JPS6361811A - Method of burning combustible lump matter - Google Patents

Abstract

PURPOSE:To continuously perform the complete burning by throwing in lump matters as they are and burying them in the fluidized bed layer in the furnace so as to minimize the surface area exposed to the fluid medium for gradual burning, and regulating the frequency of feeding and the quantity of each feed. CONSTITUTION:When tires which are fed drop in the center of the surface of the fluidized layer, they are heated like a roast as they are buried in the fluid medium and settle in the descending layer. They are pushed back from the bottom of the descending layer to the bottom of the ascending layer by the spiral flow of the fluid medium, and are burnt in the ascending layer by the collision of the oxygen and fluid medium. Remaining steel wires are softened by the high temperature of the fluidized layer and are rounded by the swirl of the fluid medium. They are gathered at the lower end of the exposing surface as they become granular shapes, and transferred to a noncombustible matters removal conveyer along with the fluid medium to be discharged out of the furnace. Thereafter, they are separated from the fluid medium, which are delivered to a feed conveyer to be returned to the top of the fluidized layer in the furnace. The separated steel wire lumps are carried outside by a conveyer for storage. By this, the labor and cost for maintaining the furnace can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a combustion method for burning lump-like combustion materials such as waste tires, waste plastic products, waste covered electric wires, etc. in the lump state.

[Conventional technology]

Conventionally, when attempting to burn this type of lumpy combustion material in a fluidized bed incinerator, it is common practice to crush it finely and scatter it over the entire surface of the fluidized bed in order to achieve complete combustion without any unburned remains in a short period of time. Met. The reason for this is that when a lump is put into a fluidized bed as it is, its surface comes into intense contact with the hot fluidized medium, causing the surface to become finely crushed, increasing the surface area, and immediately reaching the ignition point, causing it to ignite and burn quickly. Sisters,
- Problems such as temporal and local oxygen shortages and overheating of the fluidized medium, resulting in incomplete combustion and clinker generation;
Furthermore, since it is a lump, it is difficult to supply it continuously and quantitatively to a fluidized bed, making combustion management difficult. Also, when used as fuel, fluctuations in the amount of heat generated are unavoidable, so for example, it is difficult to control the amount of heat generated in a steam boiler. However, the amount of steam generated and the steam pressure change, as well as the temperature of the fluidized medium and the temperature and air volume of the generated exhaust gas, making operation control difficult.

In addition, as a method of combustion of lumpy combustion materials, there is also a method of burning over a long period of time while supplying a large amount of air using a stoker type, a rotary kiln type, etc. without using a fluidized bed.

[Problem that the invention seeks to solve]

However, when the above-mentioned lumpy combustion material is finely crushed by a crusher, metal pieces, ceramic pieces, metal wires used in tires, covered electric wires, steel wires for binding, etc. may damage the crusher's crushing teeth, or This or the incombustible material discharge device became entangled, requiring a great deal of effort and expense for repair and operation and maintenance. In addition, in the case of a combustion method that does not use a fluidized bed, there will be a local oxygen deficiency in the furnace, and at the same time there will be an excess of oxygen elsewhere, resulting in black smoke, CN,
A large amount of harmful gas such as 0 is generated, a high concentration of NOx is generated, and the furnace material is easily damaged by pit heat and corrosive gas.
In addition, a large amount of unburned remains and metal wires are entangled, making it difficult to discharge and dispose of the residue inside the furnace, which requires a great deal of effort and expense for repair costs and operation and maintenance. It was even more difficult because the work was inside the furnace.

The object of the present invention is to provide a safe and inexpensive combustion method in terms of labor, expense, and pollution when incinerating this kind of lumpy combustion material, which has been a problem in the past.

Means for Solving Problem C] In order to achieve the above-mentioned object, the present invention operates a fluidized medium made of granular solids in a combustion furnace at a temperature higher than the ignition point of the combustible material, and at a temperature higher than the melting point, softening point, and sintering point of the fluidized medium. While keeping the temperature lower than any of the nodes, a gas containing oxygen is diffused from the bottom to form a fluidized bed, and the lumpy combustion material is put in the lumped state into the fluidized bed. The present invention provides a method for burning lumpy combustible materials, which is characterized by controlling the input frequency and the quantity per frequency.

[For production]

In the present invention, when burning bulk combustion materials such as waste tires, waste plastic products, and waste coated electric wires, the materials are placed in a fluidized bed in a furnace in almost their original shape without being subjected to a crusher, and are then buried in a fluidized bed. By minimizing the surface exposed to heat, smooth combustion can be achieved as a fluidized bed combustion, and by controlling the combustion by adjusting the input frequency and the quantity per frequency, complete combustion can be achieved continuously. It made it possible. In addition, the metal wires contained in these combustion materials are entangled and rolled into particles due to the swirling flow of the fluidized medium, and are smoothly discharged from the furnace together with the fluidized medium, and are separated from the fluidized medium by a classifier. The granular lumps of metal wire are collected.

〔Example〕

The present inventors have developed a known fluidized bed incinerator (for example, JP-A-57
-124608), the following experiments were conducted and a number of findings were obtained.

(1) Before burning waste tires, a zirconia oxygen concentration sensor is inserted into the flue of the incinerator, which continuously records the oxygen concentration of the exhaust gas with high responsiveness. Inserted into the center.

As a result, the oxygen concentration in the exhaust gas changed as shown in FIG. The exhaust smoke from the chimney was also not particularly different (even when six pipes were injected at the same time, only a slight amount of thin white smoke was visible at the peak of the oxygen concentration drop in the exhaust gas). It was filled with water, indicating a good condition.

Therefore, an oxygen concentration of about 5% in the exhaust gas is considered appropriate for stable combustion of waste tires.

As shown in Figure 1, combustion peaks approximately 1 minute after the waste tire is introduced. When the amount of gas added at one time was 6, the oxygen concentration in the exhaust gas at the peak time was about 3 to 4%, and slightly thin white smoke was visually observed. Therefore, if the input amount is 5 bottles, the oxygen concentration at the peak is predicted to be about 6 to 7%. waste tires 5
The oxygen concentration when books are intermittently added at one-minute intervals is the second
As shown in the figure.

In other words, if you add 5 scrap tires at 1-minute intervals, the oxygen concentration in the exhaust gas will be approximately 5%, resulting in stable combustion! ! Continued.

This means that if you want to reduce the number of scrap tires you put in at one time, you can shorten the throw-in interval. Further, by appropriately selecting the number of fuels to be introduced and the interval between charges depending on the size of the combustion furnace, it is possible to incinerate while maintaining the oxygen concentration in the exhaust gas at about 5% or more. Figure 3 shows 30 pieces of one waste tire.
This shows the oxygen concentration in the exhaust gas when it is injected at intervals of seconds.

Note that the metal wires in the radial tire were separated and discharged from the fluid medium as a large number of granular lumps approximately 10 to 20 cm in size that were quite tightly intertwined.

(2) Metal wire incineration A large amount of steel wire, commonly known as annealed steel wire with a diameter of 3 fi and a length of about 2 m, was put into an incinerator and its behavior was observed. As a result, all the steel wires that were introduced had a large number of 10~
20c1) A lump with a diameter of the following is formed and is discharged from the fluidized medium circulation line to remove noncombustibles from the fluidized bed, that is, during operation, is discharged from the furnace together with the fluidized medium by a noncombustibles removal conveyor while maintaining a seal inside and outside the furnace. A vibrating sieve, which is a material classification device, removes the non-combustibles from the fluidized medium below the sieve, which is returned to the furnace. Thereafter, the furnace was shut down, all fluidized media was discharged, and the inside of the furnace was inspected. As a result, no fluid remained in the hearth.

Observing the above experiment, when a tire is placed in the fluidized bed and falls to the center surface of the fluidized bed, it is buried in the overflowing fluidized medium and sinks in the descending layer, heated by the fluidized bed, becomes steamed, and starts rising from the bottom of the descending layer. It is swept away by the swirling flow of the fluidized medium at the bottom of the rising layer, and combusts at the main part of the rising layer due to collision between sufficient oxygen and the violent fluidized medium. The remaining metal steel wire is scratched and softened by the high temperature of 600 to 900 degrees Celsius in the fluidized bed, and as a result, it is quickly rolled up by the movement of the swirling flow of the fluidized medium in the fluidized bed and becomes a granular lump of 10 to 20 cm or less. , they are swept up and collected at the bottom of the lower side of the diffuser surface by the movement of the swirling flow. From there, it passes through a chute, enters a noncombustible material removal conveyor together with a fluidized medium, and is discharged out of the furnace.

Thereafter, it is separated from the fluidized medium by a non-combustible material classifier using a vibrating screen or a rotary sieve, and the fluidized medium is supplied to an input conveyor by a circulation elevator or the like, and returned to the furnace from above the fluidized bed while maintaining a seal between the inside and outside of the furnace. The separated metal wire lumps are carried out and stored on a conveyor.

In addition, if other incombustible materials are mixed in, the iron and copper components can be recovered by magnetic separation or eddy current separation and reused as valuable materials.

〔Effect of the invention〕

The present invention eliminates the need to crush combustible materials such as waste tires, waste plastic products, and waste covered electric wires, which have traditionally been considered difficult.
This makes it possible to perform fluidized bed combustion in the round state, and by putting the lumpy combustion material into the fluidized medium, the surface exposed to the fluidized medium is minimized and it is covered as fluidized bed combustion. To achieve this, complete combustion is achieved continuously by controlling combustion by adjusting the amount of fuel injected into the furnace and its frequency.

Furthermore, the metal wires and bundles of covered electric wires contained therein can be taken out of the furnace together with the fluidized medium as granular lumps entangled by the movement of the swirling flow of the fluidized medium.

Therefore, not only can we incinerate bulk combustible materials such as waste tires, waste plastics, and waste covered electric wires, but we can also use these as fuel.
It is possible to recover heat from the exhaust gas or from the fluidized medium using a fluidized bed boiler, which is an energy saving measure. Furthermore, there is no need for a crusher, which was conventionally required, and the metal wire can be smoothly discharged, thereby reducing the labor and expense required for furnace maintenance.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an experimental example, FIGS. 2 and 3 are detailed explanatory diagrams of the present invention, and FIG. 4 is a schematic explanatory diagram of an apparatus for implementing the present invention.

Claims (2)

[Claims] (1) While maintaining a fluidized medium made of granular solids at a temperature above the ignition point of the combustion material and lower than any of the melting point, softening point, and sintering point of the fluidized medium in a combustion furnace, a gas containing oxygen is released from the bottom surface. A lumpy combustion method is characterized in that a fluidized bed is formed by aeration, and the lumpy combustion material is charged in the lumped state into the fluidized bed, and the frequency of injection and the quantity per frequency are controlled. How to burn combustible materials. (2) The fluidized bed forms a fluidized bed on the diffuser surface by varying the flow rate per unit area of the diffuser surface of the diffuser gas containing oxygen diffused into the bottom of the furnace, and By tilting the diffuser surface, in areas where the flow rate of the diffuser gas is relatively high, the diffuser surface is relatively low and the fluid medium rises as a whole, and in areas where the flow rate is relatively low, the diffuser surface is relatively low. is high and the fluidized medium as a whole descends, in the upper layer of the fluidized bed from a region where the flow rate of the aeration gas is relatively high to a region where it is low, and in the lower layer of the fluidized bed from a region where the flow rate of aeration gas is relatively low to a region where it is high. The fluidized medium swirls in the fluidized bed, and the lumpy combustion material containing the metal wire is thrown into the descending part of the fluidized medium, and the metal wire is entangled in the form of granular lumps that are diffused. 2. The method of burning a lumpy combustion material according to claim 1, wherein the combustion material is discharged from the furnace together with the fluidized medium from near the lower end of the surface.