JPH10185113A - Method for separating and circulating discharge solid matter of fluidized bed gasification furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce damage of bed material by circulating the material accompanied with discharged solid matter without comminuting, comminuting solid carbon and circulating it together with the material to a fluidized bed gasification furnace, thereby returning the material to the furnace without comminuting. SOLUTION: A mixture of bed material (h), incombustible matter (i) and solid carbon (j) removed from a fluidized bed gasification furnace 2 is sorted into incombustible matter (i) having a predetermined size or more, bed material (h), incombustible matter (i) and solid carbon (j) of a predetermined size or less and iron content (k) without comminuting the material (h) in suitable combination of classification by classifiers 17, 21, comminuting by a ball mill 20 and magnetic separating by a magnetic separator 19. At this time, the predetermined size is selected from an arbitrary numeric value of 1 to 10mm. The matter (i), iron content (k) of the predetermined size or more are removed out of a system, and the material (h), matter (i) and carbon (j) of the predetermined size or less are circulated and supplied to the furnace 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating and circulating solids discharged from a fluidized bed gasifier, and more particularly to municipal solid waste, solidified fuel, slurry fuel, waste plastic, waste FRP, biomass waste. Goods, automobile waste, low-grade coal,
The present invention relates to a method of separating and circulating solids discharged from a fluidized-bed gasification furnace that pyrolyzes waste such as waste oil at a low temperature.
Among the above, the solidified fuel (= RDF) is obtained by crushing and sorting municipal waste and then compression-molding by adding quicklime and the like. It is oiled by thermal decomposition.

[0002]

2. Description of the Related Art Conventionally, a fluidized-bed gasifier that pyrolyzes and gasifies at a low temperature is a new next-generation waste treatment technology that replaces incineration as a "gasification and melting system" that combines gasification and melting and combustion. It has already been used in some places. The target features of this "gasification and melting system" are as follows. Due to the low air ratio combustion, the amount of exhaust gas is greatly reduced. Dioxins and furans are hardly generated by high-temperature combustion. Ash in the waste is recovered as harmless slag from which heavy metals do not elute. As a result, the life of the landfill can be extended,
It can also be used for roadbed materials. The retained energy of gas, tar, and carbide generated by gasification can be effectively used as a heat source for melting ash. Since the functions of dioxin treatment and ash melting are incorporated in the system, the entire apparatus is made compact, and the construction cost is lower than that of a conventional incineration facility.

FIG. 3 shows a combination of a fluidized bed gasification furnace (preferably using an internal swirling type fluidized bed) and a swirling melting furnace as components of a known “gasification and melting system”. In FIG. 3, 1 is a waste supply apparatus, 2 is a fluidized bed gasifier, 3 is an air chamber, 4 is an air dispersion plate, 5 is a fluidized bed, 6
Is a free board, 7 is a rotary melting furnace, 8 is a primary combustion chamber, 9
Is a secondary combustion chamber, 10 is a slag separation section, 11 and 12 are burners for heating, a is waste, b is primary air, c is secondary air,
d is generated gas, e is tertiary air, f is exhaust gas, and g is slag. The outline of the gasification and melting system will be described with reference to FIG. The waste a is subjected to pretreatment such as crushing and sorting as required, and then supplied to the fluidized bed gasification furnace 2 by the waste supply device 1. Primary air b in the air chamber 3 of the gasifier
Is supplied, and a fluidized bed 5 is formed on the air distribution plate 4 by blowing air. The waste a is charged from above the fluidized bed 5 and falls into the fluidized bed maintained at 450 to 650 ° C., whereby it is quickly pyrolyzed and gasified to produce gas, tar and solid carbon.

[0004] The solid carbon is pulverized and refined by the disturbance motion of the fluidized bed 5. Incombustibles are discharged together with the fluidized medium from the bottom of the gasification furnace, and metals such as iron, copper, and aluminum are recovered in an unoxidized state. The secondary air c is sent to the free board 6 of the gasification furnace, and the second stage gasification is performed on the tar and the solid carbon at 650 to 850 ° C.
The generated gas d discharged from the fluidized bed gasification furnace 2 is supplied to the primary combustion chamber 8 of the swirling melting furnace 7 while entraining fine solid carbon, and is mixed with the preheated tertiary air e in the swirling flow. At the same time, high-speed combustion is performed at a high temperature of 1200 to 1500 ° C. The 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 separation unit 10. In addition, the exhaust gas f which has exited the swirling melting furnace 7 is discharged to the atmosphere through a series of heat recovery and dust removal devices. The primary combustion chamber 8 and the secondary combustion chamber 9 are provided with oil burners 11 and 12 for raising the temperature.

Since waste often contains incombustibles, it is inevitable that incombustibles enter the gasifier. If the incombustibles accumulate in the fluidized bed, it is impossible to continue the operation due to poor fluidization. Therefore, it is extremely important to discharge the incombustibles 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, incombustibles were separated by two-stage classification, and only the fluidized medium was returned to the gasification furnace. In FIG. 4, 2 is an internal swirling type fluidized bed gasifier, 13 is a deflector,
14 is an incombustible discharge chute, 15 is a discharger with trommel, 16 is a bucket conveyor, 17 is a classifier, 18 is a fluid medium feeder, h is a fluid medium, i is incombustible, and j is solid carbon.

However, it has been found that when the non-combustible material is discharged by the method shown in FIG. 4, the following problem occurs depending on the waste used. Solid carbon, which was used on the sieve of the second classifier, was discharged together with non-combustibles without being used, resulting in energy loss. The solid carbon that is sieved in the second classifier is returned to the gasifier without being crushed. Therefore, solid carbon is accumulated in the furnace, and the fluidized bed expands, and the concentration of solid carbon in the fluidized bed increases. When waste containing fine iron pieces is treated, the waste is discharged without being oxidized, so that the second-stage classifier is likely to be clogged.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problem of discharging incombustibles, and circulates a flowing medium from discharged solids without pulverization, and makes it easy to burn solid carbon. It is an object of the present invention to provide a method for separating and circulating solids discharged from a fluidized-bed gasification furnace which can be crushed into a fluidized-bed gasification furnace together with a fluidized medium.

[0008]

According to the present invention, there is provided a method of separating and circulating solids discharged from a fluidized-bed gasification furnace for pyrolyzing and gasifying waste at a low temperature. The solid substance is a mixture of a fluid medium, a non-combustible substance, and solid carbon, and the mixture is composed of (1) a non-combustible substance having a predetermined size or more, (2) a fluid medium having a predetermined size or less, a non-combustible substance, and solid carbon; 3) Classifying, pulverizing, and magnetic separation are appropriately combined with iron to separate the fluid medium without pulverizing, and take out (1) and (3) out of the system, and (2) remove the fluidized bed gas from the fluidized bed gas. The predetermined size is selected from arbitrary numerical values between 1 mm and 10 mm.

Further, according to the present invention, there is provided a method for separating and circulating discharged solids of a fluidized-bed gasification furnace for pyrolyzing and gasifying wastes at a low temperature, wherein the discharged solids are formed from a fluid medium, incombustibles, and solid carbon. A mixture comprising: first separating a large-sized non-combustible material having a size of 10 mm or more by classification;
Next, iron is separated by magnetic force separation, and further, (A), by classification, non-combustible materials of medium size or more and solid carbon (a)
And a medium having a medium size or less, a non-combustible material, and a solid carbon (b). The non-combustible material having a small size or more (c) and a fluid medium having a small size or less are obtained by grinding and classifying (B) and (a). And solid carbon (d), (C) and (c) are recovered, and (b) and (d) are circulated to a fluidized-bed gasification furnace. 1m
m to 10 mm. In the above method, the discharge of the solids from the fluidized-bed gasification furnace is performed from the bottom of the fluidized-bed gasification furnace, or is performed by overflow of the bottom and the fluidized bed.

[0010]

DETAILED DESCRIPTION OF THE INVENTION As described above, in the present invention, a mixture of a fluid medium, an incombustible material, and solid carbon taken out of a fluidized bed gasifier is subjected to classification, pulverization and magnetic separation as appropriate to obtain a fluid medium. Without pulverization, (1) a non-combustible material having a predetermined size or more, (2) a fluid medium having a predetermined size or less, a non-combustible material, and solid carbon, and (3) iron.
At this time, the predetermined size is selected from arbitrary numerical values between 1 mm and 10 mm. Then, (1) and (3) may be taken out of the system, and (2) may be supplied to a fluidized bed gasification furnace. Specifically, the mixture taken out of the gasification furnace separates large-sized (10 mm or more) incombustibles by classification. Next, after separating the iron content by magnetic force separation, (A), classification is performed to classify into medium size or larger incombustibles and solid carbon (a), medium size or smaller fluidized medium, noncombustibles and solid carbon (b) by classification, B) and (a) are crushed and classified into non-combustible materials (c) having a small size or more, non-combustible materials having a small size or less and solid carbon (d), and (C) and (c) are collected.
(B) and (d) are supplied to a gasification furnace. The medium size and the small size are within the range of the predetermined size.

At this time, the mixture is taken out of the gasification furnace only from the furnace bottom, or the discharge from the furnace bottom and the overflow from the fluidized bed are used in combination. Here, the size relationship is summarized as follows. 1mm
≤ small size <medium size ≤ 10 mm ≤ large size Next, the present invention will be described in detail. First, the points of handling the mixture of the fluid medium, the non-combustible material, and the solid carbon discharged from the gasifier are as follows. The flowing medium is returned to the gasifier without grinding. The entire amount of solid carbon is returned to the gasifier, where it is pulverized into fine powder. Incombustibles are taken out as much as possible, but fines may be returned to the gasifier. Ensure heat resistance and airtightness. Remove iron by early magnetic separation.

Is necessary to reduce wear of the flowing medium. Since the pulverized fluid medium accompanies the gas, the increase in the replenishment amount of the fluid medium causes an increase in utility costs, and also increases the amount of slag. Is necessary for 100% effective use of the combustion heat of solid carbon. By pulverizing, it is carried to the melting furnace,
Therefore, it is effectively used as fuel for combustion. If the fluidized bed is returned to the gasification furnace without being pulverized, the height of the fluidized bed may be increased. Is necessary to ensure good fluidization and to collect and recycle valuable resources in incombustibles. However, if the size becomes approximately the same as that of the fluidized medium, it can be used as a fluidized medium and can be returned to the gasification furnace. As for the fluidized bed, since the flammable and harmful gas is filled in the fluidized bed, it is necessary to pay attention to hermeticity especially when discharging from the gasification furnace. Also, since the mixture taken out of the gasification furnace contains solid carbon,
May ignite on contact with air. Therefore, classification,
During operations such as pulverization, it is necessary to avoid contact with the outside air. Cooling the solid carbon to a temperature that does not ignite is not advisable because it increases the amount of heat loss.

The reason is that the whole area in the furnace is in a reducing atmosphere. Small pieces of iron that are oxidized and ragged out of the gasifier in a normal incinerator need to be removed, especially before using a fine sieve. Next, a method of extracting the mixture from the gasification furnace will be described. Basically, the heat dissipation loss of the flowing medium should be as small as possible. Therefore, it is desirable to suppress the amount of discharge from the furnace bottom to about 10 times the amount of noncombustibles + solid carbon. With this, if the height of the fluidized bed increases due to the accumulation of solid carbon, adjust the mesh size of the sieve to increase the pulverization ratio of the solid carbon returned to the furnace, or increase the amount of the mixture discharged from the furnace bottom. It is better to Alternatively, if this does not help, the fluidized bed should be directly withdrawn by overflow.

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 solids discharged from a fluidized-bed gasification furnace according to the present invention. In FIG. 1, reference numeral 19 denotes a magnetic separator, reference numeral 20 denotes a ball mill, reference numeral 21 denotes a classifier, reference numeral 22 denotes a crushed material hopper, k denotes iron, and the same reference numerals as those in FIG. As the waste a is supplied to the fluidized bed gasification furnace 2 and pyrolyzed and gasified, incombustibles i originally contained in the waste are deposited on the bottom of the fluidized bed. For this reason, the discharger 15 with trommel directly connected to the incombustible discharge chute 14 is operated continuously or intermittently to discharge the incombustibles i together with the fluid medium h and the solid carbon j from the furnace. The incombustible discharge chute 14 has a water cooling structure, and cools a mixture of the fluid medium h, the incombustibles i, and the solid carbon j to about 300 ° C.

The purpose of the cooling is to protect equipment related to the subsequent classification, crushing, and magnetic separation. Usually the trommel pore size is 10
で 25 mm is selected, but usually about 15 mm is used. Therefore, here, the large size = 15 mm.
The non-combustible material i (large size or more) on the trommel sieve goes out of the system, and the mixture of the fluid medium h, non-combustible material i and solid carbon j (large size or less) under the sieve to the bucket conveyor 16 for gas sealing By closing the valve at all times and opening only at the time of discharge, gas is discharged while minimizing the amount of gas leakage. The mixture (large size or less) of the fluid medium h, the noncombustibles 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 iron k.

Then, it is supplied to a classifier 17 of a vibrating sieve type. Here, since a sieve having a mesh size of 4 mm is usually used, the medium size is 4 mm. The fluid medium h under the sieve, the incombustibles i,
The mixture of solid carbon j (medium size or less) is sent to a screw-type fluidized medium feeder 18 and is supplied to the fluidized bed gasification furnace 2 continuously or intermittently. The mixture (medium size or larger) of the noncombustible material i and the solid carbon j on the sieve of the classifier 17 is supplied to the classifier 21 after being crushed by the ball mill 20. Since the aperture 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.

The mixture (small size or less) of the noncombustible material i and the solid carbon j under the sieve of the classifier 21 is stored in the crushed material hopper 22 and then passed through a rotary valve at the outlet of the hopper to a waste supply device. 1 and returned to the fluidized bed gasifier 2 together with the waste a. Incombustibles i (small size or more) also on the sieve are discharged out of the system. As a result, silica sand having a size of about 0.6 mm, which is generally used as the fluid medium h, can be returned to the gasification furnace without pulverizing the entire amount if the performance of the classifier 17 is good. Further, the incombustibles i originally having a large size or more and the incombustibles i which could not be pulverized to a medium size or more and a small size or less are discharged out of the system, and the remainder becomes a fluidized medium of the gasification furnace. Solid carbon j
Only those having a medium size or larger are pulverized to a smaller size or smaller and returned to the gasification furnace.

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 object transporter. here,
A new line for supplying the fluid medium h and the solid carbon j overflowing from the fluidized bed of the fluidized bed gasification furnace 2 to the bucket conveyor 16 by using a screw type overflow transporter 23 is added to FIG. . In this case, solid carbon can be preferentially removed from the fluidized bed rather than discharged from the bottom of the fluidized bed. For specific waste (for example, scrap car shredder dust) that generates a large amount of solid carbon when pyrolysis gasification of waste a,
This is a particularly effective method. In this case, it is necessary to crush most of the extracted solid carbon and then return it to the gasifier, so that the opening of the classifier 17 needs to be smaller than the normal 4 mm.

[0019]

According to the present invention, the following effects can be obtained. (1) The fluidized medium can be returned to the gasification furnace without being pulverized, and wear of the fluidized medium can be reduced. (2) Since the entire amount of the solid carbon is pulverized and returned to the gasifier, 100% of the combustion heat of the solid carbon can be effectively used. (3) Incombustibles are taken out as much as possible, and valuables can be collected and recycled. (4) Iron can be separated in a reducing atmosphere by magnetic separation.

[Brief description of the drawings]

FIG. 1 Separation of solids discharged from a fluidized-bed gasifier of the present invention
The circulation flow figure which shows a circulation flow.

FIG. 2 Separation of solids discharged from a fluidized-bed gasifier of the present invention.
The circulation flow figure which shows the other example of a circulation flow.

FIG. 3 is a conceptual diagram of a known waste gasification and melting system.

FIG. 4 is a flow diagram of a fluidized medium circulation of the same gasifier as a conventional fluidized incinerator.

[Explanation of symbols]

1: waste supply device, 2: fluidized bed gasifier, 3: air chamber, 4: air dispersion plate, 5: fluidized bed, 6: free board,
7: Swirling melting furnace, 8: Primary combustion chamber, 9: Secondary combustion chamber, 1
0: slag separation section, 11 and 12: burner for heating, 13:
Deflector, 14: Incombustible discharge chute, 15: Discharge machine with trommel, 16: Bucket conveyor, 17:
Classifier, 18: Fluid medium feeder, 19: Magnetic force sorter, 2
0: 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

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuo Makino 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Works Co., Ltd. (72) Inventor Tetsuhisa Hirose 11-1 Asahicho Haneda, Ota-ku, Tokyo Ebara Corporation (72) Inventor Takahiro Oshita 11-1 Haneda Asahimachi, Ota-ku, Tokyo Ebara Corporation

Claims (4)

[Claims] 1. A method for separating and circulating solids discharged from a fluidized bed gasifier for pyrolyzing and gasifying waste at a low temperature,
The discharged solid is a mixture of a fluid medium, an incombustible material, and solid carbon, and the mixture is composed of (1) an incombustible material having a predetermined size or more, and (2) a fluid medium having a predetermined size or less, incombustible material, and solid carbon. , (3) the classification of the fluid medium with the iron component by appropriate combination of classification, pulverization and magnetic separation, without pulverizing the fluid medium, and taking out (1) and (3) out of the system;
(2) is circulated through the fluidized-bed gasification furnace, and the predetermined size is selected from an arbitrary numerical value between 1 mm and 10 mm. 2. A method for separating and circulating solids discharged from a fluidized-bed gasifier for pyrolyzing and gasifying waste at a low temperature.
The discharged solid is a mixture composed of a fluid medium, a non-combustible substance, and solid carbon, and the mixture is first classified into 10 m by classification.
m, a non-combustible material having a size of at least m and then a magnetic force separator to separate the iron component. And incombustibles and solid carbon (b)
(B) and (a) are divided into non-combustibles (c) of a small size or more, a fluid medium of a small size or less and solid carbon (d) by pulverization and classification, and (C) and (c) are recovered. ,
(B) and (d) are circulated to the fluidized bed gasifier,
The medium size and the small size are 1mm to 10m of the predetermined size
m, wherein the discharged solids are separated and circulated. 3. The separation and circulation of discharged solids according to claim 1, wherein the discharge of the solids from the fluidized-bed gasification furnace is performed from the furnace bottom of the fluidized-bed gasification furnace. Method. 4. The discharge solid according to claim 1, wherein the discharge of the solid matter from the fluidized bed gasification furnace is performed by an overflow of a furnace bottom of the fluidized bed gasification furnace and a fluidized bed. How to separate and circulate things.