JP3838589B2 - Method and apparatus for pyrolysis gasification and melting of waste - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for separating and circulating solids discharged from a fluidized bed gasification furnace, and in particular, municipal waste, solidified fuel, slurried fuel, waste plastic, waste FRP, biomass waste, automobile waste low grade The present invention relates to a pyrolysis gasification and melting method and apparatus for waste, such as charcoal and waste oil, which are pyrolyzed and gasified at low temperatures.
Among the above, the solidified fuel (= RDF) is a product obtained by crushing and sorting municipal waste and then adding quick lime etc. to compression molding. It is oiled by pyrolysis.
[0002]
[Prior art]
Conventionally, fluidized bed gasification furnaces that thermally decompose and gasify at low temperatures have been used in "gasification and melting systems" that combine gasification and melting combustion as a new next-generation waste treatment technology that replaces incineration. Some have already reached the point of practical use. This "gasification melting system" shows the target features.
(1) Due to low air ratio combustion, the amount of exhaust gas is greatly reduced.
(2) Dioxins and furans are hardly generated due to high temperature combustion.
(3) Ash content in waste is recovered as harmless slag from which heavy metals do not elute. For this reason, the life of the landfill can be extended and it can be used for roadbed materials.
(4) The retained energy of gas, tar, and carbide generated by gasification can be effectively used as a heat source for ash melting.
(5) Since the functions of dioxin treatment and ash melting are incorporated into the system, the entire apparatus is made compact, and the construction costs are lower than those provided for conventional incineration facilities.
[0003]
FIG. 3 shows a combination of a fluidized bed gasification furnace (preferably using an internal swirling fluidized bed) and a swirling melting furnace as components of a known “gasification melting system”. In FIG. 3, 1 is a waste supply apparatus, 2 is a fluidized bed gasification furnace, 3 is an air chamber, 4 is an air dispersion plate, 5 is a fluidized bed, 6 is a free board, 7 is a swirl melting furnace, and 8 is primary combustion. Chamber, 9 is a secondary combustion chamber, 10 is a slag separator, 11 and 12 are burners for heating, a is waste, b is primary air, c is secondary air, d is product gas, e is tertiary air, f is exhaust gas and g is slag.
The outline of the gasification melting system will be described with reference to FIG. The waste a is subjected to pretreatment such as crushing and sorting as necessary, and then supplied to the fluidized bed gasification furnace 2 by the waste supply device 1. Primary air b is fed into the air chamber 3 of the gasification furnace, and a fluidized bed 5 is formed on the air dispersion plate 4 by the air blown up. The waste a is introduced from above the fluidized bed 5 and falls into the fluidized bed maintained at 450 to 650 ° C., so that it is quickly pyrolyzed and gasified to produce gas, tar, and solid carbon.
[0004]
Solid carbon is pulverized and refined by the disturbing motion of the fluidized bed 5. Incombustible materials are discharged from the bottom of the gasification furnace together with the fluid medium, and metals such as iron, copper, and aluminum are recovered in an unoxidized state. The secondary air c is fed into the freeboard 6 of the gasification furnace, and second-stage gasification is performed on tar and solid carbon at 650 to 850 ° C.
The product gas d discharged from the fluidized bed gasification furnace 2 is supplied to the primary combustion chamber 8 of the swirl melting furnace 7 while being accompanied by fine solid carbon, and is mixed with the preheated tertiary air e in the swirl flow. However, high-speed combustion is performed at a high temperature of 1200 to 1500 ° C. Combustion is completed in the secondary combustion chamber 9, and the exhaust gas f is discharged from the upper part of the slag separation unit 10. The ash in the solid carbon becomes slag mist due to the high temperature, is captured by the molten slag phase on the furnace wall of the primary combustion chamber 9 by the centrifugal force of the swirling flow, flows down the furnace wall and enters the secondary combustion chamber 9, It is discharged from the bottom of the slag separator 10. The exhaust gas f exiting the swirl melting furnace 7 is released into the atmosphere through a series of heat recovery and dust removal devices. In the primary combustion chamber 8 and the secondary combustion chamber 9, oil burners 11 and 12 for increasing the temperature are installed.
[0005]
Since waste often contains incombustibles, it is inevitable that the incombustibles enter the gasifier. If the incombustible material is deposited in the fluidized bed, the operation cannot be continued due to poor fluidization. Therefore, it is very important to discharge the incombustible material from the fluidized bed. This incombustible discharge was attempted by the method shown in FIG. 4 which is usually employed in a fluidized bed incinerator. That is, incombustible materials were separated by two-stage classification, and only the fluidized medium was returned to the gasifier. In FIG. 4, 2 is an internal swirling fluidized bed gasification furnace, 13 is a deflector, 14 is an incombustible discharge chute, 15 is a discharger with a trommel, 16 is a bucket conveyor, 17 is a classifier, and 18 is a fluid medium supply. H is a fluid medium, i is an incombustible material, and j is solid carbon.
[0006]
However, when the incombustible material is discharged by the method shown in FIG. 4, it has been found that the following problems occur depending on the waste used.
(1) Solid carbon on the sieve of the second classifier was discharged together with incombustibles without being used, resulting in energy loss.
{Circle around (2)} The solid carbon used as the sieve of the second classifier is returned to the gasifier without being crushed. For this reason, solid carbon accumulates in the furnace, the fluidized bed expands, and the solid carbon concentration in the fluidized bed increases.
(3) When waste containing fine iron pieces is processed, it is discharged without being oxidized, so the second classifier is likely to be clogged.
[0007]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problem of incombustible discharge, the fluid medium accompanying the discharged solid material circulates without being pulverized, and pulverizes the solid carbon so that it is easy to burn, and the fluidized bed together with the fluidized medium. It is an object of the present invention to provide a pyrolysis gasification and melting method and apparatus for waste that can be circulated in a gasification furnace.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, in the present invention, in the pyrolysis gasification and melting method of waste, wherein the waste is pyrolyzed and gasified in a fluidized bed furnace and melted in a melting furnace, from the furnace bottom of the fluidized bed furnace. The solid matter is discharged, the solid carbon contained in the solid matter is pulverized and supplied from the upper part of the fluidized bed of the fluidized bed furnace, and the pulverized solid carbon is transported to the melting furnace together with the gasified gas. A waste pyrolysis gasification and melting method characterized by burning in a melting furnace.
In the pyrolysis gasification and melting method of the present invention, the solid matter discharged from the bottom of the fluidized bed furnace separates a large-size solid matter from a solid matter containing a fluid medium, an incombustible matter and solid carbon, A solid having a size not larger than the large size obtained by the separation is classified, and a solid having a size not less than a predetermined size selected from any numerical value between 1 mm and 10 mm, and a solid having a size not greater than the predetermined size. The solid material of a predetermined size or less obtained by pulverizing the solid material of the predetermined size or more can be supplied to the fluidized bed furnace together with the solid material of the predetermined size or less , and the fluidized bed furnace solids discharged from the furnace bottom, as possible out to supply to the fluidized-bed furnace to separate the iron.
[0009]
Further, in the present invention, a fluidized bed furnace for pyrolyzing and gasifying waste, a discharge means for discharging solid matter from the bottom of the fluidized bed furnace, and solid carbon contained in the solid matter discharged from the discharge means A means for supplying the solid carbon pulverized by the pulverizing means to the upper part of the fluidized bed of the fluidized bed furnace, and a means for transporting the pulverized solid carbon together with the gasified gas to the melting furnace. And a melting furnace for melting the pulverized solid carbon, and a waste pyrolysis gasification and melting apparatus.
In the pyrolysis gasification and melting apparatus for wastes according to the present invention, a solid matter containing a discharge means for discharging solid matters from the bottom of the fluidized bed furnace , the discharged fluid medium, incombustible matter and solid carbon. A means for separating a large-sized solid from the solid, and a solid having a size smaller than that obtained by classifying the solid having a size smaller than that, and a solid larger than a predetermined size selected from any value between 1 mm and 10 mm; A means for obtaining a solid having a predetermined size or less; a crushing means for crushing the solid having a predetermined size or more; and the fluidized bed together with the solid having a size not larger than the predetermined size together with the solid having the predetermined size or less. can Rukoto and a supply means for supplying to the furnace and in the pyrolysis gasification and melting apparatus, further, from the solids discharged from the fluidized-bed furnace, by providing the iron separating means for separating the iron Kill at.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
As described above, in the present invention, a mixture of a fluid medium taken out from a fluidized bed gasification furnace, an incombustible material, and solid carbon is appropriately combined with classification, pulverization, and magnetic force sorting without pulverizing the fluid medium ( 1) Non-combustible material of a predetermined size or more; (2) Fluid medium, non-combustible material and solid carbon of a predetermined size or less; and (3) Iron. At this time, the predetermined size is selected from any numerical value between 1 mm and 10 mm. Then, (1) and (3) may be taken out of the system, and (2) may be supplied to the fluidized bed gasifier.
Specifically, the mixture taken out from the gasification furnace separates incombustibles having a large size (10 mm or more) by classification. Next, after separating the iron content by magnetic separation, (A), by classification, the medium-size or larger incombustible material and solid carbon (a), medium-size or smaller fluid medium, incombustible material and solid carbon (b), ( B), (a) is pulverized and classified into a non-combustible material (c) of a small size or more, a non-combustible material of a small size or less and solid carbon (d), and (C) and (c) are recovered, (B) and (d) are supplied to the gasifier. The medium size and the small size are within the range of the predetermined size.
[0011]
At this time, there are a case where the mixture is taken out from the gasification furnace only from the furnace bottom, and a case where discharge from the furnace bottom and overflow from the fluidized bed are used in combination.
Here, the size relationship is summarized as follows.
1 mm ≦ small size <medium size ≦ 10 mm ≦ large size Next, the present invention will be described in detail.
First, the handling points of the mixture composed of the fluidized medium discharged from the gasification furnace, the incombustible material, and the solid carbon are as follows.
(1) The fluid medium is returned to the gasification furnace without being pulverized.
{Circle around (2)} The entire amount of solid carbon is returned to the gasification furnace, but it is pulverized by grinding.
(3) Incombustibles are taken out as much as possible, but fine ones may be returned to the gasifier.
(4) Ensure heat resistance and airtightness.
(5) Remove iron by magnetic sorting as soon as possible.
[0012]
(1) is necessary to reduce the wear of the fluid medium. Since the pulverized fluid medium accompanies the gas, the utility cost increases due to an increase in the replenishment amount of the fluid medium, and the amount of slag increases. {Circle around (2)} is necessary for effectively using the combustion heat of solid carbon. By being pulverized, it is transported to a melting furnace where it is effectively used as a fuel for combustion. If the gasification furnace is returned to the gasification furnace without pulverization, the fluidized bed height may be expanded. (3) is necessary for ensuring good fluidization and for recovering and recycling valuable materials in incombustible materials. However, if the size is about the same as that of the fluidized medium, it can be used as the fluidized medium, so it can be returned to the gasification furnace. Regarding (4), since the fluidized bed is filled with flammable and harmful gas, it is necessary to pay attention to airtightness particularly when discharging from the gasification furnace. Moreover, since solid carbon is contained in the mixture taken out from the gasification furnace, it may ignite upon contact with air. Therefore, it is necessary not to touch outside air during operations such as classification and crushing. Cooling the solid carbon to a temperature at which it does not ignite increases the amount of heat loss and is not a good idea.
[0013]
(5) is attributed to the fact that the entire furnace interior is in a reducing atmosphere. In normal incinerators, iron pieces that are oxidized and become tattered come out of the gasification furnace as they are, so it is necessary to remove them before using a fine sieve.
Next, a method for extracting the mixture from the gasifier will be described. Basically, the heat dissipation loss of the fluidized medium should be as small as possible. Therefore, it is desirable to suppress the discharge amount from the furnace bottom to about 10 times the amount of incombustibles + solid carbon. If the fluidized bed height rises due to solid carbon accumulation, adjust the sieve opening to increase the solid carbon pulverization rate returned to the furnace or increase the amount of mixture discharged from the furnace bottom. It is good to be. Alternatively, if this is not possible, remove it from the fluidized bed directly by overflow.
[0014]
Hereinafter, the present invention will be described specifically and in detail with reference to the drawings.
FIG. 1 is a circulation flow diagram for carrying out the method for separating and circulating the solid matter discharged from the fluidized bed gasification furnace of the present invention.
In FIG. 1, 19 is a magnetic separator, 20 is a ball mill, 21 is a classifier, 22 is a crushed material hopper, k is iron, and the same reference numerals as those in FIG. 4 represent the same words. As the waste a is supplied to the fluidized bed gasification furnace 2 and pyrolyzed and gasified, the incombustible material i originally contained in the waste accumulates at the bottom of the fluidized bed. For this reason, the incombustible material i is discharged from the furnace together with the fluid medium h and the solid carbon j by operating the discharger 15 with the trommel directly connected to the incombustible material discharge chute 14 continuously or intermittently. The incombustible discharge chute 14 has a water cooling structure and cools the mixture of the fluid medium h, the incombustible i, and the solid carbon j to about 300 ° C.
[0015]
The purpose of cooling is to protect the equipment related to classification, crushing, and magnetic separation. Normally, the trommel hole diameter is selected from 10 to 25 mm, but usually about 15 mm is used. Therefore, here, the large size = 15 mm. Non-combustible material i (large size or larger) on the trommel sieve is out of the system, and the mixture of fluid medium h, incombustible material i and solid carbon j (large size or smaller) under the sieve is to the bucket conveyor 16, both for gas sealing. The valve is normally closed and opened only at the time of discharge, so that the gas leak is reduced while being minimized.
A mixture (large size or less) of the fluid medium h, the incombustible material i, and the solid carbon j conveyed upward by the bucket conveyor 16 is supplied to a drum type magnetic separator 19 for separating and recovering the iron content k.
[0016]
Subsequently, it is supplied to a classifier 17 in the form of a vibrating sieve. Here, since a sieve having a mesh size of 4 mm is normally used, the medium size = 4 mm. A mixture (under medium size) of the fluidized medium h, the incombustible material i, and the solid carbon j under the sieving is sent to the screw-type fluidized medium feeder 18 and supplied to the fluidized bed gasification furnace 2 continuously or intermittently. The A mixture of non-combustible material i and solid carbon j (medium size or larger) on the sieve of the classifier 17 is supplied to the classifier 21 after being crushed by the ball mill 20. Since the opening of the classifier 21 is usually 1.5 mm, the small size is 1.5 mm. The ball mill 20 and the classifier 21 can be integrated into a ball mill with a screen, for example.
[0017]
The mixture (small size or less) of the non-combustible material i and the solid carbon j, which is under the sieve of the classifier 21, is stored in the crushed material hopper 22 and then supplied to the waste supply device 1 through the rotary valve at the hopper outlet. And returned to the fluidized bed gasification furnace 2 together with the waste a. Incombustible material i (small size or larger) that is also on the screen is discharged out of the system.
As a result, about 0.6 mm of dredged sand that is normally used as the fluid medium h can be returned to the gasifier without pulverizing the entire amount if the performance of the classifier 17 is good. Moreover, the incombustible material i which was originally larger than the large size and the incombustible material i which could not be pulverized to the small size which is larger than the medium size are discharged out of the system, and the rest becomes the fluidized medium of the gasifier. Only the solid carbon j having a medium size or larger is pulverized to a small size or smaller and returned to the gasification furnace.
[0018]
Next, another embodiment of the present invention will be described with reference to FIG. 2 showing another circulation flow chart of the present invention. In FIG. 2, reference numeral 23 denotes an overflow material transporter. Here, a new line for supplying the fluidized medium h and the solid carbon j overflowed from the fluidized bed of the fluidized bed gasification furnace 2 to the bucket conveyor 16 using the screw-type overflow material conveyor 23 is added to FIG. It has been. In this way, solid carbon can be preferentially extracted from the fluidized bed rather than discharged from the bottom of the fluidized bed. This is a particularly effective method for a specific waste (for example, scrap car shredder dust) that generates a large amount of solid carbon when the waste a is pyrolyzed and gasified. In this case, most of the extracted solid carbon needs to be crushed and then returned to the gasification furnace, so the opening of the classifier 17 needs to be smaller than the usual 4 mm.
[0019]
【The invention's effect】
According to the present invention, the following effects can be obtained.
(1) The fluid medium can be returned to the gasification furnace without being pulverized, and wear of the fluid medium can be reduced.
(2) Since the total amount of solid carbon is pulverized and returned to the gasification furnace, the combustion heat of the solid carbon can be effectively used 100%.
(3) Unburnable materials can be taken out as much as possible, and valuable materials can be collected and recycled.
(4) Iron can be separated in a reducing atmosphere by magnetic separation.
[Brief description of the drawings]
FIG. 1 is a circulation flow diagram showing a separation / circulation flow of discharged solids of a fluidized bed gasification furnace of the present invention.
FIG. 2 is a circulation flow diagram showing another example of separation / circulation flow of discharged solids of the fluidized bed gasification furnace of the present invention.
FIG. 3 is a conceptual diagram of a known waste gasification melting system.
FIG. 4 is a fluid medium circulation flow diagram of the same gasification furnace as the conventional fluidized incinerator.
[Explanation of symbols]
1: Waste supply device, 2: Fluidized bed gasification furnace, 3: Air chamber, 4: Air dispersion plate, 5: Fluidized bed, 6: Free board, 7: Swivel melting furnace, 8: Primary combustion chamber, 9: Secondary combustion chamber, 10: slag separation unit, 11, 12: temperature rising burner, 13: deflector, 14: incombustible discharge chute, 15: discharger with trommel, 16: bucket conveyor, 17: classifier, 18: Fluid medium feeder, 19: magnetic separator, 20: ball mill, 21: classifier, 22: crushed material hopper, 23: overflow material transporter a: waste, b: primary air, c: secondary air, d: Product gas, e: tertiary air, f: exhaust gas, g: slag, h: fluid medium, i: incombustible, j: solid carbon, k: iron

Claims (6)

In pyrolysis gasification and melting method for wastes waste by pyrolysis gasification in a fluidized bed furnace for melting in a melting furnace, and discharged solids from the furnace bottom of the fluidized bed furnace, is included in the solid was Solid waste is pulverized and supplied from the upper part of the fluidized bed of the fluidized bed furnace, and the pulverized solid carbon is transported to the melting furnace together with the gasified gas and burned in the melting furnace . Pyrolysis gasification and melting method. The solid matter discharged from the bottom of the fluidized bed furnace is separated from a solid matter containing a fluid medium, an incombustible matter and solid carbon, and a solid having a size of not more than a large size obtained by the separation. Classifying the product to obtain a solid having a size not less than a predetermined size selected from an arbitrary value between 1 mm and 10 mm and a solid having a size not greater than the predetermined size, and pulverizing the solid having a size not less than the predetermined size. 2. The method for pyrolysis gasification and melting of waste according to claim 1 , wherein the solid material having a predetermined size or less is supplied to the fluidized bed furnace together with the solid material having a predetermined size or less. The method for pyrolysis gasification and melting of waste according to claim 1 or 2, wherein the solid matter discharged from the fluidized bed furnace is separated into iron and supplied to the fluidized bed furnace. A fluidized bed furnace for pyrolyzing waste gas, a discharge means for discharging solid matter from the bottom of the fluidized bed furnace, and a pulverizing means for pulverizing solid carbon contained in the solid matter discharged from the discharge means; , Means for supplying the solid carbon pulverized by the pulverizing means to the upper part of the fluidized bed of the fluidized bed furnace , means for transporting the pulverized solid carbon together with the gasified gas to the melting furnace, and the pulverized A waste pyrolysis gasification and melting apparatus comprising a melting furnace for melting solid carbon . 5. The pyrolysis gasification and melting apparatus for waste according to claim 4 , wherein the discharge means for discharging solid matter from the bottom of the fluidized bed furnace , the solid matter containing the discharged fluid medium, incombustible matter and solid carbon. A means for separating a large-sized solid from the solid, and a solid having a size smaller than that obtained by classifying the solid having a size smaller than that, and a solid larger than a predetermined size selected from any value between 1 mm and 10 mm; A means for obtaining a solid having a predetermined size or less; a crushing means for crushing the solid having a predetermined size or more; and the fluidized bed together with the solid having a size not larger than the predetermined size together with the solid having the predetermined size or less. A waste pyrolysis gasification and melting apparatus comprising a supply means for supplying to a furnace. 6. The pyrolysis of waste according to claim 4 or 5 , wherein the pyrolysis gasification and melting apparatus is provided with iron separation means for separating iron from solids discharged from the fluidized bed furnace. Gasification and melting equipment.

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