JP2000319670A - Two-stage waste gasification system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-stage waste gasification system of waste capable of recovering metals and ashes present in waste in a state usable in recycling and also recovering a gas containing a large amount of CO and H2 to convert it into raw materials for chemical synthesis such as synthesis of NH3 (ammonia). SOLUTION: In the two-step waste gasification system comprising pyrolytically gasifying a raw material composed of waste a in a fluidized bed gasification furnace 1 at a low temperature, and introducing the resulting gaseous substance and char into a melting furnace 30 to effect gasification at a high temperature, a moving bed reservoir yard having a plurality of movable flat moving plates in parallel is provided in a raw material supply system 10 for supplying the raw material to the fluidized bed gasification furnace 1, and is constituted in such a manner that the plurality of the moving plates simultaneously move forward with the raw material loaded thereon and the plurality of the moving plates move forward and backward part by part in a time lag (1/4 τ) and the raw material is supplied by dropping on to downstream equipment with every backward movement of the moving plates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to the use of a low-temperature gasifier and a high-temperature gasifier in combination to gasify various kinds of waste through two stages of low-temperature and high-temperature processes.
The present invention relates to a waste gas two-stage gasification system for obtaining a useful gas containing a large amount of O (carbon monoxide) and H ₂ (hydrogen).

[0002]

2. Description of the Related Art NH ₃ (ammonia) is a basic raw material in the chemical industry which is mass-produced as a raw material for nitric acid, various fertilizers (ammonium nitrate, ammonium sulfate, urea), acrylonitrile, caprolactam and the like. This NH ₃ is synthesized from N ₂ (nitrogen) and H ₂ under high pressure using a catalyst, and H ₂ is composed of natural gas,
Steam reforming such as naphtha, oil, coal,
It has been obtained by partial combustion of hydrocarbons such as petroleum coke, so-called gasification. On the other hand, waste represented by municipal garbage, waste plastic, waste FRP, biomass waste, and automobile waste has been reduced in volume by incineration or landfilled untreated. The amount of these recycled, directly or indirectly, was very small overall.

Recently, waste has been regarded as a reusable resource, and the metal and ash contained in the waste have been recovered in a recyclable state by gasifying the waste using a two-stage gasification system. At the same time, a proposal has been made to recover a gas containing a large amount of CO and H ₂ and use it as a raw material such as NH ₃ (ammonia). This attempt is
By applying gasification and melting technology, that is, a two-stage combustion system of waste, waste can be effectively used by material recycling and chemical recycling.

FIG. 14 is a schematic view showing an example of a furnace main body of the above proposed waste two-stage gasification system. FIG.
4, the low temperature gasifier includes a fluidized bed gasifier 1 of a type in which a fluid medium e is swirled between a central portion and a peripheral portion of the fluidized bed 2, and the high temperature gasifier includes a low temperature gasifier. A swirling melting furnace 30 of a type that gasifies at a high temperature while swirling a combustible gas and a gasifying agent from the furnace is used. The waste a supplied to the gasification furnace 1 via a lock hopper (not shown) or the like is
In the fluidized bed 2 maintained at a predetermined temperature, preferably 550 to 850 ° C., it is thermally cracked and gasified by contact with oxygen b and steam c. The incombustibles d are withdrawn from the bottom of the gasifier 1 together with the fluidized medium e, classified by the screen 7,
Only the non-combustible material d is discharged to the outside via the lock hopper 8, and the fluid medium e is returned to the gasification furnace 1 by using some transport means. The gas, tar, and char generated by the pyrolysis gasification are supplied to the combustion chamber 31 of the later-stage swirling melting furnace 30, and gasified at a high temperature of 1200 to 1500 ° C. At the same time, the ash in the char is turned into molten slag. The generated gas is blown into the water in the water tank 34 together with the molten slag and rapidly cooled. Thus, the slag separation chamber 32
The glass-like slag particles f are collected from the water tank 34 of FIG. Reference numeral 36 denotes a lock hopper, and reference numeral 37 denotes a slag screen.

[0005] The generated gas g leaving the swirling melting furnace 30 is subjected to scrubber 38 to remove slag mist and HCl by washing with water, and to perform CO shift (CO + H ₂ O → CO ₂ + H ₂ ) and CO
_{After a 2} (carbon dioxide) removal step (not shown), it is recovered as a synthesis gas (CO + H ₂ ). in this way,
In this system, waste is converted to synthesis gas for use.
A mixed gas of oxygen b and steam c is supplied as a gasifying agent to the gasification furnace and the swirling melting furnace. The pressure in the furnace is usually 1.013 to 4.053 MPa (10 to 40 atm).
Often operated under pressure. Note that the symbol k is makeup water, and the symbol fa is fine slag.

[0006]

The two-stage gasification system for waste shown in FIG. 14 is a proposal at an early stage of the planning stage. Therefore, when a plant of a demonstration level is designed and operated, it is enumerated below. Challenges exist. 1) When storing waste that is a gasification raw material,
If a storage hopper or the like is used instead of the crane method, it is necessary to stably cut out from the storage hopper. 2) Since the fluidized-bed gasifier is operated under pressure, if the waste is in a large-lumped state, if the waste is supplied to the gasifier against the pressure, the supply becomes intermittent. 3) When supplying waste to a fluidized-bed gasification furnace, it is important to keep the raw material supply amount constant when feeding the waste into the gasification furnace. It is difficult to make the raw material supply amount constant in a system including a screw conveyor. 4) If the combustible gas or the like in the lock hopper of the raw material supply system is to be purged with air, when the furnace pressure rises rapidly, the gas in the furnace may flow backward and the waste may be burned in the raw material supply system. On the other hand, when purging with steam, the waste plastic in the waste softens inside the raw material supply system, which hinders the supply to the fluidized bed gasification furnace. 5) If the char generated by pyrolysis gasification of waste accumulates on the fluidized bed in the furnace without reacting,
It may hinder gasification of waste. 6) Boudoir reaction (C + C) on freeboard of gasifier
When an endothermic reaction such as (O ₂ → 2CO) progresses, a temperature drop occurs in the free board portion, and there is a concern about a trouble due to condensation of the tar component. 7) A metal pressure vessel is used for the outer wall of the gasification furnace, but in order to prevent corrosion of the pressure vessel, it is necessary to control the temperature by making the pressure vessel a jacket type or a boiler type. 8) The gasification furnace is provided with a fluidizing gas dispersing device for fluidizing the fluidized medium, and this dispersing device is usually composed of a gas chamber called a wind box and a nozzle. When the air is supplied from the wind box to each nozzle, the amount of air to each nozzle varies. 9) The fluidized medium withdrawn from the gasification furnace together with the incombustibles is re-introduced into the gasification furnace after separating the incombustibles, but the temperature near the inlet to the gasification furnace decreases due to the fluidized medium.
There is a risk of clogging by condensed tar.

[0007] The present invention solves the above-mentioned problems 1) to 9) of the part up to the low-temperature gasifier in the conventional two-stage gasification system for waste, and solves the problem of metal and ash contained in waste. Is recovered in a state where it can be recycled, and a gas containing a large amount of CO and H ₂ is recovered and NH 3 is recovered.
_{3. An} object of the present invention is to provide a two-stage gasification system for waste that can be used as a raw material for synthesis such as (ammonia).

[0008]

According to one aspect of the present invention, a gas obtained by pyrolyzing a raw material consisting of waste at a low temperature using a fluidized-bed gasification furnace is provided. In a two-stage gasification system for waste, in which the solid matter and char are introduced into the subsequent rotary melting furnace and gasified at a high temperature,
In a raw material supply system for supplying a raw material to the fluidized bed gasification furnace, a moving bed type storage yard composed of a plurality of horizontally movable flat plate movable plates is provided, and the plurality of flat plates are loaded with the raw material. The moving plates are simultaneously advanced in a state, and the plurality of moving plates are operated so as to retreat a plurality of times with a time lag therebetween, and each time the moving plate retreats, the loaded raw material is dropped and supplied to a downstream transport device. It is characterized by doing. According to the above-described configuration, the moving bed type storage yard is used in the raw material supply system for supplying the raw material to the fluidized bed gasifier, thereby eliminating the need for the pit and crane method which requires the construction cost, and In addition, even if there is no cut-out function in a conveyor such as a downstream conveyor, the supply of raw materials to the downstream side equipment is smoothed, so that not only does not need to make the equipment capacity of the downstream equipment excessive, but also the cut-out function becomes unnecessary. be able to. As described above, the cost can be significantly reduced in the raw material supply system.

According to one aspect of the present invention, a raw material consisting of waste is pyrolyzed to gas at a low temperature in a fluidized bed gasifier, and the resulting gaseous substance and char are introduced into a melting furnace to gasify at a high temperature. In a two-stage gasification system for waste, a raw material supply system that supplies raw materials to the fluidized bed gasification furnace, a lock hopper, and a raw material extracting device including a screw conveyor disposed downstream of the lock hopper, A feeder comprising a screw conveyor disposed downstream of the feeder and connected to the fluidized-bed gasification furnace. Further, a flow meter is provided between the raw material extracting device and the raw material supply device for measuring a falling amount of the raw material. According to the configuration described above, a two-stage raw material feeder and a raw material feeder are used in the raw material supply system, and the impact line flow rate can directly measure the amount of raw material dropped between the raw material cutout and the raw material feeder. Because the meter is installed, the raw material of the large particle size, which is obtained by compacting the raw material into RDF shape, is quantitatively cut out while crushing with a screw type raw material cutting machine, and the raw material is measured while measuring the amount of fall with an impact line flow meter It can be supplied into the gasification furnace by a supply device.

According to one aspect of the present invention, the steam for purging is supplied to the front end of the raw material feeder. According to the above configuration, since the steam for purging is supplied to the tip of the raw material feeder, even if the pressure in the furnace slightly changes, the combustible gas in the furnace and the pressure booster used in the lock hopper are used. The air does not come into direct contact with the feeder. In addition, since the temperature inside the raw material feeder can be kept low, even if the waste is thermoplastic waste plastic, it does not melt, which may hinder the supply of waste to the fluidized bed gasification furnace. Absent.

According to one aspect of the present invention, a raw material consisting of waste is pyrolyzed to gas at a low temperature in a fluidized bed gasifier, and the resulting gaseous substance and char are introduced into a swirling melting furnace to produce a gas at a high temperature. In the two-stage gasification system for waste to be converted into gas, an overflow pipe is provided above the surface of the fluidized bed of the fluidized-bed gasification furnace for extracting the char to the outside of the furnace. According to the above-described configuration, since the char overflow pipe is provided above the surface of the fluidized bed, only the char can be selectively discharged to the outside of the furnace. Therefore, even a raw material having a high char generation rate can be gasified stably.

According to one aspect of the present invention, a raw material comprising waste is pyrolyzed to gas at a low temperature in a fluidized bed gasifier, and the resulting gaseous substance and char are introduced into a melting furnace to gasify at a high temperature. In the two-stage waste gasification system, a secondary oxygen supply nozzle for supplying oxygen to a free board of the fluidized bed gasification furnace is provided. According to the above configuration, a secondary oxygen supply nozzle is installed in the freeboard section of the fluidized bed gasification furnace, and oxygen is supplied as necessary from the secondary oxygen supply nozzle, so that the gas generated in the fluidized bed is supplied. Can be burned on freeboard. Therefore, the free board is kept at 300 ° C. or more, preferably 400 ° C.
Since the above can be maintained, condensation of tar due to a decrease in gas temperature can be avoided.

According to one aspect of the present invention, a raw material comprising waste is pyrolyzed to gas at a low temperature in a fluidized bed gasifier, and the resulting gaseous substance and char are introduced into a melting furnace to gasify at a high temperature. In the two-stage gasification system for wastes described above, a heat insulating layer is provided on the inner and outer surfaces of a metallic pressure vessel constituting an outer wall of the fluidized-bed gasification furnace. Conventionally,
In order to control the temperature of the pressure vessel to prevent corrosion, it was necessary to use a jacket type or a boiler type, but as in the present invention, by providing a heat insulating layer on both sides of the pressure vessel, the furnace temperature and the outside air temperature were increased. Because it is less susceptible to
Even if there is some temperature change inside and outside the furnace, the temperature of the pressure vessel can be kept within the control value.

According to one aspect of the present invention, a raw material consisting of waste is pyrolyzed to gas at a low temperature in a fluidized-bed gasification furnace, and the resulting gaseous substance and char are introduced into a melting furnace to be gasified at a high temperature. In a two-stage gasification system for waste, a fluidized gas dispersion device for fluidizing a fluidized medium in the fluidized bed gasification furnace is constituted by an annular wind box having a blowing nozzle, Wherein a circulating flow of fluidizing gas is formed in the wind box. The circulating flow of the fluidizing gas is formed by installing a guide for guiding the fluidizing gas supplied into the wind box in one direction in the wind box. According to the above configuration, the fluidizing gas dispersing device is an annular wind box, and by actively forming a circulating flow in the wind box, the pressure distribution hardly occurs inside because of the annular shape. The variation of the air volume can be prevented.

According to one embodiment of the present invention, a raw material consisting of waste is pyrolyzed to gas at a low temperature in a fluidized bed gasifier, and the resulting gaseous substance and char are introduced into a melting furnace to gasify at a high temperature. In a waste gas two-stage gasification system, a fluidized medium circulation system for circulating a fluidized medium in the fluidized bed gasifier,
A fluid medium charging conveyor comprising a screw conveyor connected to the fluidized bed gasification furnace is provided, and the fluid medium charging conveyor is provided to be inclined upward toward the fluidized bed gasification furnace. . Then, purge air is supplied near the outlet of the fluidized medium charging conveyor. According to the present invention, a configuration in which a screw conveyor is used as the fluid medium feeding conveyor of the fluid medium circulating system, and the fluid medium feeding conveyor is attached to the gasification furnace with an inclination upward, and the inside of the conveyor is purged with air. are doing. The flow medium inlet to the gasification furnace is likely to be blocked by condensed tar unless air purge is performed, but since the inside of the conveyor is sealed with the flow medium, the amount of purge gas can be reduced and air can be used. Also has little effect on gasification efficiency.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a waste gasification two-stage gasification system according to the present invention will be described below with reference to FIGS. FIG. 1 is a schematic diagram showing a configuration of a two-stage gasification system for waste according to the present invention. As shown in FIG. 1, in the two-stage gasification system for waste according to the present invention, a fluidized-bed gasification furnace 1 is used as a low-temperature gasification furnace, and a swirling melting furnace 30 is used as a high-temperature gasification furnace. The raw material supply system 10 for supplying waste to the fluidized bed gasifier 1 includes a moving bed type storage yard 1
1. raw material transport conveyor 12, raw material hopper 13, raw material lock hopper 14, raw material extracting machine hopper 15, raw material extracting machine 1
6, an impact line flow meter 17 and a raw material feeder 18.

Inside the fluidized-bed gasifier 1, a fluidized-gas dispersing device 3 for ejecting a fluidized gas upward to form a fluidized bed 2 in the furnace is arranged. Sand such as silica sand is used as a fluid medium of the fluidized bed 2. A free board 4 is formed at the top of the fluidized bed gasifier 1, and an incombustible substance discharge port 5 is formed at the bottom. The fluidized medium circulating system 20 that circulates the fluidized medium through the fluidized bed gasifier 1 includes a noncombustible material discharge conveyor 21, a fluidized medium discharge lock hopper 22, a fluidized medium elevator 23 disposed below the noncombustible material discharge port 5, It comprises a fluid medium supply lock hopper 24, a fluid medium feeding conveyor hopper 25, and a fluid medium feeding conveyor 26.

On the other hand, a swirling melting furnace 30 for gasifying gaseous substances such as gas, tar, char and the like generated in the fluidized bed gasification furnace 1 at a high temperature comprises a combustion chamber 31 and a slag separation chamber 3.
2 is provided. In the slag separation chamber 32, a downcomer 3
3 and a water tank 34 storing cooling water.

The combustible waste applicable to the two-stage gasification system shown in FIG. 1 includes municipal solid waste, solidified fuel (RD)
F), slurried fuel, waste plastic, waste FRP, biomass waste, automobile waste, low-grade coal, etc.
Here, the solidified fuel is one obtained by crushing and sorting municipal solid waste and then compression-molding by adding quick lime and the like, and the slurried fuel is made into a water slurry after crushing municipal solid waste and hydrolyzed under high pressure to hydrolyze. Things. FRP is a fiber reinforced plastic, and waste biomass includes water and sewage waste (impurities, sewage sludge), agricultural waste (rice husk, rice straw), forest waste (sawdust, bark, thinned wood). , Industrial waste (pulp chip dust), construction waste, and the like. Examples of low-grade coal include peat with a low degree of coalification, and waste generated during coal cleaning.

In the configuration shown in FIG. 1, waste a stored in the moving-bed type storage yard 11 after pretreatment such as removal of incombustibles and compression solidification is cut out from the storage yard 11 by a predetermined amount, and the raw material is conveyed. Conveyor 12 and raw material hopper 13
Is supplied to the raw material lock hopper 14 via the Waste a
At a predetermined pressure, for example, 1..
After the pressure is increased to about 013 to 4.053 MPa (10 to 40 atm), the raw material cutting machine hopper 15 and the raw material cutting machine 1
6. It is supplied to the fluidized-bed gasification furnace 1 via the impact line flow meter 17 and the raw material feeder 18 in a fixed amount.

A mixed gas of oxygen (or air) b and steam c is sent from the fluidizing gas dispersing device 3 in the gasification furnace 1 to the fluidized bed 2 as a gasifying agent and fluidizing gas, and the fluidized medium e
Is fluidized. The waste a is charged into the fluidized bed 2 in the gasification furnace, and quickly comes into contact with the high-temperature fluidized medium, oxygen as a gasifying agent, and steam in the fluidized bed 2 maintained at 500 to 850 ° C. It is gasified by pyrolysis. The fluid medium e is intermittently or continuously discharged together with the non-combustible material d by the non-combustible material discharge conveyor 21 from the non-combustible material discharge port 5 at the bottom of the gasification furnace 1 and decompressed by the fluid medium discharge lock hopper 22. After that, the fluid medium e and the non-combustible material d are separated by a classifier (not shown), the non-combustible material is discharged outside, and the fluid medium e is transported upward by the fluid medium elevator 23.
The fluid medium conveyed upward by the fluid medium elevator 23 is pressurized via the fluid medium supply lock hopper 24, the fluid medium charging conveyor hopper 25, and the fluid medium charging conveyor 26, and returned to the gasification furnace 1. The metals contained in the incombustibles are recovered in a state where they are not oxidized because the inside of the gasification furnace is in a reducing atmosphere.

Gas, tar, and char are generated by pyrolysis gasification of the input waste a.
Is pulverized by the attack of the gasifying agent and the turbulent motion. Since the solid char is porous and lightly pulverized, it is carried along with the upward flow of gaseous gas and tar. The gaseous substance g leaving the gasification furnace 1 is supplied to the swirling melting furnace 30 and introduced into the combustion chamber 31. There, it is oxidatively decomposed at a high temperature of 1200 ° C. or higher while being mixed with the mixed gas of the injected oxygen b and steam c in the swirling flow. Generated hydrogen (H ₂ ), carbon monoxide (CO),
The gas mainly composed of carbon dioxide (CO ₂ ) and steam (H ₂ O), together with the slag f, descends in the downcomer pipe 33 installed in the slag separation chamber 32, and is then blown into the water in the water tank 34 for rapid cooling and washing. Is done. The gas g exiting the slag separation chamber 32 is subjected to the following gas scrubber (not shown) to remove dust, hydrogen chloride, and the like remaining in the gas, and then used as a synthesis gas to produce hydrogen, methanol, methane, and the like. Used. From the lower part of the slag separation chamber 32, the slag particles f accumulated in the water tank 34 are discharged. The recovered slag particles are effectively used mainly as a raw material for cement or a material for civil engineering and construction.

Next, the two-stage gasification system for wastes according to the present invention is described.
The detailed structure of each part constituting the system will be described. Figure 2
FIG. 6 shows the moving bed type storage yard 11 of the raw material supply system 10.
It is a figure showing a detailed structure. Figure 2 shows a moving floor type storage yard.
It is a top view which shows a detailed structure. As shown in FIG. 1 and FIG.
As described above, the movable floor type storage yard 11 is supported on the frame 51.
The moving floor 52 held, and the front end and both sides of the moving floor 52
And a side wall 54 erected from the portion. Moving floor 52
Is, as shown in FIG.₁~ P
₃Has a configuration in which many are arranged in parallel,
ing. A raw material transfer conveyor installed below the moving floor 52
2 is transported rightward in FIG. 2 at a speed v (m / s).
Is being driven like so. The parallel moving plates are three moving plates
P₁, P ₂, P₃Are configured as one unit,
Raw material conveyor arranged below the moving bed type storage yard 11
The arrangement is repeated in twelve transport directions. Soshi
And the moving plate P of each unit₁, Moving plate of each unit
P₂, Moving plate P of each unit₃Are different
Moving plates arranged every third sheet to be connected to the moving device
Make the same movement with a time difference (1 / 4τ)
Has become. The width of the moving plate is about 150mm
Is used.

FIGS. 3 (a) and 3 (b) show a part of the moving floor type storage yard 11 shown in FIG. FIG.
In the state shown in (a), in a state where all moving plate _P 1 to P ₃ has advanced. In the state shown in FIG.
₁ is retracted by a distance 2l. The position behind the moving end of each of the moving plates P _{1 to} P ₃ constituting the moving floor 52 by a distance l substantially coincides with the center line of the raw material transport conveyor 12.

FIGS. 4 (a) and 4 (b) are side views of the movable floor type storage yard 11 shown in FIG. 2, and FIG.
FIG. 4B shows a case in which the raw material transport conveyor 12 is disposed immediately below the raw material falling portion in the moving floor type storage yard 11, and FIG. 4B shows the positional relationship between the movable floor type storage yard 11 and the raw material transport conveyor 12 described above. And a case where an inclined plate 35 is disposed between the two. FIG. 4 (a) and FIG.
In the example shown in (b), the moving plate of each unit in the moving floor 52 operates and retreats, and the moving floor type storage yard 1
1 shows a state in which a part of the waste a, which is the upper conveyer, is supplied onto the raw material conveyor 12.

FIGS. 5A to 5E are diagrams for explaining the operation of the movable floor type storage yard 11. FIG. 5 (a) to 5
In (e), only one unit including one moving plate P ₁ , P ₂ , and P ₃ is shown. As shown in FIG. 5A, all the moving plates P _{1 to} P ₃ on the moving floor 52.
Is in the forward position with the waste (not shown) placed at time T = 0. Then, time T = (1/4) τ
In, as shown in FIG. 5 (b), the moving plate _{P 1} is the distance 2l retracted. At this time, part of the waste which has been placed on the moving plate P ₁ falls onto the feed conveyor 12 (see FIG. 4).

Next, at time T = (2/4) τ, as shown in FIG. 5 (c), the moving plate _{P 2} is the distance 2l retracted. At this time, part of the waste which has been placed on the moving plate P ₂ falls onto the feed conveyor 12. Then, at time T = (3/4) τ, as shown in FIG.
Moving plate _{P 3} is the distance 2l retracted. At this time, the moving plate P ₃
Some of the waste placed on the raw material transport conveyor 12
Fall on. Finally, at time T = τ, FIG.
(E), the all mobile plate P ₁ to P ₃ is the distance 2l advanced from a retracted position while placing the waste. FIG.
By repeating the cycle shown in (a) to (e) of FIG. 5, the raw material as waste is cut out from the moving-bed storage yard 11 to the raw material transport conveyor 12.

The transport speed v (m / m) of the raw material transport conveyor 12
sec), the total length L (m) of the moving bed 52 (see FIG. 2) and the cycle time τ (sec) are set to L / v ≧ τ. Therefore, the waste material a is continuously supplied to the raw material transport conveyor 12 from the movable floor type storage yard 11. Then, by moving the moving plates (P _{1 to} P ₃ ) arranged every third sheet with a time difference (１ ／ τ), the waste material falls from the moving floor 52 onto the raw material transporting conveyor 12 every time the moving plates (P _{1 to} P ₃ ) are moved. Therefore, the supply amount of the waste transferred to the equipment on the downstream side of the raw material transfer conveyor 12 is substantially equalized. Therefore, it is not necessary to increase the equipment capacity on the downstream side of the raw material conveyor 12.

FIG. 6 is a perspective view showing a modification of the moving floor type storage yard. When the raw material conveyor 12 at the exit of the moving floor type storage yard 11 has to be inclined due to the arrangement of downstream equipment (θ: inclination angle), the moving floor 52 is divided into several units as shown in FIG. (In the example shown in FIG. 5, the unit is divided into three units) and arranged in a stepwise manner. In the example shown in FIG. 6, the units 1, 2 and 3 is composed of the four movable plate _{P 1, P 2, P 3} , P 4. The operation and effect are the same as those in the examples shown in FIGS. The transport capacity of the moving floor storage yard is
It is determined by the moving length of the moving plate, but usually 0.0
7 to 0.6 m / min.

FIG. 7 is a side view showing a detailed structure of a path from the raw material hopper 13 in the raw material supply system 10 to the fluidized-bed gasification furnace 1 which is a low-temperature gasification furnace. As shown in FIG. 7, the waste supplied to the raw material hopper 13 from the raw material transport conveyor 12 includes a raw material lock hopper 14, a raw material extracting machine hopper 15, a raw material extracting machine 16, and an impact line flow meter 1.
7. It is supplied to the fluidized-bed gasification furnace 1 via the raw material supply device 18. The fluidized-bed gasification furnace 1 is required to be supplied with the raw material waste in a manner that is not intermittent but nearly continuous. In the example shown in FIG. 7, a screw conveyor is used for the raw material cutting device 16 and a screw conveyor is used for the raw material supply device 18, that is, a two-stage screw system is used for the raw material supply system. Further, an impact line flow meter 17 is provided between the raw material cutting device 16 and the raw material supply device 18. Therefore, the large-sized lump waste is quantitatively supplied to the impact line flow meter 17 while being crushed by the screw-type raw material cutting device 16, and is measured online by the impact line flow meter 17, and is supplied to the inside of the furnace by the raw material supply device 18. Can be supplied to That is, the waste can be continuously and leveled to the impact line flow meter 17 by the combination of the raw material extracting device 16, the impact line flow meter 17, and the raw material supply device 18.
Measurement accuracy can be improved. Also, when the waste is formed into a large particle mass, the waste may be made firm enough to be easily crushed by a screw conveyor. It is not necessary to dissolve and harden more than necessary.

A purge steam 55 is supplied to the leading end of the raw material supply device 18. And
Purging air 56 is supplied to the raw material cutting machine hopper 15. Therefore, since the tip of the raw material feeder 18 is always purged with steam, the combustible gas in the furnace and the raw material lock hopper
Does not directly contact the inside of the raw material feeder 18. In addition, since the temperature in the raw material feeder 18 can be kept low, even if the waste is plastic, it does not adhere to the melt, and does not hinder the supply of the waste to the fluidized bed gasification furnace 1. . Further, even if the gaseous substance in the furnace flows backward through the raw material feeder 18 toward the upstream side, the backflow can be prevented by the purge air 56 supplied to the raw material extractor hopper 15. In addition, the raw material lock hopper 14
When the pressure is increased, the pressure increasing air 57 is supplied, and when the pressure is decreased, the air in the raw material lock hopper 14 is exhausted. Further, in an emergency, the purge nitrogen 58 is supplied to the raw material lock hopper 14 and the raw material extractor hopper 15.

FIG. 8 is a diagram showing a detailed structure of the fluidized bed gasifier 1. FIG. 8A is a front view having a partial cross section, and FIG. 8B is an enlarged view of a portion A in FIG. 8A. FIG.
As shown in (a), the fluidized-bed gasification furnace 1 is provided with a char overflow pipe 61. The char overflow pipe 61 includes an overflow inner pipe 62, an overflow outer pipe 63, and a heat insulating material 64 sandwiched between the inner and outer pipes 62, 63. That is, the char overflow pipe 61 has a double pipe structure, the inner pipe 62 in contact with the high-temperature char or the fluid medium does not have a pressure-resistant function, the outer pipe 63 has a pressure-resistant function, and the outermost part is inside the pipe. A steam trace 66 is provided to prevent condensation of the purged steam and to control the outer tube temperature. One end of the char overflow pipe 61 is opened slightly above the surface of the fluidized bed, and the other end is connected to the incombustible discharge extraction conveyor 21. A valve 65 is provided at the lower end of the char overflow pipe 61. Also, a branch portion 61 of the char overflow pipe 61
Char can be sampled from a.

A noncombustible chute 6 connected to the noncombustible discharge port 5
The outer surface of the incombustibles extraction conveyor 21 is also covered with the steam trace 66. A viewing window 67 is provided on the side wall of the fluidized-bed gasification furnace 1, and an industrial television 68 for monitoring the inside of the furnace is provided outside the viewing window 67.

In the conventional fluidized-bed gasification furnace, char was sometimes deposited on the fluidized bed and hindered gasification of waste. Therefore, char combustion by blowing oxygen or the like became necessary. Such a phenomenon is remarkable in raw materials having a high char generation rate (for example, urethane rubber, wood, and coal). In the present invention, it is monitored that the char has accumulated on the surface of the fluidized bed 2 due to the pressure difference between the industrial television 68 and the fluidized bed. The char is drawn out by the overflow pipe 61. Thereby, only the char is selectively discharged to the outside of the furnace and, if necessary, returned to the gasifier after pulverization, so that stable operation can be performed even with a raw material having a high char generation rate.

As shown in FIG. 8A, a secondary oxygen supply nozzle 69 is provided on the free board 4 of the fluidized bed gasifier 1. By supplying oxygen from the secondary oxygen supply nozzle 69 to the free board 4 as needed, the fluidized bed 2
Can be partially burned by the free board 4. In the free board 4, since an endothermic reaction such as a Boudouard reaction and a water gasification reaction (C + H ₂ O → CO + H ₂ ) progresses to lower the gas temperature, tar may be condensed. However, if necessary, the secondary oxygen supply nozzle may be used. By supplying oxygen from 69, preferably a mixed gas of oxygen and steam, the free board 4 is heated to 300 ° C. or more, preferably 40 ° C. or more.
Since the temperature can be increased to 0 ° C. or higher, tar condensation due to a decrease in gas temperature can be avoided.

In the fluidized-bed gasification furnace 1 of the present invention, as shown in FIGS. 8A and 8B, heat insulating layers 72 and 73 are provided on both sides (inside and outside) of a pressure vessel 71 made of a steel plate. Provided. The heat insulating layer 72 is made of a heat insulating material, and the heat insulating layer 73 is made of a heat insulating material. Further, a refractory layer 74 is provided inside the heat insulating layer 72.

If hydrogen chloride contained in the produced gas condenses on the inner surface of the pressure vessel, it causes corrosion. Therefore, it is necessary to control the temperature of the inner surface of the vessel at a temperature higher than the temperature at which no dew condensation occurs (but within the design temperature range of the vessel). There is. Conventionally, in order to do this, it is necessary to provide a jacket on the pressure vessel or to control the temperature by using a boiler structure, which has been problematic in terms of cost. In the present invention, heat insulating layers 72 and 73 are provided on the inner and outer surfaces of the pressure vessel 71. Thereby, it is possible to make the pressure vessel 71 less susceptible to fluctuations in the furnace temperature and the outside air temperature, and to place the pressure vessel 71 within an appropriate temperature range at a predetermined outside temperature and a furnace operating temperature. . Also,
The incombustible chute 6 and the overflow pipe 61 in the lower part of the furnace, which have a relatively low operating temperature in the furnace, are maintained at a temperature higher than the dew condensation temperature of hydrogen chloride by applying a steam trace 66. The water dew temperature including hydrogen chloride is 1.621MPa.
It is considered to be about 160 ° C. at a (16 atm).

FIGS. 9 to 12 are diagrams showing the detailed structure of the fluidized gas dispersion device 3 installed in the fluidized bed gasifier 1 and its peripheral devices. FIG. 9 is a sectional view of a main part of a fluidized-bed gasification furnace, and FIG. 10 is a perspective view schematically showing a fluidized-bed gasification furnace and a fluidized-gas dispersing apparatus. The fluidized bed is 0.4
A fluidized bed is formed by supplying gas from below a particle packed bed filled with fluidized medium particles such as silica sand or iron oxide of about 1.0 mm to fluidize the fluidized medium and form a fluidized bed. The fluidity, uniformity and heat capacity of the fluidized bed
It is intended to make chemical reaction fast, stable and homogeneous by utilizing the size of surface area etc.It is applied to catalytic cracking of petroleum refining, combustion and incineration of solid fuel such as coal, and has many achievements .

In a reactor using a fluidized bed, it is important to obtain a fluidized state as designed, but in an actual fluidized bed reactor, the fluidized state usually has a horizontal distribution. The main cause of the distribution in the fluidized state is that the flow rate of gas blown out from the fluidized gas dispersion device below the fluidized bed varies depending on the location. This difference in the amount of fluidized gas blown out is considered to be due to the static pressure distribution in the wind box that supplies the fluidized gas to the fluidized gas dispersion device.To obtain the fluidized gas blowout speed as designed, It is important to minimize the static pressure distribution in the wind box.

However, in the design of a normal fluidized bed reactor, dynamic pressure exists in the fluidizing gas flowing into the wind box, so it is not easy to eliminate the static pressure distribution in the wind box.
In order to maintain the uniformity of fluidization, the influence of the static pressure distribution is relatively reduced by designing the ventilation resistance of the fluidizing gas blowing nozzle to be larger than the static pressure distribution width. I have. However, since a large ventilation resistance of the fluidizing gas dispersion nozzle causes an energy loss, it is desirable for the energy saving to have a wind box shape that does not generate a static pressure distribution as much as possible.

The present invention has been made in view of the above, and an object of the present invention is to provide a fluidized gas dispersing apparatus capable of obtaining a uniform fluidized state with a small energy loss of the fluidized gas. The following formula formalizes Bernoulli's theorem. The left side is the total pressure, the first term on the right side is the static pressure,
The second term is the dynamic pressure, and the third term is the position pressure (head). P = p + 1 / 2ρv ² + ρgh After the fluidizing gas having a dynamic pressure flows into the wind box and the flow velocity is reduced, the kinetic energy (dynamic pressure) of the fluidizing gas is converted to a static pressure. . Therefore, when supplying the fluidizing gas from one side with a wind box using a simple pipe, or when supplying the fluidizing gas from one location of a box-shaped wind box, the flow velocity is inevitably reduced at the inner end of the wind box. Because of this, the static pressure at the end tends to increase, and in the dispersion nozzle where the fluidizing gas is supplied from the portion where the static pressure has increased,
The amount of fluidizing gas blown out from the dispersing nozzle becomes relatively large as compared with other nozzles. Therefore, when designing a wind box for fluidized gas, it is important not to create edges. A typical closed space with no ends is a ring.

Therefore, in the fluidizing gas dispersion apparatus of the present invention, as shown in FIGS. 9 and 10, an annular wind box is used. That is, annular wind boxes 81a and 81b are provided in the fluidized gas dispersion device 3 inside the fluidized bed gasifier 1.
Is provided. Since the gasification furnace has a cylindrical shape, a ring-shaped wind box is excellent in shape conformity, but simply using a sphere or a ring as a wind box does not eliminate the internal static pressure distribution.

FIG. 11 is a detailed view showing an example of an annular wind box. FIG. 11A is a plan view of the annular wind box.
(B) is a front view of the annular wind box. As shown in FIGS. 11A and 11B, the wind box 81a includes a fluidizing gas supply pipe 82 and a plurality of fluidizing gas blowing pipes 84 having a fluidizing gas blowing nozzle 83 at the tip. It is connected. When the fluidizing gas 60 is simply supplied from one place as in the example shown in FIG. 11, the fluidizing gas flows as shown by the arrow in the figure, and the flow collides at the "A" portion on the opposite side of the supply pipe connection. Then, since the dynamic pressure is converted to static pressure, the static pressure in the "A" part increases, and the amount of fluidizing gas from the dispersion nozzle supply pipe connected near the "A" part becomes larger than the others. Would. Even if the number of fluidized gas supply points is increased to two or more, instead of one, if the flow collides and a part where dynamic pressure is converted to static pressure is formed, the static pressure in that part increases, The blowing amount of the forming gas becomes non-uniform.
Therefore, it is important to prevent the dynamic pressure from being converted to the static pressure in order to prevent the blow-off amount of the fluidizing gas from being uneven.

FIG. 12 is a detailed view showing another example of the annular wind box. FIG. 12A is a plan view of the annular wind box.
12B is a front view of the annular wind box, and FIG.
It is a B arrow view of (b). Guides 85a and 85b are provided at the outlet of the fluidizing gas supply pipe 82 in the wind box 81a so that the fluidizing gas in the wind box 81a flows in one direction. The guides 85a and 85b may have any shape as long as they can guide the flow of the fluidizing gas in one direction. However, even if the flowing medium falls into the wind box, It is desirable that the vicinity of the bottom of the wind box be open so that the gas can be discharged from the supply gas supply pipe 82. In the example shown in FIG. 11C, reference numeral 86 denotes a fluid medium discharge port. In the wind box of the present invention, since the gas flow is in a fixed direction, the fluid medium that has fallen into the wind box is blown toward the fluidizing gas supply pipe 82, and is therefore unlikely to accumulate in the wind box. In the figure, reference numeral 87 indicates a flow when the fluid medium is discharged through the fluid medium discharge port 86. In the annular wind box, the residence time of the fluidizing gas is equal to 0.
It is preferable to be designed to be 1 to 0.2 sec.

The upper portion of the guide 85a must be open so that the dynamic pressure of the fluidizing gas returned after making a round in the annular wind box is not converted to static pressure. The guide 85a is preferably arranged so as to cover the entire diameter of the fluidizing gas supply pipe 82 in order to control most of the gas flow. In the example shown in FIG. 12, the guide is composed of two sheets 85a and 85b. However, the number of guides is not necessarily two, but may be one, or may be increased as necessary. The shape of the guide may be a simple flat plate, but preferably, as shown in FIG. 12, it is good to be constituted by a curved surface according to the flow of gas. By providing such a guide in the annular wind box in the fluidized bed gasifier, the static pressure in the wind box can be kept uniform even with a small number of air supply ports, and the flow state can be made uniform. Also, even if the flowing medium falls into the wind box, the discharge becomes easy.
The waste two-stage gasification system has a capacity of 1.013 MPa.
Since the fluid medium is often operated at (10 atm) or more, the particle size of the fluid medium to be used is set to about 0.1 to 0.5 mm.

FIG. 13 is a front view showing a detailed structure of a main part of the fluid medium circulation system 20. FIG. 13 shows a fluid medium supply lock hopper 24, a fluid medium introduction conveyor hopper 25, and a fluid medium introduction conveyor 26.
A screw conveyor is used as the fluidized medium charging conveyor 26, and the fluidized medium charging conveyor 26 is inclined upward by a predetermined angle (θ) toward the fluidized bed gasifier 1 with respect to a horizontal plane. This angle (θ) is set to 10 to 20 °. Then, the hopper 25 for the fluid medium feeding conveyor
Is supplied with purge air 90. That is, the present invention employs a configuration in which a screw conveyor is used as the fluidized medium charging conveyor 26, and the fluidized medium charging conveyor 26 is mounted to be inclined upward toward the furnace, and the inside of the conveyor is purged with air. Therefore, the inlet of the fluidized medium to the gasification furnace is blocked by the condensed tar unless the purging is performed. However, the fluidized medium introduction conveyor 26 may be filled with the fluidized medium by the inclined screw conveyor. As a result, the amount of purge gas supplied to the inlet of the fluid medium can be reduced. Therefore, even if air is used, the effect on gasification efficiency is small. The pressurized air 93 is supplied to the fluid medium supply lock hopper 24. The air in the fluid medium supply lock hopper 24 can be exhausted.

[0047]

As described above, according to the present invention, the following effects can be obtained. 1) Construction costs can be significantly reduced by using a moving bed storage yard in the raw material supply system for supplying the raw material to the fluidized bed gasifier, and the downstream side can be cut even if the downstream conveyor does not have a cutting function. Since the supply of raw materials to the equipment is leveled, there is no need to increase the capacity of downstream equipment. 2) The raw material supply system adopts a two-stage screw-type raw material cutting machine and raw material supply machine, and an impact line flow meter is installed between the raw material cutting machine and the raw material supplying machine. The raw material can be continuously and quantitatively supplied while being crushed by a screw type raw material cutting machine, and can be supplied into the furnace by a raw material supply device while measuring and monitoring with an impact line flow meter.

3) Since steam for purging is supplied to the front end of the raw material feeder for charging the raw material into the raw material furnace, even if the furnace pressure slightly changes, the flammable gas and air are supplied to the raw material feeder. No direct contact inside. Further, the temperature in the raw material feeder can be kept low, and even if the waste is plastic, it does not adhere to the material, and there is no hindrance to the supply of the waste to the fluidized bed gasification furnace.

4) Since the char overflow pipe is provided above the surface of the fluidized bed, the char can be selectively discharged to the outside of the furnace, so that a raw material having a high char generation rate can be gasified stably. 5) Install a secondary oxygen supply nozzle on the freeboard of the fluidized bed gasifier and supply oxygen as necessary from the secondary oxygen supply nozzle, so that a part of the gas generated in the fluidized bed is freeboarded. Can be burned. Therefore, the temperature of the freeboard can be raised to 300 ° C. or higher, preferably 400 ° C. or higher, so that condensation of tar due to a decrease in gas temperature can be avoided.

6) Conventionally, it was necessary to use a jacket type or a boiler type for temperature control for preventing corrosion of the pressure vessel. However, as in the present invention, a heat insulating layer is provided on both sides of the pressure vessel made of a steel plate. With the provision, the temperature of the pressure vessel can be kept within the control value even if there is a slight temperature change inside and outside the furnace because the inside temperature of the furnace and the outside air temperature are less likely to be affected. 7) The fluidized gas dispersing device is an annular wind box, and a circulating flow is positively formed in the wind box. Due to the annular shape, there is no end portion and pressure distribution hardly occurs. Variation can be prevented.

8) A screw conveyor is used for the fluid medium feeding conveyor of the fluid medium circulating system, and the fluid medium feeding conveyor is mounted to be inclined upward toward the gasification furnace, and the inside of the conveyor is purged with air. are doing. The inlet of the fluidized medium to the gasifier is not blocked by the condensed tar. In addition, since the fluid medium can be filled in the conveyor, the amount of purge air can be reduced, and the effect on gasification efficiency is reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a main part of a waste gasification two-stage gasification system of the present invention.

FIG. 2 is a plan view showing a detailed structure of a moving floor type storage yard.

3 (a) and 3 (b) are views showing a part of the moving floor type storage yard shown in FIG. 2, and in the state shown in FIG. 3 (a), all groups move. FIG. 3B shows a state in which the plates have moved forward, and the state shown in FIG. 3B shows a state in which the moving plates of one group have retreated by 2 l.

4 (a) and FIG. 4 (b) are side views of the moving floor type storage yard shown in FIG. 2, and FIG. 4 (a) shows a raw material transfer conveyor immediately below the moving floor type storage yard. FIG. 4B shows a case where an inclined plate is provided between the moving floor type storage yard and the raw material transport conveyor.

5 (a) to 5 (e) are explanatory diagrams of the operation of the moving floor type storage yard.

FIG. 6 is a perspective view showing a modification of the moving floor type storage yard.

FIG. 7 is a side view showing a detailed structure of a path from a raw material hopper to a fluidized bed gasifier in a raw material supply system.

8 is a view showing a detailed structure of the fluidized bed gasification furnace, FIG. 8 (a) is a front view having a partial cross section, and FIG. 8 (b) is FIG.
It is an A section enlarged view in (a).

FIG. 9 is a sectional view of a main part of a fluidized-bed gasification furnace.

FIG. 10 is a perspective view schematically showing a fluidized bed gasification furnace and a fluidized gas dispersion device.

11 is a detailed view showing one example of an annular wind box, and FIG.
1A is a plan view of an annular wind box, and FIG. 11B is a front view of the annular wind box.

12 is a detailed view showing another example of the annular wind box, FIG. 12 (a) is a plan view of the annular wind box, FIG. 12 (b) is a front view of the annular wind box, and FIG. FIG. 13C is a view on arrow B in FIG.

FIG. 13 is a front view showing a detailed structure of a main part of a fluid medium circulation system.

FIG. 14 is a schematic diagram showing an example of a conventional two-stage gasification system for waste.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fluidized bed gasifier 2 Fluidized bed 3 Fluidized gas dispersing device 4 Free board 5 Noncombustible material outlet 6 Noncombustible chute 7 Screen 8,36 Lock hopper 10 Raw material supply system 11 Moving bed type storage yard 12 Raw material transport conveyor 13 Raw material Hopper 14 Raw material lock hopper 15 Raw material extractor hopper 16 Raw material extractor 17 Impact line flow meter 18 Raw material feeder 20 Fluid medium circulation system 21 Incombustibles extraction conveyor 22 Fluid medium extraction lock hopper 23 Fluid media elevator 24 Fluid medium Supply lock hopper 25 Fluid medium feeding conveyor hopper 26 Fluid medium feeding conveyor 30 Revolving melting furnace 31 Combustion chamber 32 Slag separation chamber 33 Downcomer 34 Water tank 35 Inclined plate 37 Slag screen 38 Scrubber 51 Frame 52 Moving floor 54 Side wall 55 Purging steam 56 Par Air for pressurization 57,93 Air for pressurization 58 Nitrogen for purging 60 Fluidizing gas 61 Char overflow pipe 61a Branch 62 Overflow inner pipe 63 Overflow outer pipe 64 Heat insulator 65 Valve 66 Steam trace 67 Viewing window 68 Industrial television 69 Secondary Oxygen supply nozzle 71 Pressure vessel 72, 73 Insulation layer 74 Refractory layer 81a, 81b Wind box 82 Fluidizing gas supply pipe 83 Fluidizing gas blowing nozzle 84 Fluidizing gas blowing pipe 85, 85a, 85b Guide 86 Fluid medium outlet 87 Fluid Medium flow P ₁ , P ₂ , P ₃ , P ₄ Moving plate a Waste b Oxygen c Steam d Incombustible e Fluid medium f Slag particles fa Fine slag g Generated gas k Make-up water

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B01J 8/24 311 B01J 8/24 311 8/44 8/44 B09B 3/00 ZAB B09B 3/00 302E 302 F27B 15 / 08 F27B 15/08 15/18 15/18 B09B 3/00 ZAB (72) Inventor Daisaku Fukuoka 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation (72) Inventor Takashi Imaizumi Ota-ku, Tokyo 11-1 Haneda Asahimachi, Ebara Works, Ltd. No. 1 EBARA CORPORATION (72) Inventor Shinichiro Chiba 11-1 Haneda Asahimachi, Ota-ku, Tokyo EBARA CORPORATION

Claims (11)

[Claims] 1. A two-stage waste gas in which a raw material consisting of waste is pyrolyzed and gasified at a low temperature in a fluidized bed gasifier, and the resulting gaseous substance and char are introduced into a melting furnace and gasified at a high temperature. In the gasification system, a moving bed type storage yard in which a plurality of movable flat moving plates are arranged in parallel is provided in a raw material supply system for supplying a raw material to the fluidized bed gasifier, and the plurality of moving plates mount the raw material. The plurality of moving plates are configured to be moved forward and backward with a time lag by a part, and the raw material is dropped and supplied to downstream equipment every time the moving plate is moved backward. A two-stage gasification system for waste. 2. A two-stage waste gas in which a raw material consisting of waste is pyrolyzed and gasified at a low temperature in a fluidized-bed gasification furnace, and the obtained gaseous substance and char are introduced into a melting furnace and gasified at a high temperature. A raw material supply system for supplying a raw material to the fluidized-bed gasification furnace, a lock hopper, a raw material extracting device including a screw conveyor disposed downstream of the lock hopper, and a downstream of the raw material extracting device. And a raw material feeder comprising a screw conveyor connected to the fluidized-bed gasification furnace. 3. The two-stage gasification system for wastes according to claim 2, wherein a flow meter for measuring a fall amount of the raw material is provided between the raw material cutting device and the raw material supply device. 4. The two-stage gasification system for waste according to claim 2, wherein a steam for purging is supplied to a front end portion of the raw material supply device. 5. A two-stage waste gas in which a raw material consisting of waste is pyrolyzed and gasified at a low temperature in a fluidized-bed gasification furnace, and the obtained gaseous substance and char are introduced into a melting furnace and gasified at a high temperature. In the gasification system, a two-stage gasification system for wastes is provided with an overflow pipe for extracting a char to the outside of the fluidized bed of the fluidized-bed gasification furnace. 6. A two-stage waste gas in which a raw material consisting of waste is pyrolyzed and gasified at a low temperature in a fluidized bed gasifier, and the obtained gaseous substance and char are introduced into a melting furnace and gasified at a high temperature. In the gasification system, a secondary oxygen supply nozzle for supplying oxygen to a free board of the fluidized bed gasification furnace is provided. 7. A two-stage waste gas in which a raw material consisting of waste is pyrolyzed and gasified at a low temperature in a fluidized-bed gasification furnace, and the obtained gaseous substance and char are introduced into a melting furnace and gasified at a high temperature. A two-stage gasification system for wastes, characterized in that a heat insulation layer is provided on the inner and outer surfaces of a pressure vessel constituting an outer wall of the fluidized-bed gasification furnace. 8. A two-stage waste gas in which a raw material consisting of waste is pyrolyzed and gasified at a low temperature in a fluidized-bed gasification furnace, and the resulting gaseous substance and char are introduced into a melting furnace and gasified at a high temperature. In the fluidizing system, the fluidized gas dispersing device for fluidizing the fluidized medium in the fluidized bed gasification furnace is constituted by an annular wind box having a fluidizing gas blowing nozzle, and the inside of the annular wind box is A two-stage gasification system for waste, characterized in that a circulating flow of fluidized gas is formed in the system. 9. The circulating flow of the fluidizing gas is formed by providing a guide in the wind box for guiding the fluidized gas supplied into the wind box in one direction. 9. A two-stage gasification system for waste according to claim 8. 10. A two-stage waste gas in which a raw material consisting of waste is pyrolyzed and gasified at a low temperature in a fluidized-bed gasification furnace, and the resulting gaseous substance and char are introduced into a melting furnace and gasified at a high temperature. In the gasification system, a fluidized medium circulating system for circulating a fluidized medium in the fluidized-bed gasification furnace is provided with a fluidized medium charging conveyor comprising a screw conveyor connected to the fluidized-bed gasification furnace, and the fluidized medium charging conveyor is fluidized. A two-stage gasification system for waste, wherein the two-stage gasification system is provided to be inclined upward toward the bed gasification furnace. 11. The apparatus according to claim 10, wherein air for purging is supplied to said fluid medium feeding conveyor.
A two-stage gasification system for the described waste.