JPH11241817A - Gasifying and melting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gasifying and melting system capable of discharging molten slag, produced by melting combustion at a high temperature, smoothly out of the slag discharging port of a melting furnace and making granulated slag. SOLUTION: A gasifying and melting system, in which waste is decomposed pyrolytically at a comparatively low temperature employing a gasifying furnace and produced gas (d) as well as char are molten at a high temperature employing a melting furnace 7, is provided with an inducing fan 19, connected to a slag cooling device through a chute 14 having at least a water-cooled jacket structure 18 at one part thereof from a slag discharging port 11 provided on the bottom part of the melting furnace 7 to introduce a part of the combustion waste gas of the melting furnace 7 into a chute. According to this method, molten slag is prevented from blocking the chute by being solidified near the molten slag discharging port and is permitted to be discharged stably and continuously from the molten slag discharging port to obtain granulated slag, whereby the long time continuous operation of the gasifying and melting system is permitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gasification and melting system, and more particularly to gasification and melting of waste such as municipal solid waste, thereby completely burning without generating dioxins and producing waste gas. The present invention relates to an environment-conserving waste treatment method capable of forming slag contained in molten slag and extracting it efficiently. In addition, in addition to municipal solid waste, solid fuel, slurry fuel, waste plastic,
Various wastes such as waste FRP, biomass waste, automobile waste, papermaking sludge, medical waste, coal preparation waste, and waste oil are included. Here, the solidified fuel (R
DF: Refuse Derived Fuel (Frequency Derived Fuel) is a product obtained by crushing and sorting municipal waste and then compression-molding by adding quicklime and the like. It is made into oil by hydrothermal decomposition under high pressure.

[0002]

2. Description of the Related Art As a new waste disposal method that replaces incineration, a "gasification and melting system" that combines pyrolysis gasification and high-temperature combustion has been developed, and has already reached the practical use.

[0003] Such a gasification and melting system has the following features. First, the slow gasification of the fluidized-bed furnace and the high-temperature combustion of the swirling melting furnace make it possible to achieve a low air ratio combustion of about 1.3, so that the amount of exhaust gas is greatly reduced and the exhaust gas treatment equipment is small. Be transformed into Next, the synthesis of dioxins and furans is suppressed by high-temperature combustion of 1300 to 1400 ° C. in a swirling melting furnace. Next, the inorganic components in the waste are converted into slag mist in the swirling type melting furnace, and are converted into molten slag with high efficiency due to centrifugal force generated by the swirling flow.
Granulation of granulated slag can reduce the mass and improve the stability of the slag, thereby extending the life of the landfill and making it possible to use it for civil engineering and construction materials.

Further, since the amount of heat recovery in the waste heat boiler is improved by low air ratio combustion, power generation efficiency exceeding 20% is possible. In addition, valuable metals such as iron, copper, and aluminum are recovered in a non-oxidized state and after removal of attached combustibles, so that they can be recycled as ingots. In addition, the energy of the waste can be used as a heat source for high-temperature combustion (self-thermal melting), and ash melting equipment that consumes a large amount of power is not required, so that the amount of power that can be transmitted is greatly improved. Also, since the functions of dioxin decomposition and ash melting are incorporated into a simple furnace configuration, construction costs are reduced and the entire plant is more compact than adding these functions to a conventional incinerator.

FIG. 3 shows a flow of a core part of a gasification and melting system in which a fluidized bed gasification furnace and a rotary melting furnace are combined. In FIG. 3, reference numeral 1 denotes a waste supply device, 2 denotes a fluidized bed gasifier, 3 denotes an air chamber, 4 denotes an air dispersion plate, 5 denotes a fluidized bed,
6 is a free board, 7 is a revolving melting furnace, 8 is a temporary combustion chamber, 9 is a secondary combustion chamber, 10 is a tertiary combustion chamber, and 11 is a slag discharge port. Symbol a is waste, b is primary air, c is secondary air, d is generated gas, e is tertiary air, f is combustion exhaust gas, g is molten slag, and h is incombustible.

The waste a to be treated is subjected to pretreatment such as crushing and sorting as required, and then the waste is supplied to the waste supply device 1.
Is supplied to the fluidized-bed gasification furnace 2 in a fixed amount. Gasifier 2
The primary air b is sent into the lower air chamber 3 and blows upward from the air distribution plate 4 to form a fluidized bed 5 of sand on the air distribution plate 4.

Fluidized bed 5 maintained at 450 to 650 ° C.
The waste a input from the waste supply apparatus 1 is pyrolyzed and gasified while being swallowed by the descending fluidized bed at the center of the fluidized bed, and generates gas, tar, and char. The char is gradually pulverized in the fluidized bed 5 by the disturbance motion of the fluidized bed 5 and the attack of oxygen. Then, incombustibles h are discharged from the bottom of the gasification furnace 2 together with the sand. The metals in the incombustibles h
Since the fluidized bed 5 has a reducing atmosphere, the fluidized bed 5 is recovered in a clean state in which deposits are removed without being oxidized. After the non-combustibles h and sand discharged from the gasification furnace 2 are mechanically classified, only the sand is returned to the gasification furnace 2. The secondary air c is fed into the free board 6 of the gasification furnace 2, and oxidizes and burns the char deposited on the bed. At this time, the temperature of the free board 6 is
Maintained at 650-850 ° C where no clinker is formed.

[0008] The product gas 6 accompanied by the fine powder char is
Part of the tertiary air e is added in the middle of the duct leading from the gasification furnace 2 to the swirling melting furnace 7 and burns at 800 ° C. Next, while being supplied to the primary combustion chamber 8 of the swirling type melting furnace 7 and mixed with the tertiary air e also supplied from the side surface of the combustion chamber in a swirling flow, high-speed combustion is performed at a high temperature of 1300 to 1400 ° C. The inorganic components contained in the char are converted into slag mist by high-temperature combustion, and most of them are captured by the molten slag phase formed on the furnace wall of the primary combustion chamber 8 and the secondary combustion chamber 9 by the centrifugal force of the swirling flow. The molten slag flowing down by the action of gravity is supplied to a slag discharge port 14 provided at the outlet of the secondary combustion chamber 9.
, And is quenched by falling into water.
The unburned portion remaining in the gas is discharged after burning the remaining tertiary air e with the rest of the tertiary air e at 900 to 1400 ° C. in the tertiary combustion chamber 10, and the exhaust gas f goes to the atmosphere after a series of heat recovery and dust removal processes. Released.

[0009]

FIG. 4 shows a conventional method for cooling and discharging molten slag in the gasification and melting system described above. In FIG. 4, reference numerals 12 and 13 are burners for heating, 14 is a chute, 15 is a granulated trough, 16
Is a slag conveyor, and 17 is a circulating water pump. Here, the symbol g ′ is slag particles, and i is water.

The granulation trough 15 is like a slide on which water i flows. A chute 1 is fed from the furnace material overhanging portion of the slag discharge port 11 provided at the bottom of the rotating melting furnace 7.
The molten slag g that has fallen in the space inside 4 is
The slag is rapidly cooled in the upper stream to become granular slag particles g ′, and is transported to the slag conveyor 16 together with the water. Next, the slag particles g ′ are continuously carried out by the slag conveyor 16. When the molten slag g is dropped directly from the slag discharge port 11 onto the slag conveyor 16 without using the granulated trough 15, when the size of the slag particles g 'becomes uneven or a large slag mass falls, This is not preferable because the generated steam may cause an increase in the furnace pressure.

In the gasification and melting system, the most problematic in operation is discharge of the molten slag g. This has the following two problems. That is, the first problem is that the steam i ′ generated when the molten slag g is rapidly cooled on the granulation trough 15 rises in the chute 14 and lowers the temperature near the slag discharge port 11. is there. As a result, the molten slag flowing down the furnace material overhang portion cools and lowers the fluidity, so that as shown in FIG. 5, an icicle-like massive solidified material 20 is formed and grown under the overhang portion. As a second problem, there is no problem if the molten slag g is cut off from the tip of the furnace material overhang portion, but sometimes the molten slag g runs down the overhang portion and flows down on the wall surface of the chute 14. As shown in FIG. 6, while flowing down the wall of the chute 14,
The molten slag that has lost its fluidity due to a decrease in temperature grows into a large lump 20 while being fixed to the wall surface.

The slag mass 20 thus produced is
Is slowly cooled, so that it becomes a very strong glass-like solidified material, and since it has strong adhesion to the wall surface, it is difficult to remove it. Then, if the operation is continued while the operation is left as it is, the chute 14 is completely closed by the slag mass 20, and the operation cannot be continued any further. From a different point of view, it is considered that the combustion temperature in the secondary combustion chamber 9 is only about 100 ° C. higher than the ash melt temperature.

The present invention has been made in view of the above circumstances, and a gasification and melting system capable of smoothly discharging molten slag generated by melting and burning at a high temperature from a slag discharge port of a melting furnace to form granulated slag. The purpose is to provide.

[0014]

According to a first aspect of the present invention, there is provided a gasification and melting system, which comprises pyrolyzing waste at a relatively low temperature using a gasification furnace, and converting the generated gas and char into a melting furnace. In a gasification and melting system that melts and burns at a high temperature by using a slag having a water-cooled jacket structure at least partially from a slag discharge port provided at the bottom of the melting furnace, the molten slag generated by the melt combustion at the high temperature is used. And discharged.

Thus, even if a slag lump adheres to the chute wall surface of the water-cooled jacket, the bonded portion is cooled by water cooling, so that the bonded portion to the wall surface of the slag block is made fragile amorphous. Before the slag mass grows large, it can be peeled off by its own weight. Therefore, it is possible to prevent the slag lump from growing and clogging in the chute connected to the slag discharge port.

In the gasification and melting system according to the second aspect of the present invention, the waste is pyrolyzed and gasified at a relatively low temperature using a gasification furnace, and the generated gas and char are heated to a high temperature using a melting furnace. In the gasification and melting system that melts and burns at the time, when the molten slag generated by the melt combustion at the high temperature is introduced into a slag cooling device via a chute from a slag discharge port provided at the bottom of the melting furnace, A part of the combustion exhaust gas from the melting furnace is introduced into the chute.

Thus, a part of the high-temperature combustion exhaust gas is introduced into the chute, so that the temperature near the molten slag discharge port can always be kept high. Therefore, it is possible to prevent the slag mass from growing largely in an icicle-like manner in the chute and clogging. The amount of the exhaust gas introduced into the chute is preferably about 1/100 to 1/10 of the amount of the exhaust gas from the melting furnace.

In the gasification and melting system according to a third aspect of the present invention, the waste is pyrolyzed and gasified at a relatively low temperature using a gasification furnace, and the generated gas and char are heated to a high temperature using a melting furnace. In a gasification and melting system that melts and burns, a slag discharge port provided at the bottom of the melting furnace is connected to a slag cooling device via a chute having a water-cooled jacket structure in at least a part of the slag discharge port. An induction fan for introducing a part into the chute is provided.

In this way, by forcibly introducing the combustion exhaust gas from the secondary combustion chamber 9 into the chute, the temperature of the upper part of the chute can be kept high, and the solidification of the slag can be prevented. The drawn combustion exhaust gas is cooled to 900 ° C. or lower through a water-cooled jacket portion, returned to a melting furnace via an induction fan, and completely burned. The water-cooled jacket portion also makes the slag bonding portion a fragile amorphous portion, so that the slag mass can be prevented from dropping before it grows large. Therefore, high-temperature combustion exhaust gas can be effectively used while preventing the upper portion of the chute from being blocked by the growth of the slag mass.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The same reference numerals in each drawing indicate the same or corresponding parts.

FIG. 1 shows a configuration of a cooling and discharging portion of a molten slag in a rotary melting furnace according to an embodiment of the present invention.
In FIG. 1, reference numeral 18 denotes a water cooling jacket, 19 denotes an induction fan, and j denotes a bypass exhaust gas. Other configurations are shown in FIG.
This is the same as the configuration of the conventional cooling / discharging portion for molten slag shown in FIG. That is, the waste is pyrolyzed and gasified at a relatively low temperature using a gasification furnace at a preceding stage (not shown), and the generated gas and char are melted and burned at a high temperature in the rotary melting furnace 7. In the primary combustion chamber 8 of the swirling type melting furnace 7, high-speed combustion is performed at a high temperature of 1300 to 1400 ° C while mixing with the supplied tertiary air e in a swirling flow. The mist-like molten slag formed in the primary combustion chamber 8 and the secondary combustion chamber 9 is collected on the wall surface by the centrifugal force of the rotating flow, captured by the molten slag phase formed on the furnace wall surface, and directed toward the furnace bottom. Flow down.

In the present embodiment, a portion below the overhang portion 11a at the upper end of the chute 14 is constituted by a water cooling jacket structure 18. And attraction fan 19
After a part j of the combustion exhaust gas in the secondary combustion chamber 9 is taken in from the slag discharge port 11 through the chute 14, the tertiary combustion chamber at the latter stage of the swirling melting furnace 7 is connected through the bypass exhaust pipe j. It is configured to return to 10.

That is, the combustion exhaust gas is sucked from the granulation trough 15 by the induction fan 19 through the chute 14 continuing below the slag discharge port 11. The amount of the combustion exhaust gas drawn into the chute 14 from the slag discharge port 11 is 1/100 to 1/1 of the combustion exhaust gas passing through the secondary combustion chamber 9.
An amount of about 0 is appropriate. Thereby, the temperature in the vicinity of the overhang portion 11a of the molten slag discharge port 11 can be always kept high. In addition, the amount of exhaust gas drawn in is determined by the slag discharge port 11.
And the processing scale of the system. The flow of the combustion exhaust gas drawn into the chute 14 by the attraction fan 19 can prevent the steam i ′ generated during the rapid cooling of the molten slag g from rising to the molten slag discharge port 11.

Thus, the fluidity of the molten slag g when flowing down from the furnace material overhanging portion 11a can be kept good. At the same time, it is possible to prevent water vapor generated when the molten slag is rapidly cooled on the granulated trough 15 from rising in the chute and lowering the temperature near the molten slag discharge port 11.

The bypass exhaust gas j containing water vapor sucked from the granulation trough 15 by the attraction fan 19 is supplied to the tertiary combustion chamber 10 of the swirling melting furnace 7. Thereby, the unburned components existing in the bypass exhaust gas j can be completely burned, and the combustion temperature in the tertiary combustion chamber 10 can be lowered. If the combustion temperature in the tertiary combustion chamber 10 can be kept low, the nitrogen oxide concentration can be reduced as compared with the conventional case.

Then, by making the chute 14 partially a water-cooled jacket structure, the temperature of the bypass exhaust gas j at the lower part of the chute is set to 900 ° C. or less, preferably 700 ° C. or less, at which the slag solidifies. At the same time, water cooling jacket 1
Even if the slag mass 20 is formed on the wall surface of No. 8, the bonded portion is forcibly cooled, so that the bonded portion is made fragile and amorphous, as shown in FIG. Then, it will fall off under its own weight. In addition, shoot 1
4 By lowering the gas temperature in the lower part, the gas temperature at the time of passing through the induction fan 19 can be set to 200 ° C. or less, for example, about 100 ° C. due to the cooling action by steam and flowing water generated in the granulation trough and the heat radiation loss from the bypass gas pipe. .

In the above-described embodiment, an example has been described in which a part of the combustion exhaust gas is drawn from the slag discharge port to the chute side using the induction fan and the inside of the chute is cooled using the water cooling jacket. Only one of them may be used. Further, the example in which the cooling inside the chute is performed using the water-cooled jacket structure has been described, but another method may be used as long as it has the same cooling function. Thus, various modifications can be made without departing from the spirit of the present invention.

[0028]

As described above, the present invention relates to a method for introducing molten slag generated by melting and burning at a high temperature from a slag discharge port provided at the bottom of a melting furnace to a slag cooling device via a chute. Then, a part of the combustion exhaust gas from the melting furnace is introduced into the chute, and a water-cooled jacket structure is arranged on a part of the chute. Thereby, the molten slag is prevented from solidifying near the molten slag outlet and closing the chute, and can be discharged stably and continuously from the molten slag outlet into granulated slag,
Long-term continuous operation of the gasification and melting system has become possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a slag cooling and discharging part according to an embodiment of the present invention.

FIG. 2 is a diagram showing spontaneous falling of a slag mass on a chute wall surface in FIG. 1;

FIG. 3 is a diagram showing a basic configuration of a gasification and melting system.

FIG. 4 is a diagram showing a configuration of a conventional slag cooling / discharging portion in FIG.

FIG. 5 is a view showing the formation of icicle-like masses at a molten slag discharge port in FIG. 4;

FIG. 6 is a view showing the formation of a slag mass adhered to the chute wall surface in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Waste supply apparatus 2 Fluidized bed gasifier 3 Air chamber 4 Air dispersion plate 5 Fluidized bed 6 Free board 7 Rotating melting furnace 8 Primary combustion chamber 9 Secondary combustion chamber 10 Tertiary combustion chamber 11 Slag discharge port 12,13 Ascending Warming burner 14 Chute 15 Granulated trough 16 Slag conveyor 17 Circulating water pump 18 Water cooling jacket 19 Induction fan 20 Slag lump a Waste b Primary air c Secondary air d Product gas e Tertiary air f Combustion exhaust gas g Melt slag g ' Slag grain h non-heated substance i water i 'steam j bypass gas

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI F23J 9/00 F23J 9/00 (72) Inventor Daisaku Fukuoka 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation ( 72) Inventor Masaaki Irie 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation (72) Inventor Tetsuhisa Hirose 11-1 Haneda Asahi-cho, Ota-ku, Tokyo Inside Ebara Corporation

Claims (6)

[Claims] 1. A gasification and melting system in which waste is pyrolyzed and gasified at a relatively low temperature using a gasification furnace and the generated gas and char are melted and burned at a high temperature using a melting furnace. A gasification and melting system, wherein a molten slag generated by melting and burning is discharged from a slag discharge port provided at a bottom portion of the melting furnace by passing a chute having a water-cooled jacket structure at least partially. 2. A gasification and melting system in which waste is pyrolyzed and gasified at a relatively low temperature using a gasification furnace, and the generated gas and char are melted and burned at a high temperature using a melting furnace. When the molten slag generated by the molten combustion is introduced into a slag cooling device via a chute from a slag discharge port provided at the bottom of the melting furnace, a part of the combustion exhaust gas of the melting furnace is introduced into the chute. A gasification and melting system. 3. The amount of flue gas introduced into the chute is 1/100 to 1/10 of the flue gas of the melting furnace.
3. The gasification and melting system of claim 2, wherein the temperature is in the order of magnitude. 4. The gasification and melting system according to claim 2, wherein the flue gas introduced into the chute is returned to the melting furnace after passing through the chute. 5. A gasification and melting system in which waste is pyrolyzed and gasified at a relatively low temperature using a gasification furnace, and the generated gas and char are melted and burned at a high temperature using a melting furnace. At least a portion of the slag discharge port provided at the bottom was connected to a slag cooling device via a chute having a water-cooled jacket structure at least in part, and an induction fan for introducing a part of the combustion exhaust gas of the melting furnace into the chute was provided. A gasification and melting system characterized by the above. 6. The combustion exhaust gas introduced into the chute is prevented from solidifying the slag by keeping the temperature of the upper part of the chute high, and is cooled to 900 ° C. or less by passing through the water-cooled jacket structure, 6. The gasification and melting system according to claim 5, wherein the gasification and melting system is returned to the melting furnace.