JP4563129B2 - Gasification system - Google Patents

Description

  The present invention relates to a gasification system, and more particularly to a gasification system for organic waste.

  Generated when solid fuel or organic waste is gasified by heating and pyrolyzing or partially combusting, and the thermal energy of the generated gas is used for power generation or converted to fuel It is necessary to remove tar or ash contained in the gas.

  As the method, a method of melting ash at a high temperature and decomposing tar, a method of combining high-temperature dust collection by a ceramic filter and tar decomposition by a catalyst, and the like are conceivable.

Specifically, as shown in FIG. 3, in a method in which waste is gasified in a fluidized bed furnace 32 and then ash is melted into slag in a melting furnace, the fluidized bed furnace 32 has a circular horizontal section. A moving bed 39 in which the fluid medium settles in the center of the furnace and a fluidized bed 30 in which the fluid medium rises in the periphery of the furnace form a circulating flow circulating through the moving bed 39 and the fluidized bed 30; By supplying the waste to the fluidized bed furnace 32 and gasifying it to generate gas and char, supplying the gas and char discharged from the fluidized bed furnace 32 to the melting furnace to melt the ash and converting it into slag, It is a proposal that can generate a product gas containing a large amount of combustible matter that can be melted by ash by self-heat amount, and can perform melt combustion (for example, see Patent Document 1).
Japanese Patent No. 3270447

  However, in the case of melting ash and decomposing tar at a high temperature, there are some problems because oxygen or the like is blown and heated to 1300 ° C. or higher by self-heating. Specifically, (1) it is necessary to blow oxygen to raise the temperature, and an expensive oxygen production apparatus for supplying oxygen is required. (2) Since it melts in a reducing atmosphere at a high temperature of 1300 ° C. or higher, the equipment becomes complicated and expensive. (3) Operation and maintenance such as slag extraction is difficult. Etc. becomes a problem.

  In addition, when high-temperature dust collection using a filter and tar decomposition using a catalyst are combined, the filter passage speed becomes relatively low, so a device for treating a predetermined amount of combustible material must be large. In addition, when a fixed bed is used as the catalyst reaction means, there is a problem that the installation space becomes large.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a compact gasification system in a relatively simple and highly workable manner while gasifying combustibles such as waste at a relatively low temperature to increase energy efficiency. There is.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by the following system and method, and have completed the present invention.

The present invention is a gasification system comprising a means for introducing a combustible, a gasification means for heating and combusting the combustible, and a gasification means disposed downstream of the gasification means. A dust collecting means for removing the generated gas, and a tar decomposition means that is disposed downstream of the dust collecting means and is filled with a catalyst that decomposes tar in the generated gas delivered from the dust collecting means, The dust collecting means and the tar decomposition means are integrated, and a partition having a plurality of passages formed at a predetermined inclination angle is disposed on the upstream side and the downstream side of the tar decomposition means to form a catalyst packed bed, A space having a predetermined volume is provided between the dust collecting means and the tar decomposing means composed of a plurality of filter members, and after diffusing the gas supplied from the filter members, the tar is divided into the plurality of passages. Introduce to disassembly means It is characterized in.

  That is, the present invention achieves efficient gasification at a relatively low temperature by using a low temperature gasification means and a tar decomposition catalyst in a combustion object gasification system, and also provides a dust collection means and a tar decomposition means. By achieving integration, it is possible to realize a compact system and energy efficiency. Therefore, it is possible to provide a compact and high energy efficiency gasification system by a relatively simple and highly workable method. In particular, it is effective in a gasification system that can effectively generate or use combustion gas from combustibles such as solid fuel containing ash and organic waste.

  The present invention is the above gasification system, wherein a partition having one or a plurality of passages formed at a predetermined inclination angle is arranged on the upstream side and the downstream side of the tar decomposition means to form a catalyst packed bed. It is characterized by that.

  In the gasification of combustibles such as solid fuel containing ash and organic waste, a large amount of tar is generated, and contamination and poisoning of the catalyst in the tar decomposition means cannot be avoided. Or cyclical exchanges are necessary. In order to maintain high efficiency of the catalyst, it is necessary to bring the sample into contact with the packed catalyst evenly, and it is preferable to pass through the catalyst packed bed without load. It has been devised that it can respond to such a request by arranging a partition having one or a plurality of passages formed at a predetermined inclination angle on the upstream side and the downstream side of the tar decomposition means. Specifically, By providing a partition having a passage with an inclination angle greater than the repose angle of the catalyst at both ends, a packed bed that allows the sample to contact the catalyst evenly without arranging a special boundary member that generates a load such as a filter. Can be formed.

  The present invention is the gasification system described above, wherein a space having a predetermined volume is provided between the dust collecting means and the tar decomposing means composed of a plurality of filter members, and the gas supplied from each filter member After being diffused, it is divided into the plurality of passages and introduced into the tar decomposition means.

  Conventionally, granular catalysts have been used for various reactions because of their increased surface area and increased reactivity. However, when a relatively large amount of sample is processed, it is very difficult to contact the packed catalyst evenly. It is difficult. In order to integrate the dust collecting means and the tar decomposing means, the inventor increases the dust collecting effect by configuring the dust collecting means from a plurality of filter members, and at the same time, the samples divided substantially equally by this. By introducing it into the catalyst packed bed as it is, it has been devised that a relatively large amount of sample can be evenly contacted and processed with the catalyst without using special means, and a highly efficient function can be made compact. It became possible to configure.

  The present invention is the gasification system described above, characterized in that a circulation means for returning the catalyst extracted from the tar decomposition means to the tar decomposition means, and a catalyst regeneration means are provided in the flow path of the circulation means.

  As described above, in the gasification of combustibles, the tar decomposition catalyst needs to be periodically or cyclically exchanged, while preventing local contamination or poisoning of the catalyst, By discharging the tar decomposition catalyst at an early stage and recycling the catalyst, the amount of catalyst used can be reduced by efficient tar decomposition and catalyst reuse. In addition, when the above-mentioned circulation is used, the life of the catalyst can be further extended by performing regeneration constantly or periodically in order to prevent the activity of the catalyst from decreasing. Such a circulation / regeneration function is very effective for the present gasification system because it can be regenerated relatively easily under conditions of contact with the sample substantially evenly. Note that, by providing the catalyst regeneration means separately from the product gas processing flow path at a high temperature, even if a catalyst regeneration method such as oxidative combustion of deposits is used, the product gas is not affected.

  This invention is the said gasification system, Comprising: The gas temperature from the said gasification means to a tar decomposition | disassembly means is controlled to 700-900 degreeC, It is characterized by the above-mentioned.

In the gasification means, the inventor suppresses energy loss due to combustion by setting the treatment temperature to 900 ° C. or less, and further performs each step such as ash removal and tar decomposition in a limited temperature range, and at the final stage. It was decided to carry out the process with consistent and optimal temperature control including heat recovery. In other words, in order to efficiently gasify the combustibles, the tar content contained in the product gas is decomposed and converted to flammable gas into carbon monoxide (CO) or hydrogen (H ₂ ). On the other hand, if the gas containing tar has a low temperature part in the flow path, it causes local condensation and accumulation, so a temperature range of 700 to 800 ° C. is secured, and dust collection and tar decomposition are ensured. Need to do. In addition, an increase or decrease in temperature during such a process causes an increase in energy to be injected and a loss. The present invention takes such viewpoints into consideration, and an efficient gasification system can be obtained by the consistency of temperature control until heat recovery.

  In the present invention, the product gas obtained by gasifying the combustible is dedusted at a high temperature and subjected to tar decomposition treatment with a catalyst. Therefore, the method is relatively simple and highly workable, and is compact and highly energy efficient. A gasification system can be provided. Further, it is possible to prevent clogging due to generation of a film layer or condensation / solidification in the gas flow path due to tar in the subsequent stage. That is, according to the present invention, it is possible to provide a gasification system capable of producing a produced gas with high efficiency even in a solid fuel having a high ash content and effectively using the produced gas.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking wastes including organic wastes as an example of combustibles. The organic waste here refers to waste captured in a broad concept including wood chips, sludge, or agriculture.

  FIG. 1 illustrates a schematic overall structure of a gasification system according to this embodiment. Waste is gasified by the pulverizing means 1, the drying means 2, and the gasifying means 3, and the generated gas is purified by the dust collecting means 4, the tar decomposing means 5, the heat recovery means 6, and the purifying means 7 and then used as fuel gas. To supply. The object of the present invention is to integrate the dust collecting means 4 and the tar decomposing means 5 so as to make the system compact and to achieve highly accurate gasification.

  The waste is pulverized to a predetermined size by the pulverizing means 1, and the pulverized waste is dried by the drying means 2 so as to have a predetermined amount or less of moisture. The drying means 2 is not particularly limited, and various conventional drying apparatuses can be used. Various drying apparatuses such as those using direct heating, those using indirect heating, those using a heater, and those using steam are used. Applicable equipment.

The dried waste is put into a circulating fluidized bed gasification means 3 which is a kind of gasification means, and is heated and gasified by partial combustion. Gasification means, such as partial oxidation combustion gasification or pyrolysis gasification, are applied, and various types of furnaces are used in addition to bubbling fluidized bed and circulating fluidized bed furnaces. For this purpose, a circulating fluidized bed gasifier is suitable. The gasification means 3 is excellent in the mixing of the fluid medium, fuel, and gasifying agent in the furnace, and can make the inside of the furnace have a relatively uniform temperature distribution. The gasification means 3 operates at 700 to 900 ° C., and can add a gasifying agent to partially combust organic matter in the waste to generate a gas containing CO, H ₂ or hydrocarbon (HC). . The gasification temperature is more preferably 800 to 900 ° C.

  As the gasifying agent, air or water vapor is usually used, but high-concentration oxygen (for example, oxygen-enriched air) or water vapor can be used instead of air.

  The generated gas is introduced into the dust collecting means 4 and removed. In this case, the ash and unburned components in the product gas can be returned to the gasification means 3 again and circulated in the gasification means 3 to ensure a sufficient residence time, thereby improving the gasification efficiency. Will be contributed. Ash content is discharged out of the system from below the dust collecting means 4. It is possible to cool by the heat recovery means before introducing it into the dust collecting means 4, but considering the processing temperature in the tar decomposition means 5 to be integrated in the present invention, the temperature of the generated gas is It is preferable to introduce into the dust collecting means 4 in a maintained state.

  Examples of the dust collecting means 4 include a cyclone type and a filter type as a method suitable for use at a high temperature. In a waste gasification system, it is preferable to use a ceramic filter, and a pore size of about several tens of μm can be used to remove fly ash and solid carbon in the gas. By removing ash and the like at this stage, it is possible to prevent poisoning of the subsequent tar decomposition catalyst (deterioration of activity due to ash adhesion, etc.) and extend the life of the catalyst.

  In the present invention, the dust collecting means 4 is preferably a filter type dust collecting means composed of a plurality of filter members. Consisting of a plurality of filter members enhances the dust collection effect and at the same time introduces a sample that is divided approximately evenly into the catalyst packed bed as it is, so that a relatively large amount of sample can be obtained without using special means. The catalyst can be contacted and treated evenly.

  Moreover, it is preferable that the dust collecting means 4 is regularly backwashed by the backwashing means. Backwashing is a method of removing the matter adhering to the filtration surface of the filter by blowing a fluid from the opposite surface, and is particularly effective for fine particles such as dust. In general, a high-pressure gas such as compressed air or vaporized nitrogen is often used. Usually, an instantaneous physical load can be given to the deposit by blowing a gas of several tens to several thousand L / min at a stretch, and removal by detachment / dropping from the filter surface can be performed. It becomes possible to effectively prevent the increase in pressure loss in the filter by diffusing and washing the adhering matter and agglomerates such as the permanent cake adhering to the filter surface.

A tar decomposition means 5 is provided at the subsequent stage of the dust collection means 4, and the tar content in the product gas is decomposed and converted to CO, H ₂ or HC. By disassembling and removing the tar content that has passed through the high temperature dust collecting means 4, it is possible to prevent the formation of a film layer on the inner wall and local clogging due to the tar content in the subsequent purification means 7 and the like. The gasification efficiency can be improved by gasifying the gas. The cracking catalyst can be selected arbitrarily for the purpose of tar decomposition. For example, a Ni-based or alkaline earth-based catalyst having a high activity in the range of 700 to 900 ° C. should be used. Is possible.

  At this time, the tar decomposition means 5 can form a catalyst layer partitioned into a predetermined space, and can provide a catalyst supply means 5a at the upper part and a catalyst discharge means 5b at the lower part to connect them to form a circulation system. preferable. This is because the catalyst can be prevented from premature deterioration due to local contamination and poisoning by circulating the catalyst. Moreover, it is preferable to provide the catalyst regeneration means 5c between the catalyst supply means 5a and the catalyst discharge means 5b. The life of the catalyst can be further extended by regenerating the packed catalyst constantly or periodically in order to prevent the activity of the catalyst from decreasing.

  As described above, the present invention is characterized in that the dust collecting means 4 and the tar decomposition means 5 are integrated, and specifically, a configuration illustrated in FIG. At this time, it is operated in the following order to enable efficient dust removal and tar decomposition treatment. In addition, in this figure, although it is set as the refractory material structure, it can also be set as a boiler structure.

  (1) The produced gas is filtered through a plurality of, for example, horizontally disposed tubular ceramic filters 8 while dust mainly composed of ash is separated and dropped by its own weight while flowing from the upper part to the lower part of the dust collecting means 4. At this time, the product gas is distributed substantially evenly through each filter 8 by the pressure load of the filter 8.

  (2) The ash adhering to the filter 8 is removed by backwashing, and is discharged by the ash extraction means 4a together with the ash that has fallen by its own weight.

  (3) The generated gas removed by the filter 8 passes through the space 9 provided between the tar decomposition means 5 while diffusing in the horizontal direction. By setting the passing speed to 1 m / sec or less, it is possible to achieve uniform contact in the tar decomposition means 5, which is preferable. Moreover, it is preferable to provide the backwashing means 10 in the space 9 and periodically backwash the filter 8 as described above. Further, by providing each backwashing means 10 at the outlet of each filter 8 as shown in FIG. 2, diffusion mixing of the product gas is also possible.

  (4) Next, the product gas is introduced into the tar decomposition means 5 through the partition 11a. The tar decomposition means 5 is provided with a tar decomposition catalyst, and the tar content that has passed through the high temperature dust collection means 4 is decomposed and reformed into CO and HC.

  (5) The product gas obtained by treating the tar content is introduced into the heat recovery means 6 or the purification means 7 through the partition 11b and purified as a clean product gas.

  At this time, the partitions 11a and 11b are for the purpose of gas dispersion and separation from the catalyst layer, and it is possible to use a porous material such as ceramics or a metal porous material such as sintered metal. However, it is preferable to have a passage having an inclination angle greater than the repose angle of the catalyst. Specifically, the slit-like opening having an angle greater than the repose angle of the catalyst in the refractory material structure illustrated in FIG. The shape provided in multiple steps can be mentioned. It is possible to form a packed bed capable of bringing the sample into contact with the catalyst evenly without arranging a special boundary member that generates a load such as a filter.

  Here, the gas temperature from the gasification means 3 to the tar decomposition means 5 is preferably controlled to 700 to 900 ° C., more preferably 800 to 900 ° C. for the following reason.

  (1) In order to make each function of this process work effectively, it is necessary to maintain the flow path or means existing from the gasification means 3 (reaction tank) to the tar decomposition means 5 at a predetermined temperature or higher.

  (2) Since the tar decomposition / reforming reaction is basically a heating reaction, it is preferably at a predetermined temperature or higher in order to effectively exhibit the tar decomposition function by the additive in the present invention.

  (3) If the gas containing tar has a low temperature part in the flow path, it causes local condensation and deposition of tar.

  (4) On the other hand, an excessively high temperature state causes deterioration of each member constituting the system, and an increase or decrease in temperature during the process causes an increase in energy to be injected and generation of a loss.

  (5) In order to ensure optimum energy efficiency of the entire system, it is preferable to reduce the width of the control temperature during the process and to reduce the vertical fluctuation.

  The actual control temperature varies depending on the function and processing procedure of each means constituting the gasification system. However, in the present invention, an efficient gasification system is obtained by taking into account the above viewpoints and consistency of temperature control. Specifically, it has been proved that the temperature range of 800 to 900 ° C. is effective. As a result, tar decomposition can be performed in a state in which generation or loss of tar in the flow path from the gasification means 3 to the tar decomposition means 5 is reduced, so that the product gas from the combusted material is efficiently obtained. In addition, it is possible to suppress an increase in pressure loss in the dust collecting means 4.

  As shown in FIG. 1, the heat recovery means 6 is not only provided in the subsequent stage of the tar decomposition means 5, but also at either the intermediate position between the gasification means 3 and the dust collection means 4 or the subsequent stage of the purification means 7. May be provided. In the heat recovery means 6, the high-temperature gas body at 800 to 900 ° C. is cooled to about 200 to 400 ° C. or even higher by the heat exchanger. The recovered thermal energy is sent to gasification means in this system, a boiler outside the system, a heating furnace, and the like for effective use. As the heat exchanger, a shell and tube type, a boiler water pipe structure, or the like is used.

  The heat-recovered product gas is further subjected to a predetermined refining process by the refining means 7, whereby a very clean combustion gas can be generated. In the refining process, dust is removed by a second dust collecting means (not shown) to remove substances precipitated at a low temperature, and then dechlorination, desulfurization, deammonization or medium is performed by wet gas purification. It can be refined as a clean product gas. The second dust collecting means preferably uses a bag filter or the like from the viewpoint of dust removal accuracy.

  As described above, the present invention effectively performs gasification of combustibles such as waste at a relatively low temperature to improve energy efficiency, and is a compact gasification method that is relatively simple and highly workable. The present invention is intended to provide a system, and is particularly effective in a gasification system that generates combustion gas from combustibles such as solid fuel with a high ash content or organic waste.

  In addition, the product gas obtained by the above gasification system is a clean gaseous fuel with stable properties and can be used effectively in a power generation system without special treatment, and the recovered thermal energy Can also be used effectively.

  In addition, it cannot be overemphasized that it can change arbitrarily about the kind or arrangement | sequence order of each said structural means by the kind and use condition of a to-be-combusted material.

  As described above, the embodiment of the present invention has been described by taking the waste including the organic waste as an example of the combusted material. However, the combusted material to which the present invention can be applied is limited to this. However, various solid fuels, industrial wastes, and the like may be used.

Explanatory drawing which illustrates gasification system outline whole structure concerning an embodiment of the present invention Explanatory drawing which illustrates the structure which integrated the dust collection means 4 and tar decomposition | disassembly means 5 which concern on embodiment of this invention. Explanatory diagram of gasification system according to the prior art

Explanation of symbols

3 Gasification means 4 Dust collection means 5 Tar decomposition means 6 Heat recovery means 7 Purification means 8 Filter 9 Space

Claims (3)

Means for introducing the combustible, gasification means for heating and gasifying the combustible, and dust collecting means disposed on the downstream side of the gasification means for removing dust generated from the gasification means; A tar decomposition means disposed downstream of the dust collection means and filled with a catalyst for decomposing tar in the product gas supplied from the dust collection means, the dust collection means and the tar decomposition means being integrated. In addition, the dust collection unit is formed of a plurality of filter members while arranging a partition having a plurality of passages formed at a predetermined inclination angle on the upstream side and the downstream side of the tar decomposition means to form a catalyst packed layer. A space having a predetermined volume is provided between the means and the tar decomposing means, and after the gas supplied from each filter member is diffused, the gas is divided into the plurality of passages and introduced into the tar decomposing means System. 2. A gasification system according to claim 1, wherein a circulation means for returning the catalyst extracted from the tar decomposition means to the tar decomposition means, and a catalyst regeneration means are provided in a flow path of the circulation means. The gasification system according to claim 1 or 2, wherein a gas temperature from the gasification means to the tar decomposition means is controlled to 700 to 900 ° C.

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