JP3836582B2 - Fluidized bed gasification melting apparatus and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for gasification and melting of a combustible material contained in municipal waste and / or various wastes using a fluidized bed.
[0002]
[Prior art]
Various treatment methods for municipal waste and various types of waste (hereinafter, simply referred to as garbage in the present invention) have been developed. Recently, as a new treatment method, waste is pyrolyzed in one system, A method of melting ash using the generated pyrolysis gas or char as a heat source is employed. One of the methods is a gasification and melting system in which combustible components contained in garbage are gasified by a fluidized bed gasification furnace, and ash is melted and solidified.
[0003]
  In the above gasification and melting system, the waste supplied to the fluidized bed gasification furnace is mixed with a fluid medium made of sand or the like and fluidized using a fluidizing fluid such as air, while reacting with the blown air. Then, it is gasified in a reducing atmosphere, and combustible pyrolysis gas and solid char are generated. All of the obtained pyrolysis gas is burned in a pyrolysis gas combustion furnace and introduced into an exhaust heat recovery device. Moreover, incombustibles such as metals and rubble (residue from the bottom of the combustion furnace) are contained in the char or separated from the char using differences in physical properties such as particle size and specific gravity. After the metals in the incombustible material are recovered, the ash is melted and solidified or used as it is in a landfill process. Flammable gas, char andAndFly ash and the like are sent to an ash melting furnace provided on the downstream side of the fluidized bed gasification furnace and used as a heat source, and most of incombustibles such as fly ash are melted. The gas after these treatments is purified by the exhaust gas purification device and then released into the atmosphere.
[0004]
[Problems to be solved by the invention]
In the fluidized bed gasification and melting system of the above prior art, a pyrolysis gas combustion furnace, melting furnace, exhaust heat recovery device, exhaust gas purification device and the like are provided on the downstream side of the fluidized bed gasification furnace. When the gasification and melting system is started up or when the system is restarted after maintenance of each device constituting the system such as a melting furnace, the fluidized fluid for the fluidized bed gasification furnace is warmed up in a steady state. It is not possible to obtain a predetermined temperature until the temperature reaches a maximum, so the fluidized bed gasifier cannot be started up quickly. That is, there is a drawback that it takes a long time to start up the entire system.
[0005]
In addition, since the waste pyrolysis unit including the fluidized bed gasification furnace and the part including the melting heat recovery unit including the subsequent melting furnace are related to each other systematically, they cannot be operated independently. . That is, when the operation is stopped at any of these portions for maintenance or due to a malfunction or the like, it is necessary to completely stop the entire system. The fluidized bed gasification furnace is filled with a fluid medium consisting of a large amount of high-temperature sand, etc., and the melting furnace is operated as much as possible (warm air operation, for example, the molten slag solidifies due to a temperature drop). However, there is a disadvantage that it is extremely difficult in the prior art fluidized bed gasification and melting system.
[0006]
Furthermore, municipal waste and various industrial wastes put into a fluidized bed gasifier contain chlorine and various heavy metals (heavy metal can be a catalytic element that accelerates corrosion of equipment). In some cases, these chlorine components are entrained in the pyrolysis gas and corrode the components of the heat recovery section. Therefore, high-temperature superheated steam could not be obtained, and therefore high-efficiency power generation could not be realized using this fluidized bed gasification melting system.
[0007]
In addition, the combustibles such as waste introduced into the fluidized bed gasification and melting system do not have a constant property, and the amount charged into the gasification furnace may fluctuate greatly over time, so a stable fluidized bed It was difficult to maintain combustion. In particular, there are fluctuations in the amount of water in the garbage as well as fluctuations in the quantity of garbage. When a large amount of garbage is thrown into the gasifier at once, the supply amount of auxiliary fuel will be drastically reduced. If it is not possible to increase the flow rate, the fluidized bed gasification combustion may not be maintained.
[0008]
An object of the present invention is to improve the function of a fluidized bed gasification and melting system of combustible materials contained in various types of waste such as municipal waste and / or industrial waste, to enable stable operation, and to generate highly efficient power generation. Is to realize.
[0009]
  In addition, the problem of the present invention is that it is possible to quickly start up at the time of start-up, and it is possible to partially operate some devices in the fluidized bed gasification processing system during maintenance or when some devices fail. It is to be.
[0010]
[Means for Solving the Problems]
  The problems of the present invention are solved by the following configuration.
  The invention described in claim 1Fluidized bed gasification furnace for pyrolytic gasification of combustible materials including solids using a fluidized mediumFluidized bed gasifier with (2)systemObtained in the series (A) and fluidized bed gasifier (2)Melting furnace that melts the solid content obtained by pyrolyzing the combustible material(4)And fluidized bed gasifier(2)And / or melting furnace(4)Recovery device that recovers heat using the hot gas obtained in(7-9)And an exhaust gas purifying device for purifying exhaust gas discharged from at least one of the devices(10) Solid content / gas treatment system (B)In a fluidized bed type gasification and melting apparatus comprising a fluidized bed gasification furnace systemTong (A)There is a fluidized bed gasifier(2)Pyrolysis gas produced in(15)Pyrolysis gas combustion furnace that burns(45)And the combustion furnace(45)Heat exchanger that exchanges heat using combustion gas(26, 29)And the independent heat exchanger(26, 29)Of the combustion gas after heat exchange in a fluidized bed gasifierTo (2)Fluidizing fluid(13)ToforRecirculation gas(19)Gas circulation system including flow path(A)Provided,The gas circulation system (a) and the solid content / gas treatment system (B) can be operated independently.Fluidized bed gasification melting equipmentIs.
  The invention according to claim 2 is the fluidized bed gasification and melting apparatus according to claim 1, wherein an addition section for adding a desalting agent is provided in the fluidized bed gasification furnace system (A).
[0011]
  The invention described in claim 3 The fluidized bed gasification and melting apparatus according to claim 1, wherein the independent heat exchanger (26, 29) is a steam superheater (26), an air preheater (29) or a feed water heater (not shown).
The invention according to claim 4 is provided with a steam superheater (26) as an independent heat exchanger (26, 29), and a steam temperature measuring means (52a) and a steam flow rate at a steam outlet of the steam superheater (26). A measuring means (52b) is provided, and based on the measured values of the two measuring means (52a, 52b), the pyrolysis gas combustion furnace (45) is used so that the superheated steam temperature and superheated steam amount at the outlet of the steam superheater become a predetermined value. The fluidized bed type gasification and melting apparatus according to claim 1, further comprising a control device (56) for performing combustion control of
[0012]
  The invention according to claim 5 Char accompanying the pyrolysis gas (15) generated in the fluidized bed gasification furnace (2) provided in the gas flow path between the fluidized bed gasification furnace (2) and the pyrolysis gas combustion furnace (45). The fluidized bed type gasification according to claim 1, further comprising a separator (25) for separating the gas from the pyrolysis gas (15) and a char storage tank (34) for storing the char separated by the separator (25). It is a melting device.
  According to a sixth aspect of the present invention, the gas circulation system (a) includes:A char transport path was provided to supply char from the char storage tank (34) to the melting furnace (4).A fluidized bed gasification and melting apparatus according to claim 5.
[0013]
  The invention described in claim 7Fluidized bed gasifier using a fluid medium for combustible materials including solids(2)Pyrolysis gas obtained by pyrolysis gasification inside(15)In a fluidized bed gasification and melting method in which a solid content obtained by pyrolyzing and gasifying the combustible material is melted in a fluidized bed gasification and melting method.(2)Pyrolysis gas produced in(15)And heat exchange from the combustion heat of the combustion gas to the heat recovery medium, and then the combustion gas after the heat exchange is fluidized bed gasifier(2)For fluidizing fluidsA gas circulation system (a), and a solid content / gas processing system for melting the solid content obtained by pyrolyzing the combustible material and recovering heat from the hot gas generated at the time of melting to a heat recovery medium ( And B), and the gas circulation system (a) and the solid content / gas treatment system (B) can be operated independently.
[0014]
  In the invention according to claim 8, in the fluidized bed gasifier (2), char is generated in addition to the pyrolysis gas, and when the char is accompanied by the pyrolysis gas, the char is separated from the pyrolysis gas. 8. The fluidized bed gas according to claim 7, wherein the separated char is temporarily stored and used as a heat source for melting the solid content obtained by pyrolyzing and gasifying the stored char as a combustible material. This is a chemical melting method.
  The invention according to claim 9 is accompanied by the pyrolysis gas (15) generated in the pyrolysis gasification of the combustible material in the fluidized bed gasification furnace (2) or generated in the fluidized bed gasification furnace (2). The fluidized bed gasification and melting method according to claim 8, wherein a desalting agent is added when the char is separated from the pyrolysis gas (15) to cause a desalting reaction of the pyrolysis gas.
  The invention according to claim 10 is: When the pyrolysis gas (15) generated in the fluidized bed gasification furnace (2) is combusted and heat is recovered from the combustion heat of the combustion gas to the heat recovery medium, superheated steam is used as the heat recovery medium, The fluidized bed gasification and melting method according to claim 7, wherein the combustion control of the pyrolysis gas (15) is performed so that the steam temperature and the amount of steam superheated by the combustion heat of the combustion gas become a predetermined value.
[0015]
Thus, according to the present invention, the combustible pyrolysis gas generated in the fluidized bed gasification furnace is burned in the pyrolysis gas combustion furnace, introduced into an independent heat exchanger such as an independent superheater, and completely burned. The combustion gas recovered by an independent heat exchanger such as an independent superheater is recirculated and used as a fluidizing fluid in a fluidized bed gasifier. With this configuration, it is possible to start the fluidized bed gasification furnace or continue the operation completely separated from the operation of the downstream melting furnace and the exhaust heat recovery unit.
[0016]
According to the present invention, since the fluidized bed gasification furnace can be operated independently in a state separated from the melting furnace and the heat recovery device, during maintenance of the fluidized bed gasification furnace or the subsequent melting furnace or the like, When stopped due to a malfunction or the like, the gas circulation system including the fluidized bed gasification furnace, the solid content including the melting furnace and the heat recovery device, and the gas processing system can be operated independently (warm-up operation). This can provide a desirable state in a gas circulation system including a fluidized bed gasification furnace, a solid content including a melting furnace and a heat recovery device, and a gas processing system where it is desired to avoid temperature drop due to shutdown as much as possible.
[0017]
In addition, when the gasification melting furnace of the present invention is started, when the amount of pyrolysis gas is small or low, the air-fuel ratio of the fluidized bed gasification furnace is adjusted to a predetermined condition by adjusting the combustion amount of auxiliary fuel in the independent heat exchanger. Therefore, it is possible to quickly start the fluidized bed gasifier.
In addition, by supplying a desalting agent such as slaked lime to the fluidized bed gasification furnace and maintaining the temperature of the fluidized bed in the fluidized bed gasification furnace at 500 to 700 ° C. Chlorine contained in it and generated hydrogen chloride react with slaked lime and calcium in ash to be immobilized, and the pyrolysis gas becomes a clean gas with a low hydrogen chloride content.
[0018]
In the present invention, when a solids separator such as a cyclone is provided in the gas flow path on the downstream side of the fluidized bed gasifier, char, ash, reaction products (calcium chloride, etc.), heavy metals, etc. Is separated from the gas component, and the reaction can be promoted in the separator to further reduce the hydrogen chloride gas content. At this time, a desalting agent such as slaked lime may be supplied into the separator.
[0019]
These clean gases, such as hydrogen chloride and heavy metals, which adversely affect the operation of the gasification and melting apparatus of the present invention, including a fluidized bed gasification furnace, are circulated and used in various apparatuses constituting the gasification and melting apparatus of the present invention. Concentration and accumulation of similar components are eliminated, and there is an effect on maintenance and maintenance of the gasification and melting apparatus.
[0020]
In particular, clean pyrolysis gas with a low chlorine content that causes high-temperature corrosion of the superheater can be supplied to the independent superheater, so that high-temperature and high-pressure steam can be recovered by the independent superheater, and high-efficiency power generation can be realized.
In addition, a clean pyrolysis gas combustion furnace with low chlorine content obtained from a fluidized bed gasification furnace is placed in front of the independent superheater, which is a typical example of an independent heat exchanger, and stabilized by combustion control. High-temperature steam (about 500 ° C.) can be easily obtained, and high-efficiency power generation can be achieved.
[0021]
  AlsoGarbage can be used as a combustible material including a solid material.Garbage before being put into the fluidized bed gasifier is put into a pretreatment device such as a great dryer. At that time, the height of the piled garbage is averaged in the pretreatment device such as a great dryer. Since it can be discharged evenly from the outlet sequentially, it becomes easy to quantitatively supply waste to the fluidized bed gasifier. At the same time, since the waste having a uniform water content is sequentially fed into the fluidized bed gasification furnace in sequence, there is an advantage that it is not necessary to use auxiliary fuel for the combustion of garbage in the fluidized bed in the gasification furnace.
[0022]
At this time, as a waste drying fluid introduced into the pretreatment device, at least one of the gasification and melting devices of the present invention, such as a fluidized bed gasification furnace, a melting furnace, a heat recovery device, or an independent heat exchanger The preheated air or hot gas obtained from the above is introduced, and further, the waste-dried fluid discharged from the pretreatment device is introduced into at least one of the gasification and melting devices of the present invention. The amount discharged out of the system of the gasification melting apparatus can be reduced.
[0023]
As the fluid after the waste is dried, a part of preheated air used in the gasification furnace is used, or a hot gas discharged from an independent heat exchanger or a heat recovery device is used. When the preheated air is used for waste drying, the waste gas is supplied to the fluidized bed gasification furnace, melting furnace, and pyrolysis gas combustion furnace after drying, and the hot gas discharged from the independent heat exchanger or heat recovery device is garbage dried. When it is used for the purpose, it is supplied to a fluidized bed gasifier or a heat recovery device after the waste is dried.
In addition, the burden of purifying the fluid after drying strongly odorous waste when it is discharged into the atmosphere is reduced, and at the same time, even if this waste drying fluid leaks, it is the system of the gasification and melting apparatus of the present invention. Therefore, trouble does not occur in post-processing.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a schematic flow of the gasification melting system of the present embodiment. The outline of this flow will be described.
Municipal waste and / or various types of waste (hereinafter sometimes referred to as garbage) input from the pretreatment facility 1 to the fluidized bed gasifier 2 are burned and separated into solid content and pyrolysis gas. After separating the solid content such as char accompanying the pyrolysis gas from the pyrolysis gas with a separator such as a cyclone separator 25, the pyrolysis gas is burned in the combustion furnace 45 in front of the independent superheater 26, which is a feature of the present invention. Is recovered by the independent superheater 26 as superheated steam. On the other hand, the ash and char in the solid content obtained in the fluidized bed gasification furnace 2 are sent to the melting furnace 4 through the separation equipment 3, and at the same time, the heat from the fluidized bed gasification furnace 2 is sent to the melting furnace 4. Solids such as char accompanied by cracked gas and the pyrolyzed gas are also supplied, and the ash in the solids obtained from the waste is melted. The hot gas obtained in the melting furnace is used for fluid heat exchange in the secondary combustion furnace 5 by the superheater 6, the evaporator 7, the air preheater 8 and the economizer 9, and then purified by the exhaust gas treatment device 10. It is processed and discharged from the chimney 31 into the atmosphere.
[0025]
In FIG. 1, the crushed garbage 11 is charged into the fluidized bed gasification furnace 2 from the charging unit 12 from the pretreatment facility 1 having a drying function and the like through the quantitative feeder 32. Under the condition that the air-fuel ratio is about 0.3 in the fluidized bed gasification furnace 2, the crushed garbage 11 is pyrolyzed by the fluidizing fluid 13, and the pyrolysis gas and char are fed from the top of the fluidized bed gasification furnace 2. It is taken out as pyrolysis gas 15. The pyrolysis gas 15 that does not contain char varies depending on the composition of the garbage, but the following components and their content (wt%) are shown as an example when the slaked lime described later is not added to the gasification furnace 2. The calorific value was 1,066 kcal / kg.
CO 12.4; CH_Four  8.4; N₂    22.7;
H₂O 50.2; CO₂  6.2; Cl₂  200ppm
[0026]
In addition, combustion residues (also referred to as furnace bottom residues) such as metal, incombustibles, and char are discharged from the bottom of the gasification furnace 2 by the incombustibles / char extraction device 33, and the recyclables 14 such as metals are collected by the separation equipment 3. And ash / char mixture 16.
The pyrolysis gas 15 generated in the fluidized bed gasification furnace 2 is sent to a cyclone separator 25, where the gas component composed of the pyrolysis gas 15 and the solid component composed of ash and char accompanied by the pyrolysis gas 15 are converted. To be separated. The gas component separated by the cyclone separator 25 is combusted in a combustion furnace 45 provided in the preceding stage of the independent superheater 26. In the combustion furnace 45, only pyrolytic gas and char having high combustibility are burned, so that a high-temperature gas of about 1100 to 1200 ° C. is obtained. However, if necessary at the time of starting the gasification melting system, the auxiliary fuel 17 using kerosene, propane gas or the like may be added and burned. And this combustion heat is supplied in the superheater 26, is utilized for superheating of about 250-300 degreeC steam in the superheater 26, and about 500 degreeC superheated steam can be obtained. This steam is used in a steam turbine (not shown).
[0027]
A part of the combustion gas 23 of about 400 to 450 ° C. used in the independent superheater 26 is used as the recirculation gas 19, and merges with the high-temperature air 24 supplied to the gasifier 2 to mix the fluidized medium and the waste. Fluidizing fluid 13. The recirculation gas 19 used as the gas recirculated to the fluidized bed gasification furnace 2 needs to be pressurized to a pressure higher than that required for the fluidizing fluid 13, but the recirculation gas 19 is increased by the recirculation pump 35. Is done. As described above, the recirculation gas 19 needs to be pressurized to a pressure higher than that required for the fluidizing fluid 13 used in the gasification furnace 2, but the pyrolysis gas 15 may be increased instead of the recirculation gas 19. .
[0028]
The char separated from the pyrolysis gas 15 by the cyclone separator 25 is temporarily stored in the char service hopper 34. Further, from the furnace bottom of the gasification furnace 2, non-combustible material and char are extracted by an extraction device 33 such as a screw conveyor through a flow path formed of a water cooling jacket, and then, for example, about 250 consisting of a multistage sieve. The non-combustible material and char cooled to 0 ° C. are separated into the recyclable material 14 such as metal or metal product and the mixture 16 of ash and char by the separation equipment 3, for example, according to the particle size or specific gravity difference. The mixture 16 of ash and char is also supplied to the char service hopper 34. The combustion residue of the combustion furnace 45 is also supplied from the furnace bottom of the independent superheater 26. When a fluid medium (sand, etc.) is contained in the mixture 16 of ash and char, the mixture may be appropriately separated and returned to the gasification furnace 2. In addition, conveyance of these solid content is performed by the air current conveyance by inert gas etc.
[0029]
A mixture 16 of ash and char is sent from the char service hopper 34 to the melting furnace 4. In the melting furnace 4, ash is melted at about 1400 to 1500 ° C. by the char supplied from the char service hopper 34 and, if necessary, the combustion heat of the auxiliary fuel 17. A part of the gas component separated by the cyclone separator 25 is also supplied to the melting furnace 4 and becomes a heat source for melting ash. The molten slag 18 from the melting furnace 4 flows down to a water-cooled water tank 21 and is recovered as a granulated slag 40.
[0030]
The hot gas of about 1400 to 1500 ° C. obtained by melting the ash in the melting furnace 4 is cooled to about 1100 ° C. by the water cooling wall of the secondary combustion furnace 5, and the superheater 6, the evaporator 7, the air preheater 8 and Used for heating the economizer 9. Further, by setting the air-fuel ratio in the secondary combustion furnace 5 to about 1.3, gas components including the gas from the melting furnace 4 are completely combusted in the secondary combustion furnace 5.
[0031]
The air preheater 8 is supplied with air at normal temperature from the air blower 28, and the air at about 300 to 400 ° C. preheated by the air preheater 8 is used as pyrolysis gas, char and auxiliary fuel 17 in the independent superheater 26. Some are used as combustion air and others are sent to the diffuser tube 22 of the fluidized bed gasification furnace 2. Further, since the ash in the scattered gas is collected at the bottom of the secondary combustion furnace 5 on the most downstream side, the collected fly ash is melted by the blower or the compressed carrier air by the compressor 38 in the melting furnace 4. To be melted again.
[0032]
Further, when a desalting agent such as slaked lime is put into the ash and char mixture 16 or the melting furnace 4, the chlorine content contained in the ash or the like is removed.
The gas discharged from the secondary combustion furnace 5 is sent to the exhaust gas treatment facility 10. Although not shown in the exhaust gas treatment facility 10, a cooling tower, a back filter, a denitration catalyst tower, an activated carbon tower, and the like are arranged, so that the exhaust gas treatment facility 10 flows about 200 ° C. into the exhaust gas treatment facility 10. The gas is cooled to about 150 ° C. to increase the dust collection efficiency of the bag filter, and then denitration is performed. In addition, although the dioxin produced by the chlorine component is almost completely suppressed in the melting furnace 4 and the secondary combustion furnace 5 in a high-temperature atmosphere, the dioxin is generated between the furnace outlet and the gas processing facility 10. Dioxins to be re-synthesized are removed by a bag filter, and trace dioxins and heavy metal components are removed by a denitration catalyst tower and an activated carbon tower.
[0033]
Combustion fly ash is discharged from the exhaust gas treatment facility 10 to the chemical treatment device 36, and the chemical treatment device 36 prevents the elution of heavy metals by chelate immobilization treatment. Further, the purified gas component discharged from the exhaust gas treatment facility 10 is sent to the chimney 31 by the induction fan 30 and discharged into the atmosphere.
Although the combustion fly ash 20 collected in the exhaust gas treatment facility 10 is to be used for landfill after being treated with the chemical treatment tank 36 in FIG. 1, it may be returned to the melting furnace 4. . Further, a channel opening / closing valve 44 is provided in each fluid channel in FIG. FIG. 1 shows an example of a melting furnace 4 that melts ash by burning char or the like, but instead of the melting furnace 4, other combustion furnaces, hot air furnaces, or heating furnaces may be arranged individually. .
[0034]
  In the present invention, a desalinating agent such as slaked lime is added from an empty portion in the fluidized bed gasification furnace 2, and the chlorine component contained in the waste is chlorinated as shown in the following formula (1). Can be immobilized as calcium.
    Ca (OH)₂+2HCl → CaCl₂+ 2H₂O (1)
  Since this reaction proceeds at an optimum temperature of 500 to 700 ° C., the temperature of the fluidized bed gasification furnace 3 is adjusted so as to be in this temperature region. This temperature adjustment is performed by controlling the amount of preheated air 24 supplied from the diffuser tube 22 and the amount of recirculated gas 19 mixed with the preheated air 24.
[0035]
As described above, since the chlorine concentration in the composition of the pyrolysis gas is about 200 ppm, about 3 to 5 moles of desalting agent such as slaked lime is added to the hydrogen chloride generated from this chlorine component in the fluidized bed gasifier. Add in 2. Here, instead of the slaked lime, other desalting agents such as quick lime, magnesium hydroxide, caustic soda and potassium may be used.
[0036]
Further, the pyrolysis gas 15 and the scattered char generated in the fluidized bed gasification furnace 2 are supplied to the cyclone separator 25 from the top of the gasification furnace 2. The reaction of the above formula (1) is performed from the fluidized bed gasification furnace 2. The process proceeds even while reaching the cyclone separator 25. Since the pyrolysis gas 15 contains an alkali component (calcium, sodium, potassium, etc.), the desalting reaction proceeds not only with the calcium component from the slaked lime added as the desalting agent but also with the alkali component. In particular, since the pyrolysis gas 15 is agitated in the cyclone separator 25, the contact efficiency between the alkali component entrained in the pyrolysis gas 15 and the chlorine component generated from the dust is good, and the reaction of the above formula (1) and this The reaction of an alkali component and a chlorine component similar to is effectively performed. According to the measured value, the hydrogen chloride concentration in the cyclone separator 25 inlet gas was 200 ppm, but the concentration in the cyclone separator 25 outlet gas was reduced to 50 ppm.
[0037]
Moreover, since the pyrolysis gas 15 and the ash / char mixture 16 are separated by the cyclone separator 25, the chlorine content is easily fixed to the ash / char mixture 16, so that the pyrolysis gas 15 supplied to the independent superheater 26 is contained in the pyrolysis gas 15. Since the chlorine content of the is further reduced, high temperature corrosion prevention of the independent superheater 26 is effective. A desalting agent such as slaked lime may be added to the cyclone separator 25.
[0038]
When the hydrogen chloride concentration in the pyrolysis gas 15 is about 50 ppm, the corrosiveness of the gas 15 hardly poses a problem. Accordingly, the pyrolysis gas 15 is used as a fuel source and burned in a combustion furnace 45 provided in the preceding stage of the independent superheater 26 to generate a hot gas of about 1100 to 1200 ° C., and a heat transfer tube (not shown) of the independent superheater 26 is shown. However, since there is almost no chlorine component, the heat transfer tube of the independent superheater 26 is not corroded.
[0039]
When combustible materials contained in conventional garbage are burned, the concentration of hydrogen chloride in the resulting combustion gas increases. High-temperature gas with high hydrogen chloride concentration is highly corrosive, so even if it is used for heating a superheater, only superheated steam at 400 ° C. can be obtained at most, so that steam that is sufficiently superheated for a steam turbine is supplied. I couldn't.
However, according to the present invention, it is possible to obtain a hot gas free from high temperature corrosion by the above-described desalting treatment using the fluidized bed gasification furnace 2 and the cyclone separator 25. Further, the high-temperature superheated steam at about 500 ° C. can be obtained from the independent superheater 26 immediately after the cyclone separator 25 by burning in the combustion furnace 45 using the high-temperature hot gas thus obtained.
[0040]
Further, the hot gas 23 at about 450 ° C. after the superheated steam is heated by the independent superheater 26 passes through the recirculation gas passage provided with the recirculation pump 35, and is supplied to the fluidized bed gasifier 2 as the recirculation gas 19. It is supplied to the air diffuser 22 and used as the fluidizing fluid 13.
Thus, the fluidized fluid 13 in the fluidized bed gasifier 2 is generally recirculated at a high temperature (about 350 to 400 ° C.) air 24 heated at the air preheater 8 or at an appropriate temperature range (about 450 ° C. or less). The gas 19 is recycled and used alone or in combination.
[0041]
Further, as shown in FIG. 4 as the independent superheater 26, the steam temperature in the steam pipe 51 at the outlet of the independent superheater 26 is detected by the thermometer 52a and the steam flow rate by the flow meter 52b, and the temperature is set to a predetermined temperature. The controller 56 reduces the temperature supplied to the pyrolysis gas 15 and the connection of the heat transfer pipe 52 of the independent superheater 26 so that the amount of steam is constant regardless of the nature of the waste and the amount of supply. The on-off valves 57 and 58 adjust the supply amount of the cooling water 55 to the vessel 53. In this way, the amount of superheated steam obtained in the independent superheater 26 can be stabilized, and drive control of a steam turbine (not shown) is facilitated. Moreover, in this invention, it replaces with the independent superheater 26 shown in FIG. 1, and facilities for fluid heating, such as an air preheater and a water heater, can be installed.
[0042]
The pretreatment device 1 is a great-type drying device, and a detailed view thereof is shown in FIG. FIG. 5A is a longitudinal cross-sectional view of the pretreatment device 1, and FIG. 2B is a diagram showing the state of dust accumulation as viewed from the direction of line AA in FIG. A casing 1c having a waste inlet 1a provided at one end of the ceiling of the pretreatment device 1 and a heat insulating material provided with a waste outlet 1b at the lower end of the side wall at the other end, and a movable grate 61 at the bottom of the casing 1c, A plurality of the fixed greats 62 are alternately arranged in parallel so as to partially overlap each other. The movable grate 61 is fixed to a movable frame 63 extending from the dust input port 1a to the discharge port 1b over the entire bottom surface of the casing 1c, and the fixed grate 62 is supported and fixed to the casing 1c at a location not shown. On the support shaft 64, the movable frame 63 reciprocates in the direction of the arrow by an extendable arm 67 driven and controlled by the hydraulic cylinder 66.
[0043]
Therefore, as shown in FIG. 5 (a), the waste introduced from the waste inlet 1a accumulates in a mountain shape having a vertex on the inlet 1a side, but moves toward the waste outlet 1b by the movable grate 61. Then, the heights of the mountain-shaped accumulated garbage are averaged in the casing 1c, and are sequentially discharged from the discharge port 1b evenly. Therefore, there is an effect that it becomes easy to quantitatively supply the garbage to the gasification furnace 2 by the quantitative feeder 32 at the next stage.
[0044]
In FIG. 5 (b), the portion where the dust does not diffuse sufficiently is the blind grade (having no holes) in the lower grade in the vicinity of the dust inlet so that the air flow can be blocked.
Below the movable frame 63, two chambers 69 and 70 are formed by a partition wall 68, and a waste drying fluid is introduced from the chamber 69 on the dust discharge port 1b side. Since the drying fluid is ejected from a large number of holes provided in the movable grate 61 or the fixed grate 62 toward the dust, the dust is dried. As the waste drying fluid, hot air may be newly introduced. Any one of the gasification and melting systems, for example, the fluidized bed gasification furnace 2, the melting furnace 4, the secondary combustion furnace 5, or the air. A hot gas or preheated air obtained from the preheater 8 or the like may be introduced. By this pretreatment device 1, for example, waste having a water content of about 50% by weight (combustible content 40% by weight, ash content 10% by weight) is dried to become a waste having a water content of about 30% by weight.
[0045]
The waste-dried fluid discharged from the pretreatment device 1 is one of the devices of the present gasification melting system, for example, the fluidized bed gasification furnace 2, the melting furnace 4, the secondary combustion furnace 5, or the pyrolysis gas combustion furnace 45. This reduces the amount of waste discharged outside the system of this system, reduces the burden of purifying the odor-rich waste-dried fluid for air discharge, and at the same time, waste-drying fluid. Even if it leaks to the fixed-quantity feeder 32 side, since it is in the system of this system, trouble does not arise in post-processing.
Since the waste-dried fluid has a high water content, it is quickly cooled after being discharged from the pretreatment device 1 and circulated and supplied to each device at a temperature lower than the dew point of the corrosive component contained in the fluid. Things are desirable.
[0046]
In addition, when waste that is non-uniform in quantity and whose water content varies greatly is introduced into the gasifier, for example, when waste with a moisture content of about 50% is put into the gasifier 2 at once. Although the combustion of waste cannot be sustained without the auxiliary fuel, in the present invention, by using a great drying device as the pretreatment device 1, the height of the dust accumulated in a mountain shape is movable grade 61 and fixed grade. 62 is averaged over and discharged from the outlet 1b evenly and dried at the same time, so that the quantitative supply of the waste to the gasification furnace 2 by the quantitative supply machine 32 is facilitated and the moisture content is uniform. Since the converted waste is introduced evenly, there is an advantage that it is not necessary to use auxiliary fuel for the combustion of waste in the fluidized bed in the gasifier.
[0047]
In addition, there is a pretreatment device that uses a rotary kiln to dry waste, but the plastic inside the waste tends to adhere to the inside of the kiln and the kiln accessories. When the working air is introduced, a part of the dust adhering to the inside of the kiln burns and partial gasification occurs, so that the calorific value of the pyrolysis gas obtained in the gasification furnace is reduced. The above-mentioned great pretreatment device 1 does not have such a problem.
[0048]
In the gasification and melting system shown in FIG. 1, the combustible pyrolysis gas 15 generated in the fluidized bed gasification furnace 2 is used by the combustion furnace 45 and possibly the auxiliary fuel 17 before being introduced into the independent superheater 26. And burn completely. A part of the combustion gas 23 used for heat recovery in the independent superheater 26 is recirculated as a fluidizing fluid in the fluidized bed gasification furnace 2. Therefore, the fluidized bed gasification furnace 2 is completely separated from the operation of the melting furnace 4 and the secondary combustion unit 5 which is the exhaust heat recovery device disposed downstream of the fluidized bed gasification furnace 2. It is possible to start or continue operation.
[0049]
For example, components of the melting furnace 4 at a high temperature of about 1400 to 1500 ° C. often need to be replaced, or the melting furnace 4 is shut down for the purpose of removing clinker deposited on the inner wall of the melting furnace 4. However, even when the operation of the melting furnace 4 and the secondary combustion section 5 that is an exhaust heat recovery device is stopped due to failure repair or repair work, the melting furnace 4 and the secondary The fluidized bed gasification furnace 2 and the independent superheater 26 can be operated separately from the operation of the combustion unit 5 or the exhaust gas purification equipment 10.
[0050]
At this time, the pyrolysis gas 15 from the fluidized bed gasification furnace 2 is not only recirculated to the fluidized bed gasification furnace 2, but also introduced into the vicinity of the superheater 6 of the secondary combustion furnace 5 that is stopped or exhaust gas. It can be introduced into the processing facility 10. Further, the combustion gas 37 in the independent superheater 26 before heat exchange is introduced into the upstream area of the superheater 6 of the secondary combustion furnace 5 by the blower 35, and for example, between the superheater 6, the steam drum 43, and the independent superheater 26. It can be used to heat boiler water and steam that are circulating.
[0051]
The char component obtained by separation with the cyclone separator 25 or the ash / char mixture 16 obtained from the bottom of the fluidized bed gasification furnace 2 is stored in the char service hopper 34, and the melting furnace 4 starts operation again. You can use this when you do.
Similarly, when the fluidized bed gasification furnace 2 and the independent superheater 26 side break down or when inspection / repair is performed, the melting furnace 4 and the secondary combustion furnace 5 side can be operated independently.
[0052]
Moreover, when starting or restarting this refuse gasification melting system, the fluidized bed gasification furnace 2 is first started. Since pyrolysis gas 15 is not generated at the initial stage of startup, combustion gas 23 is generated by burning auxiliary fuel 17 of independent superheater 26 and used as fluidizing fluid 13. When the pyrolysis gas 15 is generated, the amount of the auxiliary fuel 17 is decreased to adjust the combustion gas 23 so that the air-fuel ratio is suitable for fluidized bed gasification. However, if the calorific value of the crushed waste 11 is high, the amount of heat of the pyrolysis gas 15 is also high, and the auxiliary fuel 17 may be unnecessary because the pyrolysis gas 15 burns by itself.
[0053]
In this way, when starting up the entire refuse gasification and melting system, when the pyrolysis gas 15 is a small amount or at a low temperature, the amount of combustion of the auxiliary fuel 17 in the independent superheater 26 is adjusted to adjust the fluidizing fluid 13 to a predetermined condition. Therefore, the fluidized bed gasification furnace 2 can be started quickly.
This makes it possible to easily and quickly generate and operate the fluidized fluid 13 necessary for starting up the fluidized bed gasifier 2, and thus the fluidized bed gasifier 2 and the entire gasification and melting system. Can be quickly started or restarted.
[0054]
Another embodiment of the present invention is shown in FIGS. FIG. 2 shows an example in which the cyclone separator 25 for separating the char in the pyrolysis gas 15 shown in FIG. 1 is not installed. Since other configurations are the same as those shown in FIG. 1, their descriptions are omitted.
In the example shown in FIG. 3, an independent air preheater 29 is installed instead of the independent superheater 26, and a gas cooling tower 27 provided with the air preheater 8 is provided on the downstream side of the gas flow in the secondary combustion furnace 5. This is an example of arrangement. The installation position of the air preheater 8 may be on the downstream side of the gas flow in the gas cooling tower 27. Further, a spray nozzle 42 for spray water 41 is provided on the downstream side of the gas flow of the air preheater 8 in the gas cooling tower 27. The other configuration shown in FIG. 3 is the same as that shown in FIG. Moreover, you may install the cyclone separator 25 for isolate | separating the char in the pyrolysis gas 15 shown in FIG. 2 in the tower | column top exit of the gasification furnace 2 of the example shown in FIG.
[0055]
  In the example shown in FIG. 3, the gas cooling / melting system is started or the gas cooling tower on the melting furnace 4 and the downstream side thereof.27 sideWhen the operation is stopped, the air supplied from the air blower 28 is supplied to the independent air preheater 29 directly from the bypass passage 47 bypassing the air preheater 8.
[0056]
As in the system shown in FIG. 3, even when the water injection type gas cooling tower 27 is installed without installing the secondary combustion furnace 5 shown in FIG. The gas circulation system on the gasification furnace 2 side or the gas treatment system on the melting furnace 4 side can be operated independently, and each system can be operated independently during maintenance or failure, or the fluidized bed gasification furnace 2 and the gas. There is an effect that the chemical melting system can be started or restarted quickly.
[0057]
Further, the example shown in FIG. 2 in which the cyclone separator 25 provided in the system shown in FIG. 1 is not provided is shown in FIG. 2, but the example shown in FIG. 3 and other independent superheaters 26 in FIG. In addition, the cyclone separator 25 may or may not be installed when a fluid heating facility such as an air preheater or a water heater is provided.
[0058]
【The invention's effect】
According to the present invention, the fluidized bed gasification furnace section can be operated independently in a state separated from the melting furnace and the heat recovery device. It is possible to continue operation (warm-up operation) independently even when stopping at. In addition, the fluidized bed furnace can be quickly started up to a steady state, and there is an effect that the entire gasification and melting apparatus can be started and restarted quickly.
[0059]
  Furthermore, fluidized bed gasifierClean from less chlorineClean gasIndependent heat exchangerBy using it in a circulating manner, it does not adversely affect operation, including fluidized bed gasifiers.Hydrogen chloride and heavy metalsConcentration and accumulation of components are eliminated, and system maintenance and maintenance are effective. In particular, clean pyrolysis gas with less hydrogen chloride, which causes high-temperature corrosion of superheaters, is supplied to independent heat exchangers such as independent superheaters. This makes it possible to collect high-temperature and high-pressure steam in an independent superheater, and stabilize the amount of high-temperature superheated steam in the independent superheater by controlling the combustion of the pyrolysis gas in the previous stage of the independent superheater. Therefore, highly efficient power generation can be achieved.
[Brief description of the drawings]
FIG. 1 is a flow diagram of a fluidized bed gasification melting system according to an embodiment of the present invention.
FIG. 2 is a flow diagram of a fluidized bed gasification melting system according to an embodiment of the present invention.
FIG. 3 is a flow diagram of a fluidized bed gasification melting system according to an embodiment of the present invention.
FIG. 4 is a diagram showing an independent superheater according to an embodiment of the present invention.
FIG. 5 is a diagram of a pretreatment device according to an embodiment of the present invention.
[Explanation of symbols]
1 Pretreatment equipment 2 Fluidized bed gasifier
3 Sorting equipment 4 Melting furnace
5 Secondary combustion furnace 6 Superheater
7 Evaporator 8 Air preheater
9 economizer 10 exhaust gas treatment equipment
25 Cyclone separator 26 Independent superheater
27 Gas cooling tower 29 Independent air preheater
33 Incombustible / Char Extractor 34 Char Service Hopper
45 Combustion furnace

Claims (10)

Combustibles and fluidized-bed gasification furnace system integrated with a fluidized-bed gasification furnace for pyrolysis gasification in a fluidized medium, the combustible material to the pyrolysis gas obtained in a fluidized bed gasifier comprising solid Purification of the exhaust gas discharged from at least one of the above-mentioned apparatus and a heat recovery apparatus that recovers heat using a melting gas, a fluidized bed gasification furnace and / or a hot gas obtained in the melting furnace In a fluidized bed gasification and melting device consisting of a solid content and gas processing system equipped with an exhaust gas purification device for processing ,
The fluidized bed gasifier system integration and pyrolysis gas combustion furnace for combusting the pyrolysis gas produced in the fluidized-bed gasification furnace, a separate heat exchanger for heat exchange with the combustion gas of the combustion furnace, the A gas circulation system including a recirculation gas flow path for sending combustion gas after heat exchange in an independent heat exchanger to a fluidized bed gasification furnace and making it a fluidized fluid,
The fluidized bed type gasification and melting apparatus, wherein the gas circulation system and the solid content / gas treatment system can be operated independently . Fluidized-bed gasification and melting apparatus according to claim 1, characterized in that a addition unit for adding a dechlorinating agent into the fluidized bed gasification furnace system integration.   The fluidized bed gasification and melting apparatus according to claim 1, wherein the independent heat exchanger is a steam superheater, an air preheater or a feed water heater.   A steam superheater is installed as an independent heat exchanger, steam temperature measuring means and steam flow rate measuring means are provided at the steam outlet of the steam superheater, and the superheater at the outlet of the steam superheater is based on the measured values of the two measuring means. 2. A fluidized bed gasification and melting apparatus according to claim 1, further comprising a control device for performing combustion control of the pyrolysis gas combustion furnace so that the steam temperature and the amount of superheated steam become predetermined values. Provided in the gas flow path between the flow fluidized bed gasification furnace and the pyrolysis gas combustion furnace, the char entrained in the pyrolysis gas produced in the flow fluidized bed gasification furnace and a separator for separating the pyrolysis gases The fluidized bed gasification and melting apparatus according to claim 1 , further comprising a char storage tank for storing the char separated by the separator . 6. The fluidized bed gasification and melting apparatus according to claim 5, wherein the gas circulation system is provided with a char conveyance path capable of supplying char from a char storage tank to a melting furnace . Heat recovery is performed on a heat recovery medium using pyrolysis gas obtained by pyrolysis gasification in a fluidized bed gasification furnace using a fluid medium as a heat source, and the combustible substance is obtained by pyrolysis gasification. In a fluidized bed type gasification melting method for melting the obtained solid content,
After the pyrolysis gas generated in the fluidized bed gasification furnace is combusted and heat exchange is performed from the combustion heat of the combustion gas to the heat recovery medium, the combustion gas after the heat exchange is used as the fluidized medium of the fluidized bed gasification furnace. and use are gas circulation system as a fluidizing fluid, said combustibles and by melting solid obtained by pyrolysis gasification, solid-gas process for heat recovery in heat recovery medium from the heat gas generated during the melting A fluidized bed type gasification and melting method, characterized in that a gas circulation system and a solid content / gas treatment system can be operated independently . After separating the char generated in the fluidized bed gasification furnace from the pyrolysis gas also generated in the fluidized bed gasification furnace, the separated char is temporarily stored, and the stored char is heated as a combustible material. fluidized-bed gasification and melting method according to claim 7, which comprises using a solid obtained by decomposing a gas as a heat source you melt. When a pyrolysis gasification of the combustible material in the fluidized bed gasification furnace or a char accompanying the pyrolysis gas generated in the fluidized bed gasification furnace is separated from the pyrolysis gas, a desalting agent is added, 9. The fluidized bed gasification melting method according to claim 8 , wherein a desalting reaction of the cracked gas is performed. When the pyrolysis gas generated in the fluidized bed gasification furnace is burned and heat is recovered from the combustion heat of the combustion gas to the heat recovery medium, superheated steam is used as the heat recovery medium, and the combustion heat of the combustion gas The fluidized-bed gasification and melting method according to claim 7 , wherein combustion control of the pyrolysis gas is performed so that the temperature and amount of steam to be superheated have a predetermined value.

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