JPH10128288A - Gasification treatment of waste product and device therefore - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gasification treatment method of a waste product for treating various waste products in batch and dissolving various problems such as destruction of the environment in accordance with the discharge and enabling to obtain a low calorie- or a middle calorie-gas becoming a chemical industrial raw material or a fuel gas. SOLUTION: In this gasification treatment method of the waste product, the waste product is gasified at low temp. by a fluidized layer gasification furnace 4, and obtained gaseous substance and char are introduced into a fusion furnace 6 to gasify them at high temp. and obtain the low calorie- or the middle calorie-gas e'. The fluidized bed gasification furnace 4 is preferred to use an internal circulation type fluidized bed gasification furnace, while the fusion furnace 6 is preferred to use a circulation fusion furnace. The fluidizing layer gasification furnace 4 has 450-800 deg.C internal temp. and the feed gas for gasification is preferred to be selected from among air, oxygen-rich air and a mixture of oxygen with steam and the internal temp. is >=1,300 deg.C and the feed gas for gasification is preferred to be selected from oxygen-rich air or oxygen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to gasification of waste, and more particularly to gasification of waste at a low temperature and then at a high temperature.
The present invention relates to a waste gasification treatment method and apparatus for recovering and utilizing energy, useful materials such as metals, and gases used as chemical industrial raw materials or fuels.

[0002]

2. Description of the Related Art Conventionally, municipal waste, waste tires, sewage sludge,
A significant proportion of industrial sludge was treated by dedicated incinerators, and night soil and highly concentrated wastes were treated by dedicated wastewater treatment facilities.On the other hand, many industrial wastes were dumped untreated. Has polluted the environment. As a new environmental protection waste treatment technology that replaces the conventional incineration method, companies are currently competing for the development of a "gasification combustion system" that combines gasification and high-temperature combustion, and the technology has already reached the practical range. There is also. At present, the development of the “gasification combustion system” is ahead of the others, using a vertical shaft furnace as the gasification furnace (S method) and a system using a rotary kiln furnace (R method). is there.

In the former S method, a drying / preheating zone (200-300 ° C.) and a pyrolysis zone (300
~ 1000 ° C), combustion / melting zone (1500 ° C or higher)
Are formed in layers from top to bottom, and the waste and coke introduced from the upper part of the furnace descend in the furnace while exchanging heat with the gas generated in the lower zone. The product gas that has risen in the furnace is burned at about 900 ° C. in a downstream combustion furnace. The carbide generated in the pyrolysis zone descends to the melting / combustion zone together with the charged coke, and is burned at high temperature by the oxygen-enriched air supplied from the tuyere, thereby melting the entire amount of ash and inorganic substances. In the latter R method, waste is crushed and then supplied to a drum-type rotary furnace externally heated by high-temperature air, and the waste is crushed for about 45 minutes.
It is pyrolysis gasified slowly at 0 ° C. over time. The carbide generated at this time is discharged from the furnace and cooled to a temperature that does not ignite. Next, the finely pulverized carbide is supplied to a later-stage revolving-type melting furnace, and is burned at a high temperature of 1300 ° C. together with a generated gas from a gasification furnace to convert ash into molten slag.

The problems of these two systems will be described. In the S-type shaft furnace, since a melting zone reaching 1700 to 1800 ° C. is present at the bottom of the gasification furnace, the use of auxiliary materials such as coke and oxygen-enriched air is inevitable, thereby increasing operating costs. In addition, there is a problem that the use of coke or the like increases the amount of carbon dioxide emitted. further,
Since almost all of the metal in the waste is melted, it cannot be recycled as bullion for each type of metal. The gasification furnace of this system belongs to the type of fixed-bed furnace, but it is difficult to operate stably because wastes of various shapes are stacked in layers and a combustion / melting zone is provided at the bottom. This is because in a fixed-bed furnace, it is very important to flow gas uniformly in the bed, that is, to ensure gas permeability.However, this is difficult due to the variety of waste shapes, and gas blow-through and drift are likely to occur. is there. The addition of coke has the purpose of ensuring such air permeability in addition to the auxiliary fuel, but it is not sufficient, and it is difficult to suppress fluctuations in gas flow rate and furnace pressure. Further, since not all of the generated gas passes through a high-temperature portion exceeding 1000 ° C., it is impossible to completely suppress the production of dioxins and furans.

On the other hand, since the R type gasification furnace is an external heating type rotary furnace using high-temperature air, the heat transfer is not good, so that the furnace is inevitably increased in size. In addition, there is a problem that heat transfer is deteriorated because tar and undecomposed substances generated by thermal decomposition cover the heat transfer surface. Obtaining high-temperature air as high as 600 ° C. by heat exchange with exhaust gas is impossible on the material of the heat exchanger. On the other hand, the generated carbide is
After being discharged from the rotary furnace, it is pulverized and then supplied to the combustion furnace, where it is combined with the gas supplied directly from the rotary furnace and burned at a high temperature. For this reason, handling equipment for carbides such as discharge, cooling, pulverization, storage, and supply is required. During such handling, the loss of heat possessed by the carbide due to cooling or heat radiation is also undesirable in terms of energy utilization. If the carbide is discharged to the outside without cooling, it may ignite when it comes into contact with air.

As described above, as a new technique for incineration of waste, various methods have been proposed for decomposing dioxin by gasifying the waste and then burning it at a high temperature and melting ash into molten slag. However, from the viewpoint of chemical recycling, a technique for recovering combustible gas by gasification has not yet been put to practical use. On the other hand, NH ₃ (ammonia), which is a typical raw material for the chemical industry, is a basic raw material for the chemical industry that is mass-produced as a raw material for nitric acid, various fertilizers (ammonium nitrate, ammonium sulfate, urea), acrylonitrile, caprolactam, and the like. NH ₃ is synthesized from N ₂ and H ₂ under high pressure using a catalyst. H ₂ is formed by steam reforming of natural gas, naphtha, etc., or partial combustion of petroleum, coal, petroleum coke, etc., so-called gasification. It has been obtained.

[0007] In addition to the above-mentioned ammonia, H ₂ is used in the synthesis of methanol, hydrodesulfurization, hydrocracking, hydrogenation of oils and fats, and welding. However, since many of these H ₂ raw materials are imported from overseas, , After two oil shocks, H
Chemical products using ₂ , especially ammonia products, have lost international competitiveness. For this reason, inexpensive and procurement can be H ₂ raw materials in their own country was Hisashika' long-awaited. On the other hand, CO
(Carbon monoxide) is used in the synthesis of gasoline, alcohols, organic acids, esters, etc., but CO is obtained by gasification of coal, coke, etc., and many of these raw materials are abroad as well as H ₂ raw materials. Therefore, products that are inexpensive and can be procured in the home country have been long-awaited.

[0008]

DISCLOSURE OF THE INVENTION In view of the above prior art, the present invention provides a low-calorie or low-calorie fuel cell which is easy to operate, has excellent safety, has high thermal efficiency, and is used as a power generation or industrial fuel gas and a chemical industrial raw material. It is an object of the present invention to provide a method of gasifying waste to obtain medium-calorie gas.

[0009]

In order to solve the above-mentioned problems, in the present invention, waste is gasified at a low temperature in a fluidized-bed gasification furnace, and the obtained gaseous substance and char are directly introduced into a melting furnace. A gasification treatment method for waste, characterized in that gasification is performed at a high temperature to obtain low calorie gas or medium calorie gas. In the above method, the fluidized bed gasifier is preferably an internal circulation type fluidized bed gasifier, and the melting furnace is preferably a swirling melting furnace, and it is optimal to use both in combination, The internal temperature of the fluidized bed gasifier is 450 to 800 ° C., and the temperature of the fluidized bed is 450 to 6
The temperature is set to 50 ° C., and the internal temperature of the melting furnace is preferably set to 1300 ° C. or higher.

[0010] The fluidized bed gasifier may be configured to supply gas for gasification with air, air and steam, oxygen-rich air,
It is good to select from oxygen-rich air and steam, a mixture of oxygen and steam, and the melting furnace is good to select the feed gas for gasification from oxygen-rich air or oxygen. The total amount of oxygen contained in the fluidized bed gasification for gasification of the gas and the gas fed into the melting furnace is 0.1% of the theoretical combustion oxygen amount necessary for completely burning the waste.
It is preferable that the amount of oxygen supplied to the fluidized-bed gasification furnace is in the range of 0.1 to 0.3 of the theoretical combustion oxygen amount. The melting furnace can collect ash as molten slag and almost completely decompose dioxins and their precursors.

The low-calorie or medium-calorie gas obtained by the method of the present invention has a normal pressure or a high pressure, and can be used as a power generation or industrial fuel gas or a raw material for chemical industry. The fluidized bed is in a reducing atmosphere, and metals in the waste can be recovered in an unoxidized state. The fluidized-bed gasification furnace used in the present invention can detect a temperature or the like of the fluidized-bed portion, and can adopt a control method of adjusting a mixing ratio of the low-calorie waste and the high-calorie waste. If the quality of the waste is low, it is possible to adjust the calories by adding coal. further,
In the present invention, a waste gas having a fluidized bed gasification furnace for gasifying waste at a low temperature and a melting furnace for introducing the obtained gaseous substance and char as it is and gasifying it at a high temperature to obtain a low-calorie gas or a medium-calorie gas It is an apparatus for gasification of material.

The fluidized-bed gasification furnace used in the present invention includes:
It has a fluidized bed part and a free board part, and the temperature of the fluidized bed part is 4
50-650 ° C, and the temperature of the free board section is 600-
The whirl melting furnace used can be used at 800 ° C., and the whirl melting furnace to be used is composed of a combustion chamber and a slag separation chamber. It is melted and separated in the slag separation chamber.
Further, the internal circulation type fluidized bed gasifier used in the present invention,
A strong circulating flow of a fluidized medium is formed in a fluidized bed in the same reaction vessel, and the circulating flow is generated by setting a partial strong and weak portion of a fluidized gas blown into the fluidized bed. Things. Therefore, unlike a simple bubbling type fluidized bed, it has excellent waste dispersion and crushing functions, does not have the complexity and size of a simple circulating (external circulation) type fluidized bed, and has better dispersion and crushing functions than this. Therefore, it is easy to take a form and configuration that are easy to use as a pressurized mold. The internal circulation type fluidized bed gasification furnace is particularly preferably a cylindrical type.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The waste used in the present invention includes municipal solid waste, solidified fuel (RDF), slurry fuel (SWM), biomass waste, plastic waste (including FRP), automobile waste (shredder dust, waste tires), and household electric appliance waste. Low-grade coal, such as waste, special waste (medical waste, etc.), sewage sludge, night soil, highly concentrated waste liquid, industrial sludge, etc.
These can be appropriately combined. Here, the solidified fuel, RDF (Refuse-derived Fuel), is obtained by crushing and sorting municipal solid waste, adding quicklime, and compression molding.
Slurried fuel, SWM (Solid Water Mixture), is obtained by crushing municipal solid waste into a water slurry and hydrolyzing it under high pressure to make oil. FRP is a fiber reinforced plastic, and low-grade coal is lignite, lignite, or peat having a low degree of coalification, or a kind of scum that is generated during coal cleaning.

[0014] These wastes are first supplied to a fluidized-bed gasifier to be pyrolyzed and gasified. In particular, by employing an internal circulation type fluidized-bed furnace in this gasifier, the wastes can be reduced. It becomes possible to supply by pretreatment of the degree of crushing. The reason for this is that the strong swirling flow of the fluid medium makes it possible to improve the heat transfer to the input waste and to discharge large-sized incombustibles. The effect of the swirling flow of the fluid medium will be described later. For this reason, among the wastes, municipal waste, biomass waste, plastic waste, automobile waste, and the like are roughly crushed to about 30 cm. Sewage sludge and urine with a high moisture content are converted into dehydrated cake using a centrifugal separator or the like at a dedicated treatment plant, and then transported to the plant site. Solid fuel, slurry fuel, high-concentration waste liquid, etc. are used as they are. Coal added for calorie adjustment can be used as it is if it is crushed to 40 mm or less.

The above-mentioned wastes are roughly classified into high-calorie wastes and low-calorie wastes according to the calories of the wastes themselves and the level of their water content. In general, municipal solid waste, solidified fuel, slurry fuel, plastic waste, automobile waste, and household electric appliance waste are the former, biomass waste, special waste (medical waste, etc.), sewage sludge / sewer Dewatered cake and high-concentration waste liquid belong to the latter. These are received in a pit for high-calorie waste, a pit for low-calorie waste, and a tank, sufficiently stirred and mixed in each pit and a relay tank, and supplied to a gasification furnace as appropriate. Even if the metal mixed into the waste enters the gasification furnace, it is recovered in an unoxidized state if the melting point is higher than the fluidized bed temperature. Therefore, the recovered metal can be used as bullion for each type.

If the quality of the input waste is constant, the ratio of the amount of the input waste to the gas sent for gasification is constant, but the ratio of the low-calorie waste to the input waste is low. As the water content increases or the total water content increases, the fluidized bed temperature falls from a predetermined value. In such a case, it is desirable from the viewpoint of the gas utilization equipment at the subsequent stage that the calorific value of the input waste is kept constant by adjusting the ratio of the amount of the low-calorie waste to the amount of the high-calorie waste in the input waste. Alternatively, the calorie of the input waste can be adjusted by adding an auxiliary fuel such as coal having a high calorific value.

Next, a fluidized-bed gasification furnace used for gasification at a low temperature in the present invention will be described. One of the features of the present invention is that the fluidized bed gasifier is used for gasification at a low temperature. The fluidized bed furnace itself is already known as a combustion furnace or a gasifier, but it is a new technique different from the prior art in that a combination of a fluidized bed gasifier and a melting furnace is used to obtain combustible gas. . Techniques for supplying coal as pulverized coal or as a water slurry to a high-temperature gasifier are already known, but in the case of waste, it is not as easy to pulverize as waste coal. Especially metal, rubble,
It can be said that it is almost impossible when it contains incombustibles such as stones. However, if a fluidized-bed gasification furnace is used, the waste can be pyrolyzed and gasified as it is in bulk, thereby making combustible gaseous substances and fine char. This can be sent to a subsequent melting furnace as it is and gasified at a high temperature. The fluidized-bed gasifier can convert the waste into a combustible gaseous substance and char by a slow pyrolysis gasification reaction, so that the fluidized-bed can be kept at a relatively low temperature.

As the fluidized-bed gasification furnace that can be used in the present invention, a known normal-pressure or pressurized-type fluidized-bed furnace, such as a bubbling-type fluidized-bed furnace, may be used in consideration of the properties of the waste to be used. However, it is particularly preferable to use an internal circulation type fluidized bed gasification furnace developed by the present inventors. The internal circulation type fluidized bed gasifier has a good horizontal cross section of the furnace, a relatively slow fluidized bed in the center of the furnace bottom,
By forming a relatively active fluidized bed around the furnace bottom and providing an inwardly inclined wall along the inner wall near the surface of the fluidized bed, by turning the flow of the fluidized medium from the periphery to the center,
The fluidized medium descends while flowing in the slow fluidized bed at the center of the furnace bottom, and rises while fluidized in the active fluidized bed near the furnace bottom, and the fluidized medium flows from the central part to the lower part of the fluidized bed. The fluidized-bed portion has a fluidized-bed portion that causes an active swirling motion of the fluidized medium such that the fluidized medium moves while flowing from the peripheral portion to the central portion at the upper portion of the fluidized bed.

The features when such a special fluidized bed is used for gasification are shown below. Since the generated char does not accumulate on the fluidized bed and is well and uniformly dispersed in the fluidized bed, the oxidation of the char in the active fluidized bed is particularly efficiently performed. The heat generated by the oxidation of the char is transferred to the fluidized medium and is effectively used as a heat source for pyrolysis gasification in the central part. On the surface of the fluidized bed, the fluid medium whose upward motion has been turned by the inclined wall collides violently in the center,
The char is pulverized. If hard silica sand is used as the fluidized medium, pulverization is further promoted. The solid waste can be supplied to the gasification furnace in the degree of fine crushing by the swallowing action accompanying the downward movement of the fluidized medium in the slow fluidized bed. For this reason, the crushing equipment can be omitted, and the power for crushing can be greatly reduced.

[0020] Due to the swirling flow of the flowing medium, even coarse incombustibles generated as a result of charging by fine crushing can be easily discharged. Due to the swirling flow of the fluid medium throughout the fluidized bed,
Since the generated heat is diffused, it is possible to avoid troubles caused by a sintered product or clinker. In the case of a commonly used bubbling type fluidized bed, the fluidized medium is uniformly fluidized in the fluidized bed, but the dispersion in the lateral direction is not so good. Accordingly, it is considered that the internal circulation type fluidized bed of the present invention is superior to the commonly used bubbling fluidized bed in the above points.

The fluidized bed gasifier used in the present invention has a fluidized bed temperature of 450 to 650 ° C. If the temperature is lower than 450 ° C., the reaction of pyrolysis gasification becomes extremely slow, which causes a problem that undecomposed substances are deposited in the fluidized bed. Also, the amount of char whose combustion speed is low increases. Conversely, if the gasification temperature is increased, the problem of undecomposed matter accumulating in the fluidized bed is resolved because the pyrolysis gasification reaction becomes faster, but fluctuations in the amount of waste supplied will cause fluctuations in the amount of gas generated. Will be invited. This hinders the operation of the subsequent rotary melting furnace. This is because it is impossible to finely adjust the amount of gas supplied to the rotary melting furnace in accordance with the amount of gas generated in the gasification furnace. For this reason, the upper limit is 650 ° C., at which the reaction of pyrolysis gasification is somewhat slow. The portion having a large diameter above the fluidized bed is usually referred to as a free board. By supplying oxygen-containing gas such as oxygen or oxygen-enriched air thereto, the load on the subsequent melting furnace is reduced, and the tar content in the generated gas is reduced. And char gasification can be promoted.

In the fluidized bed gasifier of the present invention, primary combustion is performed at 450 to 650 ° C. in the fluidized bed portion, and then 600 to 800 ° C., preferably 650 to 7 ° C. in the free boat portion.
Secondary combustion at 50 ° C. The feed gas (gasifying agent) for gasification into the fluidized bed of the fluidized bed gasifier is a mixture of air, air and steam, oxygen-enriched air, oxygen-enriched air and steam, oxygen and steam. It is selected from among them, and sand (silica sand, olivine sand, etc.), alumina, iron powder, limestone, dolomite, etc. are used as the fluid medium. In addition to these gases, oxygen supplied to the free board may further include oxygen as an option. The gas generated in the fluidized-bed gasification furnace contains a large amount of tar and carbides. The carbides are pulverized in the fluidized bed to form fine-grained char, which is directly introduced into the melting furnace together with the gas. on the other hand,
Since the fluidized bed has a reducing atmosphere, the metal in the waste can be extracted in an unoxidized state useful as a metal.

The metals that can be recovered are limited to those whose melting point is lower than the gasification temperature. Therefore, aluminum (melting point 6)
(60 ° C.), the fluidized bed temperature must be 650 ° C. or less. As described above, the use of a fluidized bed gasifier for low-temperature gasification of waste enables processing of various wastes, for example, those having a size of several mm to several tens of mm, and has a high processing capacity and scale. Up is easy. Further, since there is no mechanical drive unit, the operation of adjusting the temperature and the like is easy, the heat transfer between the heat medium and the layer is good, and the temperature in the layer is easily kept uniform. Furthermore, when an internal circulation type fluidized bed gasifier is used as a fluidized bed gasifier, waste can be crushed without being crushed, and the carbides are efficiently pulverized in the fluidized bed into a char, and the char in the fluidized bed is formed. Because of its good dispersion, there are effects such as high processing capacity, uniform temperature in the layer, and high gasification efficiency.

Next, the melting furnace will be described. In the melting furnace, gaseous substances introduced from a fluidized-bed gasification furnace and char are brought into contact with a feed gas to gasify the gas at a high temperature of 1300 ° C. or more, and gasify tar and char completely, thereby containing ash content. Is discharged from the furnace bottom as molten slag. As a melting furnace that can be used, a type that only blows in from the upper side, such as a Texaco furnace, can be used, but preferably, a swirling melting furnace, that is, a gaseous substance and char are mixed in a combustion chamber together with a feed gas for gasification. It is preferable to use a melting furnace of a type in which high temperature gasification is performed while forming a swirling flow to melt ash, and the melted ash is separated and discharged. The use of a swirling melting furnace enables high load and high speed combustion, narrows the gas residence time distribution, and increases the carbon conversion rate and slag mist collection rate due to the centrifugal force generated by the swirling flow. The body can be made more compact.

The gas supplied to the melting furnace for gasification can be selected from oxygen-enriched air and oxygen. The amount of oxygen in the supplied gas is adjusted to 0.1% of the theoretical amount of oxygen required to completely burn the waste by combining the supplied gas for gasification into the fluidized bed gasifier. It is better to be in the range of 0.6. Thus, from the melting furnace, low calorie (1
000-1500 kcal / Nm ³ (dry)) or medium calories (2,500-4500 kcal / Nm)
³ (dry)) of fuel gas can be obtained. These gases contain many useful gas components such as CO and H ₂ . CO and H ₂ gas are obtained from waste,
The use of industrial fuel gas or a raw material for the chemical industry is a particularly excellent feature of the present invention. By converting the ash in the char derived from the fluidized-bed gasification furnace into slag in the subsequent melting furnace, harmful heavy metals are contained in the slag,
No longer elutes. In addition, dioxins and their precursors, PCBs, and the like are almost completely decomposed by high-temperature combustion of 1300 ° C. or more.

Next, with reference to FIG. 1, a method for utilizing the obtained gas for a purpose according to its properties will be described. There are two types of usage: thermal recycling using energy and chemical recycling for raw materials in the chemical industry. When the gas is combustion exhaust gas at normal pressure and high temperature, the steam collected by the steam boiler is supplied to a steam turbine and collected as electric power. When the gas is a normal pressure fuel gas, power is generated using a gas engine or a diesel engine, or used as industrial fuel gas. This industrial fuel gas can be used, for example, in steelmaking and steelmaking processes. On the other hand, when the gas is a high-pressure (20 to 40 atm) fuel gas, a combined power generation using a gas turbine or an industrial fuel gas is used. When the gas is a high-pressure, medium-calorie fuel gas containing no N ₂ , hydrogen, methane (SNG), alcohols such as methanol, and synthesis gas for gasoline production are used.

Hydrogen is produced by converting the produced gas into CO and then removing CO _2.
Is obtained by Methane is converted to CO / H ₂ by CO conversion.
After adjusting the ratio, it is obtained by methanation reaction. Methanol is obtained by a methanol synthesis reaction after CO conversion. A mixture of a higher alcohol such as methanol and ethanol is obtained by an alcohol synthesis reaction. Gasoline is
Synthesized by the Fischer-Tropsch reaction, as practiced in Sasol, South Africa. In this way, the quality and quantity of the target waste,
It is necessary to select an optimal process in consideration of the target product and the like. Next, the use of slag will be described. When waste is used as a raw material, slag contains a greater or lesser amount of chlorine, so it is effective to use it as a raw material for ecocement. Ecocement is a new type of cement made from incineration ash: sewage sludge: additive = 4: 3: 3, and has applications as unreinforced concrete products and solidifying materials. The collected slag includes granulated slag and slowly cooled slag, but can also be used as civil engineering and construction materials such as roadbed materials, aggregates, and water-permeable materials, or as horticultural materials.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings. Embodiment 1 FIG. 2 shows a schematic configuration diagram of an example of an apparatus used for the gasification treatment method of the present invention. FIG. 2 shows a high pressure (20 to 40 atm)
2 is an example of producing a synthesis gas of FIG.
Is a lock hopper system, 2 is a hopper, 3 is a screw feeder, 4 is a fluidized bed gasifier, 5 is a fluidized bed, 6 is a swirling melting furnace, 7 is a primary combustion chamber, 8 is a secondary combustion chamber, and 9 is a secondary combustion chamber. Slag separation room, 10 is a waste heat boiler, 11 is a scrubber,
a is waste, b is oxygen, c is steam, d is non-combustible, e
Denotes a low-temperature gasified gas, e ′ denotes a high-temperature gasified gas, f denotes slag, f ′ denotes ash, and g denotes generated gas.

[0029] The waste a is uniformly mixed and fed into the hopper 2 through the lock hopper system 1. Next, a fixed amount is supplied to the fluidized bed gasification furnace 4 by the screw feeder 3. A mixed gas of oxygen b and steam c is supplied to the bottom of the gasification furnace 4 as a fluidizing gas. The raw material that has fallen into the fluidized bed section 5 of the gasification furnace 4 is 450 to 650 ° C
In the fluidized bed held in the tank, the gas comes into contact with the gas supplied from oxygen and steam for gasification, and is rapidly pyrolyzed into gas. As a result, gas, tar, carbide, and H ₂ O are generated, but the carbide is pulverized by the disturbance motion of the fluidized bed to become char. These are supplied collectively to the primary combustion chamber 7 of the later-stage swirling melting furnace 6, where they are oxidized at a high temperature of 1300 ° C. or higher while being mixed with oxygen b also supplied for gasification in the swirling flow. . For this reason, the ash contained in the char becomes slag mist, is captured by the slag phase on the furnace wall by the centrifugal force of the swirling flow, flows down the furnace wall, enters the secondary combustion chamber 8, and becomes the slag separation chamber 9 as slag f. From the bottom of the furnace. The oxidation reaction of high temperature gasification is completed in the secondary combustion chamber 8,
It becomes a medium calorie gas (2,500 to 4500 kcal / Nm ³ ) composed of H ₂ , CO, and CO ₂ and H ₂ O.

Since the fluidized bed portion 5 of the gasification furnace 4 is in a reducing atmosphere, the metals in the raw material having a melting point higher than the fluidized bed temperature are in a non-oxidized and clean state together with rubble, stone, glass and the like, and are incombustible. It is discharged from the furnace bottom as d. For this reason,
It can be reused as metal bullion. The gas that has left the melting furnace 6 is recovered in a waste heat boiler 10 after steam c is recovered.
It is cooled and washed by a scrubber 11 using an aqueous solution to remove dust and HCl in gas poisoning the CO conversion catalyst. Thus, a purified product gas g is obtained. This gas can be used for industrial fuel gas, but in this case, there is no need for CO conversion, so that the scrubber 11 can be simplified. The obtained gas composed of H ₂ , CO, CO ₂ and H ₂ O is used as a synthesis gas for chemical industry raw materials.

Embodiment 2 Next, gasification using an internal-circulation type fluidized-bed gasification furnace at normal pressure for obtaining low-calorie gas will be described with reference to FIG. 3, the same reference numerals as those in FIG. 2 denote the same names,
12 is a free board, 13 is a burner, 14 is a trommel, 15 is a bucket conveyor, and 16 is a burner. After the crushed waste a and coal j are supplied to the hopper 2, they are supplied to the fluidized-bed gasification furnace 4 using the screw type quantitative supply device 3. Preheated air b ″ is inserted as a fluidizing gas from below the gasification furnace 4 to form a fluidized bed 5 of silica sand on the dispersion plate. Wastes a and coal j are injected above the fluidized bed 5. Then, it comes into contact with O ₂ in the air in the fluidized bed 5 maintained at 450 to 650 ° C., and is quickly pyrolyzed to gas. The coarse incombustible material d is discharged out of the system by the trommel 14.

The separated silica sand h is supplied to the bucket conveyor 15.
And then returned to the gasifier 4. Although metals are contained in the noncombustible material d, iron, copper, and aluminum can be recovered in a recyclable state by setting the fluidized bed temperature to 500 to 600 ° C. Fluidized bed 5
Gas, tar, and carbides are generated by the low-temperature gasification reaction in the reactor. The gas and tar vaporize and rise in the furnace. The carbide is finely pulverized by the disturbance motion of the fluidized bed 5 to form char. Because the char is porous and light, it is entrained in the upward flow of product gas. By using hard silica sand as the fluidized medium, the grinding of carbides is promoted. Air b 'is blown into the free board 12, and gasification at 600 to 800 ° C is performed again. In this way, the molecular components of the gas components are reduced, and the gasification of tar and char proceeds.

The product gas e exiting the gasification furnace is supplied to the primary combustion chamber 7 of the swirling melting furnace 6, where it is mixed with the preheated oxygen-enriched air b 'in a swirling flow and is heated to a high temperature of 1300 ° C. or more. Gasify. The combustion is completed in the secondary combustion chamber 8, and the combustion exhaust gas e 'is discharged from the slag separation chamber 9. The ash contained in the char becomes slag mist due to the high temperature, is captured by the molten slag phase on the furnace wall of the primary combustion chamber 7 due to the centrifugal force of the swirling flow, flows down the furnace wall and enters the secondary combustion chamber 8, It flows down from the bottom of the slag separation section 9. In the primary combustion chamber 7 and the secondary combustion chamber 8 of the swirling melting furnace 6, one heating burner 16 is installed. Thus, low calories (1000-
A combustible gas of 1500 kcal / Nm ³ ) can be obtained.

Example 3 FIG. 4 shows a 10 to 40 at using another type of swirling melting furnace.
Another example for obtaining m synthesis gas. In FIG. 4, the gasification furnace uses an internal circulation type fluidized bed gasification furnace 4, and the carbide of the supplied waste a is not uniformly deposited on the fluidized bed but is uniformly dispersed in the fluidized bed. Pulverization and gasification are promoted. In this type of fluidized bed furnace, the raw material waste can be increased in crushing particle size at the time of supply, and large-sized incombustibles can be discharged. In addition, it has features such as less clinker trouble due to excellent diffusion of generated heat. The product gas e exiting the gasification furnace 4 is supplied to a combustion chamber 7 of a swirling melting furnace 6 and gasified at 1300 ° C. or higher while being mixed with preheated oxygen b in a swirling flow.

Embodiment 4 FIG. 5 shows another embodiment using another type of swirling melting furnace. A radiation boiler 19 is installed inside the slag separation chamber 9 of the swirling melting furnace 6, and a water tank 20 is provided below the slag separation chamber 9, so that the gas that has once descended to near the water surface can flow to the back side of the water pipe near the water surface. I have. In the radiation boiler 19, since the direction of gas flow and the direction of gravity match, the slag attached to the wall falls without growing large. Further, since the radiation boiler 19 also recovers the heat of the slag flowing down, the efficiency of heat recovery is increased. Furthermore, since the flow direction of the gas changes rapidly near the water surface, much of the slag mist contained in the gas is recovered by the water due to its inertial force. The gas e 'that has left the melting furnace 6 is supplied to a convection boiler 21 where heat is recovered. The secondary combustion chamber 8 can be omitted. This embodiment is most suitable for a process intended for power generation.

Embodiment 5 Here, representative test data in the configuration diagram of FIG. 3 is shown. Table 1 shows the properties of the raw material waste used for gasification. This is the result of calorie adjustment by adding coal to ordinary municipal waste. Tables 2 to 4 show the results obtained when this raw material waste was gasified at a low temperature of 500 to 600 ° C in a fluidized bed gasification furnace and then gasified at a high temperature of 1350 ° C in a swirling melting furnace. Table 2 shows the mass balance of the entire gasification, that is, the gasification balance obtained by adding a melting furnace to the gasification furnace, where the raw material waste is set to 100. Oxygen 46 and steam 36 are consumed as a gasifying agent for gasification. As a result, the generated gas is 112, which is larger than that of the raw material waste, mainly because oxygen of the gasifying agent has been added. Table 3 also shows the heat balance of both furnaces. Also in this case, the combustion heat of the raw material waste is set to 100 as a reference, but since the combustion heat of the generated gas is 60, the cold gas efficiency is 60%.

This cold gas efficiency has almost the same meaning as the energy recovery rate. The heat of combustion of the generated gas per unit time (higher base) is the heat of combustion of the raw material waste (higher base).
Is the ratio to From the above, it can be seen that, for the purpose of recovering the combustible gas, the lower limit of the calorific value of the raw material waste is substantially set to 3500 kcal / kg set here. As the lower heating value exceeds 3500 kcal / kg, the cold gas efficiency becomes greater than 60%. The heat loss from the furnace wall is 5.9, but if this can be reduced, it is expected that the cold gas efficiency will be further increased. Table 4 shows the dry gas composition of the produced gas, and the moisture in the gas was not counted.
Accounting for 77% in H ₂ and CO is combustible components. Therefore, the volume corresponding to this 77% is H ₂ after CO conversion.

[0038]

[Table 1]

[0039]

[Table 2]

[0040]

[Table 3] Note) This heat balance is based on the higher calorific value. Q: heat of combustion, H: enthalpy

[0041]

[Table 4]

Embodiment 6 FIG. 6 shows an overall configuration diagram of an example of another apparatus used in the present invention. FIG. 6 shows a case in which after a low-calorie fuel gas is produced at a high pressure (about 20 atm), combined power generation is performed using a gas turbine. 6, reference numeral 32 denotes a ceramic filter, 33 denotes a gas turbine, 34 denotes a steam turbine, k denotes electric power, m denotes exhaust gas, and the rest is the same as FIG. Since air b ″ is supplied to the gasification furnace 4 and oxygen-enriched air b ′ is supplied to the melting furnace 6, the generated gas from the melting furnace 6 is a low-calorie gas composed of H ₂ , CO, CO ₂ , N ₂ and steam. (1000 to 1500 kcal / Nm ³ (dr
y)). Example 1 The temperature conditions of the gasification furnace and melting furnace
Is the same as

Thereafter, the steam c is collected by the waste heat boiler 10, and the ash f 'is separated by the ceramic filter 32, and then supplied to the gas turbine 33. After the electric power k is generated, the steam c is collected by the waste heat boiler 10. And is released to the atmosphere. The recovered steam c is supplied to the steam turbine 34 to generate electric power k. Here, a method was shown in which the generated gas was dedusted at a high temperature and then supplied to the gas turbine.
In the same manner as described above, the product gas can be supplied to the gas turbine 33 after being purified at normal temperature. However, in this method, the power generation efficiency is slightly reduced.

Embodiment 7 FIG. 7 shows an overall configuration diagram of an example of another device used in the present invention. FIG. 7 shows a case in which a low-calorie fuel gas is produced under normal pressure, and then combined power generation is performed using a gas engine. In FIG. 7, 35 is a gas engine. In this case, the lock hopper is unnecessary when supplying the waste a and the coal j to the hopper 2. Since air b ″ is supplied to the gasification furnace 4 and oxygen-enriched air b ′ is supplied to the melting furnace 6,
Configuration of the product gas is N _2, H _2, CO, low calorie gas composed of _{CO 2, H 2 O (1000~1500kcal} /
Nm ³ (dry)). The temperature conditions of the gasification furnace and the melting furnace are the same as in Example 1. Thereafter, the steam c is collected by the waste heat boiler 10, and the generated gas is cooled and washed by the scrubber 11. The obtained normal-temperature generated gas is supplied to the gas engine 35 to generate electric power k, and then the steam c is collected again by the waste heat boiler 10 and released to the atmosphere. The entire amount of the recovered steam is supplied to the steam turbine 34 to generate electric power k. For cost reduction, the waste heat boiler 10 after the gas engine 35 can be omitted, but the power generation efficiency is reduced.

[0045]

Industrial Applicability The present invention provides a resource recycling method for converting waste into fuel gas or a raw material for chemical industry, and provides a technology for recovering resource valuables while maintaining environmental conservation. It aims to utilize waste as a new resource through chemical recycling. Specifically, the following effects can be obtained. Chemical recycling of converting waste into medium-calorie synthesis gas by gasification combining low-temperature gasification and high-temperature gasification, and then converting it into chemical industrial raw materials such as ammonia and methanol becomes possible.

The ash can be made slag and harmless during the process of syngas generation. The generated slag can be recycled as civil engineering materials. Since valuable metals such as iron, copper, and aluminum contained in waste can be recovered in an unoxidized state, material recycling becomes possible. By recovering low-calorie combustible gas, it is also possible to thermally recycle it as fuel for gas turbines or industrial fuel gas. Since it passes through a high temperature range of 1300 ° C. or more, harmful dioxins can be almost completely decomposed.

[Brief description of the drawings]

FIG. 1 is an overall conceptual diagram of gasification utilization by a treatment method of the present invention.

FIG. 2 is a conceptual configuration diagram showing an example of an apparatus used for the processing method of the present invention.

FIG. 3 is a schematic configuration diagram showing another example of an apparatus used for the processing method of the present invention.

FIG. 4 is a schematic configuration diagram showing another example of an apparatus used for the processing method of the present invention.

FIG. 5 is a schematic configuration diagram showing another example of an apparatus used for the processing method of the present invention.

FIG. 6 is a schematic configuration diagram showing another example of an apparatus used for the processing method of the present invention.

FIG. 7 is a schematic configuration diagram showing another example of an apparatus used for the processing method of the present invention.

[Explanation of symbols]

1: Lock hopper system, 2: Hopper, 3: Screw feeder, 4: Fluidized bed gasifier, 5: Fluidized bed section,
6: swirling melting furnace, 7: primary combustion chamber, 8: secondary combustion chamber,
9: Slag separation room, 10: Waste heat boiler, 11: Scrubber, 12: Free board, 13: Burner, 14, 1
4 ': Screen (Trommel), 15: Fluid medium circulation path (bucket conveyor), 16: Burner, 17, 1
7 ': lock hopper, 18: inclined wall, 19: radiation boiler, 20: water tank, 21: convection boiler, 22, 22': storage tank, 32: ceramic filter, 33: gas turbine, 34: steam turbine, 35: Gas engine a: waste, b: oxygen, b ': oxygen-enriched air, b ": air, c: water vapor (steam), d: incombustible, e: low-temperature gasification product gas, e': high-temperature gasification Product gas, f: molten slag, g: synthesis gas, h: flowing medium, i: water, j: lime, k: electric power, m: exhaust gas

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F23G 5/16 ZAB F23G 5/32 ZAB 5/32 ZAB F23L 7/00 C F23L 7/00 AB C10G 1/00 B // C10G 1/00 1/10 1/10 B09B 3/00 ZAB 303L (72) Inventor Masaaki Irie 11-1 Haneda Asahimachi, Ota-ku, Tokyo Ebara Corporation (72) Inventor Tetsuhisa Hirose Ota, Tokyo (71) Inventor Takahiro 11-12 Haneda Asahi-cho, Ota-ku, Tokyo Inside Ebara Manufacturing Co., Ltd.

Claims (17)

[Claims] 1. Gasification of waste at a low temperature in a fluidized-bed gasification furnace, introduction of the resulting gaseous substance and char into a melting furnace to gasify at a high temperature to obtain a low calorie gas or a medium calorie gas. Waste gasification method. 2. The method according to claim 1, wherein the fluidized bed gasifier is an internal circulation type fluidized bed gasifier. 3. The method according to claim 1, wherein the melting furnace is a rotary melting furnace. 4. The waste gasification method according to claim 1, wherein the fluidized bed gasification furnace is an internal circulation type fluidized bed gasification furnace, and the melting furnace is a swirling melting furnace. 5. The fluidized bed gasifier has an internal temperature of 45.
The gasification treatment method for waste according to claim 1, wherein the temperature is 0 to 800C. 6. The waste gasification method according to claim 1, wherein the fluidized bed gasification furnace has a temperature of the fluidized bed of 450 to 650 ° C. 7. The waste gasification method according to claim 1, wherein the melting furnace has an internal temperature of 1300 ° C. or higher. 8. The fluidized-bed gasification furnace is configured to supply gas to the fluidized bed for gasification with air, air and steam, oxygen-enriched air, oxygen-enriched air and steam, and a mixture of oxygen and steam. The method for gasifying waste according to claim 1, wherein the method is selected from the group consisting of: 9. The gasification treatment method for waste according to claim 1, wherein the melting furnace selects a feed gas for gasification from oxygen-enriched air or oxygen. 10. The gas fed into the fluidized-bed gasification and melting furnace for gasification has a total oxygen content of 0.1% of the theoretical combustion oxygen amount required for completely burning waste. 2. The method for gasifying waste according to claim 1, wherein the amount is in the range of 1 to 0.6. 11. The amount of oxygen supplied to the fluidized-bed gasifier of the input gas is 0.1 to 0.3 of the theoretical combustion oxygen amount.
The method for gasification of waste according to claim 10, wherein: 12. The waste gasification method according to claim 1, wherein the melting furnace collects ash as molten slag and decomposes dioxins and their precursors almost completely. 13. The gasification of waste according to claim 1, wherein the obtained low-calorie or medium-calorie gas is at normal pressure or high pressure and used as power generation or industrial fuel gas or chemical industrial raw material. Processing method. 14. The gasification treatment of waste according to claim 1, wherein the fluidized bed gasifier has a fluidized bed part in a reducing atmosphere and recovers metal in waste in an unoxidized state. Method. 15. The waste gasification method according to claim 1, wherein the waste supplied to the fluidized-bed gasification furnace is adjusted in a mixing ratio of low calorie waste and high calorie waste. . 16. The waste gasification treatment method according to claim 1, wherein when the waste is of low quality, coal is used as an auxiliary fuel. 17. A fluidized-bed gasification furnace for gasifying waste at a low temperature, and a melting furnace for gasifying the obtained gaseous substance and char at a high temperature to obtain a low-calorie gas or a medium-calorie gas. Waste gasification treatment equipment.