JP3004201B2 - Rotary kiln - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is, rotary kiln
It relates to.

[0002]

2. Description of the Related Art In recent years, sewage sludge, industrial waste and general waste, such as sludge, plastic, paper, wood, waste oil, waste acid, waste alkali, kitchen dust, etc., have been increasing with the economic development. However, disposal is also an important issue in public organizations and businesses. Since the amount of generated waste fluctuates and the calorific value and elemental composition fluctuate, it is possible to stabilize the amount of treatment and the characteristics of flue gas in a conventional incinerator, and to incinerate a predetermined amount at low cost. It was difficult. Therefore, there is a demand for the development of an incineration treatment device that stabilizes the properties of the combustion exhaust gas and incinerates such an incinerated material quickly and at low cost.

For example, as shown in FIG. 8, a conventional rotary kiln has a rotary support (57) for rotatably supporting a furnace body (52) around an axis inclined several degrees with respect to the horizontal.
Supplies the incinerated material from the incinerated material supply port (55) of the upstream lid (53) of the cylindrical furnace body, and rotates the furnace body (52) or transports provided on the furnace wall. The burner (5) provided on the discharge port side while transporting the incinerated material toward the other end
8) The combustion gas and air are supplied to the furnace from the incinerator and incinerated, and the incinerated ash is discharged from the incinerated ash outlet (56) of the downstream lid (54) and stored in the incinerated ash storage tank. This is an incinerator that discharges combustion exhaust gas from the exhaust gas outlet. However, since the conventional rotary kiln supplies combustion gas or air from the combustion section (58) and directly incinerates the incinerated material, it takes time for the massive incinerated material to be crushed. Efficiency is low, and the supply of incinerated materials such as sewage sludge, industrial waste, and general waste supplied to the furnace increases,
When the calorific value decreases or the water content increases, there is a high possibility that unburned matter will be generated without complete incineration. For this reason, if the total length of the machine is increased, a large site is required, and there are problems in terms of equipment scale and cost.

[0004] As an incinerator for sewage sludge, industrial waste and general waste to be incinerated, an air supply pipe is provided at the lower part of a cylindrical furnace body, and several meters of fluidized sand is poured thereon. Filling to form a fluidized sand layer, and while maintaining the inside of the furnace at a predetermined temperature, inject primary air from the air supply pipe to fluidize the fluidized sand and incinerate the incineration material supplied above the fluidized sand layer Fluidized furnaces are known. Since the fluidized-bed furnace supplies and incinerates the incinerated material in the fluidized sand heated to a predetermined temperature and burns the incinerated material, the amount of the incinerated material supplied into the furnace increases. It is possible to cope with a decrease in the calorific value or an increase in the moisture. However, crushing, drying, thermal decomposition, and combustion occur instantaneously, and the response to the incineration material is too fast, so that the combustion state fluctuates greatly and stable combustion cannot be performed. NOx, CO, HCl in the flue gas of flue gas The production of hazardous substances such as dioxins and dioxins, the height of the furnace body and the height of plants and buildings, and the need for high-pressure, large-size blowers due to the thick fluidized sand layer And so on.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing circumstances, and has been made in consideration of the size and supply of incinerated materials such as sewage sludge, industrial waste, and general waste supplied to a furnace. Even when the amount fluctuates, the calorific value decreases, or the moisture increases, the object is to achieve stable incineration with less generation of harmful substances in the combustion exhaust gas and to reduce the equipment scale. .

[0006]

A rotary kiln according to the present invention for solving the above-mentioned problems is provided with a cylindrical furnace body which rotates around an axis which is horizontal or slightly inclined with respect to the horizontal. A rotary kiln that incinerates the supplied incineration material and discharges the incinerated ash and combustion exhaust gas generated by the incineration while maintaining the length along the inner peripheral surface of the furnace body
A large number of air supply pipes are provided in the hand direction, and the upstream side of the furnace body
The upstream lid covering the downstream side and the downstream lid covering the downstream side
Each furnace body is airtightly sealed but does not rotate
The upstream lid is located in the upper secondary air chamber,
Is divided into primary air chambers and supplied to secondary air chambers.
The burned air is burned into the furnace through the upper air supply pipe in the furnace.
And supplied to the primary air chamber.
The supplied air is supplied to the furnace through the lower air supply pipe in the furnace.
Is supplied as primary air into the furnace, and the incineration in the furnace is incinerated while flowing along with the heated fluidized sand ,
And, regardless of the rotation of the furnace body,
Install the air supply pipe for secondary air supply at the lower position inside the furnace.
The air supply pipe to be installed is for primary air,
It can supply air for incineration of incinerated materials
Things .

[0007] The present invention also provides the furnace body having a double structure.
And a plurality of air supply pipes are provided by providing partitions in the longitudinal direction.
And a furnace for the air supply pipe
Rotary with inner wall made of porous ceramic
Can be embodied in a kiln.

[0008]

[0009]

[0010]

[0011]

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. The first embodiment shown in FIG. 1 is, for example, a rotary kiln for incinerating sewage sludge or industrial waste having a water content of 45 to 85% and an equivalent diameter of 10 to 200 mm at a rate of 20 to 40 t / day. (1), wherein the diameter D = 1 to 2 m and the length L = 5
FIG. 6 shows a furnace body (2) having a length of 10 m and a D / L of 0.2 to 0.4.
As shown in the figure, air injection holes (27a) having a diameter of 3 to 4 mm are drilled at intervals of about 50 mm as primary air supply means.
A long primary air supply pipe (12a) having a length of about 60 mm is shown in FIG.
As shown in the figure, a large number of tubes are fixed to the furnace body in the longitudinal direction along the inner peripheral surface of the furnace body, the pressure for supplying air to the primary air supply pipe (12a) is about 1000 to 1500 mmAq, When the sand is silica sand having a diameter of 0.3 to 2 mm, the linear velocity of the primary air in the sand layer is about 0.5 m / sec, and the fluidization start linear velocity at which the fluidized sand starts to flow is 1-2. Preferably it is twice. Further, it is preferable that the inside of the furnace is maintained at a negative pressure of 0 to 50 mmAq to prevent the combustion exhaust gas from leaking out of the furnace.

Due to the rotation of the cylindrical furnace body that rotates about an axis that is horizontal or slightly inclined with respect to the horizontal, for example, the incinerated material having a diameter of 200 mm is conveyed from the supply port side to the discharge port side. However, by providing the transfer blades in the furnace body, the transfer force can be increased. A number of long primary air supply pipes (12a) fixed to the furnace body (2) along the circumferential surface of the furnace body (2) in the longitudinal direction from the supply port side to the discharge port side. Air injection holes (27a) provided at least in the lower part of the cylindrical furnace and provided in the secondary air supply pipe (13a) for injecting fluidized sand into the air supply pipe. To make it less likely that
As shown in FIG. 6, it is preferable to provide on the furnace wall side instead of the center side of the furnace body (2). Further, as shown in FIG. 7, the air injection hole (27a) for injecting air can be formed not at right angles to the axis of the air supply pipe but at an angle. Since the flow path does not sharply bend, the air resistance can be reduced. In addition, it is preferable to increase the number and diameter of the air injection holes (27) formed in the primary air supply pipe (12a) and the secondary air supply pipe (13a) on the upstream side and reduce the number on the downstream side, Thereby, the disintegration of the incinerated material near the incinerated material supply port by the liquid sand can be enhanced.

As in the second embodiment shown in FIG. 4, the furnace body (2) has a double-pipe structure without the air supply pipe fixed to the furnace body (2). By forming the primary air supply pipe (12b) and the secondary air supply pipe (13b) directly in a predetermined portion of the furnace body (2), the air injection holes (27b) provided on the wall surface are used. Air can also be injected. In order to prevent clogging of the air injection hole (27b), a hole is drilled in the air supply pipe, a bubble cap is attached to the upper part thereof, and the air injection hole (27b) is provided on the side wall of the cap.
It is also possible to open b).

Further, as in the third embodiment shown in FIG. 5, the furnace body (2) has a double pipe structure, and a primary air supply pipe (12c) is provided at a predetermined portion of the furnace body (2). Alternatively, a secondary air supply pipe (13c) may be formed to inject air from the front side of a porous body such as a ceramic porous body having a particle size of 2 mm or less provided on the wall surface side.

In the first embodiment shown in FIG.
Fluid sand such as silica sand having a particle size of 0.3 to 2 mm is filled to a depth of about 1/3 to 1/4 of the diameter of the furnace body (2), and the furnace body (2) is substantially horizontal or horizontal. The rotary support (7) is installed on the rotary support (7) in a state of being slightly tilted (for example, about 3 to 5 degrees). Make 5 rotations. By providing a weir in the longitudinal direction in the furnace, it is possible to increase the filling depth of the fluidized sand on the supply side of the incinerated material that particularly requires crushing of the incinerated material. An upstream lid (3) for covering the upstream side of the furnace body (2) and a rotating furnace body (2)
Is sealed airtight, but the upstream lid (3) is
It does not rotate with the rotation of the furnace body (2). Similarly, a downstream lid (4) for covering the downstream side of the furnace body (2)
And the rotating furnace body (2) are hermetically sealed,
The downstream lid (4) does not rotate with the rotation of the furnace body (2).

In the first embodiment shown in FIG.
The upstream lid (3) is partitioned, and an opening communicating with a secondary air chamber (11) as a secondary air supply means and a secondary air supply pipe (13a) is provided at an upper portion thereof. The air supplied to the upstream lid (3) is supplied to the secondary air supply pipe (13a) which rotates together with the furnace body (2) when the secondary air supply pipe (13a) communicates with the opening of the secondary air chamber (11). Secondary air is supplied into the furnace through the air injection holes (27a) of the pipe (13a). Similarly, an opening communicating with a primary air supply means (10) and a primary air supply pipe (12a) is provided at a lower portion, and the primary air supply pipe (12) is provided.
When a) communicates with the opening of the primary air chamber (10), the primary air is supplied into the furnace through the air injection holes (27a) of the primary air supply pipe (12a). I have. In addition,
A method for supplying primary air to the primary air supply pipe (12a) and 2
The method of supplying the secondary air to the secondary air supply pipe (13a) is not limited to the above.

In the first embodiment shown in FIG.
The downstream lid (4) has a combustion section (8) including a combustion burner for heating the inside of the furnace to a predetermined temperature (for example, 800 to 900 degrees Celsius), and an exhaust gas outlet serving as a means for discharging combustion exhaust gas. (9) A mixture discharge port for discharging a mixture of fluidized sand and incinerated ash is provided, and is in communication with a mixture discharger (14) which is a mixture discharge means. The rotary kiln is supplied with hot air from the outside, or the temperature is raised to a predetermined temperature by the amount of heat from a combustion section (8) for burning by a combustion burner. Primary air ratio of air = 0.7 to 1.2, and total air ratio of total air including primary air and secondary air = 1.2 to 2.
A value of 0 is preferable from the viewpoint of preventing generation of harmful substances. When the incinerated material has a high calorific value and self-burns, it is not necessary to supply the calorific value from the combustion part (8) into the furnace after ignition.

The primary air has a function of flowing the fluidized sand and supplying oxygen for burning the incinerated material.
The secondary air has a function of supplying oxygen for burning the incinerated material or combustible gas, and it is necessary to maintain a predetermined oxygen amount necessary for the incinerated material to burn as a whole. Here, the primary and secondary air in the present invention are:
In addition to air, it also contains gas such as air with high oxygen concentration and combustion exhaust gas containing some oxygen, and it is preferable that the gas be preheated by a heat exchanger in order to save energy and improve thermal efficiency.

The material to be incinerated is dried while being crushed by the heated fluidized sand flowing by the primary air injected from the primary air supply pipe (12a) in the furnace. And is incinerated while being conveyed downstream by the conveyer blades provided in the furnace body to form incinerated ash. The incinerated ash of incinerated materials originally fine like sewage sludge becomes fine and light incinerated ash, so it accompanies the combustion exhaust gas. Not accompany. In addition, fluidized sand heated to a high temperature hardly accompanies combustion flue gas because it has a greater diameter and specific gravity than incinerated ash. These incinerated ash move as a mixture with the fluidized sand to the mixture discharger (14). When incineration ash with large particle size including incombustibles and unburned matter increased,
The mixture discharger (14) such as a screw feeder is intermittently operated to discharge the mixture, and the mixture is separated into fluidized sand and incinerated ash by a separator such as a vibrating sieve, and the fluidized sand is circulated. It is circulated and supplied into the furnace by a fluidized sand feeder (19). The mixture can be continuously discharged little by little.

In the first embodiment shown in FIGS. 1 to 3, a mixture of incinerated ash and liquid sand is discharged from the downstream lid (4) by a mixture discharger (14) as incineration ash discharging means. It is discharged outside the furnace. When the amount of the mixture increases due to an increase in incombustibles and unburned matter, the mixture discharged by the mixture discharger (14) is separated into fluidized sand and incinerated ash by a separator (15) such as a vibrating sieve. The separated fluidized sand having a predetermined particle size passes through a fluidized sand circulation path (18), which is a circulation means, while maintaining a high temperature of 400 to 500 degrees Celsius, and is supplied to a furnace by a fluidized sand feeder (19). It is preferable to circulate the water quickly. In addition, in order to maintain the amount of fluidized sand in the furnace at a predetermined amount,
New fluid sand is supplied from the fluid sand storage tank (17) to the fluid sand feeder (19) as needed. On the other hand, the incinerated ash separated by the vibrating sieve or the like is stored in an incinerated ash storage tank (16) as incinerated ash storage means.

An exhaust gas outlet (9) is provided in the downstream lid (4) of the furnace body (2), so that fine incineration ash and combustion exhaust gas are discharged from the furnace to the outside of the furnace. Since unburned components remain in the flue gas depending on the properties of the incinerated material, the unburned components in the flue gas are incinerated in a reburning furnace (20) as a reburning means as necessary, and reburned. The combustion exhaust gas after combustion is a heat exchanger (21) such as a boiler which is a heat exchange means.
Heat exchange with primary air and secondary air supplied into the furnace, and dust in the combustion exhaust gas is removed by a dust remover (2).
Dust is removed in 2), and the combustion exhaust gas after dust removal is discharged to the atmosphere from a chimney (23) as exhaust gas discharging means. Dust remover (2
The dust collected in 2) is stored in a dust storage tank (24) as dust storage means. Dust storage tank (24)
The dust stored in the container is added with a stabilizing material such as cement by a dust stabilizing device (25) which is a dust stabilizing means,
Heavy metals and the like contained in the dust are stabilized and stored in the stabilized material storage tank (26).

[0023]

As is clear from the above description, the present invention has the following effects. Unlike conventional rotary kilns, convection heat or radiative ripening does not incinerate the incinerated material only at a limited location near the heating section, so even if it is a massive incinerated material, it is heated. The incinerated material is easily crushed by liquid sand such as silica sand and atomized to increase the heat transfer effect, and due to the ripening and combustion heat of the liquid sand, the incinerated material is gradually dried and incinerated throughout the furnace. Therefore, the combustion efficiency is improved. Fluctuation and agitation with heated fluidized sand can increase the heat transfer effect and quickly respond to fluctuations in the amount of supply, heat generation, moisture, and size of the incinerated material, which can quickly respond to unburned materials. And a predetermined processing amount can be stably processed. Since stable incineration is possible even if the machine length is short, the machine length (good machine) of a normal rotary kiln is 4 to 6 times the diameter, whereas it is 4 to 10 times the diameter. , Necessary land can be reduced. (A conventional rotary kiln has a straight line D = 2m and D / L = 0.1,
When the length L is 20 m, the rotary kiln of the present invention has a diameter D = 2 m and D / L = 0.4.
m, and the required land is halved. )

An air supply pipe is provided at the lower part of the cylindrical furnace body, and several meters of fluidized sand is filled on the top of the furnace to form a fluidized sand layer, and primary air is fed into the air supply pipe at 2500 mmAq or more. In comparison with a fluidized-bed furnace in which fluidized sand is fluidized to incinerate the incineration material supplied above the fluidized sand bed, the rotary kiln of the present invention has a fluidized sand bed having a height of 1 m or less, Combined with the effect of the sand layer moving due to the rotation, the inlet pressure from the primary air supply pipe is 1500 mmAq
In the following, the blower can be reduced in size and the required power can be reduced. Disintegration, drying, thermal decomposition, and combustion of the incinerated material occur temporarily, causing the furnace temperature to rise sharply and the amount of harmful substances such as NOx, HCl, CO, and dioxin in the flue gas to be generated suddenly. Compared to a fluidized kiln that increases in number, the rotary kiln of the present invention has a fear that the harmful substances are not generated in the combustion exhaust gas because the combustion is gradually performed in the entire area of the furnace, and the exhaust gas treatment device in the subsequent stage It will be simple. Compared to a fluidized-bed furnace where the height of the furnace body is as high as several tens of meters,
Since the rotary kiln of the present invention has a furnace body as low as several meters, the height of a plant or building can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a rotary kiln showing a first embodiment of the present invention.

FIG. 2 is a flow sheet of the incineration treatment apparatus showing the first embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of a rotary kiln according to a first embodiment of the present invention, taken along a line AA, and a sectional view taken along a line BB.

FIG. 4 is a longitudinal sectional view of a rotary kiln according to a second embodiment of the present invention, taken along a line AA, and a sectional view taken along a line BB.

FIG. 5 is a longitudinal sectional view of a rotary kiln according to a third embodiment of the present invention taken along a line AA and a sectional view taken along a line BB.

FIG. 6 is a perspective view of an air supply pipe of a rotary kiln showing a second embodiment of the present invention.

FIG. 7 is an example of a cross-sectional view of an air injection hole of an air supply pipe of a rotary kiln showing a first embodiment of the present invention (a).
(B).

FIG. 8 is a sectional view of a conventional rotary kiln.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotary kiln 2 Furnace 3 Upstream lid 4 Downstream lid 5 Incineration material supply port 6 Mixture discharge port 7 Rotation support section 8 Burning section 9 Exhaust gas discharge port 10 Primary air chamber 11 Secondary air chamber 12a, 12b, 12c Primary air supply pipe 13a, 13b, 13c Secondary air supply pipe 14 Mixer discharger 15 Separator 16 Incineration ash storage tank 17 Fluid sand storage tank 18 Fluid sand circulation path 19 Fluid sand feeder 20 Reburning furnace 21 Heat exchange Container 22 Dust remover 23 Chimney 24 Dust storage tank 25 Dust stabilizer 26 Stabilized substance storage tank 27 Air injection hole

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-53-110267 (JP, A) JP-A-59-97338 (JP, U) JP-B-60-47504 (JP, B2) JP-B-49-49 18953 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23G 5/30 ZAB F23G 5/20 ZAB

Claims (3)

(57) [Claims] 1. An incineration of a supplied incinerator while maintaining the inside of a cylindrical furnace body rotating around an axis that is horizontal or slightly inclined with respect to the horizontal, at a predetermined temperature, and generated by incineration. In a rotary kiln that discharges incinerated ash and combustion exhaust gas , a large number of tubes in the longitudinal direction along the inner peripheral surface of the furnace body
An upstream lid that is provided with an air supply pipe and covers the upstream side of the furnace body
And the downstream lid covering the downstream side are airtight with the furnace body, respectively.
But is provided so that it does not rotate.
The upstream lid is located in the upper secondary air chamber and the lower primary air chamber.
The air supplied to the secondary air chamber is
Secondary air for incineration was introduced into the furnace through the inner upper air supply pipe.
And the air supplied to the primary air chamber is
Primary air is introduced into the furnace through the lower air supply pipe in the furnace.
To be incinerated while flowing the incineration material in the furnace together with the heated fluidized sand , and rotating the furnace body.
Regardless of the air supply always located on the upper side of the furnace
Tube for secondary air supply, air supply tube located in the lower part of the furnace
Is used for primary air for fluidized sand flow and incineration of incinerated materials.
A rotary kiln characterized by being able to supply air . 2. The furnace body has a double structure, and has a longitudinal structure.
Cuts are provided to form the multiple air supply pipes.
The rotary kiln according to claim 1. 3. A furnace inner wall surface of the air supply pipe according to claim 2.
With a ceramic porous body
N.