JPH06347172A - Denitration device of kiln for light-weight aggregate - Google Patents

Abstract

PURPOSE:To provide a denitration device which can effectively perform a denitration process by adding ammonia or an ammonia compound at a low cost even for a rotary kiln for burning of a light-weight aggregate, of which the exhaust gas temperature is comparatively low. CONSTITUTION:Denitration agent feeding ports 9, 10 with a cover to communicate the inside and outside of a rotary kiln are provided at around an intermediate location of a body part 2 of the rotary kiln 1 to burn a light-weight aggregate, and lid body opening/closing mechanisms 13, 14 to open the denitration agent feeding ports when the denitration agent feeding ports face a specified direction are provided on lid bodies 11, 12 for the denitration agent feeding ports. In addition, denitration agent feeding mechanisms 15, 16 to inject a urea solution into the rotary kiln by a high pressure from the feeding ports, while linking with the opening motion of the lid bodies at the denitration agent feeding ports, are provided around the outer periphery of the body part of the rotary kiln.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a denitration device for a firing furnace for lightweight aggregates, and more particularly to nitrogen oxides (hereinafter referred to as "NO" contained in combustion exhaust gas of a rotary kiln for burning lightweight aggregates).
x ") is efficiently removed at low cost.

[0002]

2. Description of the Related Art Rotary kilns have conventionally been used for firing cement clinker and lightweight aggregate for concrete.

Such a rotary kiln 101 has a cylindrical body 102 of several tens of meters as shown in FIG.
Is slightly inclined and placed on the rotation supporting roller 103, is rotated by the rotation driving device 104, and is inserted through the lower end opening 105 of the body 102.
6, the fuel such as coal and oil is burned, and the body 1
The raw material charged through the upper opening 107 of No. 02 is fired while flowing down while rolling inside the body 102.

Here, the exhaust gas of the rotary kiln 101 contains a large amount of NOx generated by high temperature combustion in the firing zone of the kiln 101, and if it is released into the atmosphere as it is, it causes air pollution. .

Therefore, in a rotary kiln for burning cement clinker, a denitration method is used in which a denitration agent such as ammonia or an ammonia compound is added as a reducing agent to combustion exhaust gas, and NOx is decomposed into nitrogen and water by a gas phase homogeneous reaction. Has been done.

This denitration method uses ammonia or an ammonia compound at 700 to 1,100 ° C., preferably 850.
It is most desirable to add to the exhaust gas in the temperature range of ~ 1,000 ° C from the viewpoint of denitration efficiency, but a rotary kiln for burning cement clinker that requires a firing temperature of about 1,500-1,600 ° C. Then, the temperature of the exhaust gas discharged from the rotary kiln becomes a high temperature of about 1,000 ° C. Therefore, in the rotary kiln for burning cement clinker, in the exhaust gas passage 108 outside the rotary kiln, a denitration agent such as ammonia or an ammonia compound is deoxidized. Even if the configuration in which is added was adopted, sufficient denitration efficiency was obtained.

However, in the rotary kiln for burning lightweight aggregate, when shale containing foaming gas as a raw material is fired, the firing temperature is from 1,100 to
The temperature of the exhaust gas is 3 120 ° C because the heat exchanger of the rotary kiln is often installed in the body of the rotary kiln to effectively use the heat of the exhaust gas.
The temperature is around 00 ° C., and the temperature range in which the denitration by the addition of ammonia or an ammonia compound is effectively performed does not exist in the exhaust gas passage 108 outside the rotary kiln. In the rotary kiln, there is no choice but to use another denitration method.
Therefore, there is a problem that a large amount of equipment costs and maintenance costs are required.

The present invention has been made in view of the problems of the above-described conventional light-weight aggregate firing furnace, and its object is to provide a rotary kiln for firing light-weight aggregate having a relatively low exhaust gas temperature. Another object of the present invention is to provide a denitration device for a lightweight aggregate firing furnace, which can effectively perform denitration treatment by adding ammonia or an ammonia compound at low cost.

[0009]

In order to achieve the above object, the present invention provides a denitration agent supply port with a lid for communicating the inside and outside of the rotary kiln near the middle position of the body of the rotary kiln for firing the lightweight aggregate. A lid opening / closing mechanism is provided on the lid of the denitrification agent supply port to open when the denitrification agent supply port is in a predetermined direction, and further, the denitrification agent supply port is provided near the outer periphery of the body of the rotary kiln. A denitration device for a lightweight aggregate firing furnace provided with a denitration agent supply mechanism for injecting the denitration agent from the supply port into the rotary kiln at a high pressure in association with the opening operation of the lid.

Here, the vicinity of the intermediate position of the body of the rotary kiln refers to the body part located in a temperature range where the denitration treatment by adding a denitration agent such as ammonia or an ammonia compound can be effectively performed. The position is not limited to the intermediate position.

A plurality of denitration agent supply ports are provided on the same circumference of the body (for example, one for each 180 °, or 9).
It may be possible to provide one or a plurality of denitration agent supply mechanisms common to these, one for each 0 °), and further install these at a plurality of positions offset in the axial direction of the rotary kiln. The denitration agent and the combustion gas may be efficiently contacted with each other.

Further, in the present invention, the open position of the lid of the denitration agent supply port is for directly ejecting the denitration agent at a predetermined high pressure, not for free fall. It is not necessary to limit the position to one position when facing upward, and for example, at the two positions when facing diagonally upward at 45 ° and 135 °, the lid of the denitration agent supply port is opened by the lid opening / closing mechanism. A denitration agent supply mechanism is provided near the outer circumference of the body portion facing each position, and the denitration agent is injected from the supply port into the rotary kiln in conjunction with the opening operation of the lid of the denitration agent supply port. Also good.

Further, as the above-mentioned denitration agent used in the present invention, an aqueous solution of ammonia or an ammonia compound, particularly an aqueous solution of urea [(NH ₂ ) ₂ CO], is preferable in terms of denitration efficiency and cost.

[0014]

As described above, according to the denitration device for the lightweight aggregate firing furnace according to the present invention, the denitration agent supply port is provided near the middle position of the body of the rotary kiln, and the lid of the denitration agent supply port is provided in a predetermined manner. Since it is opened at the same time and the aqueous solution of ammonia or ammonia compound is injected at high pressure into the rotary kiln through the denitration agent supply port, it is in a temperature range where denitration by addition of ammonia or ammonia compound is effective. The NOx in the combustion gas can be efficiently brought into contact with the combustion gas in the body.
Thus, the denitration treatment for decomposing nitrogen into water by a gas phase homogeneous reaction can be effectively performed at low cost.

Further, according to the present invention described above, a lid is attached to the denitration agent supply port formed for adding the denitration agent into the rotary kiln, and the lid is mounted in a predetermined direction, for example, the denitration agent supply port. Because it is configured to be opened only when facing upward, or diagonally upward, the lightweight aggregate raw material flowing down while rolling the bottom of the trunk does not leak from the denitration agent supply port, and Even if a molten raw material or the like is solidified at the denitration agent supply port, in the present invention, the composition is such that the denitration agent is injected from the supply port into the rotary kiln at a high pressure. It is possible to blow off the solidified material by the injection of, and the denitration device can be used for a long period of time.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS.

In the figure, reference numeral 1 denotes a rotary kiln, and the rotary kiln 1 has a cylindrical body 2 of several tens of meters. The body portion 2 is placed on the rotation supporting roller 3 in a slightly inclined state, and the rotation driving device 4
Is rotated by. A raw material charging shooter 6 is inserted into the upper end opening 5 of the body 2, and a combustion burner 8 for burning fuel such as coal and petroleum is inserted into the lower end opening 7 of the body 2.

Further, near the middle position of the body portion 2, denitration agent supply ports 9 and 10 are provided penetrating the body portion 2 at 180 ° positions on the same circumference. Slide-type lid bodies 11 and 12 are attached to the denitration agent supply ports 9 and 10, respectively. The lid bodies 11 and 12 are provided with lid body opening / closing mechanisms 13 and 14 each using an electric motor as a drive source, and the denitration agent supply ports 9 and 10 are 45 ° and 135 by the lid body opening / closing mechanisms 13 and 14, respectively. The lids 11 and 12 of the respective denitration agent supply ports are configured to be opened at two positions when they are directed obliquely upward at an angle of °.

Further, two denitration agent supply mechanisms 15 and 16 are provided at two positions diagonally above the body of the rotary kiln 1 so as to correspond to the open positions of the denitration agent supply ports 9 and 10.

The denitration agent supply mechanisms 15 and 16 respectively have nozzles 17 and 18 directed toward the opening direction of the denitration agent supply ports 9 and 10 as shown in FIG. 2, and high-pressure urea aqueous solution to the nozzles 17 and 18. Supply pipes 19 and 20, and electromagnetic valves 21 and 22 provided in the middle of the pipes 19 and 20,
And electromagnetic valve opening / closing mechanisms 23 and 24 for opening the electromagnetic valves 21 and 22 in conjunction with the opening operation of the denitration agent supply port lids 11 and 12, and further the pipe 1
9 and 20 are connected to a pump 26 for supplying the urea aqueous solution stored in the tank 25 in a predetermined high pressure state.

The denitration device for a lightweight aggregate firing furnace according to the present invention, which is constructed as described above, is operated as follows.

First, the rotary drive device 4 for rotating the body 2 of the rotary kiln 1 is driven, and fuel such as coal and petroleum is supplied to the combustion burner 8 and burned.
After the inside of the body 2 reaches a predetermined temperature, the shale W is quantitatively supplied into the body 2 from the shooter 6 for charging the raw material.
Is fired and foamed to produce a lightweight aggregate.

The above-mentioned operation is the same as the conventional one, and the same operation is performed when the present invention is carried out. In the present invention, in addition to the above operation, an operation of filling the urea aqueous solution in the tank 25, an operation of driving the high-pressure pump 26,
It is also necessary to turn on the drive power of the lid opening / closing mechanisms 13 and 14 of the denitration agent supply port and the electromagnetic valve opening / closing mechanisms 23 and 24 of the nozzle. These operations are performed at the same time as quantitatively supplying the shale W into the body portion 2, or continuously or intermittently after a predetermined time has elapsed from the supply of the shale W.

By performing the above operation, the denitration agent supply ports 9 and 10 provided in the vicinity of the middle portion of the body of the rotary kiln for the combustion gas containing a large amount of NOx generated by the high temperature combustion in the firing zone of the rotary kiln 1.
The urea aqueous solution can be contacted more efficiently, and the denitration treatment for decomposing NOx in the combustion gas into nitrogen and water by a gas phase homogeneous reaction can be performed.

Here, the urea solution is supplied into the rotary kiln 1 by providing the denitration agent supply ports 9 and 10 one by one at 180 ° intervals on the same circumference in the above-mentioned embodiment. , These denitration agent supply ports 9, 1
2 when 0 points diagonally upward at 45 ° and 135 °
Denitration, which is opened at each position by the lid opening / closing mechanisms 13 and 14, and the urea aqueous solution is injected at high pressure into the rotary kiln 1 through the denitration agent supply ports 9 and 10 in conjunction with the opening operation of the denitration agent supply ports 9 and 10. Agent supply mechanism 15,1
Since two 6 are provided corresponding to the open positions of the denitrifying agent supply ports 9 and 10, while the body 2 of the rotary kiln 1 makes one revolution, the urea aqueous solution can be fed into the rotary kiln 1 four times. It becomes possible to supply it, and it becomes an apparatus that can efficiently perform denitration treatment.

Further, according to the above-described apparatus of the present invention, the denitration agent supply ports 9 and 10 formed for adding the urea aqueous solution into the rotary kiln 1 are covered with lids 11 and 12.
Since the lids 11 and 12 are attached only at two positions when they are directed obliquely upward at 45 ° and 135 °, as shown in FIG. The shale W flowing down while rolling does not leak from the denitration agent supply ports 9 and 10, and even if the raw materials and the like melted at the denitration agent supply ports 9 and 10 are solidified, the urea aqueous solution Is injected from the supply ports 9 and 10 into the rotary kiln 1 at a high pressure as described above, the solidified substance can be blown off by the injection of the denitration agent, and a denitration device that can be used for a long period of time. Become.

Although one embodiment of the present invention has been described above, the present invention is not limited to the embodiment described above,
Various modifications and changes can be made based on the technical idea of the present invention.

[0028]

As described above, according to the denitration device for a lightweight aggregate firing furnace according to the present invention, the inside of the body in the temperature range where the denitration by the addition of the denitration agent such as ammonia or the ammonia compound is effectively performed. The denitration agent can be efficiently brought into contact with the combustion gas, and NOx treatment for decomposing NOx in the combustion gas into nitrogen and water by a gas phase homogeneous reaction can be effectively performed at low cost.

Further, according to the present invention, the lightweight aggregate raw material flowing down while rolling on the bottom of the body does not leak from the denitration agent supply port, and the molten raw material or the like is solidified at the denitration agent supply port. Even if it occurs, the solidified substance can be blown off by the injection of the denitration agent, and the denitration device can be used in a stable state for a long period of time.

[Brief description of drawings]

FIG. 1 is a side view showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a vertical sectional view showing a schematic configuration of an embodiment of the present invention.

FIG. 3 is a side view showing a schematic configuration of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotary kiln 2 body part 3 support roller 4 rotation drive device 5 upper end opening part 6 raw material shooter 7 lower end opening part 8 combustion burner 9,10 denitration agent supply port 11,12 lid body 13,14 lid body opening / closing mechanism 15,16 denitration agent Supply mechanism 17,18 Nozzle 19,20 Pipe 21.22 Electromagnetic valve 23,24 Electromagnetic valve opening / closing mechanism 25 Tank 26 High pressure pump

Claims (2)

[Claims] 1. A denitration agent supply port with a lid for communicating the inside and outside of the rotary kiln is provided near the middle of the body of a rotary kiln for firing lightweight aggregate, and the denitration agent is provided on the lid of the denitration agent supply port. A lid opening / closing mechanism for opening the supply port when the supply port is in a predetermined direction is provided, and the denitrification agent is provided near the outer periphery of the body of the rotary kiln in association with the opening operation of the lid of the denitration agent supply port. A denitration device for a light-weight aggregate firing furnace, which is provided with a denitration agent supply mechanism for injecting at high pressure into the rotary kiln. 2. The denitration agent injected into the rotary kiln is an aqueous urea solution.
A denitration device for a light-weight aggregate firing furnace.