JP2000074349A - Method for reburning exhaust gas from refuse incinerator or the like and reburning apparatus used for the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently suppress generation of a dioxin of an exhaust gas by introducing the exhaust gas into a cylindrical combustion chamber, reburning the gas at a specific temperature or higher, passing the reburned gas through a layer of ceramic particles of a small particle size, exhausting the gas and then guiding the gas to a dust collector. SOLUTION: An exhaust gas inlet 2 connected to a refuse incinerating furnace D is provided at a lower end of a longitudinally disposed combustion chamber 1 via a duct, and an exhaust port 3 connected to a cooling tower via a duct is provided at an upper end of the chamber 1. The exhaust gas exhausted from the furnace is introduced into the chamber 1. Fuel is reburned at 800 deg.C or higher by an oxygen burner 4 for burning the fuel with high concentration oxygen. The reburned gas is passed through a layer 5 of ceramic particles of a small particle size in the chamber 1, then exhausted from the port 3, and introduced into a dust collector. Thus, generation of a dioxin of the exhaust gas can be efficiently suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an incinerator for municipal garbage, an incinerator for industrial waste, and other incinerators that generate a large amount of dioxin. The present invention relates to a reburn method and a reburn apparatus used for the method.

[0002]

2. Description of the Related Art In recent years, regulations on harmful substances, particularly dioxins, emitted from incinerators for municipal waste and incinerators for industrial waste have become a problem. As a mechanism of dioxin generation, it has been clarified so far that most of combustible substances are generated when burned, and the combustion is performed in a relatively low temperature range, for example, about 600 to 700 ° C. It has been found that a larger amount of CO is generated, that is, it is closely related to the amount of CO generated by incomplete combustion.

[0003] In view of such a situation, the design of a new refuse incinerator or the existing incinerator is maintained at a high combustion temperature for a predetermined time, for example, 4 seconds or more.
Accordingly, regulations for suppressing the generation of CO and consequently the generation of dioxin have been adopted. Of course, in existing small garbage incinerators that are not subject to regulation, some countermeasures must be taken.

[0004] Regarding refuse incinerators and the like (new and existing) to be regulated, it is possible to greatly suppress the generation of dioxin by laying a reburn zone continuously to the combustion zone of the refuse incinerator and the like. Although it was obliged, various causes have been examined and investigated to detect the generation of dioxin in the exhaust gas that has passed through the reburning zone. It is presumed that dioxin is resynthesized in the process in which the exhaust gas exiting through the duct reaches the cooling tower (or heat exchanger) and the dust collector, and the mechanism of the resynthesis has not been elucidated.

[0005]

In view of these circumstances, the present inventor has found that the temperature of a refuse incinerator or the like without a reburn zone and a refuse incinerator with a reburn zone when passing through the exhaust duct are reduced. It was speculated that dioxin may be resynthesized due to residual CO.

Therefore, in the next process such as a garbage incinerator,
Separately, we considered re-burning the exhaust gas, but it was difficult to achieve complete combustion of residual CO simply by laying a re-burning chamber and supplying air as in the re-burning zone of a garbage incinerator. In addition, exhaust gas is drawn by the blower of the dust collector and flows through the duct at a relatively high flow rate. There is also a problem that it is difficult. In addition, since the stirring action is not particularly provided, it is difficult to sufficiently exert the reburning action over the entire exhaust gas.

In view of the above situation, the present invention provides a method for efficiently suppressing the generation of dioxin in exhaust gas discharged from a refuse incinerator or the like (with or without a reburning chamber) and a reburning apparatus used in the method. The purpose is to provide.

[0008]

According to the method for reburning exhaust gas from a refuse incinerator or the like according to the present invention, the exhaust gas discharged from the refuse incinerator or the like is cooled using cooling means in order to achieve the above object. Then, after that, a method of reburning exhaust gas discharged from a garbage incinerator or the like that is released to the atmosphere via a dust collector, wherein the exhaust gas discharged from the garbage incinerator or the like is introduced into a cylindrical combustion chamber, The fuel is reburned at 800 ° C. or higher by an oxygen burner that burns the fuel with high concentration oxygen, and
In the combustion chamber, a measure was taken in which the reburn gas was passed through a layer of small-diameter ceramic particles, then exhausted, and led to a dust collector.

In the present invention, it is preferable that the combustion chamber is oriented vertically, exhaust gas flows upward from below, and the reburning time of the exhaust gas in the combustion chamber is preferably 4 seconds or more.

In the present invention, the small-diameter ceramic particles preferably have a particle size of 0.5 mm to 5 mm.

In order to achieve the above object, the apparatus for reburning exhaust gas from a refuse incinerator or the like according to the present invention cools the exhaust gas discharged from the refuse incinerator or the like by using cooling means, and then switches the dust collector. A reburning device for exhaust gas discharged from a garbage incinerator or the like which is released to the atmosphere via a refuse incinerator, wherein an exhaust gas inlet 2 is provided at one end of a cylindrical combustion chamber 1 connected to the garbage incinerator or the like. At the same time, an exhaust port 3 is provided
An oxygen burner 4 that burns fuel with high-concentration oxygen and reburns exhaust gas at 800 ° C. or higher is provided on the inflow port 2 side of the combustion chamber 1, and is provided at a substantially middle position in the longitudinal direction of the combustion chamber 1. A means was provided in which a layer 5 of small-diameter ceramic grains was provided so as to be orthogonal to the longitudinal direction of the combustion chamber 1.

In the present invention, the combustion chamber 1 is arranged vertically, the inflow port 2 is located at the lower end side, and the exhaust port 3 is located at the upper end side. Is preferably set so as to be 4 seconds or more.

In the present invention, the small-diameter ceramic grains preferably have a particle size of 0.5 mm to 5 mm, and the layer 5 of the ceramic grains preferably has a thickness of 300 mm to 600 mm.

The garbage incinerator and the like referred to in the present invention include municipal garbage incinerators, industrial waste incinerators, and various other incinerators.

[0015]

According to the present invention, exhaust gas discharged from a refuse incinerator or the like is introduced into a cylindrical combustion chamber, and the fuel is burned at 800 ° C. by a high-concentration oxygen burner.
By performing the reburning as described above, complete combustion can be expected at a higher temperature and with sufficient oxygen compared to the reburning zone of the incinerator simply adding ordinary air, and the residual CO in the exhaust gas can be expected.
Can be almost eliminated, and the resynthesis of dioxin due to this can be suppressed.

Then, in the combustion chamber, the reburned gas is exhausted after passing through a layer (300 mm to 600 mm) of small-diameter ceramic particles (0.5 mm to 5 mm). This layer stores the amount of heat by the oxygen burner, and can perform reburning with good thermal efficiency. At the same time, because the ceramic particles are incandescently heated, the exhaust gas is sufficiently contact heated as it passes through this layer of ceramic particles, so that more complete combustion can be achieved.

Furthermore, since the exhaust gas passes through the gaps between the ceramic grains while twisting and bending, a long residence time of the exhaust gas in the combustion chamber can be ensured. Even if the combustion chamber itself is not long, the required combustion can be achieved. Time (4 seconds or more) can be easily secured.

Further, when the combustion chamber is of a vertical type, and the exhaust gas flows in from below and discharges the exhaust gas from above, the exhaust gas blows up from below the ceramic particle layer, and the support frame (basket) )), The gap between the ceramic grains is not filled (it is likely to occur in the case of downward flow), and the ceramic grains can be passed through the gap in a slightly floating state. The above-described complete combustion can be achieved without increasing suction negative pressure.

However, this combustion chamber may, of course, adopt a configuration in which exhaust gas is introduced from above and discharged from below.
The intended purpose is fully achievable.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method for reburning exhaust gas from a refuse incinerator and the like and a reburning apparatus used in the method according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic explanatory view showing the laying of the reburning device of the present invention, D shows a refuse incinerator, and exhaust gas discharged from the incinerator passes through a duct,
After being introduced into the reburning device A, where it is subjected to the reburning action, it is cooled to a predetermined temperature in a cooling tower B (here, a water cooling tower), and then filtered in a dust collector C (here, a bag filter type), and Will be released. Since the cooling tower B and the dust collector C have a known configuration, a detailed description thereof will be omitted.

FIG. 2 shows a longitudinal section of the exhaust gas reburning apparatus A, which is formed in a substantially circular cylindrical shape, and is provided with a duct at one end (lower end) of a vertically arranged combustion chamber 1. An exhaust gas inlet 2 connected to the refuse incinerator D is provided, and an exhaust port 3 connected to the cooling tower B via a duct is provided at the other end (upper end). Incidentally, in this embodiment, the combustion chamber 1 has an inner diameter of 2.4 m, a distance (length) between the center of the inflow port 2 and the center of the exhaust port 3 is about 10 m, and the reburning time of the exhaust gas as a whole is It is set to be 4 seconds or more.

On the inlet 2 side of the combustion chamber 1, there is provided an oxygen burner 4 for burning fuel with high-concentration oxygen and reburning exhaust gas at 800 ° C. or higher. This fuel uses LPG here, but other gas or liquid fuels may be used. In addition, the structure of the oxygen burner 4 may be any ordinary structure. This oxygen burner 4 has a very high combustion temperature (flame is around 200 ° C.) by using high-concentration oxygen.
Although it can be heated more easily than C, the generation of nitrogen oxides can be reduced because the nitrogen content is low like ordinary air.

At a substantially middle position in the longitudinal direction of the combustion chamber 1,
A layer 5 of small-diameter ceramic grains is provided so as to be orthogonal to the longitudinal direction of the combustion chamber 1. Layer 5 of this ceramic grain
In this embodiment, the ceramic particles have a particle size of 0.5 mm to 1 mm, and the thickness of the layer 5 of the ceramic particles is about 500 mm. However, the grain size of the ceramic grains is, for example, about 5 mm, and of course, a larger grain size of about 1 cm to 2 cm may be used, and the thickness of the ceramic grain layer 5 may be 300 mm to 60 mm.
It may be about 0 mm. Of course, it goes without saying that such a size appropriately changes depending on the scale and the flow velocity of the combustion chamber 1.

The layer 5 of ceramic grains is accommodated in a support frame 6 (cage) supported by a grid 7.
The ceramic particles are not packed in a pressurized state, but are housed in a state where there is a margin such that the ceramic particles slightly float due to the passage of exhaust gas from below.

In FIG. 2, 8 denotes a temperature sensor, 9 denotes a dust drain, and 10 denotes a safety valve.

Therefore, in the above-mentioned method for reburning exhaust gas, exhaust gas discharged from a refuse incinerator or the like is introduced into a cylindrical combustion chamber, and LPG as fuel is converted into high-concentration oxygen (oxygen concentration 50%).
The reburning is performed at 800 ° C. or more by the oxygen burner burned in the above), and in the combustion chamber, the reburned gas is exhausted after passing through a layer of small-diameter ceramic particles and guided to a dust collector. Is done.

In this case, the combustion chamber is oriented vertically, the exhaust gas flows upward from below, and the reburning time of the exhaust gas in the combustion chamber is set to 4 seconds or more. The small-diameter ceramic particles have a particle size of 0.5 mm to 5 mm, and pass through a layer of the ceramic particles and re-burn the exhaust gas over the entire exhaust gas by contact with the incandescent ceramic particles. Is performed. In addition, since the ceramic particles can accumulate the heat of combustion of the burner, reburning can be performed with good thermal efficiency.

As a result of using the above-described method and apparatus of the present invention, the residual CO of the exhaust gas at the outlet of the combustion chamber 1 can be reduced to １ ／ to ５ of the exhaust gas at the inlet as a result of the measurement. It is presumed that as a result, the generation and resynthesis of dioxin with CO as a factor will be significantly reduced in proportion to this.

[0029]

According to the present invention, the exhaust gas from a garbage incinerator or the like is reburned by using a high-concentration oxygen burner to remove residual C.
O is eliminated, and furthermore, the reburning exhaust gas is passed through the layer of the ceramic particles so that the exhaust gas is sufficiently contacted for a long time to ensure complete combustion. At the same time, the heat is stored in the ceramic particles and the heat efficiency is improved. After reburning, even if there is a reburn zone as well as an incinerator without a reburn zone, the generation of dioxin, which is considered to be recombined after leaving this incinerator, is greatly reduced. There is an advantage that can be suppressed. Other advantages of the present invention are as described in detail in the above-mentioned embodiments and examples of the present invention.

[Brief description of the drawings]

FIG. 1 is an overall explanatory diagram in which an exhaust gas reburning device according to the present invention is arranged.

FIG. 2 is a vertical side view of the exhaust gas reburning apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combustion chamber 2 Exhaust gas inflow port 3 Exhaust port 4 Oxygen burner 5 Layer of ceramic particles

Claims (6)

[Claims] A method for reburning exhaust gas discharged from a refuse incinerator or the like, wherein the exhaust gas discharged from a refuse incinerator or the like is cooled using cooling means and then discharged to the atmosphere via a dust collector. Then, the exhaust gas discharged from a refuse incinerator or the like is introduced into a cylindrical combustion chamber, and reburned at 800 ° C. or higher by an oxygen burner that burns the fuel with high concentration oxygen. A method for reburning exhaust gas from a garbage incinerator or the like, in which the combustion gas is exhausted after passing through a layer of small-diameter ceramic particles and guided to a dust collector. 2. The exhaust gas from a refuse incinerator or the like according to claim 1, wherein said combustion chamber is oriented vertically, exhaust gas flows upward from below, and the exhaust gas reburn time in said combustion chamber is 4 seconds or more. Reburn method. 3. The method for reburning exhaust gas from a refuse incinerator or the like according to claim 1, wherein said small-diameter ceramic particles have a particle size of 0.5 mm to 5 mm. 4. A reburning device for exhaust gas discharged from a refuse incinerator or the like, which cools the exhaust gas discharged from a refuse incinerator or the like using a cooling means and then discharges the exhaust gas to the atmosphere via a dust collector. An exhaust gas inlet 2 is provided at one end of a cylindrical combustion chamber 1 connected to a refuse incinerator or the like, and an exhaust port 3 is provided at the other end. An oxygen burner 4 that burns with high-concentration oxygen and reburns exhaust gas at 800 ° C. or higher is provided, and is provided at a substantially middle position in the longitudinal direction of the combustion chamber 1 so as to be orthogonal to the longitudinal direction of the combustion chamber 1. An apparatus for reburning exhaust gas from a garbage incinerator or the like, provided with a layer 5 of small-diameter ceramic particles. 5. The combustion chamber 1 is arranged vertically, the inflow port 2 is located at a lower end thereof, and the exhaust port 3 is located at an upper end side. The apparatus for reburning exhaust gas from a refuse incinerator or the like according to claim 4, wherein the combustion time is set to be 4 seconds or more. 6. The ceramic particle having a small diameter is 0.5 to 5 mm in diameter, and the layer 5 of the ceramic particle has a thickness of 3 mm.
The apparatus for reburning exhaust gas from a refuse incinerator or the like according to claim 4 or 5, wherein the diameter is from 00 mm to 600 mm.