JPH04350409A - Circulating fluidized bed type incinerator - Google Patents

Abstract

PURPOSE:To provide an incinerator capable of being sufficiently adapted for a regulation over a discharging of dioxin by accommodating a circulating fluidized bed type combustion furnace of which high efficient combustion can be expected at a high probability to the incinerator for city-dust and the like and in which chlorine becoming a cause of occurrence of dioxin is easily removed at a stage of thermal decomposition gas without using any special desalting agent. CONSTITUTION:A circulating fluidized bed type incinerator is comprised of a main incinerator 1 for igniting ignited material within a high-speed fluidized bed, a cyclone 2 for collecting flowing medium particles discharged from the main incinerator 1, a thermal decomposing furnace 3 having an ignited material feeding part 31 and for thermally decomposing the ignited material with heat got from the flowing medium particles, a pneumatic control valve 4 for controlling flowing medium particles and the ignited material to be supplied to the main incinerator 1, a thermal decomposing gas supplying flow passage 5 for supplying the thermal decomposed gas generated from the thermal decomposing furnace 3 to the main incinerator 1 and a thermal decomposing gas cooling part 6 disposed in the thermal decomposing gas supplying flow passage 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an incinerator for municipal waste, and more particularly to a circulating fluidized bed incinerator.

0002

[Prior Art] For the past few years, in incinerators that incinerate municipal waste, etc., there has been a need for high-efficiency combustion to reduce the level of carbon monoxide emissions from incineration, in order to suppress dioxin emissions, etc. Various improvements have been made to the conventional bubbling fluidized bed incinerator. However, all of these require complicated furnace shapes and air distribution mechanisms, and the simplicity that was originally an advantage of bubbling fluidized bed incinerators is lost, and even with these improvements, high efficiency cannot be achieved. There are many uncertainties as to whether combustion will be reliably achieved.

[0003] Incidentally, in combustion furnaces that use coal or the like as fuel, there are
Circulating fluidized bed combustion furnaces are rapidly expanding their market share.

[0004] There are various types of circulating fluidized bed combustion furnaces, but in general, fluidized medium particles made of refractory particles such as silica sand are fluidized by blowing air into the furnace. A main combustion furnace that fluidizes the fuel at high speed to form a high-speed fluidized bed and burns the fuel in this fluidized bed, a cyclone that separates and collects the fluidized medium particles discharged from the main combustion furnace from the exhaust gas, and a cyclone that It mainly consists of an external heat exchanger that controls the temperature of the collected fluidized media particles and a pneumatic control valve that controls the amount of fluidized media particles supplied from the external heat exchanger to the main combustion furnace. Coal or the like serving as fuel is charged into the main combustion furnace, circulates along with fluidized medium particles through a circulation path consisting of the main combustion furnace, a cyclone, an external heat exchanger, and a pneumatic control valve, and is burned.

[0005]

[Problem to be Solved by the Invention] However, when incinerating municipal waste, etc., there is a concern that a stable high-speed fluidization state may be hindered because the properties of the incinerated materials vary widely. Due to reasons such as the fact that the structure tends to be complicated, circulating fluidized bed combustion furnaces have not been used as incinerators until now, even though they are expected to provide highly efficient combustion. In view of the above-mentioned circumstances, the purpose of this invention is to adapt a circulating fluidized bed combustion furnace, which can be expected to achieve highly efficient combustion with a high degree of certainty, to an incinerator for municipal waste, etc., and to reduce dioxins, which are expected to be subject to stricter regulations in the future. An object of the present invention is to provide an incinerator that satisfactorily complies with emission regulations and can easily remove chlorine, which is a factor in the generation of dioxins, without using a special desalination agent.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the circulating fluidized bed incinerator according to the present invention fluidizes fluidized medium particles at high speed to form a high speed fluidized bed, and in this fluidized bed, A main incinerator that burns the incineration material, a cyclone that separates and collects the fluidized medium particles released from the main incinerator from the exhaust gas, and a part that inputs the incinerated material and that collects the fluidized medium particles by the cyclone. A pyrolysis furnace that thermally decomposes the material to be incinerated using the heat of a pyrolysis gas supply channel for supplying the pyrolysis gas generated by the pyrolysis gas to the main incinerator;
It consists of a pyrolysis gas cooling section provided in a pyrolysis gas supply flow path.

[0007]

[Operation] Waste to be incinerated, such as municipal waste, is charged into the pyrolysis furnace from the incineration material input section and is thermally decomposed by the heat of the fluidized medium particles. The pyrolysis gas generated by the pyrolysis of the material to be incinerated flows into the pyrolysis gas supply channel leading from the pyrolysis furnace to the main incinerator, and passes through a pyrolysis gas cooling section on the way. Pyrolysis gas contains water vapor, ammonia, chlorine gas, etc. that cause the generation of dioxins, and when the pyrolysis gas that has passed through the pyrolysis gas cooling section is cooled to below the dew point, chlorine is added to the condensed water. The gas is dissolved and neutralized by ammonia to form ammonium chloride, so that the pyrolysis gas, free of chlorine gas, is fed to the main incinerator. On the other hand, the material to be incinerated after being pyrolyzed is supplied to the main incinerator together with the fluidized medium particles through the pneumatic control valve. The pyrolysis gas and the material to be incinerated after pyrolysis supplied to the main incinerator are completely combusted in a high-speed fluidized bed formed by high-speed fluidization of fluidized medium particles. The exhaust gas discharged from the main incinerator and the fluidized medium particles are separated in a cyclone, the exhaust gas is discharged outside the cyclone, and the fluidized medium particles are collected in the pyrolysis furnace.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The circulating fluidized bed incinerator shown in FIG. 1 includes a main incinerator (1) in which particles of a fluidized medium are fluidized at high speed to form a high-speed fluidized bed, and the material to be incinerated is burned in this fluidized bed. It has a cyclone (2) that separates fluidized media particles discharged from the incinerator (1) from exhaust gas and collects them, and an incineration material input section (31), and the fluidized media collected by the cyclone (2). A pyrolysis furnace (3) that thermally decomposes the materials to be incinerated using the heat of the particles, and a pneumatic type that controls the amount of fluidized medium particles and materials to be incinerated that are supplied from the pyrolysis furnace (3) to the main incinerator (1). A control valve (4) and a pyrolysis gas supply channel (
5) and a pyrolysis gas cooling section (6) provided in the pyrolysis gas supply channel (5).

[0010] The incineration material input section (31) provided in the pyrolysis furnace (3) communicates with the waste dryer (7).
The materials to be incinerated, such as municipal waste, are first dried in a waste dryer (7). The garbage dryer (7) is a rotary kiln with a rotation axis slightly inclined from horizontal, and the materials to be incinerated are indirectly heated by the heat of exhaust gas piped to the bottom of the kiln while moving along the inner wall of the kiln. , dried. By drying the material to be incinerated, the pyrolysis gas cooling section (6
) The amount of cooling processing of the pyrolysis gas is reduced, and the cooling processing can be performed efficiently. In addition, the gas generated by drying the materials to be incinerated in the garbage dryer (7) has an odor, so it is supplied to the main incinerator (1) together with secondary combustion air to remove this odor. be burned. Note that the waste dryer (7) may include a tube and a jacket inside the kiln, or may use heating means other than exhaust gas heating.

The pyrolysis furnace (3) is activated by the cyclone (2).
) The fluidized medium particles having combustion heat collected in the pyrolysis furnace (3) form an extremely low-velocity fluidized bed by air or exhaust gas introduced from the lower part of the pyrolysis furnace (3), and in this fluidized bed, the incinerated material input section (31 ) The materials to be incinerated are thermally decomposed. In addition, as a means of fluidizing the fluidized medium particles in the pyrolysis furnace (3), if low-oxygen gas such as exhaust gas is used, the material to be incinerated can be thermally decomposed efficiently, but the exhaust gas recirculation piping etc. are complicated. If so, air may be used.

The pyrolysis gas generated in the pyrolysis furnace (3) is passed through the pyrolysis gas supply channel (5) leading to the main combustion furnace (1).
flows into. The pyrolysis gas supply channel (5) is equipped with a gas descending section (51) through which the pyrolysis gas descends, and a pyrolysis gas cooling section (6) is provided above the gas descending section (51).
A drain (52) is provided at each lower end. In addition, as a cooling means in the pyrolysis gas cooling section (6),
By using the combustion air introduced into the main incinerator (1), the combustion air is preheated and the main incinerator (1) is heated.
This can contribute to improving combustion efficiency. In the pyrolysis gas cooling section (6), when the pyrolysis gas is cooled below its dew point, chlorine gas is dissolved in the condensed water, which is neutralized by ammonia and becomes ammonium chloride. As a result, the pyrolysis gas from which chlorine has been removed is transferred to the main incinerator (1).
while ammonium chloride is supplied to the gas descending section (5
1) is discharged to the outside of the pyrolysis gas supply channel (5) from the drain (52) provided at the lower end.

[0013] Into the main combustion furnace (1), primary combustion air is introduced from the lower part of the furnace, and secondary combustion air is introduced from the secondary combustion air introduction part (11) provided at the side of the furnace. be done. In addition, a non-combustible material discharge port (12) is provided at the bottom of the furnace.
The incombustible materials in the incineration material are discharged together with the fluidized medium particles. The incombustibles and fluidized medium particles discharged from the incombustibles discharge port (12) are sieved by a vibrating sieve or the like, and the fluidized media particles are returned to the pyrolysis furnace (3). In the primary combustion zone below the secondary combustion air introduction part (11) in the main incinerator (1), a fluidized bed with a slightly low velocity is formed by controlling the amount of primary combustion air, and non-combustible materials are This makes it easy to discharge incombustibles from the discharge port (13). In the secondary combustion zone above the secondary combustion air introduction section (11), a high-speed fluidized bed is formed by fluidized medium particles by controlling the amount of secondary combustion air. The pyrolysis gas supplied from the cracked gas supply channel (5) and the pneumatic control valve (4)
The pyrolyzed incineration material supplied together with the fluidized medium particles is completely combusted through the combustion chamber.

The cyclone (2) consists of an upper cylindrical part and a lower funnel-shaped part, and the upper part communicates with the upper part of the main combustion furnace (1), and the lower end reaches into the pyrolysis furnace (3). The cyclone outer cylinder (21) is arranged at the center of the upper part of the cyclone outer cylinder (21), and the upper end thereof is connected to the cyclone (3).
The cyclone inner cylinder (22) extends to the outside of the cyclone. Exhaust gas discharged from the main incinerator (1) is blown in tangentially from the upper part of the cyclone outer cylinder (21), enters the funnel-shaped lower part while swirling inside the cyclone outer cylinder (21), and gradually rises in the gas flow in the center. It is then discharged from the cyclone inner cylinder (22). On the other hand, the fluidized medium particles collide with the wall surface due to the large centrifugal force, and are collected into the pyrolysis furnace (4) while settling.

[0015] The exhaust gas discharged from the cyclone (2) is heat-recovered in the heat recovery section and then treated with the exhaust gas or introduced into the flue, but some of it is sent to the garbage dryer (
7) and used for heating and drying of the materials to be incinerated, or supplied to the pyrolysis furnace (4) and used as a means for fluidizing fluidized medium particles.

[0016]

[Effects of the Invention] According to the circulating fluidized bed incinerator of the present invention, incineration of materials to be incinerated such as municipal waste is carried out in a high-speed fluidized bed formed by high-speed fluidization of fluidized medium particles. High-efficiency combustion makes it possible to reduce carbon monoxide emissions, making it fully compliant with current dioxin emission regulations.

[0017] Furthermore, the pyrolysis gas generated by the thermal decomposition of the material to be incinerated passes through a pyrolysis gas cooling section provided in the pyrolysis gas supply flow path leading to the main incinerator, and is cooled to below the dew point. By doing so, chlorine gas is dissolved in the condensed water,
It is neutralized by ammonia to become ammonium chloride, so that the pyrolysis gas from which chlorine gas has been removed is fed to the main incinerator using special desalting agents (NaOH,
Chlorine can be easily removed without using Ca(OH)2).

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view showing one embodiment of a circulating fluidized bed incinerator according to the present invention.

[Explanation of symbols]

1... Main incinerator 2...Cyclone 3...Pyrolysis furnace 4...Pneumatic control valve 5...Pyrolysis gas supply channel 6...Pyrolysis gas cooling section

Claims (1)

[Claims] Claim 1: A main incinerator that fluidizes fluidized media particles at high speed to form a high-speed fluidized bed and burns the materials to be incinerated in this fluidized bed, and separates fluidized media particles discharged from the main incinerator from exhaust gas. a cyclone that collects the incinerated material, a pyrolysis furnace that has a part for incinerating the material to be incinerated and thermally decomposes the material to be incinerated by the heat of the fluidized medium particles collected by the cyclone, and a pyrolysis furnace that supplies the material to the main incinerator. a pneumatic control valve that controls the amount of fluidized media particles and incineration materials; a pyrolysis gas supply channel that supplies pyrolysis gas generated by thermal decomposition of the incineration materials to the main incinerator; A circulating fluidized bed incinerator consisting of a pyrolysis gas cooling section provided in a gas supply channel.