JPH03199809A - Fluidized bed type incinerator for igniting waste material containing high rate of moisture - Google Patents

Abstract

PURPOSE:To provide an incinerator for igniting waste material of high moisture content under a high thermal efficiency by a method wherein an auxiliary burner is fixed adjacent to a free board of a combustion chamber. CONSTITUTION:As combustion air is fed into an air chamber 2 at an inlet port 3a and an auxiliary combustion burner 3 to which fuel such as heavy oil or the like is operated, hot gas is blown up from a gas dispersion plate 4, supplied to a combustion chamber 5 and then a combustion fluidized bed 6 is formed. In turn, in the combustion chamber 5, the fuel such as a heavy oil or the like from a plurality of auxiliary burners 8 arranged at an incinerator wall is ignited with combustion air taken through an inlet port 8a and then a flame is discharged toward the free board 7. As beercake containing a high rate of moisture passes from a plurality of raw material injection nozzles 9 and is supplied, a predetermined amount of moisture is evaporated under a combustion of the auxiliary burners 8, the beer-cake dispersed uniformly by the combustion fluidized bed 6 is brought into contact with the flowing medium 6a (sand) of high temperature forming the fluidized bed 6, its moisture content is instantaneously evaporated, thereafter it is agitated with the sand 6a and easily burned.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a fluidized bed that burns and incinerates high water content wastes (residues) such as beer lees, coffee bean grounds, sludge, etc. that contain a large amount of water. This relates to a high water content waste incinerator.

[Conventional technology]

In conventional fluidized bed incinerators, in which highly water-containing waste is burned in a fluidized bed, air is supplied to the combustion chamber for both combustion and fluidization through a gas distribution plate located at the bottom of the incinerator. An auxiliary combustion burner is installed in the air chamber for combustion, and the temperature of the fluidized bed in the combustion chamber is controlled to a high temperature of the target value (-fixed value), and a large amount of water contained in the high water content waste is instantly evaporated in the fluidized bed.
In addition, by burning the waste, the high water content waste is stably combusted and incinerated.

[Problems to be solved by the present invention]

In this way, in a fluidized bed type high water content waste incinerator equipped with an auxiliary combustion burner in the air chamber, when burning high water content waste, especially high water content waste containing 80% or more water, or Even if the moisture content of the waste during normal operation is lower than this value, if it exceeds this high value, the amount of auxiliary combustion will increase, and with normal air volume, the gas temperature in the air chamber will increase. rises too much, and in order to maintain the heat resistance of the air chamber, the amount of air must be increased and the temperature must be lowered.

In such a situation, it is natural to be forced to operate with poor thermal efficiency.

On the other hand, in order to deal with such problems, a sand burner is installed in the combustion chamber so as to face the fluidized bed (fluidized medium).
There is a method of injecting fuel such as heavy oil into a fluidized bed, but this method requires a large number of burners due to the limited capacity of each burner, and combustion is greatly affected by the temperature of the fluidized medium, resulting in unstable combustion. The problem is that it is difficult.

The present invention aims to eliminate such problems and provide a fluidized bed type high water content waste incinerator with good thermal efficiency.

[Means to solve the problem]

In order to achieve the above object, the fluidized bed type high water content waste incinerator of the present invention has an air chamber equipped with an auxiliary combustion burner in the lower stage, and a free board provided with a gas distribution plate in the upper stage. A fluidized bed having a combustion chamber for burning the supplied high-water content waste in a fluidized bed formed by fluidizing the supplied high-water content waste with high-temperature air supplied from the air chamber, and having an exhaust gas outlet on the downstream side of the combustion chamber. In the type high water content waste incinerator, an auxiliary burner is attached to the combustion chamber so as to face the freeboard of the combustion chamber.

[For production]

By performing combustion with flame in the freeboard (combustion chamber space), the temperature of the gas in the freeboard is increased, and by utilizing the radiant power (radiant heat) of the gas, the temperature of the fluidized bed in the combustion chamber is increased. This makes it possible to reduce the amount of auxiliary combustion of the auxiliary combustion burner in the air chamber, thereby eliminating the need to use unnecessary cooling air. Therefore, thermal efficiency is improved and boiler efficiency is improved.

In addition, as the temperature of the freeboard rises, high water content waste is fed into the freeboard, and while it reaches the fluidized bed, a predetermined amount of moisture in the high water content waste is evaporated and dried, and at the same time, it is dried from the combustion fluidized bed. Since a part of the unburned matter (unburned carbon) discharged is burned, the combustion of the unburned matter also contributes. In particular, this combustion chamber is a primary combustion chamber, and a secondary combustion chamber having a fluidized bed is provided downstream of this primary combustion chamber to form a two-stage combustion furnace, and complete combustion is carried out in this secondary combustion chamber. In some cases, the combustion of a portion of the unburnt material on the freeboard has the effect of raising the temperature of the fluidized bed in the secondary combustion chamber, further enhancing the characteristics of two-stage combustion.

〔Example〕

Fig. 1 and Fig. 2 explain the present invention in detail, Fig. 1 is a schematic vertical cross-sectional view of a fluidized bed type high water content waste incinerator, and Fig. 2 is a view taken in the direction of the arrow ■ in Fig. 1. FIG. 3 is a side view of main parts.

In FIG. 1, the overall configuration of a fluidized bed type high water content waste incinerator 1 includes an air chamber 2 located at the bottom, a primary combustion chamber 5 located above it via a gas distribution plate 4, and further A secondary combustion chamber 11 is connected to the upper stage through another gas distribution plate IO.
is located and configured. In the air chamber 2, an auxiliary combustion burner 3 having a combustion air intake port 3a is attached to the furnace wall.

A large number of gas distribution pipes 4a are attached to the lower gas distribution plate 4, and the high temperature air in the air chamber 2 is transferred to the gas distribution pipes 4.
It is supplied into the primary combustion chamber 5 through a. -Next combustion chamber 5
At the upper part of the gas distribution plate 4, a fluidized medium 6a made of silica sand or the like having a particle size of 1+ nm or less is transferred from the air chamber 4 to the gas distribution plate 4.
The primary combustion fluidized bed 6 is fluidized by the high temperature air dispersed and blown up from the gas distribution pipe 4a.

The upper part of this secondary combustion fluidized bed 6 is a free board (space part)
7, and an auxiliary burner 8 is attached to the furnace wall facing the freeboard 7. A combustion air intake port 8a is attached to the auxiliary burner 8. On the furnace wall above the auxiliary burner 8, there is a 'ax mist nozzle (also called a raw material supply dispersion nozzle) 9 for beer (wheat) lees (hereinafter sometimes referred to as raw material) as high water content waste. is set up.

The raw material spray nozzle 9 disperses and supplies high water content waste, which is a raw material supplied from the center, forward while mixing it in a mixing chamber at the tip with compressed air or steam supplied from the periphery. Further, as shown in FIG. 2, a plurality of auxiliary burners 8 and a plurality of raw material spray nozzles 9 are each mounted facing the furnace wall, and the auxiliary burner 8 is installed so as to be located between the raw material spray nozzles 9.

- A secondary combustion chamber 11 is located above the combustion chamber 5 with a gas distribution plate 10 interposed therebetween. The gas dispersion pipe 10a of the gas dispersion plate 10 is formed of a straight pipe so that the combustion ash of the waste in the primary combustion chamber 5 can travel straight when passing together with the exhaust gas, and is designed to prevent adhesion as much as possible. There is. At the upper part of the gas distribution plate 10, a secondary combustion fluidized bed 12 formed of a fluidized medium 12a made of silica sand or the like with a particle size of 1 mm or less, similar to the primary combustion fluidized bed 6, is fluidized by the combustion exhaust gas from the primary combustion chamber 5. and formed. An exhaust gas outlet 13 is attached to the upper part of the secondary combustion chamber 11.

The operation of the fluidized bed type high water content waste incinerator 1 configured as described above will be explained.

In the air chamber 2, combustion air is introduced from the intake port 3a, and fuel such as heavy oil is supplied to the auxiliary combustion burner 3, so that the auxiliary combustion burner 3 is operated. This will result in 800-100
High-temperature gas at 0°C is blown up from the gas distribution plate 4 and supplied to the primary combustion chamber 5 to form a primary combustion fluidized bed 6. The temperature of this dry-burning fluidized bed 6 is maintained at, for example, 750° C. by controlling the combustion amount of the auxiliary combustion burner 3.

On the other hand, in the grilling chamber 5, fuel such as heavy oil is combusted by the combustion air taken in from the intake port 8a from a plurality of auxiliary burners 8 provided on the furnace wall, as shown by the symbol A in FIG. The flame is emitted toward the freeboard 7, which raises the temperature of the freeboard 7, and the temperature of the fluidized bed in the combustion chamber due to the radiation of the gas. In this case, - when the temperature of the sintered fluidized bed 6 is 750°C, the temperature of the freeboard 7 is 800°C.
~900°C. Further, since a plurality of auxiliary burners 8 are arranged in the width direction, the temperature of the freeboard 7 can be made as uniform as possible. Then, from a plurality of raw material spray nozzles 9 arranged on the furnace wall above it, beer lees is passed through the free board 7 as a highly water-containing waste containing, for example, 80% water, as shown by the symbol B in FIG. It is evenly distributed and supplied to the six sides of the primary combustion fluidized bed, drawing a trajectory. While the beer grounds reach this primary combustion fluidized bed 6, a predetermined amount of water is evaporated by combustion in the auxiliary burner 87=8, and the load on the primary combustion fluidized bed 6 is reduced. When the beer lees comes into contact with the fluidized medium 6a (sand) heated to a high temperature that forms a fluidized bed in the primary combustion fluidized bed 6, its water content is instantaneously evaporated.

Beer lees that have lost moisture are easily combusted while being stirred by sand in a fluidized bed. An analysis example of this beer lees shows that the higher calorific value is 4850 Kcal/dry kg, and the elemental components are carbon 48.86%, hydrogen 6.91%, oxygen 37.14%, nitrogen 3.23%, and ash content 3. 28%, others 0.58%.

Approximately 70 to 80% of the beer lees is combusted in this Kinranyaki fluidized bed 6, and the remaining approximately 30 to 20% is unburned matter (unburned carbon).
accompanies the combustion gas and passes through the freeboard 7 and the gas distribution plate IO together with the ash, and then enters the secondary combustion chamber 11.
will be introduced to At this time, while the unburned matter passes through the freeboard 7, a part of it is combusted in a high-temperature atmosphere caused by combustion in the auxiliary burner 8. A secondary combustion fluidized bed 12 is formed in the secondary combustion chamber 11, and the remaining unburned matter introduced therein is finally combusted and completely combusted. Secondary combustion fluidized bed is created by combustion of such unburned matter on the freeboard 7]2
temperature can be increased, and the characteristics of two-stage combustion can be further enhanced.

From the secondary combustion chamber 11, combustion exhaust gas at a temperature of 800 to 900°C is discharged from an exhaust gas outlet 13 and guided to a waste heat boiler (not shown), where the amount of heat is recovered and converted into steam.

However, in the present invention, since the auxiliary burner 8 is operated in the primary combustion chamber 5 as described above, even when high water content waste containing as much as 80% water is burned and incinerated, free board Since the temperature of the primary combustion fluidized bed 6 can be raised by increasing the gas temperature at 7 and utilizing the radioactivity of the gas, there is no need to increase the amount of auxiliary combustion in the auxiliary combustion burner 3 in the air chamber 2, and the accompanying cooling No need to use air (excess air). Therefore, boiler efficiency can be increased. Furthermore, even if the waste contains high water content and has relatively little water content, even when the water content has increased significantly, the same can be done without increasing the amount of auxiliary combustion in the auxiliary combustion burner 3.

0 In this embodiment, the combustion chamber is composed of the primary combustion chamber 5 and the secondary combustion chamber 11 to perform two-stage combustion. Since it can be completely captured and completely combusted, combustion efficiency is high.
Further, a blast hearth load of 400 to 450 kg/bohr can be obtained. Moreover, compared to an incinerator consisting of a fluidized bed with only one stage, the cylinder velocity can be increased, the area of the fluidized bed can be reduced, and the furnace can be made smaller and more compact.

In FIG. 1, the raw material spray nozzle 9 is installed horizontally, but depending on the raw material, the nozzle 9 may be installed with its tip side tilted downward.

〔Effect of the invention〕

As is clear from the above explanation, in the present invention, the temperature of the fluidized bed can be raised by increasing the freeboard temperature of the combustion chamber with the auxiliary burner and utilizing the gas radiation ability, so the auxiliary combustion burner in the air chamber is There is no need to increase the amount of auxiliary combustion in the cooling air (excess air).
There is no need to use . Therefore, boiler efficiency can be increased.

In addition, as the temperature of the freeboard section rises, high water content waste is fed into the freeboard section, and while it reaches the fluidized bed, a predetermined amount of moisture in the high water content waste can be evaporated and dried. Not only can the combustion state in the bed be improved, but also part of the unburned matter (unburnt carbon) discharged from the combustion fluidized bed can be combusted in the freeboard, resulting in improved combustion efficiency.

[Brief explanation of drawings]

Figures 1 and 2 are detailed explanations of the present invention, with Figure 1 being a schematic vertical cross-sectional view of a fluidized bed type high water content waste incinerator, and Figure 2 being taken in the direction of the arrow ■ in Figure 1. FIG. 3 is a side view of main parts. 1... Fluidized bed type high water content waste incinerator, 2... Air chamber, 3... Burner for auxiliary combustion, 4, IO... Gas distribution plate,
5...-Kinzenyaki room, 6...-Kinzenyaki fluidized bed, 7...
- Free board, 8... Auxiliary burner, 9... Raw material spray nozzle, 11... Secondary combustion chamber, 12... Secondary combustion fluidized bed, 13... Exhaust gas outlet. 3

Claims (1)

[Claims] The lower stage has an air chamber equipped with an auxiliary combustion burner, and the upper stage is provided through a gas distribution plate, and the highly water-containing waste supplied to the freeboard is fluidized with high-temperature air supplied from the air chamber. In a fluidized bed type high water content waste incinerator that has a combustion chamber for combustion in a fluidized bed and has an exhaust gas outlet on the downstream side of the combustion chamber, an auxiliary burner is installed facing the freeboard of the combustion chamber. A fluidized bed type high water content waste incinerator characterized by the following: