JP2007009045A - Treatment system for gasifying waste and treatment method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment system for gasifying a waste, with which in gasifying especially an agglomerative waste without producing clinker, the waste is properly treated, energy is recovered in high efficiency and gasification cost is reduced and a treatment method. <P>SOLUTION: The treatment system for gasifying a waste comprises a gasification furnace 1 for heating and gasifying a waste containing ash having ≤900°C melting point at 550-700°C, high-temperature dust collecting equipment 2 for removing dust from gasified gas generated from the gasification furnace 1 at least at ≥350°C, and equipment for using heat of the gasified gas from which the dust is removed by the high-temperature dust collecting equipment 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a waste gasification processing system and a processing method thereof, and more particularly, a waste gasification processing system effective for waste processing including an agglomerated component that is difficult to gasify using a gasification furnace. It relates to the processing method.

  For example, as shown in FIG. 3, the treatment process for burning general waste and various industrial wastes is performed by putting various wastes into an incinerator 21, where the incineration process by sufficient combustion is performed, and then an exhaust gas treatment facility. At 22, the harmful components in the exhaust gas are processed and discharged from the chimney or the like.

  In this case, in order to properly incinerate, the generated incineration temperature is 900 ° C. or more and the residence time is 2 seconds or more so that dioxins are not discharged, and complete combustion with effective mixing and stirring of combustion gas is required. It has been.

  There are two types of wastes, one with a high melting point of ash after combustion and one with a low melting point, depending on the components contained. When the waste is combusted, the combustible substance becomes exhaust gas, and the incombustible substance remains as an incineration residue (ash). Among the remaining non-combustible residues, those having a melting point of 900 ° C. or less are likely to agglomerate and adhere to ducts or furnace walls during heating, so they are referred to as agglomerated components and agglomerated waste containing a large amount of these agglomerated components. It can be called sexual waste.

The main aggregating components are Na, K, and P, and others include S and Cl. When recovered as ash, these become inorganic substances such as NaCl, KCl, and K ₂ SO _4. .

  When such a cohesive waste is heat-treated at 900 ° C. or higher in the fluidized bed furnace 23, the coagulating component remaining as an incombustible component of the cohesive waste is melted, as shown in FIG. Adhering to a furnace wall or the like to produce a clinker 24, or as shown in FIG. 4 (b), the fluidizing media 25 are adhered to each other to stop fluidization, and the fluidized air passage 26 to be fed is supplied. Therefore, various adverse effects such as causing a situation where the fluidized bed furnace 23 has to be stopped are brought about.

As a method for treating such cohesive waste containing a large amount of cohesive components, the waste is gasified in a heating furnace, and the generated gasified gas is once cooled below the melting point of the salts (the above inorganic substances) and removed by a dust removing device. At the same time, a method has been proposed in which gasified gas is supplied to a combustion furnace for processing (Patent Document 1).
JP-A-2005-55030

  However, in the above prior art, the gasified gas generated by gasification is once cooled and then heated again to a high temperature and burned, and the high amount of heat of the gasification gas cannot be effectively used, and it is energy-efficient. There is waste and it is never energy efficient.

  Therefore, in view of the above-mentioned problems of the prior art, the object of the present invention is to appropriately process without generating clinker, particularly when gasifying cohesive waste, and to efficiently save energy. It is an object of the present invention to provide a waste gasification processing system and a processing method that can be recovered and can reduce gasification processing costs.

  The above-mentioned subject is achieved by the invention described in each claim. That is, the characteristic configuration of the waste gasification processing system according to the present invention includes a gasification furnace that heats and gasifies waste having an ash content of 900 ° C. or less at 550 to 700 ° C., and the gasification furnace. A high-temperature dust collection facility that dusts the gasification gas generated from at least 350 ° C. or higher, and a facility that uses heat from the gasification gas removed by the high-temperature dust collection facility.

  According to this configuration, even if the waste contains an agglomerated component, heat treatment is performed at or below the agglomeration temperature, so that the agglomerate adheres to the furnace wall surface and generates clinker, or fluidization in a fluidized bed furnace. Stopping trouble does not occur, tar is also vaporized, so troubles in high-temperature dust collection equipment can be suppressed, and dust removal can be performed without wasting the heat of gasification gas. Energy can be recovered efficiently.

  As a result, especially when coagulating waste is gasified, waste gas that can be properly treated without generating clinker and that can recover energy efficiently and reduce gasification costs. We were able to provide an integrated processing system.

  The gasification furnace is a fluidized bed furnace or a circulating fluidized bed furnace, and preferably has a boiler structure.

  According to this configuration, since the fluidized bed furnace or the circulating fluidized bed furnace is excellent in mixing and stirring, the efficiency of gasification treatment is high and the boiler structure is used, so that steam generated from the boiler can be used.

  It is preferable that the gasification furnace has a facility for introducing water or steam.

  According to this configuration, the furnace temperature can be controlled within a predetermined range even with respect to the waste having fuel properties that are likely to vary greatly, and stable and reliable operation can be performed.

  It is preferable to have a tar decomposition facility for removing tar in the gasified gas removed by the high-temperature dust collection facility.

  According to this configuration, even if tar is contained in the gasified gas removed by the high-temperature dust collection equipment, the tar can be effectively removed, and troubles on the downstream equipment can be reliably prevented.

  In addition, the characteristic configuration of the waste gasification method according to the present invention is that the waste having a melting point of ash content of 900 ° C. or less is heated and gasified in a gasification furnace at 550 to 700 ° C., and the generated gasification is generated. The purpose is to remove the gas at a temperature of 350 ° C. or more with a high-temperature dust collecting facility and to use the dusted gasified gas as heat.

  According to this configuration, particularly when coagulating waste is gasified, it can be properly processed without generating a clinker, energy can be recovered with high efficiency, and gasification cost can be reduced. A waste gasification method can be provided.

  In the gasification furnace, waste is preferably gasified at an air ratio of 0.2 to 0.5.

According to this configuration,
In the gasification treatment in the gasification furnace, when there is a risk of raising the temperature to 700 ° C. or higher, it is preferable to cool by introducing water or steam.

  According to this configuration, stable and reliable operation can be performed.

  It is preferable to remove the tar in the gasification gas removed by the high-temperature dust collection facility in the tar decomposition facility.

  According to this structure, the tar in gasification gas can be removed effectively and the trouble with respect to the downstream installation can be prevented reliably.

Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic flow of the waste gasification processing system according to the first embodiment of the present invention, and FIG. 2 shows a schematic flow of the waste gasification processing system according to the second embodiment.
<First Embodiment>
The waste gasification system according to the first embodiment is a kind of gasification furnace, and uses a fluidized bed gasification furnace 1 with good mixing and stirring. In the fluidized bed gasification furnace 1, the gasification temperature is controlled to maintain a predetermined temperature that is higher than the ignition temperature of the waste and lower than the agglomeration temperature by operating and operating at an air ratio of 0.2 to 0.5. . Specifically, the temperature is about 550 to 700 ° C. If the air ratio is less than 0.2, the degree of combustion is low and the temperature does not easily rise, and if the air ratio exceeds 0.5, the combustion proceeds remarkably, and a high temperature field of 900 ° C. or higher may be locally formed. Yes, unburned carbon is less likely to occur. However, the fuel properties (content of water, constituent elements, and amount of heat) of the waste vary greatly and are likely to fluctuate. Therefore, it is difficult to maintain the predetermined temperature only by temperature control based on the supply amount of gasified air, and it rises more than necessary. For this reason, it is preferable to provide a facility (for example, water or steam injection device) capable of supplying water (or steam) in the fluidized bed gasification furnace and cool it when it rises too much. In particular, when a boiler structure is used as a fluidized bed gasification furnace, steam generated in the boiler can be used, so that no special equipment is required.

  When the gasification treatment is performed at a relatively low temperature as in this embodiment, the waste containing the agglomerated components is heat-treated at a temperature lower than the agglomeration temperature, so that the agglomerates adhere to the furnace wall surface or flow in the fluidized bed furnace. There will be no trouble of stoppage. However, since it is incomplete combustion, dioxins, CO, and the like are generated at this stage, but the dioxins are decomposed by combustion on the downstream side or high-temperature treatment in a gas utilization facility.

  The waste containing agglomerated components has a fluctuating fuel property (agglomerated component content such as Na and K), and the agglomeration temperature may vary depending on the season and time, etc. Since a large amount of unburned carbon is generated by the gasification treatment by No. 1, even if the operation is performed at a temperature higher than the agglomeration temperature, the unburned carbon adsorbs and takes in the agglomerated component, and as a result, a lump with the agglomerated component as a nucleus is formed. It can produce | generate and can prevent adhesion to a furnace wall surface.

  And, since the operation in the gasification furnace is operated at a theoretical air ratio of 0.2 to 0.5 as in this embodiment, the amount of air supplied to the gasification furnace may be small. Compared with an incinerator that treats the same amount of waste, the capacity of the forced air blower is small, and both the equipment cost and the power consumption during driving can be reduced. Not only that, but the capacity of the forced blower is small, so the amount of gas generated is smaller than the combustion method (about 1/2), and the capacity and installation area for handling gasified gas can be reduced accordingly. The occupied area can be reduced. In addition, the operation of the gasification furnace at a low temperature causes less equipment wear and maintenance costs compared to the high temperature furnace.

  The high-temperature gasification gas generated in the fluidized bed gasification furnace 1 is supplied to the high-temperature dust collection facility 2 while maintaining its heat quantity, and is removed. A large number of ceramic filters are densely arranged in the high-temperature dust collection facility 2, and ash and unburned carbon in the gasification gas are efficiently removed. Among these, unburned carbon acts as an adsorbent, so it adsorbs various gaseous molten substances and functions to prevent clogging of the ceramic filter. Even if it adheres, it easily falls off by washing (washing appropriately with a backwash device). In this case, since dioxins are in a gaseous state, dioxins are not contained in the ash from which dust has been removed.

  In this way, dust is collected by the high-temperature dust collection equipment 2, so (1) there is no loss of energy (sensible heat) of the gasification gas, and (2) it is partially molten or gaseous When molten material is filtered, it is adsorbed by unburned carbon, so it is possible to reliably capture ash containing agglomerated components and volatile alkali metals. (3) Due to high temperature, tar is vaporized. There is an advantage that the ceramic filter is not clogged.

  If the gas temperature is lowered with a boiler or the like at the gasification furnace outlet and introduced into the high-temperature dust collection facility 2, tar content or dust adheres to the heat transfer tube surface of the boiler and the heat transfer efficiency is lowered. In order to gasify and transfer tar and dust adhesion characteristics and dioxins in gaseous form even when the temperature is unavoidably reduced, the gas temperature introduced into the high-temperature dust collection facility 2 is 350 ° C. or more, more preferably Set to 500 ° C. or higher. For dust removal at high temperatures, as described above, if a ceramic filter is used, dust removal efficiency is high, and the application range when using gas on the downstream side is wide, but a cyclone may be used instead of the ceramic filter.

The gasified gas (including flammable gas such as CO, CO ₂ , and H ₂ and tar) discharged from the high-temperature dust collection equipment 2 and introduced into the boiler 3 at a high temperature is completely burned and heated. Collected. In the case of a gas fuel-fired boiler, since the combustibility is good, operation at a low air ratio becomes possible. That is, the air ratio here may be about 1.1.

The steam generated in the boiler is used as it is for various types of heat or for power generation by a steam turbine. Since such a gasification gas is a combustible gas, the following utilization methods can be considered.
(1) When only waste is treated, combustible gas is treated at high temperature and gasified gas is made harmless.
(2) Gasified gas is burned in a boiler and used as thermal energy. The obtained steam is used for various uses as a heat source and also used for power generation in a steam turbine.
(3) Directly drive a gas engine or gas turbine with gasified gas for power generation. Steam turbine power generation enables highly efficient power generation.
(4) The gasification gas is converted to a fuel with higher added value than liquid fuel by using a catalyst.

  On the other hand, the gas burned in the boiler 3 contains NOx, SOx, HCl, etc. depending on the fuel type, and therefore is detoxified by the appropriate wet or dry exhaust gas treatment equipment 4 that is usually employed, and from the chimney 5 or the like. Released.

As described above, according to the present embodiment, the gasification treatment of cohesive waste, which has been difficult to process with the prior art, can produce clinker as much as possible not only in the gasification furnace but also in piping and incidental facilities. It is possible to prevent and reduce energy loss and to recover energy with high efficiency.
Second Embodiment
The waste gasification processing system according to this embodiment uses a circulating fluidized bed gasification furnace 11 instead of the fluidized bed gasification furnace used in the first embodiment. In the circulating fluidized bed gasification furnace 11, since the fluidized medium circulates in the furnace, the mixing and stirring is better than the fluidized bed gasification furnace, and the temperature in the furnace is easily controlled. The circulating fluidized bed gasification furnace 11 is also operated under the same operating conditions as the fluidized bed gasification furnace of the first embodiment. That is, the air ratio is operated / operated at 0.2 to 0.5, and the gasification temperature is heated at a predetermined temperature not lower than the ignition temperature of the waste and not higher than the aggregation temperature, for example, about 550 to 700 ° C.

  Since the variation in the fuel property of the waste is likely to fluctuate greatly, it is preferable that the circulating fluidized bed gasification furnace 11 is also provided with equipment capable of supplying water (or steam) into the furnace.

  The gasification gas produced | generated by the circulating fluidized bed gasification furnace 11 is sent to the high temperature dust collection equipment 2 provided with the ceramic filter similarly to the case of 1st Embodiment, and the calorie | heat amount of produced | generated gas is hold | maintained. Ashes in the gasification gas are removed. Since this gasification gas contains a small amount of tar, the gasification gas removed from the high-temperature dust collection facility 2 passes through the tar decomposition facility 6. The tar decomposition facility 6 includes a high-temperature catalyst (for example, a Ni-based catalyst) that decomposes the tar content. Here, in order to ensure the temperature required for the catalytic reaction, air is supplied to the tar decomposition facility 6 and a part of the gas is burned to form a high temperature reaction field. If it does in this way, it can be made not to contain dust and tar in gasification gas.

Thereafter, the temperature of the gasified gas is lowered to some extent and introduced into the boiler 3 where the heat is further recovered and the temperature is lowered. The gasified gas that has been heat-exchanged by the boiler and reduced in temperature to about 250 ° C. or less is fed to the low temperature gas cleaning equipment 7 to remove harmful acidic components and alkaline components in the gasified gas. That is,
The low-temperature gas cleaning equipment 7 includes a bag filter, an electric dust collector, a cyclone, and the like, and dust is removed after a chemical such as slaked lime or baking soda is introduced.

  The gasified gas removed from the dust by the low temperature gas cleaning equipment 7 can be used for various purposes. For example, the gasified gas can be sent to a gas use equipment such as the power generation equipment 8 directly connected to the gas engine and effectively used for direct power generation and the like. In this case, an appropriate amount of air may be supplied.

  In this way, even waste containing agglomerated components that have been difficult to gasify with the prior art can be properly treated according to this embodiment, without generating clinker in the furnace, Moreover, energy can be recovered with high efficiency. Needless to say, it is possible to gasify a normal waste with high efficiency.

[Another embodiment]
(1) In the above embodiment, the example using a fluidized bed gasification furnace and a circulating fluidized bed furnace as the gasification furnace has been described. However, the gasification furnace is not limited to this, but a fixed bed. Various gasification furnaces such as a formula, a kiln type, and a spouted bed type can be used. Any gasification method can be used, such as dry distillation gasification with external heat (steaming method), partial combustion gasification method with air, oxygen, steam, etc., from fuel to CO, CO ₂ , CmHn, H ₂ , H ₂ O, etc. Any method that can obtain combustible gas may be used.
(2) Examples of gas utilization equipment applicable to the present invention include power generation equipment such as a gas engine and a gas turbine, and liquid fuel production equipment such as methanol production equipment.
(3) Examples of the fuel that can be applied to the present invention include various solid fuels and industrial wastes in addition to various organic wastes.

Schematic flowchart showing the waste gasification system according to the first embodiment of the present invention. Schematic flowchart showing a waste gasification system according to a second embodiment of the present invention Schematic flow diagram showing a waste treatment system according to the prior art The figure explaining the problem of the waste disposal system concerning a prior art

Explanation of symbols

1 Gasification furnace 2 High-temperature dust collection equipment 6 Tar decomposition equipment

Claims (8)

A gasification furnace that heats and gasifies waste having an ash melting point of 900 ° C. or less at 550 to 700 ° C., and high-temperature dust collection that removes gasification gas generated from the gasification furnace at least 350 ° C. or more A waste gasification processing system having equipment and equipment for heat-using gasified gas removed by the high-temperature dust collection equipment. The waste gasification processing system according to claim 1, wherein the gasification furnace is a fluidized bed furnace or a circulating fluidized bed furnace and has a boiler structure. The waste gasification processing system according to claim 1 or 2, wherein the gasification furnace has equipment for introducing water or steam. The waste gasification processing system according to any one of claims 1 to 3, further comprising a tar decomposition facility that removes tar in the gasification gas removed by the high-temperature dust collection facility. The waste having a melting point of ash content of 900 ° C. or less is gasified by heating at 550 to 700 ° C. in a gasification furnace, and the generated gasification gas is removed at least 350 ° C. or more with a high-temperature dust collecting facility. A waste gasification method using heat from dusted gasification gas. The waste gasification method according to claim 5, wherein the gasification furnace gasifies the waste at an air ratio of 0.2 to 0.5. The waste gasification method according to claim 6, wherein, in the gasification treatment in the gasification furnace, when there is a risk of raising the temperature to 700 ° C. or higher, water or steam is introduced to cool the waste gasification treatment method. The waste gasification method according to claim 6 or 7, wherein tar in the gasification gas removed by the high-temperature dust collection facility is removed by a tar decomposition facility.

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