calciner. Next, the annular flow that descends down the furnace wall side is repeated as it is entrained by the spouted layer of the rotary furnace exhaust gas, and the degree of calcination is further increased, and the rotary furnace tJl gas and the above-mentioned reversal gas are merged. calcining furnace υ
1 gas, it rises through the center of the calciner and exits the furnace. The present invention is a method for calcination of cement raw materials having such characteristics.

In addition, the present invention provides that in the calcination method described above, fuel 1 is supplied to the spouted bed formed by rotary furnace waste and raw material powder, and the atmosphere of the spouted bed is changed to the reducing layer 1. This invention relates to a method for calcination of cement raw materials, characterized in that the calcination is carried out by reducing nitrogen oxides in rotary furnace exhaust gas.

Furthermore, the present invention provides a calcination device suitable for direct use in carrying out the calcination method described in 1-1 above. This is a calcining furnace constructed by connecting an inverted truncated conical furnace body to the bottom of the cylinder. This calcining furnace is incorporated into a rotary furnace exhaust gas: t-J Niri pipe, and an air introduction pipe is connected tangentially to the upper end of the outer cylinder of the double cylindrical furnace body to introduce air from the clinker cooler. A fuel supply port S0 and a preheating source l (supply 1) are provided at the top of the calciner near the air introduction part, and the inner cylinder of the double cylindrical furnace body is connected to the calciner exhaust gas pipe. It is said that

Next, the present invention will be explained with reference to the drawings.

Figure 1 is a system diagram of a cement firing equipment, where 1 is a suspension preheater, 2 is a calcining furnace, 3 is a rotary furnace, and 4 is a clinker cooler. In the figure, the broken line indicates the path of the raw material powder, and the raw material powder preheated by the suspension preheater 1 is calcined in the calciner 2, then introduced into the rotary furnace 3 and fired, and then in the clinker cooler 4. cooled down. The clinker is cooled by a clinker cooling machine and the air becomes high temperature.
The air is introduced into the rotary furnace 3 and the calcining furnace 2 and used as secondary air for combustion.

2 and 3 show an embodiment of the calcining furnace 2 used for implementing the method of the present invention, FIG. 2 is a longitudinal cross-sectional view, and FIG. 31 is a flat 101
It is a diagram.

The calcining furnace 2 is made up of an upright concentric double cylindrical furnace body 11, 12 with an inverted truncated conical furnace body 13 connected to the lower part of the outer cylinder 11, and the dome end is connected to the exhaust gas riser pipe 14 of the rotary furnace 3. are doing. −
An air introduction pipe 16 is connected tangentially to the 14 ends of the double cylindrical furnace body outer cylinder 11, and a fuel supply port 17 and a raw material supply 1118 are provided at the top of the calciner near this air introduction part. The inner cylinder 12 of the double cylindrical furnace body is connected to a waste waste conduit 15.

This calciner is supplied with fuel separately from the rotary furnace main burner. The fuel 22 is supplied from a fuel supply port 17 provided near the calciner C1 of the air introduction pipe 16.

Air 21 is supplied into the calcining furnace from the air introduction pipe 16.

This air 21 is expressed as "French air" in problem (2) mentioned above, and in the case of solid fuel, especially low-grade fuel, the combustion speed will be increased. desirable. Usually, high-temperature bleed air 7 from the clinker cold 2i11 machine is supplied, and at the same time, this is supplied to the calcining furnace.
Fuel and cement raw material powder are also supplied to the calciner and mixed immediately.

The fuel quickly starts to burn, and the generated combustion heat is applied to the raw material powder to start heating or calcination of the raw material.

The above-mentioned system consisting of a mixture of fuel, raw material powder, and air is rotated inside the calciner, which is constructed to resemble the 11 parts of a cyclone and the 1 part of a cyclone. descend. That is, since the air introduction pipe 16 is provided in the most part of the calcining furnace 2, the connection between the first cylindrical furnace body 11 and the second cylindrical body 12, which is similar to the inner cylinder of a cyclone, is provided inside the cylindrical furnace body 11. The system consisting of the above mixture of fuel, raw material powder, and air moves in the direction F in the furnace while making a rotating movement. This system ultimately leaves the raw material powder in the furnace, and the rest becomes exhaust gas that passes through the inside of the second cylindrical body 12, reaches the yuzu waste conduit 15, and is discharged outside the furnace.

Since the above system rotates, descends, and turns (I), the residence time of the fuel and raw material powder in the calciner becomes longer, and the intense mixing promotes the combustion of the fuel and the calcining of the raw material powder. At the same time, it is possible to take a longer calcination time. The raw material powder is subjected to centrifugal force similar to that in a cyclone,
Due to this effect, it is collected toward the outer periphery of the circular M-shaped furnace body 11 and falls toward the outside, but when it enters the inverted conical truncated cone 13, the diameter of the furnace is large, so it remixes with the combustion gas and heats up. Exchange efficiency is improved. The raw material powder further falls in the direction inside the furnace along the 16 barrel surface.

-The lowest part of the power calcination furnace 2 is completely different from a cyclone,
The rotary furnace waste 8 is introduced from below the calcining furnace 2 through the rotary furnace 11/knee 1 pipe 14. The rotary furnace waste 8 forms a jet stream, and the raw material powder descending within the calcining furnace 2 is deposited in an annular shape, forming a so-called annular portion. Rotary Furnace 4: The 11 gas and the raw material powder form a spouted bed 27 and an annular flow 28, and this also allows the raw material powder to stay in the furnace for a longer time, so that the calcination further progresses.

This spouted bed is formed by the rotary furnace exhaust gas and has a low content of elemental resistance. If fuel is supplied to the spouted bed portion throughout the fuel supply day 30, intense stirring will cause the fuel to melt into the furnace! V
It is possible to easily create a reducing atmosphere in the spouted bed without having to remove nitrogen oxides from the exhaust gas.

The upper A flow 29 of the rotary furnace scraps and the swirling flow scraps 25 merge and are extracted outside the calcining furnace, but at this time, the calcined raw powder is carried along with the waste scraps 4 pipes 15. The powder is then introduced into the cyclone 9 shown in FIG. 1 and, after separating the raw >1 powder, is treated with a known suspension preheater 1.

By having one or more configurations, the method and device of the present invention have the following effects.

(1) When the fuel, raw material powder, and high-temperature air are supplied to the calciner, they come into contact with each other and mix, and the former two are uniformly dispersed in the air, and their residence time in the calciner is long. High thermal efficiency and high calcination rate of raw materials.

(2) Since a spouted bed is formed by both the rotary furnace exhaust gas and the raw material powder, and the residence time of the original 4 powders in the calcination furnace is long, the raw material calcination rate is increased.

(3) To y to reduce nitrogen oxides in υ1 gas
It is also possible.

[Brief explanation of drawings]

FIG. 1 is a system diagram of a cement combustion apparatus, FIG. 2 is a vertical sectional view of a calcining furnace for carrying out the calcining method of the present invention, and FIG. 3 is a plan view thereof. ■...Suspension preheater, 2...Calcination furnace, 3...Rotary furnace, 4...Clinker cooler, 5...
- Raw material powder, 6... Exhaust fan, 7... Clinker cooler bleed pipe, 8... Rotary furnace exhaust gas, 9... Cyclone, 11... Cylindrical furnace outer cylinder, 12... Cylinder , shaped furnace body cylinder, 13... inverted truncated conical furnace, 14... rotary furnace vertical tube, 15... exhaust gas conduit, 16... air introduction pipe 117... combustion chamber 1 supply port, 18... Raw material powder supply +1-1.21... Fresh air, 22... Fuel, 23... Raw material powder, 24... Swirling flow, 25...
Reverse flow, 26... system of mixture of fuel, raw material, and air, 2
7... Spouted bed, 28... Annular flow, 29... 1 flow of rotary furnace exhaust gas, 30... Fuel supply port, Patent a1 applicant Mitsubishi Mining and Cement Co., Ltd. agent Go'
Buried soil Yoshio Kosugi Figure 2

Claims (1)

[Scope of Claims] l Air is introduced into the upper end of the calciner to swirl and lower the inside of the calciner, and fuel and preheated raw material powder are supplied from the top of the calciner into the swirling flow, and the raw material powder is The powder is calcined in the swirling flow, and the swirling flow is reversed at the lower part of the calcination furnace to bring the center of the calcination furnace upward, and the raw material powder is separated from the gas flow and flows to the center of the lower end of the calcination furnace. On the other hand, the rotary furnace exhaust gas is introduced upward into the center of the lower end of the calcination furnace, and a spouted bed is formed with the rotary furnace exhaust gas and the aggregated raw material powder/powder to further progress the calcination of the raw material powder. . A method for calcination of cement raw materials, characterized in that the calcined raw material is entrained in the calciner discharged dregs to raise the center of the calciner and discharged from the top of the calciner. 2. Air is introduced into the upper end of the calcination furnace and the inside of the calcination furnace is swirled downward, and fuel and preheated raw material powder are supplied from the top of the calcination furnace into the swirling flow, and the raw material powder is fed into the swirling flow. The swirling flow is reversed at the bottom of the calcination furnace to raise the center of the calcination furnace, and the raw material powder is separated from the gas flow and concentrated at the center of the bottom end of the calcination furnace, while the rotary furnace exhaust gas is introduced into the center of the lower end of the calcination furnace in two directions, and a spouted bed is formed with the rotary furnace exhaust gas and the aggregated raw material powder, and fuel is supplied to the spouted bed to make the atmosphere reducing, and the raw material powder is A cement raw material characterized in that the calcination of the powder is further progressed, the calcined raw material I is entrained in the calcination furnace exhaust gas, the central part of the calcination furnace is raised upwards, and the mixture is discharged from the top of the calcination furnace. Calcination method. 3. A calcining furnace formed by connecting an inverted truncated conical furnace body to the lower part of the outer cylinder of an upright concentric double cylindrical furnace body is connected to a rotary furnace gas riser pipe, and the upper end of the outer cylinder of the double cylindrical furnace body is connected to the rotary furnace gas riser pipe. An air introduction pipe is connected tangentially to the air inlet pipe, and a fuel Fl supply port and a preheating raw energy 1 supply port are provided at the top of the calciner near this air introduction part, and the single cylindrical furnace cylinder is - A cement calcining device characterized by being connected to a Q-pipe.