JP3183226B2 - Gasification and melting furnace for waste and gasification and melting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas (hereinafter referred to as energy) which can be used as a fuel by gasifying organic substances contained in general waste and industrial waste (hereinafter simply referred to as waste). Gas) or low-boiling heavy metals contained in these wastes as dust, and ash and valuable metals (hereinafter also simply referred to as metals) contained in these wastes, respectively. The present invention relates to a gasification and melting furnace and a gasification and melting method for waste collected as molten slag and molten metal.

[0002]

2. Description of the Related Art As a method of treating general waste mainly composed of municipal waste and industrial waste mainly composed of shredder dust of discarded automobiles and home electric appliances, a method of landfill disposal or landfill disposal after incineration is known. Has been adopted. However, given the recent tight situation that it is extremely difficult to secure landfill sites, the incineration method generally used so far has been reviewed.

Further, instead of directly discarding the waste or landfilling it after incineration, the waste once reduced in volume and solidified, that is, RDF (Refuse Derived) is generally used.
Fuel is a solid fuel called waste-derived fuel) and then incinerated, and some have been put to practical use. Examples of the waste treatment system using this method include a TC-system by Japan Recycling Management Co., Ltd., a J-Catrel system by Ebara Corporation, and a recycling energy center concept in Mie Prefecture (No. 6). Of the seminar “Seminar on Solid Waste Fuel Technology”, June 28, 1996 (Environmental Planning Center).

On the other hand, from the standpoint of protecting limited resources, these wastes or RDF are not simply incinerated,
It is desirable to recover recyclable materials as resources (useful substances) or energy (heat energy).
The following are examples that are currently in practical use. 1. Material recovery Separation and recovery of metals (aluminum cans, steel cans, etc.) Separation and recovery of plastics (PET bottles, etc.) Separation and recovery of waste paper (newspaper, etc.) 2. Material conversion and recovery Recovery of plastics as fuel oil by pyrolysis oil recovery Recovery of plastics as fuel gas by pyrolysis gasification Thermal energy recovery Steam recovery at the time of waste incineration Since the above item 1 is a pre-treatment method before waste, the recovery of useful substances from waste after separation must rely on the above two or three means. I can't. In particular, recently, general waste and industrial waste contain various substances due to changes in lifestyle (diversification). Chemical systems are in the spotlight.

[0005] The gasification system is as follows. A. Nippon Steel's coke bed type direct melting system (“Steel Industry Bulletin” No. 1674, 1996.3.21
(Japan Iron and Steel Federation), “Fuel and Combustion,” Vol. 61, No. 8, (1994), pp. 572-578, and Tokuhei 7-35
The melting furnace main body is a single-stage tuyere vertical shaft furnace, into which coke and limestone are charged together with waste from the center of the furnace.
Inside the furnace, from the top, a preheating / drying zone (about 300 ° C), a thermal decomposition zone (300 to 1000 ° C), and a combustion / melting zone (1700)
８００1800 ° C.). In the preheating / drying zone, waste is heated and moisture evaporates. The dried waste gradually descends and moves to the pyrolysis zone where the organic matter is gasified. The generated gas is exhausted from the upper part of the furnace, is completely burned in a combustion chamber at a later stage, and heat energy is recovered by a heat recovery system such as a waste heat boiler.

[0006] On the other hand, the remaining gasified ash and inorganic substances fall into the combustion / melting zone together with coke. The coke is burned by the air supplied from the tuyere, and the heat causes the ash and inorganic substances to completely melt. The melt is adjusted to an appropriate viscosity and basicity by the charged limestone, and discharged from the taphole to the outside of the furnace.

In order to reduce coke, a method is disclosed in which a separate charging system for coke and waste is used to utilize the sensible heat of exhaust gas for drying and preheating waste, thereby increasing the thermal efficiency of the furnace. (Japanese Patent Publication No. 7-35889). B. NKK high-temperature gasification direct melting system ("Steel Industry Report" No. 1674, 1996.3.21
(The Japan Iron and Steel Federation)) The melting furnace body is a vertical furnace having tuyeres divided into three stages in the height direction, and the flow formed by the dry distillate of waste maintained at a high temperature of about 1000 ° C. Waste is directly injected into the formation along with auxiliary fuel such as coke. By blowing air from the middle tuyere (two-stage tuyere) into the fluidized bed, part of the generated gas is burned and the temperature is maintained.

[0008] The dry distillate containing incombustibles descends to the moving bed at the lower part of the furnace together with the auxiliary fuel, and is burned and gasified at high temperature by oxygen-enriched air from the lower tuyere (main tuyere). It is melted, dropped and separated from metal by the difference in specific gravity. On the other hand, the freeboard temperature is always 1000 by the air blown from the tuyere (three-stage tuyere) installed under the freeboard.
The temperature is maintained at not less than ° C., thereby preventing the generation of tar components and the production of dioxins and their precursors. C. Thermoselect method (Thermoselect (1995.5.26),
PART1 "Foundation for the continuos conversio
ns of solid waste ”) The furnace used in this method is a pressurized tubular pyrolyzer that evaporates water in waste and pyrolyzes organic matter, and the combustion of pyrolysis residue (char) by oxygen, ash This is a pyrolysis melting furnace that is integrally connected with a combustion melting furnace that melts and reforms gas.In the combustion melting furnace, first, the decomposition gas of organic substances from the pyrolyzer is sent to the middle part of the furnace. Guided,
The char descends to the bottom of the furnace, and is burned at a high temperature by oxygen to melt the ash. At the same time, conversion of organic decomposition gas to CO and H ₂ (gas reforming) proceeds in a high-temperature atmosphere at the top of the furnace. However, the above conventional method has the following problems. That is, the vertical shaft furnace of the system of the above-mentioned method A requires expensive coke, and completely burns the generated gas, so that only the sensible heat can be recovered. Further, in this method, since the temperature of the preheating / drying zone in the upper part of the furnace is about 300 ° C., a large amount of hydrocarbons such as tar and dioxins which cannot be sufficiently decomposed are discharged outside the furnace. further,
Since low-boiling heavy metals are not sufficiently gasified and remain in the molten slag, coke is essential to reduce the slag. The vertical furnace of the system B also requires expensive coke as in the case of the system A. This is because heavy metals having a low boiling point are not sufficiently gasified and remain in the molten slag, so that the slag is reduced. Furthermore, a large free board is required to keep the free board always at 1000 ° C. or higher, and the furnace is inevitably increased in size. Although the furnace used in the system C is said to have two reactors (furnace) connected integrally, it is actually clearly separated into two furnaces, a pyrolysis furnace and a combustion melting furnace. Therefore, it is structurally complicated and the equipment cost increases. Further, since the pyrolysis furnace is an indirect heating type furnace separated from the combustion melting furnace, the exhaust gas sensible heat of the combustion melting furnace is not sufficiently utilized.

[0009]

SUMMARY OF THE INVENTION In connection with the problem of landfill sites, the present invention is to effectively use combustibles, ash, iron, etc. in wastes, and to reduce the costs associated with landfills. It is intended to utilize the by-product gas generated as fuel for power generation and the like. That is, an object of the present invention is not to simply incinerate general waste and industrial waste, but to gasify organic substances contained in the waste and recover it as an energy gas, and to reduce ash content and iron contained in the waste. It is an object of the present invention to provide a method for recovering valuable metals such as (Fe) and copper (Cu) as a molten slag and a molten metal, respectively, and a furnace therefor. Specifically, a series of steps of gasification and melting of waste, dehydration / pyrolysis, and gas reforming were carried out in one furnace without using expensive coke to solve the above-mentioned problems in the prior art. It is another object of the present invention to provide a gasification melting furnace and a gasification melting method capable of producing clean exhaust gas free of tar, dioxin, and the like.

[0010]

[First Zone]

Injection of combustible gas and auxiliary fuel in the amount determined from the level value of the charged waste from the lower tuyere, burning and gasifying the carbide generated in the second zone to generate reducing gas and converting it to carbide The contained ash and metals are melted to form molten slag and molten metal. [Second zone] Amount of flammable gas and auxiliary fuel determined from the temperature measurement value near the middle tuyere are blown from the middle tuyere, and the reducing gas generated in the first zone is subjected to secondary combustion, The waste loaded from the waste loading inlet is dehydrated and heated to thermally decompose into carbide and hydrocarbon gas. [Third zone] Amount of the oxidizing gas and auxiliary fuel determined from the temperature measurement value of the atmospheric gas in the upper part of the furnace are blown from the upper tuyere, and the hydrocarbon gas generated in the second zone is thermally decomposed. CO and H
Energy gas mainly composed of ₂ (3) A part of the recovered energy gas is directly blown into the third zone of the gasification and melting furnace as a recycle gas, or at least a part of the blown energy gas is burned to generate CO ₂ and H ₂ O, Inject the gas after inclusion as a recycle gas, or
The method for gasifying and melting waste according to the above (2), wherein the mixed gas of the recycled gas and oxygen is blown. (4) Injection of a recycled gas or a mixed gas of a recycled gas and oxygen is performed using a tuyere provided at an angle θ of 0 ° <θ <90 ° with respect to a tangent in a circumferential direction of the gasification and melting furnace. The method for gasifying and melting waste according to 3). The “multiple stages” of the “tuples divided into plural stages” in the above (1) are practically three stages, but are not necessarily three stages.
The number of stages is not limited to four, and may be four or more, including tuyeres provided as auxiliary.

The "zone" of the above (2) is a region in the furnace, which will be described later, and is referred to as a first zone, a second zone and a third zone according to the reaction occurring therein.

The "metals" in (1) refer to valuable metals as described above, and include, for example, aluminum (Al), nickel (N) in addition to iron (Fe) and copper (Cu).
Metals such as i) and oxides thereof, which are generally evaluated as valuable if recovered.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention (the inventions (1) to (4) above) will be described below in detail with reference to the drawings.

FIG. 1 is a schematic longitudinal sectional view showing an example of the configuration of a waste gasification and melting furnace according to the invention (1), in which there are three stages of tuyeres in the height direction. Hereinafter, this case will be described as an example.

As shown, waste gasification and melting furnace 1
Is a waste inlet 11- for charging waste at the top.
1 and a gas outlet 3-1 for discharging generated gas. The hopper 11 is installed at the waste loading port 11-1.
-2 and a pusher 10 are attached, and a gas exhaust port 3-1 has a duct 3 for collecting exhaust gas 4.
-2 is attached. A discharge port 9 for discharging the molten slag and the molten metal 13 is provided in the lower part of the furnace.

Between the waste loading port 11-1 on the furnace side wall and the discharge port 9 for the molten slag and the molten metal, the height direction in which the supporting gas and the auxiliary fuel can be independently blown is 3 The tuyeres are divided into stages. That is, in order from the bottom of the furnace, the packed bed 1 mainly composed of carbide generated by dehydrating and heating and thermally decomposing waste.
Tuyere (lower tuyere, hereafter referred to as "primary tuyere 5-1")
) And a tuyere for injecting the combustible gas 7-2 and the auxiliary fuel 6-2 into the packed bed 15 composed mainly of waste in a charged state (middle tuyere, hereinafter referred to as "2 Next tuyere 5-
2)) and the free board 16 has the supporting gas 7-3.
And a tuyere for injecting the auxiliary fuel 6-3 (the upper tuyere, hereinafter referred to as "tertiary tuyere 5-3"). The supporting gas is pure oxygen or a gas containing oxygen, and the auxiliary fuel is a solid fuel such as pulverized coal, a liquid fuel such as heavy oil, or a gas fuel such as natural gas.

Further, a sounding device 17 as a means for measuring the level of the waste charged in the furnace (height level, hereinafter referred to as a raw material layer top level) is provided at the upper part of the furnace. A sounding weight 18 attached to the tip of the device 17 is suspended in the furnace.

A thermocouple 20 for measuring the temperature in the vicinity of the middle tuyere (secondary tuyere 5-2) is provided on the side wall of the furnace, and the temperature of the atmosphere gas in the upper part of the furnace (ie, free board) Thermocouple 21 for measuring the temperature of the exhaust gas in the space) and a temperature converter 1 for converting the signal of the thermocouple into a temperature.
9 is attached. The temperature in the vicinity of the middle tuyere (secondary tuyere 5-2) refers to the temperature of the second zone corresponding to the secondary tuyere 5-2.

As described above, the gasification and melting furnace of the present invention comprises:
This is a vertical, single-furnace gasification and melting furnace. The reason for using the single-furnace method is to simplify the equipment and reduce the equipment cost. Also, in order to suppress heat loss from the furnace body, the one-furnace method is preferable. In this gasification and melting furnace, the reason why the tuyere is provided in three stages in the height direction of the furnace, the sounding device 17 is provided, and the reason why a thermocouple is attached to a predetermined portion of the furnace side wall is as follows. This will be described together with the waste gasification and melting method of the invention (2) described below. The method for gasifying and melting waste according to the invention (2) includes the method (1) described above.
And a method for gasifying and melting wastes using the gasification and melting furnace of the invention. Hereinafter, the case of using the gasification and melting furnace shown in FIG. 1 will be described.

First, the waste is put into the hopper 11, pushed into the furnace through the waste inlet 11-1 by the pusher 10, and then into the first to third zones described in detail below.
By the reaction in the zone, the energy gas mainly composed of CO and H ₂ , the molten slag and the molten metal are collected, and the former is recovered from the gas outlet 3-1 provided in the upper part of the furnace, and the latter is provided in the lower part of the furnace. The collected molten slag and molten metal are recovered from the outlet 9. In the furnace, there are three regions according to the reaction that occurs, namely, a region where carbide gasification and melting occur sequentially from the bottom of the furnace (first zone), a region where waste dehydration / pyrolysis occurs (second zone), and It is divided into regions (third zone) in which gas reforming proceeds (see FIG. 1), and each region, that is, the first zone, the second zone and the third zone, has a support necessary for the reaction. The above-mentioned primary tuyeres 5-1 and 2 that can independently inject flammable gas and auxiliary fuel.
The next tuyere 5-2 and the third tuyere 5-3 are respectively mounted. By adopting such a configuration, it is possible to avoid the occurrence of hanging or blowing through the shelves, which is peculiar to the vertical furnace (in particular, easily occurring when coke is not used as in the method of the present invention). In addition, the tuyere for supplying the supporting gas and the auxiliary fuel is not limited to the above-mentioned three stages, and in order to supply an amount necessary for the reaction, a plurality of stages are provided in each zone as necessary, and as a whole, Four or more stages may be provided.

In the first zone, a reaction represented by the following equation occurs. This reaction is a reaction in which the carbide (filled bed) formed in the second zone and descending is burned by the oxidizing gas 7-1 blown from the primary tuyere 5-1. It becomes a reducing gas mainly composed of CO at a temperature of 2000 ° C. or higher. In addition, the ash (inorganic oxide) and metals contained in the carbide are melted by the sensible heat to form molten slag and molten metal. The primary tuyere 5-1 may be used if necessary.
Supplies the auxiliary fuel 6-1.

The reducing gas moves to the second zone,
The molten slag and the molten metal are recovered from an outlet 9 at the bottom of the furnace. C + 1 / 2O ₂ = CO where C: carbide supplied from the second zone O ₂ : oxygen in the combustible gas blown from the primary tuyere In addition, the waste is dehydrated in the second zone The reason why the carbide is packed and layered by pyrolysis and the carbide is gasified and melted in the first zone is that the two-stage process promotes the heating of the carbide, the heat loss from the molten slag and the molten metal. This is because it is possible to effectively suppress the above.

In the first zone, it is necessary to completely melt the ash and metals contained in the carbide by the sensible heat of the reducing gas to be generated.
It is preferable to keep the temperature at or above C. For this purpose, the oxygen concentration in the supporting gas is set to 50% by volume or more (hereinafter,% of the gas means volume%), and auxiliary fuel is blown if necessary. In order to smoothly extract the molten slag and the molten metal from the outlet at the bottom of the furnace without causing clogging or the like, limestone is simultaneously charged from above the furnace when the waste is charged into the furnace, or It is preferable to reduce the viscosity of the slag by blowing powdery limestone as a slag-making material from the next tuyere. In the second zone, reactions represented by the following formulas (1) to (3) occur. The reaction of the formula is carried out by sensible heat of the high-temperature reducing gas supplied from the first zone by dehydration heating of the waste. The reduction gas is also generated by sensible heat generated when the secondary combustion is performed in accordance with the reaction formula of the combustible gas 7-2 blown from the secondary tuyere 5-2.
As a result, the organic matter in the waste is thermally decomposed into a hydrocarbon (however, represented as C in the formula and the formula) and hydrocarbon gas according to the formula and the formula. The auxiliary fuel 6-2 is supplied from the secondary tuyere if necessary.

The carbide obtained in this step moves to the first zone, and the hydrocarbon gas moves to the third zone. _{H 2 O (liq) = H} 2 O (gas) ··· C p H q O r = r / 2CO 2 + q / nC m H n + (p-r / 2-qm / n) C ··· C _{m H n = n / 4CH 4} + {m- (n / 4)} C ··· CO + 1 / 2O 2 = CO 2 ··· here, H ₂ O (liq): water attached C _p in the waste H _q O _r: organics C _m H _n in waste: hydrocarbon gas produced by the decomposition of organic substances in waste C: carbides are supplied to the first zone CO: produced carbides in the first zone is combusted CO O ₂ : oxygen in the combustible gas blown from the secondary tuyere In this step, if necessary, auxiliary materials (eg, limestone, quicklime, etc.) are added to the waste charged into the furnace. A filling layer is formed. That is, the waste is relatively densely packed. By forming such a packed layer of waste, the contact time between solid and gas when a high-temperature gas passes through the layer is prolonged, and thermal efficiency is improved.

The reason why the high-temperature reducing gas is subjected to secondary combustion is to use the secondary combustion heat of the formula to promote heating and control the thermal decomposition temperature to 800 to 1000 ° C.
This secondary combustion heat is much larger than the combustion heat (primary combustion heat) in the above equation, and is effective in replenishing the heat required for dehydration and thermal decomposition of waste. At this time, in order to suppress the sensible heat loss by reducing the amount of generated gas to prevent scattering of waste and to suppress the calorie reduction of the generated gas, the oxygen concentration in the supporting gas should be 50% or more. It is preferred that In the third zone, the following formula and the reaction represented by the formula occur. These reactions are thermal decomposition reactions (gas reforming reactions) of hydrocarbon gas supplied from the second zone, and a gas (energy gas) containing CO and H ₂ as main components is obtained. These reactions proceed by the reaction with the combustible gas 7-3 blown from the tertiary tuyere 5-3. The auxiliary fuel 6-3 is supplied from the tertiary tuyere if necessary. In _{C m H n + m / 2O} 2 = mCO + n / 2H 2 ··· CH 4 + 1 / 2O 2 = CO + 2H 2 ··· Here, C _m H _n: hydrocarbon waste in the second zone is generated by thermal decomposition hydrogen gas CH _4: second zone C _m H methane gas _n is generated by thermal decomposition O _2: in the oxidizing gas blown from 3 tuyeres oxygen reaction freeboard in the third zone The reaction is carried out in such a cavity, but the gas reforming reaction, which is a reaction between gases, proceeds smoothly. Controlling the atmosphere temperature in the cavity to 800 to 1000 ° C. is preferable because the reforming reaction sufficiently proceeds.

The oxygen concentration in the supporting gas is preferably 50% or more. This is because the calorie of the recovered gas is increased so that the gas can be easily used in applications such as power generation in the next process. Further, in order to suppress the generation of dioxins and their precursors, the temperature of the gas is preferably 500 ° C. or higher.

As described above, in the method for gasifying and melting waste according to the invention (2), the reaction gas in the first to third zones causes the energy gas containing CO and H ₂ as main components, Collect the molten slag and molten metal. Therefore, three stages of primary to tertiary tuyeres are required. In addition, the tuyeres of each stage must be capable of independently injecting the supporting gas and auxiliary fuel. The reason is as follows.

First, in the case of the primary tuyere, the amount of C (carbide) involved in the reaction of the formula varies depending on the formula and the degree of progress of the reaction represented by the formula. In addition, if the type of waste changes, the formula and the amount of reaction products represented by the formula naturally change. Therefore, the amount of the supporting gas blown from the primary tuyere must be determined independently of the other steps. The same applies to auxiliary fuel supplied as needed. Next, the amount of the supporting gas blown from the secondary tuyere is determined by the reaction formula, and the amount of CO in the formula is determined by the reaction formula. Is considered to be. However, in fact, it is not necessary to perform secondary combustion on all CO gas generated by the reaction formula. In the second zone, at least heat necessary for dehydration heating of attached moisture in waste and thermal decomposition of organic matter in waste is added. Further, it is only necessary to apply heat necessary to maintain the atmosphere temperature in the second zone at 800 to 1000 ° C. Therefore, the amount of supporting gas from the secondary tuyere is
It varies greatly depending on the components contained in the waste. That is, the amount of the combustible gas blown from the secondary tuyere must also be determined independently. The same applies to auxiliary fuel. The amount of the supporting gas blown from the tertiary tuyere is determined by the reaction formula and the formula. In this case also the amount of C _m H _n and CH ₄ by-containing compounds in the waste is changed, must be placed as may define its own also combustion supporting gas amount blown from 3 tuyeres. The same applies to the auxiliary fuel.

In the gasification and melting furnace of the invention (1) described above, the tuyeres are provided in three stages, and the supporting gas and the auxiliary fuel can be blown independently of each other. This is for the above reason.

The blowing amount of the supporting gas and the amount of the auxiliary fuel to be supplied as necessary are determined as follows.

When the object to be treated is, for example, general waste in which different kinds of wastes are mixed, since the component analysis is not usually performed before charging into the furnace, unknown components are burned in the furnace. Or thermal decomposition, and it is practically impossible to predict the amount of generated gas and its components.

Under such conditions, the level of the loaded waste (raw material layer top level) is sequentially measured. This makes it possible to indirectly grasp the change in the thickness of the packed bed in the furnace (the packed bed of waste and the packed bed of carbide). That is, as the amount of combustion increases, the loading of the carbide packed layer formed in the first zone decreases, and the top level of the raw material layer decreases. Therefore, a predetermined raw material layer top level is determined empirically in advance, and then the supporting gas from the primary tuyere and the auxiliary fuel supplied as necessary are blown based on the vertical fluctuation of the raw material layer top level. The amount may be determined. In addition, as a raw material layer top level meter to be used, a sounding device known as a raw material layer top level meter inside a blast furnace in the field of steelmaking is suitable. By the way, since the packed bed of the waste formed in the second zone is present on the packed bed of the carbide formed in the first zone, the measured top level of the raw material layer is equal to the first and second zones. It appears as the sum of the respective changes in the zone. Therefore, it is necessary to distinguish the amount of change between the first zone and the second zone, but the change in the reaction in the second zone can be indirectly grasped by sequentially measuring the temperature change in the second zone. That is, in the second zone, at least heat required for dehydration heating of the adhering moisture in the waste and thermal decomposition of the organic matter in the waste is added, and furthermore, it is necessary to maintain the atmosphere temperature in the second zone at 800 to 1000 ° C. Since it is only necessary to apply a large amount of heat, the temperature change of the waste in the area of the second zone is sequentially measured, and if it decreases, it is judged that the heat is insufficient, and the amount of the supporting gas from the secondary tuyere is reduced. Increase the amount of CO to be secondary-burned (the amount of CO to be secondary-burned among the CO generated by the reaction formula). Conversely, if the temperature rises, it can be determined that there is sufficient thermal margin.
What is necessary is just to reduce the amount of CO to be subjected to secondary combustion by reducing the amount of supporting gas from the next tuyere. The temperature change of the waste can be regarded as the temperature change of the second zone, and the temperature change of the second zone can be determined, for example, by installing a thermocouple on the surface of the lining brick of the second zone, Can be determined by measuring

As described above, by successively measuring the level value by the raw material layer top level meter and the surface temperature of the lining brick in the second zone, the auxiliary gas to be supplied and the supporting gas in the first and second zones as necessary. Each fuel injection amount can be independently determined. In the third zone,
The ambient temperature at the exit of the second zone (freeboard side) is 80
If the temperature is maintained at 0 to 1000 ° C., all hydrocarbons in the exhaust gas, particularly hydrocarbons having 5 or more carbon atoms (C _m H _n : m ≧ 5) such as tar, which cause troubles such as pipe clogging, are decomposed. it can. Therefore, a thermometer is installed in the free board space of the third zone and its temperature is measured successively.
When the temperature is lower than 0 ° C., the combustion supporting gas and, if necessary, auxiliary fuel may be blown from the third tuyere. In particular, immediately after the waste is charged into the furnace, the temperatures at the top of the raw material layer in the second zone and the freeboard in the third zone drop sharply, so judging from the temperatures in the second and third zones, hydrocarbons produced: in order to decompose the _{(C m H n m ≧ 5} ), it is effective to carry out the blowing of the auxiliary fuel necessary and combustion-supporting gas. According to the waste gasification / melting method of the invention (2), a series of steps of gasification / melting, dehydration / pyrolysis, and gas reforming of waste can be performed in one furnace without using expensive coke. A clean exhaust gas which is implemented and does not contain tar or the like can be obtained. The method for gasifying and melting waste according to the invention (3) includes the method (2) described above.
3. The gasification and melting method according to (1), wherein
A part of the recovered energy gas is directly blown into the zone as a recycle gas, or at least a part of the blown energy gas is burned to reduce CO ₂ and H ₂ .
_This is a method in which ₂ O is generated and a gas containing CO ₂ and / or H ₂ O or either of them is blown as a recycle gas, or a mixed gas of these recycle gas and oxygen is blown. FIG. 2 is a diagram showing a configuration of an example of a waste gasification and melting furnace for carrying out the present invention. This gasification and melting furnace has the same configuration as the gasification and melting furnace shown in FIG. 1 described above.
An exhaust gas combustion chamber 28 for burning at least a part of the energy gas (which is also exhaust gas discharged from the furnace) blown into the third zone, and a supportive gas 7-3 and an auxiliary fuel 6-3 are supplied to the free board 16. A tertiary tuyere 5-3 is provided for blowing a part of the recovered energy gas as a recycle gas while blowing. In order to carry out the method of the invention of (3) using this gasification melting furnace,
As in the case of carrying out the gasification melting method of the invention of (2),
First, waste is put into the hopper 11 and the pusher 10
Into the furnace through the waste inlet 11-1. Next, by the reaction in the first to third zones in the gasification and melting furnace, an energy gas containing CO and H ₂ as main components, a molten slag and a molten metal are formed, and the former is a gas exhaust gas provided in the upper part of the furnace. At this time, a part of the recovered energy gas (exhaust gas) is blown into the third zone of the gasification and melting furnace as a recycle gas 7-4 or 7-5. The molten slag and the molten metal are recovered from an outlet 9 provided at the lower part of the furnace. The reactions in the first zone and the second zone are the same as in the case of carrying out the gasification melting method of the invention (2).

However, in the third zone, the above-mentioned equation and the reaction shown by the equation occur, and the recycle gas or the mixed gas of the recycle gas and oxygen is blown, so that the following -2, -2, -3 And-
The reaction of 3 occurs. Incidentally, the recycle gas, as described above, the recovered energy gas itself or at least a part of the by burning to produce a _{CO 2, H 2 O, CO} 2 and H ₂ O or any of them, whereas Gas. In _{C m H n + m / 2O} 2 = mCO + n / 2H 2 ··· CH 4 + 1 / 2O 2 = CO + 2H 2 ··· Here, C _m H _n: hydrocarbon waste in the second zone is generated by thermal decomposition hydrogen gas CH _4: methane gas O ₂ to C _m H _n in the second zone is generated by thermal decomposition: 3 in the oxidizing gas blown from tuyeres oxygen _{addition, C m H n + mCO 2} = 2mCO + n _{/ 2H 2 ··· -2 CH 4 +} CO 2 = 2CO + 2H 2 ··· -2 C m H n + mH 2 O = mCO + {m + (n / 2)} H 2 ·· -3 CH 4 + H 2 O = CO + 3H here ₂ · · · -3, CO _2: CO ₂ in the recycled gas blown from 3 tuyeres 5-3 (i.e., CO ₂ generated in the second zone, was or, and their CO _2, energy CO ₂ produced by combustion of at least part of the gas) H ₂ O: 3 tuyeres 5- Recycle gas blown from H ₂ O (i.e., H ₂ O generated in the second zone, were or, its H ₂ O, H ₂ O produced by combustion of at least part of the energy gas) i.e. By injecting a recycled gas or a mixed gas of a recycled gas and oxygen, the above-mentioned reactions from -2 to -3 occur in addition to the reactions represented by the equations and the equations, and are generated by the thermal decomposition reaction of the waste. The thermal decomposition reaction of hydrocarbon gas, especially hydrocarbon gas having a high boiling point and existing as a liquid at room temperature, is promoted, and CO and H
_It is reformed into a gas containing ₂ as the main component (energy gas). As the recycled gas, as shown in FIG. 2, a part of the recovered energy gas may be directly blown into the third zone as a recycled gas 7-4, or a part of the energy gas may be introduced into the exhaust gas combustion chamber 28. After burning at least a part of the recycled gas,
5 may be blown. When the former method is adopted, CO ₂ and H ₂ O generated in the second zone are contained in the recycle gas, and when the latter method is adopted, CO ₂ generated by combustion in the exhaust gas combustion chamber 28 is further added. ₂ and / or H ₂ O is also included, these components are described above -
It contributes to the thermal decomposition reaction of hydrocarbon gas from 2 to -3. Further, a mixed gas obtained by adding oxygen to the recycled gas may be blown into the third zone. In this case, in addition to the thermal decomposition of the hydrocarbon gas by CO ₂ and H ₂ O contained in the recycle gas, a large amount of oxygen is contained. Is further promoted. The ratio of oxygen to be added to the recycled gas is not particularly limited.
_2, in order to suppress the formation of H ₂ O, preferably with m / 2 or less the molar amount of hydrocarbons produced by pyrolysis (C _m H _n). The method for gasifying and melting waste according to the invention (4) includes the method (3) described above.
In the method described above, the blowing of the recycled gas or the mixed gas of the recycled gas and oxygen into the gasification and melting furnace is performed by changing the angle θ with respect to the circumferential tangent of the gasification and melting furnace 1 as shown in FIG. This method is performed using the tuyere 5-3 set as 0 degrees <θ <90 degrees. That is, instead of blowing in a direction perpendicular to the furnace wall, blowing is performed in an oblique direction.

This promotes the mixing of the hydrocarbon gas generated by the thermal decomposition reaction of the waste, especially the hydrocarbon gas having a high boiling point and existing as a liquid at room temperature, with the recycle gas blown into the furnace. The gas decomposition reaction (gas reforming reaction) is promoted. According to the waste gasification / melting method of the above (3) or (4), the thermal decomposition reaction of hydrocarbon gas generated by the thermal decomposition reaction of the waste, especially the hydrocarbon gas having a high boiling point and existing as a liquid at room temperature. Is promoted, so that the recovery efficiency of a gas (energy gas) containing CO and H ₂ as main components can be increased.

[0036]

EXAMPLES (Example 1) A gasification melting test of waste was performed using a vertical furnace having the configuration shown in FIG. In addition, the dimension of each part of a vertical furnace, the number of tuyere and other attachment parts, and their arrangement are as follows. Dimensions Furnace diameter: 0.5 m (furnace inner diameter after brick lining) Furnace height: 2.7 m (however, height from furnace bottom to furnace top after brick lining) Height from furnace bottom to primary tuyere Height: 0.5 m Height from furnace bottom to secondary tuyere: 1.1 m Height from furnace bottom to tertiary tuyere: 1.9 m Position of thermocouple in second zone: 1.5 m (second The position of the thermocouple in the zone means the height of the thermocouple attached to the surface of the lining brick in the second zone from the bottom of the furnace.) The position of the thermocouple in the third zone: 1.7 m (for the third zone) The position of the thermocouple means the height of the thermocouple installed in the freeboard space from the furnace bottom.) Quantity Primary tuyere: 3 Secondary tuyere: 3 Tertiary tuyere: 3 Discharge port of molten slag and molten metal: 1 Sounding device (raw material layer top level meter): 1 Sounding weight: 1 Zone 2 Thermocouples: 3 Thermocouples in the third zone: 3 Arrangement Primary tuyere: equidistant every 120 degrees in the circumferential direction Secondary tuyere: equidistant every 120 degrees in the circumferential direction Tertiary tuyere: circumferential Discharge outlet of molten slag and molten metal: Furnace bottom end Sounding device: Center of the furnace Thermocouple in the second zone: Circumferentially every 120 degrees in the circumferential direction Thermocouple in the third zone: Circumferential Equal intervals every 120 degrees The wastes used in the above test were three types of mixed general municipal solid waste and waste plastic (samples 1, 2 and 3), each of 5718 kca / kg of waste.
1, 3506 kcal and 1506 kcal. Table 1 shows the composition of these wastes.
Table 2 shows the composition of the auxiliary material (limestone) used, and Table 3
Shows the composition of the auxiliary fuel (pulverized coal) used in Example 1. The size of the waste was 10 to 100 mm.

[0037]

[Table 1]

[Table 2]

[Table 3] The limestone used as an auxiliary material was a lump of 10 to 50 mm. The pulverized coal used as the auxiliary fuel was a powdery material of 3 mm or less that had been dried in advance.

The combustible gas blown from the primary tuyere, the secondary tuyere and the tertiary tuyere is a gas based on oxygen and slightly mixed with nitrogen. Table 4 shows their flow rates (the flow rates of oxygen and nitrogen, respectively). In the table,
Primary means primary tuyere. The same applies to the second and third orders.

The test conditions and results are shown in Table 4. In the table, the conditions are the conditions under which this test was performed (steady state), and were determined for each of samples 1, 2 and 3 according to the following procedures (1) to (8). In the test, sample 1 was first charged into the furnace and
The sample was processed under the conditions shown in the column of sample 1, and then changed to sample 2 and processed under the same conditions as shown in the column of sample 2, and further changed to sample 3 and shown in the column of sample 3. Processing was performed under the conditions. The processing time of each sample was 24 hours, and the amount of waste during that time was 1 ton (3 tons in total) for each sample. (Procedure for Setting Processing Conditions) (1) The composition of waste initially charged (here, sample 1) was determined by analyzing in advance the composition. This is necessary to determine the approximate value of the amount of oxygen to be blown, and also to determine the amount of limestone to be charged as a slag-making material. In this test, the amount of limestone was adjusted such that the fluidity of the molten slag was slag basicity considered to be the best (that is, slag basicity = 1.0). (2) Preheat the gasification and melting furnace with a burner, etc.
Waste was ignited even at room temperature where the combustion supporting gas blown from the tuyere was not heated. (3) Waste is charged into the furnace and the sounding height is 1.5
Stacked up to ~ 1.7m. The sounding height means the height from the furnace bottom to the top of the raw material layer. (4) After gradually flowing oxygen gas from the primary tuyere, the outlets for the molten slag and the molten metal were opened. (5) During the test, since the top level of the raw material layer decreased with the burning of the waste, the raw materials (waste and limestone) were sequentially charged so as to maintain the level in the range of 1.5 to 1.7 m. In the steady state, the input speed of waste is always 40 kg /
h. (6) The temperature measured by the thermocouple attached to the surface of the lining brick in the second zone and the thermocouple attached to the freeboard space in the third zone is always 800 to 1
The amount of oxygen gas blown from the primary tuyere, the secondary tuyere and the tertiary tuyere was adjusted so as to maintain 000 ° C.

That is, the unloading speed is high and the second
When the temperature in the zone and the zone in the third zone exceeded 1000 ° C., the oxygen gas from the primary tuyere was reduced.
Conversely, if the temperature of the second zone is lower than 800 ° C., 2
Oxygen gas was blown from the next tuyere. When the temperature of the third zone was lower than 800 ° C., pulverized coal was blown together with oxygen gas from the third tuyere. In this case, CO in the exhaust gas can be burned only by blowing oxygen gas from the tertiary tuyere, so that a predetermined temperature rise is possible. Charcoal was used. (7) Measure the temperature of the molten slag and the molten metal (this measurement is conventionally performed), and a predetermined temperature (at least a temperature at which the molten slag and the molten metal do not solidify, but a preferable temperature in consideration of the post-treatment) Range (1400-16
00 ° C.), pulverized coal was blown from the primary tuyeres. In the case where the sample 3 corresponds to the case, when the calorific value of the waste itself is small, it is necessary to supply the auxiliary fuel from the primary tuyere. (8) By repeating the above (5) to (7), it was possible to derive the optimum amount of the supporting gas and auxiliary fuel to be blown (that is, the amount shown in the condition column of Table 4). In addition, even when the sample was changed (from sample 1 to sample 2 and from sample 2 to sample 3), it was possible to appropriately cope with the case.

The results obtained in the above tests are shown in the column of results in Table 4. The unit is the amount per ton of waste. In Samples 2 and 3 in Table 4, only oxygen gas was blown in the second zone, and the temperature of the second zone was controlled at 800 to 1000 ° C by utilizing the heat of reaction caused by the secondary combustion of the reducing gas. The secondary combustion rates at this time were 34% and 84% for Samples 2 and 3, respectively. Here, the secondary combustion rate is a value calculated by the following equation.

The secondary combustion rate _{= {% CO 2 / (%} CO +% CO 2)} × 100 where,% CO: second CO%% in the zone CO _{2: 2%} CO in the second zone should be noted that Table 4 Although not described, pulverized coal is blown together with oxygen gas from the secondary tuyere and the combustion heat is used to raise the temperature of the second zone to 800 to 1000 ° C.
It was possible to control. As shown, CO
And (identified in the Table, the exhaust gas and display) high caloric energy gas and H ₂ as main components and, it was possible to recover the molten metal and molten slag as a main component Fe. Also, hydrocarbons in the exhaust gas, in particular, hydrocarbons, such as C _m H _n is a cause of pipe clogging (m ≧ 5) were at a concentration that completely negligible.

[0043]

[Table 4] <Comparative Example> For comparison, a waste gasification melting test was performed using the same furnace as that used in the examples. However, as shown in the condition column of Table 5, the amount of the supporting fuel gas and the amount of the auxiliary fuel blown from the primary tuyere, the secondary tuyere and the tertiary tuyere are the same (the total amount is the same as in the example). The height of the sounding, the surface temperature of the lining brick in the second zone, and the temperature of the freeboard space were sequentially measured. Based on the data, the amount of the supporting gas and the amount of the auxiliary fuel from each tuyere were measured. Did not change.

The results are shown in the column of results in Table 5. As is evident from this result, under the same waste input rate,
The level of the top of the raw material layer (that is, the sounding height) fluctuated greatly, and was 1.0 to 2.2 m. Further, the temperature fluctuation in the second zone and the third zone is large, and
200 ° C was indicated.

The reason why both the level and the temperature at the top of the raw material layer both fluctuated greatly is that oxygen required for each of the first to third zones and heat supplied by the reaction with the oxygen were not supplied. is there. The reason why the temperature deviated extremely to the low temperature side is that the level at the top of the raw material layer was extremely high at 2.2 m. Conversely, the reason for shifting to the high temperature side is that the level at the top of the raw material layer is extremely low at 1.0 m. Furthermore, since the oxygen and fuel required for the first zone were insufficient, the temperature of the molten slag and the molten metal shifted to a low temperature side, the dispersion thereof was large, and the discharge was unstable.

[0046] Also, hydrocarbons contained in the exhaust gas, in particular, the concentration of hydrocarbons, such as C _m H _n is a cause of pipe clogging (m ≧ 5) is high, clean can be recovered directly as energy gas No gas was obtained. Moreover, the calories of the exhaust gas excluding C _m H _n (m ≧ 5) were about 20 to 30% lower than those of the examples. Such a situation was observed for all of the samples 1 to 3, and it was also very difficult to take appropriate measures when the sample was changed.

[0047]

[Table 5] Example 2 A gasification melting test of waste was performed using a rigid furnace (gasification melting furnace) having the configuration shown in FIG. In addition,
The number, arrangement and installation angle of the tuyeres are as described below, and the dimensions of each part of the vertical furnace, the number of other mounting parts and their arrangement are the same as in the first embodiment. The installation angle (θ) of the tertiary tuyere: θ = 90 ° or 30 ° The waste used in the above test is general municipal waste, which has a low-calorific value of 5700 kcal / kg of waste and a moisture reference. is there. Table 6 shows the composition of this waste. This waste is compressed in advance to reduce the size to 10
Was molded into an RDF having a size of 50 mm from the above. Also,
The limestone used as an auxiliary material was a lump of 10 to 50 mm.

[0048]

[Table 6] Table 7 shows the main experimental conditions. RDF is 60 per hour
kg. The amount of coke charged was 100 kg per 1 t of waste disposal amount. The supporting gas blown from the tuyeres 5-1 and 5-2 was slightly mixed with nitrogen gas based on oxygen gas.

[0049]

[Table 7] In Comparative Example 1, blowing oxygen of 7.5 nm ³ / h from 30 Nm ³ / h, 2 tuyeres from the primary tuyere, not blown oxygen from 3 tuyeres.

Example No. 1 to No. Even in 3, 1
Next, 30Nm ^{3 /} h, 7.5N from each tuyere
m ³ / h of oxygen was blown. Further, in Example No. 1
Then, 1.0 Nm ³ / h of oxygen and the energy gas generated in Comparative Example 1 were burned from a tertiary tuyere installed at an angle of 90 ° with respect to the circumferential tangent of the gasification and melting furnace, and C
O ₂ and H ₂ O generated gas (CO ₂ : H ₂ O:
N ₂ = 58: 22: 20) as a recycled gas.
5 Nm ³ / h was blown.

Embodiment No. In No. 2, oxygen was not blown from the tertiary tuyere, and the gas after burning the energy gas generated in Comparative Example 1 was blown as 5.0 Nm ³ / h as a recycle gas.

Example No. In No. 3, the installation angle of the tertiary tuyere was set to 30 degrees with respect to the tangent in the circumferential direction of the gasification and melting furnace, oxygen was not injected, and the gas after burning the energy gas generated in Comparative Example 1 was also used. As a recycle gas was blown at 5.0 Nm ³ / h.

Table 8 shows the test results. The obtained energy gas contained gases such as CO, CO ₂ , methane, ethylene, and hydrogen (in the table, indicated as exhaust gas concentration), and at room temperature having 5 or more carbon atoms, liquid hydrocarbons were generated. . Liquid hydrocarbons are gases at the top of the gasification and melting furnace due to high temperatures, but exist as liquids at room temperature.

In a comparative example in which oxygen or a recycle gas was not injected from the tertiary tuyere, 700 g / h of a liquid hydrocarbon having 5 or more carbon atoms was recovered at room temperature. On the other hand, in Example No. 3 in which recycled gas and oxygen were blown from the third tuyere. In 1, the liquid hydrocarbon at room temperature is CO,
Since it was reformed to H ₂ , the recovered amount was 175 g / h,
It decreased as compared with Comparative Example 1. Further, CO and H ₂ contained in the exhaust gas by the reforming reaction of
, The calorific value of the recovered energy gas (in the table, indicated as exhaust gas calories) increased compared to Comparative Example 1.

Example No. 1 in which only recycled gas was blown from the third tuyere In the case of Example No. 2, the amount of hydrocarbon liquid at room temperature was Example 1 was the same as Example 1, but the amount of CO was increased by the reforming reaction. Increased compared to 1.

Example No. No. 3 is a case where only the recycled gas is blown from the tertiary tuyere installed at an angle of 30 degrees with respect to the tangent in the circumferential direction of the gasification and melting furnace. In this case, the blown recycled gas and the waste are discharged. The mixture of the hydrocarbons generated by the gasification was obtained in Example No. 2, the reforming reaction was promoted, the amount of liquid hydrocarbons generated was significantly reduced, and the calorie of the exhaust gas was also increased.

[0057]

[Table 8]

According to the present invention, if the waste gas is incinerated in accordance with the method of the present invention using the gasification and melting furnace of the present invention, the organic matter contained in the waste is gasified and recovered as an energy gas, and the waste gas is recovered. Can be recovered as molten slag and molten metal, respectively.
As a result, it is possible to reduce the cost of landfilling general waste and industrial waste, which is a problem at present, and to use the generated by-product gas as a fuel for power generation.

Further, by injecting a part of the energy gas as a recycled gas into the furnace, the efficiency of recovering the energy gas can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view showing a configuration of an example of a waste gasification and melting furnace of the present invention.

FIG. 2 is a schematic vertical sectional view showing the configuration of another example of the waste gasification and melting furnace of the present invention.

FIG. 3 is an explanatory diagram of a blowing angle of a recycle gas into a gasification and melting furnace.

[Explanation of symbols]

1: Gasification and melting furnace body 2: Refractory brick 3-1: Gas discharge port 3-2: Gas discharge duct 4: Exhaust gas 5-1: Primary tuyere 5-2: Secondary tuyere 5-3: Tertiary Tuyere 6-1: Auxiliary fuel to be blown into primary tuyere 6-2: Auxiliary fuel to be blown into secondary tuyere 6-3: Auxiliary fuel to be blown into tertiary tuyere 7-1: Fuel support to be blown into primary tuyere 7-2: Combustion gas blown into secondary tuyere 7-3: Combustion gas blown into tertiary tuyere 7-4: Recycle gas blown into tertiary tuyere 7-5: Tertiary tuyere 8: flow of molten slag and molten metal 9: outlet of molten slag and molten metal 10: pusher 11-1: waste loading port 11-2: hopper 12: waste 13: molten slag And molten metal 14: packed bed mainly composed of carbide 15: mainly composed of waste Packing layer 16: Free board 17: Sounding device (raw material layer top level meter) 18: Sounding weight 19: Temperature converter (Device for converting thermocouple signals to temperature) 20: On the surface of the lining brick in the second zone Thermocouple provided 21: Thermocouple provided in the freeboard space of the third zone 28: Exhaust gas combustion chamber

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI F23G 5/50 ZAB F23G 5/50 ZABN ZABQ (72) Inventor Hirotaka Sato 4-33 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd. In-company (56) References JP-A-9-60830 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F23G 5/24 ZAB F23G 5/44 ZAB F23G 5/50 ZAB

Claims (4)

(57) [Claims] 1. Gasification and melting of vertical waste in which the waste is burned, the organic matter in the waste is gasified and recovered as an energy gas, and the ash and metals in the waste are recovered as a melt. A furnace having a waste loading inlet for charging the waste and a gas outlet for discharging generated gas at an upper portion, and a molten slag and a molten metal outlet at a lower portion; A tuyere is provided between the inlet and the discharge port of the molten slag and the molten metal. have a means for measuring the temperature of the incoming and levels means for measuring the waste, means for measuring the temperature of the middle of the tuyere and near the furnace upper portion of the atmosphere gas, the tuyere is the waste Measuring the level of
Means, means for measuring the temperature near the tuyere of the middle stage, and furnace
Of the means for measuring the temperature of the atmosphere gas above
Independently based on combustible gas and auxiliary fuel
Waste gasification and melting furnace characterized by being able to blow air 2. A method for gasifying and melting wastes using the waste gasification and melting furnace according to claim 1, wherein the wastes charged into the furnace from a waste charging inlet are: By the reaction in each zone, energy gas mainly composed of CO and H ₂ , molten slag and molten metal were collected, and the former was recovered from a gas outlet provided in the upper part of the furnace, and the latter was provided in the lower part of the furnace. A method for gasifying and melting waste, comprising recovering molten slag and molten metal from outlets. [First Zone] Amount of combustible gas and auxiliary fuel determined from the level value of the charged waste are blown from the lower tuyere, and the carbide generated in the second zone is burned and gasified to generate a reducing gas. The ash and the metals contained in the carbides are generated and melted to form molten slag and molten metal. [Second zone] Amount of flammable gas and auxiliary fuel determined from the temperature measurement value near the middle tuyere are blown from the middle tuyere, and the reducing gas generated in the first zone is subjected to secondary combustion, The waste loaded from the waste loading inlet is dehydrated and heated to thermally decompose into carbide and hydrocarbon gas. [Third zone] Amount of the oxidizing gas and auxiliary fuel determined from the temperature measurement value of the atmospheric gas in the upper part of the furnace are blown from the upper tuyere, and the hydrocarbon gas generated in the second zone is thermally decomposed. CO and H
Energy gas mainly composed of ₂ 3. A method in which a part of the recovered energy gas is directly blown into the third zone of the gasification and melting furnace as a recycle gas, or at least a part of the blown energy gas is burned to produce CO ₂ and / or H _{2. The} method for gasifying and melting waste according to claim 2, wherein the gas containing 2O is blown as a recycled gas, or a mixed gas of the recycled gas and oxygen is blown. 4. Injection of a recycled gas or a mixed gas of a recycled gas and oxygen is performed using a tuyere provided at an angle θ with respect to a circumferential tangent of the gasification and melting furnace at 0 ° <θ <90 °. The method for gasifying and melting waste according to claim 3.