JPH0882410A - Rotary kiln type incinerator - Google Patents

Abstract

PURPOSE: To provide a rotary kiln type incinerator which is constituted to perform stable and excellent combustion and incineration of a substance to be incinerated. CONSTITUTION: An air nozzle 8 for combustion is arranged at a front cover body 2 of a kiln 1. First nozzle groups 16a... through which air for combustion is injected in a kiln rotation direction against a kiln front half region A and second nozzle groups 16b... through which air for combustion is injected in the direction of the central part of the kiln against a kiln rear half region B are arranged on a refractory layer 20 being the inner peripheral wall of the kiln 1. First and second windboxes 17a and 17b communicated with the nozzle groups 16a... and 16b... are formed between the refractory layer 20 and an external casing 19a. Thus, blowers 18a and 18b attached to the kiln outer periphery 19a are connected to the wind boxes 17a and 17b, respectively. An amount of air fed to the windboxes 17a and 17b by the blowers 18a and 18b is controlled based in the detecting temperatures of the temperature detectors 22a and 22b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary kiln configured to supply a material to be incinerated and combustion air from the front surface of the kiln while rotating a cylindrical kiln inclined rearward in a certain direction. Type incinerator.

[0002]

2. Description of the Related Art Generally, as an incinerator for incinerating various industrial wastes including municipal waste and sludge, a stair type stoker that combines a movable grate and a fixed grate in a staircase is used. A stoker type incinerator that transfers and agitates incinerated materials, and a fluidized bed type incinerator that combusts while incinerating materials while flowing by a fluidized bed formed on the bottom of the furnace. A well-known rotary kiln-type incinerator is configured to rotate the kiln in a certain direction in a downward slanted state and to burn the incineration material supplied from the front part of the kiln while flowing down backward. There is.

However, in a stoker-type incinerator, even when a large-sized incineration object is included, it can be incinerated as it is without performing pretreatment such as crushing treatment, but recent municipal solid waste, etc. Since a large amount of high-calorie, lightweight paper, plastic, etc. are contained in, the burning rate on the stoker becomes fast, and the ash layer on the stoker cannot be sufficiently secured. Therefore, troubles such as burnout of the grate are likely to occur, and stable combustion is also difficult. Moreover, since the stoker is generally composed of a dry stoker, a combustion stoker, and a post-combustion stoker, the burning loss of the incineration ash is large and the hearth load factor (about 200 Kg / m ² h) is small, which is also considered. ,
The hearth will inevitably become large, and the entire furnace will become larger than necessary.

Further, in the fluidized bed type incinerator, the hearth load is larger than that of the stoker furnace (about 500 Kg / m ² h), the ignition loss is 1% or less, and the ignition and stop are easy.
However, since the combustion ratio changes greatly depending on the shape and properties of the incineration material supplied to the fluidized bed, it is necessary to perform pretreatment such as crushing treatment in advance, which leads to poor treatment efficiency and equipment required for pretreatment. The financial burden such as operating costs and operating costs is large.
Moreover, when the incineration material containing the high calorie lightweight material as described above is crushed, the rate of floating combustion increases, and the amount of combustion in the fluidized bed decreases, so that the fluidized bed is heated to a predetermined temperature. Difficult to hold. Moreover, the crushed high-calorie lightweight material explosively burns, which causes large pressure fluctuations in the furnace, resulting in a large amount of CO generation due to lack of combustion air. As described above, the burning rate ratio in the fluidized bed changes depending on the shape and properties of the incineration object, so that a stable fluidized bed temperature cannot be obtained and stable combustion is difficult. Also,
Since it is necessary to periodically discharge incombustibles together with the fluid medium from the center hole of the inverted pyramid-shaped furnace bottom, continuous operation cannot be performed for a long time, and the incineration efficiency is poor.

On the other hand, in the rotary kiln type incinerator, there is no problem in such a stoker type incinerator and the fluidized bed type incinerator, and even when a large-sized incineration object is included, before the crushing process, etc. It can be incinerated as it is without treatment, and can incinerate many types of incineration materials with different combustion characteristics, and is suitable for incineration of high calorie plastics, oil mud, etc. In addition, there is no problem in mixing and discharging incombustibles.

[0006]

However, in the rotary kiln type incinerator, since the combustion air is supplied only from the front part of the kiln, it is not possible to mix the material to be incinerated with the air in the kiln. It is sufficient, and the flammability is not so good. In addition, when a large number of kilns are to be burnt when a large number of types of materials to be incinerated having different combustion characteristics are mixed, a local high-temperature portion is inevitably generated, and clinker easily occurs. Conversely, shortening the kiln will result in insufficient combustion,
It will be necessary to install post-combustion equipment such as a step stoker furnace.

An object of the present invention is to provide a rotary kiln type incinerator capable of stably and satisfactorily burning and incinerating an incineration object without causing such a problem.

[0008]

In order to achieve the above object, the rotary kiln type incinerator of the present invention has a nozzle group for ejecting combustion air onto the peripheral wall of the kiln, especially in the first half region and the second half region of the kiln. Is provided. In such a rotary kiln type incinerator, it is assumed that the nozzles in the first half region eject the combustion air toward the kiln rotation direction, and the nozzles in the latter half region eject the combustion air toward the kiln center. It is preferable to set. Further, the peripheral wall of the kiln is composed of a metal casing and a refractory layer formed on the inner periphery thereof, the nozzle group is provided in the refractory layer, and the casing is configured as a wind box communicating with the nozzle group as a hollow structure. It is preferable to attach a blower connected to the wind box so as to communicate therewith.

[0009]

Since the combustion air is supplied not only from the front surface of the kiln but also from the peripheral surface, the incineration material in the kiln and the combustion air are sufficiently mixed, and the air distribution becomes uniform in the entire area of the kiln. No local high temperature part. Therefore, the material to be incinerated is burned and incinerated well, and the occurrence of clinker is prevented as much as possible.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be specifically described below based on the embodiments shown in FIGS.

In the rotary kiln type incinerator shown in FIG. 1, 1 is a cylindrical kiln, 2 is a lid for closing the front part of the kiln 1, and 3 is a gas cooling tower connected to the rear part of the kiln 1. .

As shown in FIGS. 1 and 3, the kiln 1 inclines rearward by receiving the metal tires 4 and 4 fitted on the outer periphery thereof by the rollers 6 and 6 provided on the base 5. It is rotatably supported in this state, and is rotatably driven in a fixed direction (C direction) by an appropriate driving means (for example, by rotatably driving the roller 6).

As shown in FIG. 1, the lid 2 is fixed to a base 5 and closes the front surface of the kiln 1 so as to be relatively rotatable. The lid 2 is provided with a supply device 7 for supplying an incineration material such as municipal waste into the kiln 1, a primary air ejection nozzle 8 for blowing combustion air into the kiln 1, and an ignition burner 9. Combustion air is supplied to the nozzle 8 from an air supply pipe 11 by a blower 10, and the supply amount thereof can be adjusted by a damper 12 provided in the air supply pipe 11. The amount of combustion air supplied to the kiln 1 is significantly limited as compared with the case where the combustion air is supplied only from the front of the kiln so that the incineration object supplied from the supply device 7 into the kiln 1 does not instantly ignite. I'll do it. Specifically, 20-40 of the required combustion air amount
%.

The gas cooling tower 3 has a base 5 as shown in FIG.
And is connected to the rear surface of the kiln 1 so as to be relatively rotatable. An exhaust gas treatment system 13 that connects the exhaust gas discharged from the kiln 1 to a chimney via a waste heat recovery device (waste heat boiler, etc.), an exhaust gas treatment device (dust collector, etc.), and an induction fan is connected to the upper part of the gas cooling tower 3. Has been done. Further, a residue treatment system 14 for treating the incineration residue discharged from the kiln 1 is connected to the lower part of the gas cooling tower 3.

As shown in FIGS. 1 to 3, the kiln 1 includes nozzle groups 16a, 16b, and wind boxes 17a, 17b.
A combustion air ejecting mechanism 15 composed of b and blowers 18a and 18b is provided so that the combustion air can be ejected from the peripheral wall 1a of the kiln 1 into the kiln 1 over the entire area thereof.

That is, the peripheral wall 1a of the kiln 1 is composed of a metal casing 19 and a refractory layer 20 lined therein, and the refractory layer 20 has a plurality of first nozzles opening in the front half region A of the kiln 1. 16a and a plurality of second nozzles 16b that open in the latter half region B are provided at predetermined intervals in the kiln axis direction and the circumferential direction. First nozzle 16
As shown in FIG. 2, a is configured to inject the combustion air in the rotation direction C, and the first nozzle group 6
A swirling flow is formed in the kiln 1 by the air blown from a. As shown in FIG. 3, the second nozzle 16b is shaped so as to inject the combustion air toward the center of the kiln. Further, as shown in FIGS. 1 to 3, the casing 19 has a double structure including an outer casing 19a and an inner casing 19b, and the inside thereof has an annular partition wall 21.
The first air box 17a communicating with the first nozzles 16a ... And the second air box 17 communicating with the second nozzles 16b.
and b. Further, as shown in FIGS. 1 to 3, a first blower 18a connected to the first air box 17a and a second blower 18b connected to the second air box 17b are attached to the outer peripheral portion 19a of the kiln 1. ing. Further, on the peripheral wall 1a of the kiln 1, the first temperature detector 22a for detecting the temperature of the first half region A and the first temperature detector 22a for detecting the temperature of the second half region B are provided at the substantially central portion and the rear end portion in the axial direction thereof. Two temperature detectors 22b are provided.

The amount of air ejected from each of the nozzle groups 16a, 16b, ... Is supplied from each of the blowers 18a, 18b to the wind box 17.
It is controlled by the air volume supplied to a, 17b, and this air volume is controlled by controlling the rotation speed of each blower 18a, 18b. Such air volume control is performed by the controller 23 arranged on the base 5 side. Temperature detectors 22a, 20
It is performed as follows based on the detected temperature of b. In addition,
The jetting of this combustion air requires an appropriate velocity at the nozzle jet outlet (velocity for ensuring the air reaching distance) for proper mixing, and the air pressure loss corresponding to this velocity is required. It is necessary to have a wind pressure that is commensurate with. Therefore, it is preferable to select, as the blower, one capable of producing a wind pressure corresponding to the air velocity including the required pressure loss. In this embodiment, the air supply system from the blower to the nozzle to the nozzle does not have a relative rotating portion, so that the required wind pressure can be obtained easily and appropriately.

That is, regarding the amount of combustion air ejected from the first nozzle group 16a to the first half region A of the kiln 1, the temperature detected by the first temperature detector 22a is equal to or lower than the clinker generation temperature (for example, 800 to 900 ° C. or lower). ), The amount of combustion air ejected from the second nozzle group 16b to the second half region B of the kiln 1 has a temperature detected by the second temperature detector 22b equal to or lower than the clinker generation temperature (for example, 800 to
The temperature is controlled to be 1000 ° C. or lower). The amount of air supplied from both nozzle groups 16a ..., 16b ... To the kiln 1 is 30 to 100% of the required combustion air amount as a whole.
Controlled by the range of.

By the way, the electrical input from the control device 23 and the power source on the base 1 side to the blowers 18a, 18b and the temperature detectors 22a, 22b on the kiln 1 side is, as shown in FIGS. It is performed by relative rotational contact between the appropriate number of conductive material slip rings 24 provided and the appropriate number of conductive material brushes 25 provided on the base 5 side. That is, each slip ring 24 has the outer peripheral portion 19 a of the kiln 1.
Is mounted concentrically with the kiln 1 via a mounting member (for example, an insulator) 26 made of an insulating material.
a, 18b and temperature detectors 22a, 20b are electrically connected. Further, each brush 25 is electrically connected to the control device 23 and a power source, and is always in contact with each slip ring 24 regardless of the rotation of the kiln 1.

In the rotary kiln type incinerator configured as described above, the material to be incinerated supplied from the supply device 7 into the kiln 1 is agitated by the rotation of the kiln 1 and is moved backward by the inclination of the kiln 1. It is moved, burned and incinerated during this period, and its exhaust gas and incineration residue are discharged to the gas cooling tower 3.

At this time, in the first half region A of the kiln 1, the combustion air is ejected from the primary air ejection nozzle 8 and the first nozzles 16a, but the combustion air is ejected from the first nozzles 16a. Since it is jetted into C to form a swirling flow, the combustion air blown from the front surface of the kiln 1 by the nozzle 8 is evenly diffused, and the combustion air and the incineration object are sufficiently mixed. Become. Moreover, the amount of air jetted from the first nozzles 16a is monitored and controlled by the first temperature detector 22a, and the temperature of the first half region A is maintained at the clinker generation temperature or lower (800 to 900 ° C. or lower). Further, since the air supply amount from the front nozzle 8 of the kiln 1 can be made smaller than that of the conventional device by the air supply from the first nozzles 16a (about 20 to 40% of the total amount), the supply device 7 supplies the air. The incinerated material does not ignite instantly. Therefore, in the first half region A, a local high temperature region does not occur, and uniform combustion can be obtained. As a result, clinker is not generated, and the internal volume of the kiln can be effectively used.

Further, unburned gas and unburned substances which are not completely combusted in the first half region A are brought to the second half region B,
In the second half region B, since the combustion air is ejected from the second nozzles 16b in the center direction of the kiln, the unburned gas and the unburned substances are sufficiently mixed with the combustion air and secondarily burned to complete the combustion. Burned. Also in this case, the amount of air jetted from the second nozzles 16b ... Is monitored and controlled by the second temperature detector 22b, and the temperature of the first half region A is kept below the clinker generation temperature (800 to 1000 ° C.). Therefore, clinker does not occur.

As described above, since the material to be incinerated and the combustion air are sufficiently mixed in the kiln 1 and the combustion is improved, the material to be incinerated can be removed without making the kiln 1 longer than necessary. Can be completely burned. Moreover, since the refractory layer 20 is surrounded by the wind boxes 17a and 17b, the refractory layer 20 is air-cooled. Therefore, it is possible to further prevent the occurrence of clinker and prevent the refractory from being burnt out or dropped as much as possible.

The present invention is not limited to the above-mentioned embodiments, but can be appropriately changed and improved without departing from the basic principle of the present invention. For example, the number and arrangement of the nozzles 17a and 17b are arbitrary, and can be set appropriately according to the combustion conditions such as the properties of the incineration object. Further, although the wind boxes 17a and 17b are formed in the casing 19 in the above-described embodiment so that they can be used as an air cooling mechanism for the refractory layer 20, the air boxes 17a and 17b are not necessary for such a case. Is the casing 19
It may be separately provided outside. In addition, each nozzle group 1
Air supply to 6a ..., 16b ..
However, it is also possible to communicate the air boxes 17a and 17b without partitioning and to supply air from the common air box to both nozzle groups 16a ... 16b. In this case, both nozzle groups 16a ..., 16b ...
The amount of air blown out from is controlled collectively, but the control range is preferably 30 to 100% of the required combustion air amount as described above. Further, in the above embodiment, the first nozzles 16a in the first half area A are made to eject air in the kiln rotation direction C, and the second nozzles 16b in the second half area B are made to eject air in the kiln center direction. The ejection direction from such a nozzle can be appropriately set as required. For example, all the nozzles are replaced by the first nozzle 16a.
Alternatively, the second nozzle 16b may be used. In particular, when all the nozzles are the first nozzles 16a, there is an effect of cooling the surface of the refractory layer 20 with jet air. Further, the number of blowers 18a and 18b is appropriately set according to the number of wind boxes, the amount of air jets, and the like. Of course, the blower 18a,
18b can be provided outside kiln 1, but
Since the kiln 1 rotates, in such a case,
There is a risk that a relative rotation portion will occur in the air supply system and pressure loss will occur in that portion, and it is necessary to take measures against it. In this case, as a countermeasure, it is conceivable to arrange a seal mechanism in the relative rotation portion of the air supply system. However, according to such a countermeasure, when the air pressure becomes high, air flows out from the seal portion. It should be noted that there is a limit to the air pressure and it is not possible to obtain a sufficient flow velocity at the nozzle ejection portion. Further, the type of rotary kiln type incinerator to which the present invention is applied is arbitrary,
In particular, the front and rear closing structure of the kiln 1 is arbitrary. For example,
The front surface or both surfaces of the kiln 1 may be closed by a lid body integrated with the kiln 1.

[0025]

As can be easily understood from the above description, according to the present invention of claim 1, the combustion air is supplied not only from the front surface of the kiln but also from the peripheral wall of the kiln to the first half region and the second half region of the kiln. Since the air can be ejected at an appropriate air velocity, the combustion air and the material to be incinerated are sufficiently mixed throughout the kiln, the air distribution is uniform, and the waste is satisfactorily completely combusted. In addition, by controlling the amount of air blown from the peripheral wall of the kiln, it is possible to control the temperature inside the kiln, preventing the occurrence of localized high-temperature parts and preventing the occurrence of clinker. It can be prevented as much as possible. Therefore, according to the present invention, it is not necessary to make the kiln longer than necessary or to provide a post-combustion facility such as a step stoker furnace.

Further, according to the invention of claim 2, the combustibility of the waste can be further improved. Further, according to the invention of claim 3, it is possible to more reliably prevent the occurrence of clinker and the burnout and dropout of the refractory layer due to the air cooling effect of the wind box. Moreover, in combination with being able to select a blower that can obtain the wind pressure corresponding to the air velocity including the necessary pressure loss, it is possible to appropriately eject the air from the nozzle on the peripheral wall of the kiln. .

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of a rotary kiln incinerator according to the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

3 is a sectional view taken along line III-III in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Kiln, 1a ... Peripheral wall, 8 ... Nozzle which injects combustion air from the front part of a kiln, 16a ... 1st nozzle, 16
b ... 2nd nozzle, 17a, 17b ... Wind box, 18a, 18
b ... Blower, 19 ... Casing, 19a ... Outer casing, 19b ... Inner casing, 20 ... Refractory layer, A ... Kiln first half area, B ... Kiln second half area, C ... Kiln rotation direction.

Claims (3)

[Claims] 1. A rotary kiln type incinerator configured to supply a material to be incinerated and air for combustion from a front portion of a kiln while rotating a cylindrical kiln inclined downward to the rear in a certain direction. A rotary kiln incinerator characterized in that a group of nozzles for ejecting combustion air is provided in the first half region and the second half region of the kiln on the peripheral wall of the kiln. 2. The nozzle in the first half area is for ejecting combustion air toward the rotational direction of the kiln, and the nozzle in the latter half area is for ejecting combustion air toward the center of the kiln. The rotary kiln type incinerator according to claim 1. 3. A kiln has a peripheral wall composed of a metal casing and a refractory layer formed on the inner periphery of the kiln. The nozzle group is provided in the refractory layer and the casing has a hollow structure to form a wind box communicating with the nozzle group. The blower connected to the casing in communication with the wind box is attached to the casing.
Alternatively, the rotary kiln type incinerator according to claim 2.