JPS6235004B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to solid wastes such as municipal waste and waste plastics, solid organic matter contained in large amounts in liquids such as sludge, solid fuels such as coal, and other solid materials. This invention relates to a combustion method and apparatus.

When burning solid materials, a fluidized bed incinerator that uses solid particles such as sand as a heat medium has many advantages as is well known, but has the following drawbacks. That is, if a raw material with an extremely high calorific value, such as municipal waste containing a large amount of plastic, is burned under excessive load, and the heat generation rate per unit surface area of the solid exceeds the maximum heat transfer rate of the fluid heat medium (sand),
The local temperature becomes abnormally high, and the heating medium becomes semi-molten, forms a coagulum, and finally becomes unable to be fluidized.

For raw materials with high calorific value such as plastics, the amount of air required for combustion is extremely large, far exceeding the amount of gas required for fluidization, so the diameter of the fluidized bed must be set larger than necessary, which is uneconomical. becomes.

In fluidized bed combustion, ash is mixed into the combustion gas in the form of fine particles, but because the particle size is so small that it cannot be sufficiently captured by general mechanical dust collectors, and even after dust collection. Special measures are required to prevent dust generation.

If the raw materials contain harmful heavy metals, such as municipal waste, waste plastics, sewage sludge, or coal, the heavy metals will be concentrated in the collected ash, so solidification treatment is required to prevent heavy metals from leaching out when landfilling. Measures such as these are required.

There were problems such as.

To solve this problem, a fluidized bed pyrolysis method is used, and since this method is an endothermic reaction, it solves the above problem, and the problem can also be solved using a partial combustion method or the like. However, even in the fluidized bed pyrolysis method, the above problems could not be solved.

On the other hand, the well-known cyclone combustion furnace not only enables efficient combustion due to the powerful swirling flow of air, but also improves dust collection performance by trapping and melting ash on the inner wall of the cyclone when performing high-load combustion. However, in order to apply a cyclone combustion furnace, it is necessary to crush the raw material to a fine particle size, which causes a loss of power and wear and tear of equipment for pre-treatment, and also requires the use of oil. There were problems such as the need for fuel such as

The inventors have repeatedly conducted research to solve the above-mentioned problems, and the technical idea of the present invention has been created. The disadvantage is that these ash are difficult to capture and remove because they are fine, but they can be decomposed into flammable gas and fine solid particles. must be finely crushed,
By combining the characteristics of efficient combustion and dust collection, and the ability to extract ash as molten slag, it was created with the focus on the point that it could compensate for the shortcomings of both and provide an excellent combustion method. It is something.

The present invention performs the pyrolysis process using a fluidized bed, and takes advantage of the fact that the char and ash contained in the gas produced by pyrolysis become fine particles.This gas is introduced into a cyclone combustion furnace, where it is pressurized. By burning combustibles (gas and char) with air, in addition to the above-mentioned drawbacks of the conventional method, there is no agglomeration of the heating medium, and the dust collection performance of ash is good.
The size of the fluidized bed furnace is reduced, the elution of heavy metals is prevented, and a high performance, compact, and simple structure combustion method for solids that does not require special pulverization pretreatment for cyclone incinerators, and its The purpose is to provide a device.

The present invention thermally decomposes solid raw materials in a fluidized bed pyrolysis furnace, introduces the pyrolysis products into a cyclone combustion furnace, burns combustibles with pressurized air in the cyclone combustion furnace, and removes ash. A method for combustion of solids, characterized by separating the
a fluidized bed pyrolysis furnace and a cyclone combustion furnace, the furnace top outlet of the fluidized bed pyrolysis furnace and the furnace top inlet of the cyclone combustion furnace are connected by a pyrolysis product transfer path, and the cyclone combustion furnace an air supply device for supplying pressurized air for combustion to the fluidized bed pyrolysis furnace;
The solid matter combustion apparatus is characterized in that the lower part is equipped with a non-combustible material discharge port, the upper part of the cyclone combustion furnace is equipped with an exhaust gas outlet, and the lower part is equipped with an ash discharge mechanism.

Embodiments of the present invention will be described with reference to the drawings. In FIGS. 1 and 2, 2 is a fluidized bed pyrolysis furnace, and 11 is a cyclone combustion furnace. The fluidized bed pyrolysis furnace 2 is equipped with a raw material supply device 1 in the upper part, and a gas chamber 5 is partitioned with a dispersion plate 6 in the lower part. 4 is a gas inlet for introducing fluidizing gas into the gas chamber 5, and this fluidizing gas is ejected from the dispersion plate 6 to form a fluidized bed 3 using sand as a heat medium. 7 is a free board, and 8 is an outlet led out in the tangential direction of the circular cross section of the cylinder of the free board 7. The dispersion plate 6 has a loose conical shape,
Double discharge valve 2 for taking out non-combustible materials at the bottom of the center
2 is provided.

In the cyclone combustion furnace 11, an inlet 23 is provided in the upper part in a tangential direction, and an outlet 18 for exhaust gas is provided in the center of the upper part. 13 is an arrow indicating the flow of molten slag, and 14 is a molten slag discharge port. 15 is a water chamber for cooling and solidifying the molten slag into granules; 16 is a conveyor; and 17 is a double discharge valve.

The outlet 8 and the inlet 23 are connected by a gas flow path 24 as a pyrolysis product transfer path, and an air ejector 9 is provided in the middle. Pressurized air is supplied to the air ejector 9 by a blower 10, which sucks gas from the freeboard 7 and supplies it to the cyclone combustion furnace 11. 12 is an arrow indicating the swirling flow in the cyclone combustion furnace 11.

19 is a heat exchanger, 20 is a dust collector such as an electrostatic precipitator, and 21 is a blower that supplies air as a fluidizing gas.

To explain the operation, raw materials such as municipal waste and sludge are supplied from the raw material supply device 1 to the fluidized bed pyrolysis furnace 2, and the remainder is heated and thermally decomposed by partial combustion in the fluidized bed 3.

Air enters the gas chamber 5 through the gas inlet 4 and passes through the gas distribution plate 6 to fluidize the sand and combust some of the raw material. The char and combustible gas generated by thermal decomposition and the ash and combustion exhaust gas generated by partial combustion are all transferred from the tower top freeboard 7 to the cracking furnace outlet 8.
The mixture of air and gas is sucked and accelerated by the pressurized air supplied by the blower 10 in the air ejector 9, and is sent to the cyclone combustion furnace 11 at high speed in the tangential direction, in the direction of the arrow 12. The pyrolysis products (gas and char) are combusted by creating a strong swirling flow. That is, the freeboard section has a reducing atmosphere, and the cyclone section has an oxidizing atmosphere. The outer surface of the cyclone combustion furnace 11 is preferably a water-cooled chamber (not shown), and the inner surface is preferably made of carborundum or chromite refractory. When high-load combustion is performed, the ash melts and the dotted line arrow 13
The ash and chir collide with the wall surface due to the centrifugal force caused by the swirling flow, and adhere to the wall surface which is wetted by the molten ash. Because it produces a large relative velocity, it burns at an extremely high burning rate. Also, due to the centrifugal force effect and the wet wall effect, ash is captured with high efficiency, becomes molten slag, falls from the discharge port 14 into the water chamber 15, is solidified into granules, and is sent to the double discharge valve 17 via the conveyor 16. It is then taken out of the system. Since the heavy metals in the ash are contained by melting and solidifying the ash, it is possible to prevent heavy metals from leaching out during landfilling.

The combustion exhaust gas is discharged from the cyclone furnace outlet 18 to the outside of the system through a heat exchanger 19 and, if necessary, an electrostatic precipitator 20 for collecting uncollected dust. In addition, when the electrostatic precipitator 20 is provided, it is preferable to supply the dust discharged from this to the cyclone combustion furnace 11 again (the supply device is not shown) and melt and solidify it.

The air supplied to the fluidized bed pyrolysis furnace 2 is supplied to the blower 21.
The temperature of the gas is raised through the heat exchanger 19 and the gas is supplied to the gas inlet 4. In addition, the fluidized bed pyrolysis furnace 2 is shown in the figure.
A starting burner, an ignition device, etc. necessary for each of the cyclone combustion furnaces 11 and 11 are not shown.

In the pyrolysis furnace, the exhaust gas contains harmful components such as carbon monoxide and cyan gas, so it is necessary to sufficiently prevent gas leakage from the raw material supply device 1. In this embodiment, the pyrolysis product gas from the fluidized bed pyrolysis furnace 2 is sucked in by the air ejector 9, so it is easy to reduce the pressure of the freeboard 7 to below atmospheric pressure. By maintaining such a pressure, gas leakage from the raw material supply device 1 to the outside air can be prevented, and there is also the advantage that the configuration of the raw material supply device can be simplified.

If the fluidizing gas requires an air amount greater than that required for partial combustion, a portion of the outlet gas of the cyclone combustion furnace 11 may be supplied to the gas chamber 5 of the fluidized bed pyrolysis furnace 2 as the fluidizing gas.

The above-described embodiment is constructed and operates as described above, and has the following effects.

Since pyrolysis is an endothermic reaction, it is only necessary to supply a small amount of air to cause partial combustion commensurate with the calorific value required for pyrolysis, so even raw materials with extremely high calorific values such as plastics can be processed in a fluidized bed. heat medium (sand) due to local abnormally high temperatures
There is no coagulum formation and the amount of air required is small due to partial combustion.
There is no need to set the column diameter of the fluidized bed excessively.

Furthermore, after the pyrolysis process is completed, the cyclone combustion furnace itself not only functions as a dust collector, but also when high-load combustion is performed, ash is captured and melted on the inner wall of the cyclone, and the inner wall surface becomes wet and fine ash is removed. Dust collection performance is improved, and harmful heavy metals in the raw materials are contained by melting the ash, making it unnecessary to take measures such as solidification treatment to prevent heavy metals from leaching during landfilling.

Furthermore, since the solids supplied to the cyclone combustion furnace are fine particles such as char produced by thermal decomposition and ash produced by partial combustion, the fine crushing treatment of raw materials, which was indispensable to the conventional cyclone combustion method, is no longer necessary. No longer needed.

Extremely excellent effects such as these can be obtained.

The present invention thermally decomposes solid raw materials in a fluidized bed pyrolysis furnace, introduces the pyrolysis products into a cyclone combustion furnace, burns combustibles with pressurized air in the cyclone combustion furnace, and removes ash. By separating the
That is, fine ash is generated, which is difficult to capture, and the ash contains heavy metals, making it difficult to remove them.Furthermore, the ash is removed by melting it at high temperatures because it causes melting of the fluid medium. The cyclone combustion furnace compensates for the disadvantage that it is not possible to
Ash can be captured by melting and removed effectively.
At the same time, it is possible to remove heavy metals, and on the other hand, the disadvantages of cyclone combustion furnaces, namely, that the material to be treated must be pulverized in advance in order to perform combustion in a short time, and fuel such as oil is required, can be solved by using fine particles. The fluidized bed pyrolysis furnace generates combustible gas mixed with ash, etc., which eliminates the need for pre-fine crushing equipment, and since the pyrolysis gas is combusted, no fuel is required. be effective.

In other words, by combining the fluidized bed pyrolysis method and the cyclone combustion method, the advantages of both methods are utilized and the disadvantages are offset and eliminated, and the synergistic effect is to create a solid combustion method and apparatus with extremely significant effects. can be provided, and has extremely great practical effects.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a flow diagram of a cross section taken along the OPQR line in FIG. 2, and FIG.
- Z-line cross-sectional plan view. 1... Raw material supply device, 2... Fluidized bed pyrolysis furnace, 3...
Fluidized bed, 4... Gas inlet, 5... Gas chamber, 6... Dispersion plate, 7... Free board, 8... Outlet, 9... Air ejector, 10... Blower, 11... Cyclone combustion furnace, 12... Arrow, 13... Arrow, 14...Exhaust port, 1
5...Water chamber, 16...Conveyor, 17...Double discharge valve,
18... Outlet, 19... Heat exchanger, 20... Dust collector,
21...Blower, 22...Double discharge valve, 23...Inlet,
24...Gas flow path.

Claims (1)

[Claims] 1. A solid raw material is pyrolyzed in a fluidized bed pyrolysis furnace, the pyrolysis product is introduced into a cyclone combustion furnace, and combustible components are combusted with pressurized air in the cyclone combustion furnace. A method for burning solid materials, which is characterized by separating the ash and ash. 2 comprising a fluidized bed pyrolysis furnace and a cyclone combustion furnace, the furnace top outlet of the fluidized bed pyrolysis furnace and the furnace top inlet of the cyclone combustion furnace are connected by a pyrolysis product transfer path, and the cyclone combustion furnace The furnace is equipped with an air supply device that supplies pressurized air for combustion, the upper part of the fluidized bed pyrolysis furnace is equipped with a raw material solid supply mechanism, the lower part is equipped with an incombustible material discharge port, and the upper part of the cyclone combustion furnace A solid material combustion device characterized by having an exhaust gas outlet at the bottom and an ash discharge mechanism at the bottom.