JP2006183998A - Method of improving properties of incineration residues produced in incineration plant, and method of treating the residues - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of solving defects such as generation of soot dust and a problem related to air entrainment from a furnace by use of a minimized device and further reducing consumption of water by adjusting a combustion process so that perfectly sintered main ash having necessary properties can be obtained without using downstream fusion or a glassifying unit. <P>SOLUTION: A combustion control system is operated so that combustion residues are preliminarily sintered and/or fused in the incineration bed of a main incineration zone to main ash, and residues not fused or sintered are pushed out at the end of the combustion process, and then returned again to the combustion process. Wet incineration residues which come out of a wet slag remover are firstly divided into two fractions by means of a mechanical separating process, after which a main fraction substantially composed of rough fractions and oversize fractions is washed with water taken from the wet slag remover to separate off fine pieces adhered to the combustion residues. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a method for improving the properties of combustion residues produced in a combustion plant, in particular a waste / energy conversion plant, in which fuel is burned on a combustion grate and the temperature of the resulting combustion residue is raised by appropriate fuel control. .
The invention is also produced by a combustion plant, in particular a waste incineration unit, which burns fuel on a combustion grate, quenches the resulting residue in a wet ashing device and then transports it out of the wet ashing device. It relates to a method of processing the residue.
Still further, the present invention deals with combustion residues produced by combustion plants, particularly waste / energy conversion plants, where fuel is burned on a combustion grate and the temperature of the resulting combustion residue is raised by appropriate fuel control. Regarding the method.

  In this type of process, known from EP 0667490 B1, the temperature of the main ash produced by the combustion is that of the fuel on the combustion grate, before it moves to a melting process separate from the combustion grate. It is heated until it reaches a temperature just below the melting temperature of the main ash. This method adjusts the combustion so that the temperature of the main ash at the end of the grate is as high as possible in order to reduce the amount of energy required for the downstream melting process as much as possible. However, at this time, the main ash is not sintered or melted. Therefore, in order to obtain the required main ash properties, a downstream dissolution step is required. The downstream melting process not only requires the related equipment, but also requires a high amount of energy despite the fact that the above heating has been performed in advance.

  For the required properties of main ash, the inorganic and organic pollutants mixed into the main ash from waste are important factors. In particular, heavy metals and salts are major inorganic contaminants. Organic pollutants are particularly caused by incomplete combustion. Furthermore, when assessing the properties of the main ash, it is important how much the contaminants contained in the main ash are dissolved during the dissolution test. In addition, the mechanical properties of the main ash are important when assessing suitability for use in landfill, civil engineering, and road construction.

  Since the treatment of the combustion residue in the melting process is carried out at a high temperature, the molten combustion residue contains only a small amount of organic compounds. Typical main ash removed from a waste / energy conversion plant usually has an unburnt amount of 1-5% by weight measured as loss on ignition, but the loss on ignition of the molten combustion residue is Less than 0.3% by weight. The melted combustion residue is characterized by a low content of eluted salts and heavy metals. The reason is that both salts and heavy metals have already been stripped or integrated into the glass body formed by cooling the melt.

  On the other hand, German Patent No. 701606C describes a technique in which combustion residues are conveyed to an ashing device having an inlet portion and an extrusion soot having an upward outlet chute and taken out therefrom by an extrusion ram. These combustion residues are called main ash. Water for rapidly cooling the main ash is supplied to the extrusion trough. Only the fresh water necessary to supplement the amount of water extruded with the wet main ash is introduced into the jar. The concentration of various substances and compounds attached to the residue, such as salts, is in a stable state, and as a result, the concentration cannot be reduced. The properties of this main ash for landfill and compatibility with recycled civil engineering materials are inadequate. The fact that the residue is not separated (classified) into a classified product with a good quality and a classified product with a poor quality is the reason for such a drawback. As a result, the entire combustion residue inevitably has insufficient properties.

  In addition, German Patent No. 4423927 describes a technique in which a residue from a furnace is directly transferred to a water tank and subjected to rough cleaning without rapid cooling. The dried and roughly washed main ash is separated into at least two classifications. All particles less than 2 mm are assigned to the first class and other particles are assigned to the second class. The second classification is then separated into at least two classifications by a sieve sorting process. All particles less than 27-35 mm are assigned to the third class. The remaining particles are assigned to the fourth class.

In this way, a residue classification product having good properties is obtained. The disadvantage of this method, however, is that there are problems associated with the generation of soot and air entrainment from the furnace.
European Patent No. 0667490B1 German patent No. 701606C German Patent No. 4423927

The present invention has been made in view of the various problems in the prior art described above.
Among the present inventions, the object of the first group of inventions is a method by which the combustion process can be adjusted so that a fully sintered main ash having the required properties can be obtained without using a downstream melting or vitrification unit. Is to provide.
The object of the second group of the present invention is that the main main ash classification can be separated and the problems related to generation of dust and air entrainment from the furnace can be solved. Another object is to embody a method that can reduce water consumption.
Still further, of the present invention, the purpose of the third group of inventions is to adjust the combustion process so that a fully sintered main ash having the necessary properties can be obtained without using a downstream melting or vitrification unit, An object of the present invention is to realize a method capable of eliminating drawbacks such as problems related to dust generation and air entrainment from a furnace, and further reducing water consumption by using a minimum apparatus.

Method for improving the characteristics of combustion residues produced in a combustion plant according to the first group of inventions The object of the above first group of inventions is to pre-sinter and / or sinter the combustion residues in the fuel bed of the main combustion zone. Characterized in that the combustion control system is operated so as to melt into main ash and extrude the residue not melted or sintered to the outside at the end of the combustion process and then back to the combustion process This is achieved by the method described.

  That is, the first group of inventions is based on two basic features, one of which implements a combustion process on the grate so that sintering and / or melting occurs in advance in the fuel bed of the main combustion zone. The other is to return the combustion residue which has not been sintered and / or melted, and to achieve the required level of sintering / melting more than once, preferably up to the third time. .

With respect to the first group of inventions, the term “fully sintered main ash” means a material consisting of a lump of sintered and / or molten material typically having a particle size of, for example, 8 mm or more. These agglomerates consist of combustion residues obtained from waste that has agglomerated by global melting or surface melting.
Such a mass obtained by sintering and / or melting preferably has a porous structure due to separation of gas during sintering or melting. The porosity of the fully sintered main ash is not high enough that the temperature of the molten ash in the fuel bed results in a sufficiently low viscosity, and gas bubbles have escaped by a process similar to the known degassing process in glassmaking. This is due to the phenomenon of holes remaining later. In terms of this porosity, fully sintered main ash differs from main ash characterized by vitrification obtained by downstream high temperature processing using a refractory lined crucible furnace or other melting unit.

  Strictly speaking, waste components such as glass or metal that have passed over the grate without being substantially affected by the combustion process are not melted or sintered in the fuel bed. However, the completely sintered main ash may contain such glass or metal. These components have indispensable properties with respect to the prevention of pollutants with a risk of post-combustion and leaching.

  Literature [Hemmel, Waste and Waste 31, Addendum on Disposal of Main Ash and Other Residues, p. 142, 1994: Hammerli (Mull und Abfall 31, Supplement on Disposal of Bottom Ash and Other Residues, page 142, 1994)] “Sintering” is described as a special case of melting and solidification. Therefore, the term “sintering” used in the following description in the sense of “particle surface melting or particle mutual melting” may deviate from general scientific interpretation. The mass obtained by sintering the completely sintered main ash may be completely melted or partially melted.

  The main ash component that has not been sintered and / or melted is defined as residual main ash. Residual main ash is characterized in that it has a small particle size, high ignition loss, and a high content of contaminants that are likely to elute, compared to fully sintered main ash.

  The first group of inventions focuses on sintering and / or melting the combustion residue already in the fuel bed of the main combustion zone, which has not been considered so far. As a practical matter, if liquid main ash is generated between individual combustion grate or between moving parts of the grate, the combustion grate is significantly adversely affected. For this reason, so far, melting of the main ash on the grate has been avoided, and care has been taken to prevent the main ash from reaching the melting point in the fuel bed.

  The sintering and / or melting process by the method according to the first group of inventions takes place in the upper region of the fuel bed. The reason for this is that the highest thermal shock is applied from above by the flame radiation, and the temperature of the material placed directly on the grate is lower (in a relative sense) as a refrigerant than at the top of the fuel bed. This is because it is lowered by the heating air. When such combustion adjustments are made, not all combustion residues are converted to fully sintered main ash with the essential properties, so that combustion residues that do not have the characteristics of fully sintered main ash are in the combustion process. Returned to

  In order to achieve the sintering and / or melting process in the fuel bed, it is not necessary to add an external energy source. The properties of the main ash obtained are very similar to those of the main ash obtained by a high temperature process that achieves downstream melting and vitrification known to those skilled in the art. These high heat processes use units such as rotary kilns, crucible furnaces, and melting chambers. However, the disadvantages of such known methods are that they require very complex additional units and that high energy is consumed. The invention of the first group can solve such a problem, and can generate main ash having properties substantially similar to the properties of main ash obtained by a known method.

  According to a very preferred form of the combustion control system according to the first group of the invention, the oxygen content of the heating air from below is about 25-40% by volume, preferably 25-30% by volume. As shown, it is enriched according to the quality (waste quality) of the waste to be burned. According to a further preferred embodiment, the heating unit from below is preheated to about 100 ° C to 400 ° C. These forms may be applied singly or in combination depending on the situation. Preferably, the temperature of the fuel bed (typically the dust bed), which is a function of the fuel properties, is set between 1000 ° C and 1400 ° C.

  In order to achieve the preferred conditions of converting the combustion residue into sintered and / or molten main ash, the combustion control performed in various forms can all involve a certain proportion of combustion residue (e.g. 25% to the total amount of combustion residue). It may be set so that about 75% by weight) becomes completely sintered main ash. According to this configuration, since there is a sufficient amount of non-molten material in the fuel bed in the main combustion zone to surround the molten ash, the mechanical part of the grate is not adversely affected.

  According to a further preferred embodiment according to the invention, fly ash is returned to the combustion process. The fly ash is separated from the fuel bed together with the combustion gas, and is led to the downstream side flue filter through the boiler.

  The incompletely sintered main ash and the completely sintered main ash can be separated in a main ash sorting step (for example, with a particle size of 2 to 10 mm as a boundary) after being extruded from the combustion system. Oversize is fully sintered main ash, and undersize is the classification to be returned. There are various mechanical separation methods known to those skilled in the art for performing this separation process.

  Separation may be performed by either sieve screening or a combination of sieve screening and washing steps as described in the preferred embodiment of the present invention.

  It goes without saying that other techniques for improving the properties of the main ash may be applied outside the combustion plant, for example in special cleaning processes, with or without chemical additives.

  A microclassification having a particle size of less than 2-10 mm is returned to the combustion process. This return can be done by adding the microclassification to the supplied fuel or by adding the microclassification directly to the fuel bed. In order to avoid soot accumulation and from the viewpoint of ease of handling, it is preferable that the fine classified product is granulated or tableted before being returned.

Method for treating combustion residue produced in a combustion plant according to the second group of inventions The object of the invention according to the second group is achieved by the technical features described below on the basis of two different procedures. The

  The first procedure consists of mechanically separating the wet combustion residue taken from the wet ashing device into two classifications. The main classification consists essentially of coarse classification and oversize classification. This main classified product is washed with water extracted from the wet ashing device, the fine particle part adhering to the combustion residue is separated, and the washing water is transferred to the wet ashing device together with the fine particle part released during the washing process. To do.

  By circulating the water in the wet ashing device in this way, the main classified product having good properties can be washed and the fine particle portion can be separated without using a large amount of fresh water. Experience has shown that the fine particle portion adhering to the combustion residue adversely affects the properties of the main classification. Thus, the combustion residue from which the fine particle portion has been washed off has a good property and is effectively used as a main ash for recycling, for example, a civil engineering material.

  The second procedure consists of mechanically separating the wet combustion residue taken from the wet ashing device into two classifications. The main classification consists essentially of coarse classification and oversize classification. This main classification is first pulverized and subsequently washed with water drawn from the wet ashing device to separate the fine particle portions adhering to the combustion residue. The washing water is transported to the wet ashing device together with the fine particle parts detached during the washing process.

  The second procedure has the advantage of removing contaminants contained in the main classification before washing. These contained contaminants are removed by a cleaning process. Another advantage resides in that the efficiency of cleaning can be improved because the ground material has a large surface. This point is particularly important because the material obtained from the main classification has a porous form. The second procedure is when a very high quality combustion residue is desired, when the main classification has inclusions consisting of many contaminants, or when the porosity of the combustion residue is important Is used. The second procedure is also used when the main classified product of main ash is further pulverized in a subsequent processing step. For example, when the main classified product (final product) of the main ash needs to be pulverized in the dissolution test for assessing the properties, the second procedure may be used. The main and fine classifications that have been ground and washed should not be confused. In most cases, since the main classification is melted or sintered, the content of unburned material or contaminants that are at risk of elution is low, and these properties are not changed by grinding. Therefore, the main classified product pulverized by the second procedure has various characteristics different from the fine classified product of the main ash having a high content of contaminants.

  According to one embodiment of the invention of the second group, the ultra-fine classification product and the micro-classification product generated during the mechanical separation process are conveyed (circulated) to the combustion process. These classifications are again subjected to a combustion process, and are melted and sintered.

  This approach eliminates the disadvantages of the prior art procedure described earlier (all combustion residues are transported as recycling residues even if they contain a small amount of residues with undesirable properties). Can be resolved. Also, the disadvantages related to dust generation and furnace sealing can be eliminated as compared with the second prior art method. In addition, by returning the ultra-microclassified product with undesirable properties and the micro-classified product to the combustion process, the microparticle portion so returned is agglomerated by either the first return or further repeated return. And may be converted into a combustion residue having a preferable property, so that the ratio of the combustion residue recycled can be further increased. The second prior art method does not have this advantage because there is no step back to the combustion process.

  According to yet another embodiment according to the first or second procedure of the second group of inventions, the main classification pre-washed with water from the wet ashing device is rinsed with fresh water and is relatively bulky. By removing the water from the ashing device with the contaminants, the combustion residue and / or the quality of the sintered main ash can be further improved. Since fresh water is used for rinsing the coarse fraction, the water used for the rinsing is low in the amount of contaminants and should be supplied to the flue gas cleaning system without pre-cleaning part of the water. Can do. Furthermore, there is an advantage that a part of the water used for rinsing can be supplied to the wet ashing device. According to this configuration, the water level of the ashing device can be kept constant. Since water is always carried away with the combustion residue being pushed out, the level of the water in the ashing device is lowered and the level of the water has to be kept at the highest level in any case. The water used for rinsing contains negligible amounts of calcium and sulfur, so there is no risk of clogging pipes and nozzles.

  According to the second procedure according to the second group of inventions, even after the first separation step is performed, even if the main classified material contains a large amount of oversized classified material (usually containing a large amount of scrap metal). In the mechanical separation process according to still another embodiment of the present invention, the oversized coarse product is further separated. The metal is removed with a magnetic separator.

  In the embodiment of the second group of the invention, as an example, the particle size of the ultra-fine classified product is in the range of less than 2 mm, the particle size of the fine classified product is in the range of 2 mm to less than 8 mm, and the particle size of the coarsely-classified product. Stipulates a range of 8 mm or more and less than 32 mm, and a particle size of the oversized classification in a range of 32 mm or more. These values serve as guidelines for understanding the present invention. Obviously, each classification contains a negligible amount of finer secondary classification.

  Usually, microclassifications having a particle size of, for example, less than 8 mm, supplied directly from the ashing device have undesirable properties and should preferably be returned to the combustion process. In the second procedure, a pulverized main classification having a particle size comparable to those microclassifications is produced, but the pulverized main classification has very favorable properties and is used as a civil engineering material.

  For example, in the second procedure, when the separation particle size in the first coarse separation step is 32 mm and an oversized classification having a particle size larger than that is separated, the remaining combustion residue is, for example, the separation particle size Is further separated in a second mechanical separation step set to 8 mm, and all combustion residue less than 8 mm may be returned to the combustion process.

  In order to obtain as large a recycle classification as possible, according to a further embodiment of the second group of inventions, the coarse classification separated from the main classification is subjected to an oversize classification crushing step (crusher It may be mixed with the pulverized combustion residue generated by a rock drill or the like. In this case, particles having a particle size that is not desirable for recycling, specifically, particles having a particle size that should be returned to the combustion process, are produced by pulverization, so that the first mixed classification obtained by the above mixing is machined. Separation may be applied to remove particles of undesirable particle size.

  When used for specific applications of road construction foundations, formability may be required for combustion residues. Such characteristics cannot be achieved unless a microclassified product (having a particle size of, for example, 2 mm or more and less than 8 mm, as described above) is included. For this reason, in order to intentionally obtain the required fine classified product, a part of the coarse classified product may be pulverized. The fine classified material having the above particle diameter may be contained in a certain ratio. Preferably, about 30% of the coarsely classified product may be pulverized in the pulverization step. The obtained micro-classified product and ultra-micro-classified product are mixed with the coarse classified product to form a second mixed classified product. As a combustion residue for road construction, 70% of the mixed classification product is preferably a coarse classification product.

  In this second mixed classified product, the particle size occupying the majority is larger than 8 mm, and experience has shown that such components have the properties necessary for recycling. However, a small amount of a particle size of 2 mm or more and less than 8 mm is also necessary to ensure the above-described formability of the road construction residue.

  According to still another embodiment of the invention of the second group, the second mixed classified product is washed with water from the wet ashing device, and the first mixed classified product is released. In this case, a particle portion of less than 2 mm, which is likely to contain a lot of contaminants, can be reliably separated from the residue for recycling.

  This washing water is preferably conveyed to a wet ashing device as described above. By returning the water in this way, the consumption of fresh water can be reduced as much as possible.

  The separated metal may be washed with water from the ashing device in order to wash away the adhering combustion residue. Preferably, the mechanical separation of the classified product is performed by sieving.

  By adding the precipitant for soluble heavy metal to the water in the ashing device, the properties of the combustion residue used for recycling can be remarkably improved. Specifically, heavy metals can be separated by adding a precipitant.

A method for treating combustion residue produced in a combustion plant according to a third group of inventions The above object is based on two different methods according to the composition of the fuel, and is based on the third group of inventions described below. Achieved by the method.

  According to the first method, the combustion control system is operated so that the combustion residue is pre-sintered and / or dissolved in the fuel bed in the main combustion zone into main ash, and all the generated residue is removed from the wet ash. Rapid cooling in the apparatus, then taken out from the wet ashing device, the wet combustion residue taken out from the wet ashing device is first separated into two classifications by a mechanical separation process, then essentially The main classification product consisting of coarse classification and oversize classification is washed with the water extracted from the wet ash removal device, the fine particle part adhering to the combustion residue is separated, and the fine particles are separated from the washing water during the washing process. It is transported to the wet ashing device together with the part.

  This first approach is useful when the recyclable main classification contains negligible contaminants that can be washed away, such as salts or heavy metals.

  The third group of inventions mainly has two technical features. The first technical feature includes a combustion control system, and the second technical feature includes mechanical processing of residue generated by the combustion process. Of these, the second technical feature includes two different approaches depending on the fuel composition.

  Combustion control included in the first technical feature is common to both of the following two approaches relating to mechanical processing of the residue, causing sintering or melting to occur on the grate in the main combustion zone and sintering Alternatively, it is based on a combustion process on a grate that is carried out so as to achieve the required level of sintering and / or melting by two or three cycles by returning unburned combustion residues.

  The term “fully sintered main ash” means a material composed of a lump of sintered and / or molten material typically having a particle size of, for example, 8 mm or more. These agglomerates consist of combustion residues obtained from waste that has agglomerated by global melting or surface melting.

  The lump by sintering and / or melting may have a porous structure due to separation of gas during sintering or melting. The porosity of the fully sintered main ash is not high enough that the temperature of the molten ash in the fuel bed results in a sufficiently low viscosity, and gas bubbles have escaped by a process similar to the known degassing process in glassmaking. This is due to the phenomenon of holes remaining later. In terms of this porosity, fully sintered main ash differs from main ash characterized by vitrification obtained by downstream high temperature processing using a refractory lined crucible furnace or other melting unit.

  Strictly speaking, waste components such as glass or metal that have passed over the grate without being substantially affected by the combustion process are not melted or sintered in the fuel bed, but are completely fired. The main ash may contain such glass or metal. These components have indispensable properties with respect to the prevention of pollutants with a risk of post-combustion and leaching.

  The literature (supra Henmel) describes "sintering" as a special case of melting and solidification. Therefore, the term “sintering” used in the following description in the sense of “particle surface melting or particle mutual melting” may deviate from general scientific interpretation. The lump of fully sintered main ash may be completely melted or partially melted.

  The main ash component that is not sintered and / or melted is defined as residual main ash. Residual main ash is characterized in that it has a small particle size, high ignition loss, and a high content of contaminants that are likely to elute, compared to fully sintered main ash.

  The focus of the present invention is on sintering and / or melting the combustion residue already in the fuel bed of the main combustion zone, which has not been considered before. As a practical matter, if liquid main ash is generated between individual combustion grate rods or between moving parts of the grate, the combustion grate is significantly adversely affected. For this reason, so far, melting of the main ash on the grate has been avoided and care has been taken to prevent the melting point of the main ash from reaching the fuel bed.

  The sintering and / or melting process according to the method of the third group of inventions takes place in the upper region of the fuel bed. The reason for this is that the greatest thermal shock is applied from above by the flame radiation, and the temperature of the material placed directly on the grate is lower (in a relative sense) as a refrigerant than at the top of the fuel bed. This is because it is lowered by the heating air. When such combustion adjustments are made, not all combustion residues are converted to fully sintered main ash with the essential properties, so that combustion residues that do not have the characteristics of fully sintered main ash are in the combustion process. Returned to

  No additional external energy source is required to accomplish the sintering and / or melting process in the fuel bed. The properties of the main ash obtained are very similar to those of the main ash obtained by a high temperature process that achieves downstream melting and vitrification known to those skilled in the art. These high heat processes use units such as rotary kilns, crucible furnaces, and melting chambers. However, the disadvantages of such known methods are that they require very complex additional units and that high energy is consumed. The invention of the third group can solve such a problem, and can generate main ash having properties almost similar to those of the main ash obtained by a known method.

  In the first method relating to the mechanical treatment, by circulating the water in the wet ashing device, the main classified product having good properties is washed without using a large amount of fresh water, and the fine particle portion Can be removed. Experience has shown that the fine particle portion adhering to the combustion residue adversely affects the properties of the main classification. Thus, the combustion residue from which the fine particle portion has been washed away has good properties and is effectively used as main ash for recycling.

  A second approach suitable for the treatment of combustion residues that can be washed away, eg, rich in contaminants such as salts or heavy metals, is mainly by sintering and / or dissolving the combustion residues in the main combustion zone fuel bed. Operate the combustion control system to be ashed, quench all of the generated residue in the wet ashing device, then take it out from the wet ashing device, and wet combustion removed from the wet ashing device The residue is first separated into two classifications by a mechanical separation step, then (the separated main classification consisting essentially of the coarse and oversized classifications is ground by a grinding step and then wet This is achieved by a method characterized in that the washing water is transported to the wet ashing device together with the fine particle parts separated during the washing step. According to this configuration, by pulverizing the main classification product, the contaminants captured by the large particles in the combustion residue are washed away by the subsequent cleaning process and separated from the recyclable main classification product. In this way, a large amount of residues can be obtained without performing a large-scale wash to wash away the contaminants in the subsequent cleaning step, even though those residues contain many contaminants. Recyclable main ash can be obtained by separating only the particle portion.

  In the second method, the combustion control included in the first technical feature according to the present invention is performed before the mechanical processing.

  According to a very preferred embodiment of the combustion control system according to the method of the invention, the oxygen in the heating air from below is preferably waste or the like so that its content is about 25-40% by volume. Depending on the quality (garbage quality), it is enriched to 25-35% by volume. Moreover, according to a more preferable aspect, the heating unit from below is preheated to about 100 ° C to 400 ° C. These forms may be applied singly or in combination depending on the situation. Preferably, the temperature of the fuel bed (typically the dust layer), which is a function of the fuel characteristics, is set between 1000 ° C and 1400 ° C.

  In order to achieve favorable conditions for converting the combustion residue into sintered and / or molten main ash, the combustion control performed in various forms is performed at a certain ratio (25 to 75 weight of the total amount of the combustion residue). %) Should be set to be completely sintered main ash. According to this configuration, since there is a sufficient amount of non-molten material in the fuel bed in the main combustion zone to surround the molten ash, the mechanical part of the grate is not adversely affected.

  According to a further preferred embodiment according to the invention, fly ash is returned to the combustion process. The fly ash is separated from the fuel bed together with the combustion gas and led to the downstream flue filter through the boiler.

  The second technical feature of the third group of inventions, that is, the mechanical treatment of the combustion residue including the two methods is as follows.

  According to one embodiment according to the third group of inventions, the ultra-fine classification product and the micro-classification product generated during the mechanical separation process are conveyed to the combustion process. These classifications are again subjected to a combustion process, and are melted and sintered.

  This approach eliminates the disadvantages of the prior art procedure described earlier (all combustion residues are transported as recycling residues even if they contain a small amount of residues with undesirable properties). Can be resolved. Further, as compared with the second prior art method, the disadvantages related to dust generation and furnace sealing (air entrainment) can be eliminated. In addition, by returning the ultra-microclassified product with undesirable properties and the micro-classified product to the combustion process, the microparticle portion so returned is agglomerated by either the first return or further repeated return. And may be converted into a combustion residue having a preferable property, so that the ratio of the combustion residue recycled can be further increased. The second prior art method does not have this advantage because there is no step back to the combustion process.

  According to yet another embodiment of the third group of inventions, the main fraction pre-washed with water from the wet ashing device is rinsed with fresh water, with a relatively large amount of contaminants. By removing the water from the ashing device, the properties of the combustion residue / sintered main ash can be further improved. Since fresh water is used for rinsing the coarse fraction, the water used for the rinsing has a low amount of contaminants and is supplied to the flue gas cleaning system without pre-washing at least a portion of the water. be able to. Furthermore, there is also an advantage that at least a part of the water used for rinsing can be supplied to the wet ashing device. According to this configuration, the water level of the ashing device can be kept constant. Since water is always carried away with the combustion residue being pushed out, the level of the water in the ashing device is lowered and the level of the water has to be kept at the highest level in any case. Since the water used for rinsing contains negligible amounts of calcium and sulfur, there is no risk of clogging pipes and nozzles.

  In the second method of mechanical processing according to the present invention, even after the first separation step is performed, even if the main classified material contains a large amount of oversized classified material (usually containing a large amount of scrap metal), In the mechanical separation step according to yet another embodiment of the invention, the crude fraction is further separated. Separation of the metal is performed by a magnetic separator.

  In an embodiment according to the invention of the third group, for example, the particle size of the ultra-classified product is in the range of less than 2 mm, the particle size of the micro-classified product is in the range of 2 mm to less than 8 mm, and the particle size of the coarsely-classified product. Is in the range of 8 mm or more and less than 32 mm, and the particle size of the oversized classification is defined in the range of 32 mm or more. These values serve as guidelines for understanding the present invention. Obviously, each classification contains a negligible amount of finer secondary classification. The microclassification having a particle size of 2 mm or more and less than 8 mm supplied directly from the ashing device is preferably the part of the combustion residue to be returned to the combustion process. On the other hand, the particle size of the fine particle portion included in the particle size distribution of the main ash obtained by the pulverization procedure according to the second method is comparable to the particle size of the fine classified product directly supplied from the ashing device. The part has preferred properties suitable for recycling. Therefore, the fine particle portion in the pulverized main ash is called a high quality fine classified product.

  For example, in the second method, when the separation particle size in the first coarse separation step is 32 mm and an oversized classification having a particle size larger than that is separated, the remaining combustion residue is, for example, separated particle size. May be further separated in a second mechanical separation step set to 8 mm, and all combustion residue less than 8 mm may be returned to the combustion process.

  In order to prevent the mechanical separator from being damaged by large scrap metal, the metal may be separated from the main classification.

  From the main classification including undersize, that is, a coarse classification of less than 32 mm, not only large scrap metal but also other metal parts are separated. Such metal parts can be used in another recycling process.

  Depending on the recycling procedure and type in which the generated combustion residue is utilized, the metal may be removed separately from the oversized and coarsely classified products.

  When the combustion residue is used for road construction, for example, after removing a metal portion larger than 32 mm that is not suitable for road construction, the oversized classification product may be further pulverized in a pulverization step.

  In the second approach, in order to obtain the largest possible classification for recycling, according to yet another embodiment of the third group of inventions, the coarse classification separated from the main classification is converted to an oversized classification. It is good to mix with the grinding | pulverization combustion residue produced by the grinding | pulverization process of this, and to form a 1st mixed classification product. In this case, since particles having an undesired particle size for recycling, specifically, particles having a particle size to be returned to the combustion process, are produced by pulverization, the first mixed classified product is subjected to mechanical separation. It is advisable to remove particles with an undesirable particle size.

  When used for specific road construction applications, the combustion residue may require formability. Such properties cannot be achieved unless a microclassified product (having a particle size of 2 mm or more and less than 8 mm as described above) is included. For this reason, a part of the coarse classified product may be pulverized in order to intentionally produce the required fine classified product. The fine classified material having the above particle diameter may be contained in a certain ratio. Preferably, about 30% by weight of the coarsely classified product may be pulverized in the pulverization step. The obtained fine classified product and ultra-fine classified product are mixed with the coarse classified product to form a second mixed classified product. As a combustion residue for road construction, it is preferable that 70% by weight of the mixed classification product is a coarse classification product.

  In this second mixed classified product, the particle size occupying the majority is larger than 8 mm, and experience has shown that such components have the properties necessary for recycling. However, a small amount of a particle size of 2 mm or more and less than 8 mm is also necessary to ensure the above-described formability of the road construction residue.

  According to still another embodiment of the invention of the third group, the second mixed classified product is washed with water from the wet ashing device, and the first mixed classified product is released. In this case, a particle portion of less than 2 mm, which is likely to contain a lot of contaminants, can be reliably separated from the residue for recycling.

  This washing water is preferably conveyed to a wet ashing device as described above. By returning the water in this way, the consumption of fresh water can be reduced as much as possible.

The separated metal may be washed with water from the ashing device in order to wash away the attached combustion residue.
Preferably, the mechanical separation of the classified product is performed by sieving.

  By adding the precipitant for soluble heavy metal to the water in the ashing device, the properties of the combustion residue used for recycling can be remarkably improved. Specifically, heavy metals can be separated by adding a precipitant.

Among the present inventions, according to the first group of inventions, the combustion process can be adjusted so that a fully sintered main ash having the required properties can be obtained without using a downstream melting or vitrification unit. Is provided.
Moreover, according to the second group of the present invention, a good main ash classification product can be separated, and problems related to generation of dust and air entrainment from the furnace can be solved. In addition, a method is provided that can further reduce water consumption.
Still further, of the present invention, according to the third group of inventions, the combustion process is adjusted so that a completely sintered main ash having the necessary properties is obtained without using a downstream melting or vitrification unit, A method is provided that uses minimal equipment to eliminate disadvantages such as the problems associated with dust generation and air entrainment from the furnace, and to reduce water consumption.

Embodiments of the present invention relating to the first to third groups will be described below with reference to the accompanying drawings. Note that the specific values (amounts) such as weight and% used in the following are merely examples for explaining the embodiments, and the present invention is interpreted to be limited to these values (amounts). It is not something.
1 and 2 are two work system diagrams illustrating the method according to the first group of inventions. Based on these, the invention of the first group will be described in more detail.
In the method shown in FIGS. 1 and 2, 1000 kg of waste (block 100 in the figure) having 220 kg of ash is supplied to the batch combustion system so that 25-75% by weight of the combustion residue becomes completely sintered main ash. (Block 102). A combustion residue of a total amount of 300 kg is obtained. These residues fall into the wet ashing apparatus (block 104), quenched, and then extruded (block 106). 200 kg of completely sintered main ash is separated (block 110) by the separation process (block 108) including sieving and, if necessary, a cleaning step (block 110), and becomes the main ash for regeneration (block 112). Unsintered 100 kg of combustion residue (block 114) is returned to the combustion process. The weight of the fly ash that has left the furnace along with the flue gas is 20 kg, and this fly ash is collected in the flue filter (block 116) and by washing the boiler tube (block 118). The collected fly ash is transported to another disposal route (block 120).

  In the method shown in FIG. 2, 310 kg of combustion residue is conveyed to a wet ash removal device and 10 kg of fly ash is returned to the combustion process. The rest is the same as the method shown in FIG. Therefore, the same reference numerals are assigned to the same blocks as in FIG.

Next, an embodiment of the method according to the invention of the second group will be described based on the work system diagrams of FIGS.
As shown in FIG. 3, 1000 kg of waste with 220 kg of ash (block 300) is fed to the grate system (block 302) and then burned. The combustion produces 800 kg of flue gas (block 301) and 300 kg of combustion residue. The residue is supplied to a wet ashing device (block 304) and 315 kg of combustion residue or main ash (block 306) is removed by humidification. The removed residue is subjected to mechanical separation, in this case, sieve selection through which particles having a particle size of 8 mm are passed (block 308). This process separates 215 kg of combustion residue or main ash into main classification (block 310) having a particle size greater than 8 mm and about 100 kg of micro- and ultra-micro classification (block 312) of less than 8 mm. Humidification treatment (block 314) is performed on the main ash having a particle size larger than 8 mm, which is composed of a coarse classification product and an oversize classification product. In this process, 1000 liters of water taken from the wet ashing device is added to wash the main ash and wash away 15 kg of fines with a particle size of less than 8 mm. Actually, the main ash is washed on a sieve through which a classified product of 8 mm or less is passed. The water used for washing the main ash is returned to the wet ashing device together with the fine classified material and the ultra fine classified material. The washed main ash is removed and used for a recycling process such as road construction (block 316). Also, about 100 kg of the fines removed by sieving is usually returned to the grate system for re-sintering. However, the microclassification may be used for other processes (block 318). In addition, since water is accompanied when taking out a combustion residue from a wet ashing device, 40 liters of replenishing water, that is, fresh water, is added to supplement the shortage of water in the wet ashing device.

  The above process may be modified as shown in FIG. In this modified embodiment, rinsing with fresh water is performed following the humidification of the main classification having a particle size greater than 8 mm. Specifically, 80 liters of fresh water (block 320) is added to 200 kg of the main classified product (block 322) in order to remove the components mixed by the humidification process using water from the wet ashing device. 40 liters of this rinse water is used for flue gas cleaning or other waste disposal, and the other 40 liters are returned to the wet ashing device to make up for the lack of consumed water. The main ash washed in this way can be introduced into other recycling processes.

  FIG. 5 shows another form of the process of the second group of inventions. In this modified embodiment, 1000 kg of waste (Block 500) with 220 kg of ash is fed to the grate system (Block 502). The combustion process produces 800 kg of flue gas (block 504) and 320 kg of combustion residue. The combustion residue is supplied to the wet ashing device (block 506). 336 kg of combustion residue is removed from the wet ash removal device. This increase in weight is due to the fine particles from the main ash, that is, the fine particles contained in the main ash wash water returned to the wet ashing device. To make up for the shortage of water consumed, 40 liters of water is added to the wet ashing device. 336 kg of main ash, i.e., combustion residue, is conveyed to a filter through which a classification having a particle size of 32 mm is passed (block 508). An oversize classification having a particle size greater than 32 mm is first conveyed to a metal separator (block 510). The main ash from which the metal has been separated is conveyed to a pulverizer (block 512) that generates main ash having a particle size of about 8 mm. The pulverized main ash is conveyed to another filter (block 514) through which a classified product having a particle diameter of 8 mm is passed. 100 kg of main ash having a particle size of less than 8 mm, i.e. combustion residues, is removed by this mechanical separation process, and the removed fine main ash is preferably returned to the grate system. The main ash is discarded or further processed (block 515). The remaining coarse particle size residue is conveyed to a metal separator (block 516). The metal parts removed by the metal separator and the metal parts separated by the above-described metal separation process are collected and humidified. By this humidification process, the main ash particles adhering to the metal portion are washed away (block 518). As a result, ferrous and non-ferrous metals used in the 20 kg recycling process (block 520) are obtained. The main ash from which the metal has been removed, that is, the coarsely classified product (particle size: 8-32 mm) (block 522) has a weight of 215 kg. Among these, 60 kg of coarsely classified material is conveyed to a pulverizer (block 524) and pulverized to a particle size larger than 2 mm. After the pulverization step, the pulverized classification is mixed with 155 kg of unground crushed classification, and the mixture is humidified using a filter that passes the classification having a particle size of 2 mm (block 526). 1000 liters of washing water necessary for the humidification treatment is supplied from the wet ashing device. By this humidification treatment, 155 kg of main ash having a particle size of 8 or more and less than 32 mm and 45 kg of a fine classified product having a particle size in the range of 2 or more and less than 8 mm are obtained. These two types of classified products are used in the recycling process. That is, it is used for civil engineering materials and road auxiliary base layers (block 528). On the other hand, the fine classified material having a particle diameter of less than 2 mm removed by the humidification treatment is returned to the wet ashing device.

  The working system diagram of FIG. 6 shows a basic modification of the embodiment shown in FIG. 3 using a soluble heavy metal precipitant. This precipitant is introduced into the wet ashing device to reduce the lead concentration in the wet ashing device water from the normal level of 2 mg / L to 0.05 mg / L (block 326). This precipitating agent reduces the dissolved lead in about 20 liters of main ash water that humidifies 200 kg of main ash to 1 mg. 400 g of lead is trapped in the flue gas produced by the combustion process (block 302). In a mechanical separation process using a sieve having a particle size of 8 mm (block 308), 200 kg of main ash (block 310) from which 200 g of 400 g of lead is sent to the recycling process after washing. While 200 g of lead is returned to the grate system (block 302) with a microclassifier having a particle size of less than 8 mm (block 312).

Further, embodiments of the method according to the third group of the invention will be described in more detail with reference to FIGS.
As shown in FIG. 7, 1000 kg of waste with 220 kg of ash (Block 700) is fed to the grate system (Block 702) and the generated 25-75 wt% combustion residue is completely burned. It is burned to be converted into the main ash. The combustion produces 800 kg of flue gas (block 704) and 300 kg of combustion residue. The residue is supplied to a wet ashing device (block 706), and 315 kg of combustion residue or main ash is removed by humidification (block 708). The removed residue is subjected to mechanical separation, in this case, sieve sorting through which particles with a particle size of 8 mm are passed (block 710). This process separates 215 kg of combustion residue, or main ash, into a main classification having a particle size greater than 8 mm (block 712) and about 100 kg of less than 8 mm micro and ultra fine classification (block 714). . Humidification (block 716) is applied to the main ash having a particle size larger than 8 mm, which is composed of a coarse classification product and an oversize classification product. In this process, 1000 liters of water taken from the wet ashing device is added to wash the main ash and wash away 15 kg of fines with a particle size of less than 8 mm. Actually, the main ash is washed by using a filter that allows a classified product of 8 mm or less to pass through. The water used for cleaning the main ash is returned to the wet ashing device together with the fine classified material and the ultra fine classified material. The washed main ash is removed and used for a recycling process such as road construction (block 718). Also, about 100 kg of the fines removed by sieving is usually returned to the grate system for re-sintering. However, the microclassification may be used for other processes (block 720). It should be noted that because the combustion residue is accompanied by water when it is removed from the wet ashing device, 40 liters of make-up water, ie fresh water, is added to make up for the lack of water in the wet ashing device.

  The above process may be modified as shown in FIG. In this embodiment, the main classification product having a particle size larger than 8 mm is humidified, followed by a rinse (block 724) block with fresh water (block 722). Specifically, 80 liters of fresh water is added to 200 kg of the main classified product in order to remove components mixed by the humidification process using water from the wet ashing device. 40 liters of this rinse water is used for flue gas cleaning (block 726) or other waste treatment, and the other 40 liters are returned to the wet ashing device to make up for the lack of consumed water. The main ash thus battled can be introduced into other recycling processes.

  FIG. 9 shows another embodiment of the process of the third group of inventions. In this embodiment, 1000 kg of waste (block 900) with 220 kg of ash is fed to the grate system (block 902). Combustion produces 800 kg of flue gas (block 904) and 320 kg of combustion residue. The combustion residue is supplied to a wet ashing device (block 906). 336 kg of combustion residue is taken from the wet ash removal device. This increase in weight is due to the fine particles contained in the main ash wash water returned to the wet ashing device. To replenish the shortage of water consumed, 40 liters of water is added to the wet ashing device. 336 kg of main ash, i.e., combustion residue, is conveyed to a filter (block 908) that passes a classification having a particle size of 32 mm. Oversized classification having a particle size greater than 32 mm is first conveyed to a metal separator (block 910). The main ash from which the metal has been separated is conveyed to a pulverizer (block 912) that generates main ash having a particle size of about 8 mm. The pulverized main ash is conveyed to another filter (block 914) through which a classified product having a particle diameter of 8 mm is passed. 100 kg of main ash having a particle size of less than 8 mm, i.e. combustion residue, is removed by this mechanical separation process, and the removed fine main ash is preferably returned to the grate system. Alternatively, it is discarded or further processed (block 915). The remaining coarse particle size residue is conveyed to a metal separator (block 916). The metal parts removed by the metal separator and the metal parts separated by the above-described metal separation step are collected and subjected to a humidification process (block 918). By this humidification treatment, the main ash particles adhering to the metal portion are washed away. As a result, 20 kg of ferrous and non-ferrous metals are obtained (block 920). The main ash from which the metal has been removed, that is, the coarse classified product (particle size: 8 or more and less than 32 mm) (block 922) has a weight of 215 kg. Among these, 60 kg of coarsely classified product is conveyed to a pulverizer (block 924) and pulverized to a particle size larger than 2 mm. After the pulverization step, the pulverized classification is mixed with 155 kg of unground crushed classification, and the mixture is humidified by a filter that passes a classification having a particle size of 2 mm (block 926). 1000 liters of washing water required for the humidification treatment is supplied from the wet ashing device. By this humidification treatment, 155 kg of main ash having a particle size of 8 or more and less than 32 mm and 45 kg of a fine classified product having a particle size in the range of 2 or more and less than 8 mm are obtained. These two classifications are used in the recycling process (block 928). On the other hand, the fine classified product having a particle diameter of less than 2 mm removed by the humidification treatment is returned to the wet ashing device.

  The working flow diagram of FIG. 10 shows a basic embodiment of the embodiment shown in FIG. 7 using a soluble heavy metal precipitant. This precipitant is introduced into the wet ashing device to reduce the lead concentration in the wet ashing device water from the normal level of 2 mg / L to 0.05 mg / L (block 728). This precipitating agent reduces the dissolved lead in about 20 liters of main ash water that humidifies 200 kg of main ash to 1 mg. 400 g of lead is trapped in the flue gas (block 702) generated by the combustion process (block 702). In a mechanical separation process using a sieve having a particle size of 8 mm (block 710), 200 kg of main ash (block 712) in which 200 g of 400 g of lead is sent to the recycling process after washing. While remaining in, 200 g of lead is returned to the grate system (block 706) with a microclassifier having a particle size of less than 8 mm (block 714).

It is a work system diagram explaining the embodiment about the method concerning the invention of the 1st group. It is an operation | work system diagram explaining other embodiment about the method which concerns on invention of 1st group. It is a work system diagram explaining the embodiment about the method concerning the invention of the 2nd group. It is a work system diagram explaining other embodiment about the method which concerns on invention of 2nd group. It is a work system diagram explaining further another embodiment about the method concerning invention of the 2nd group. It is a work system diagram explaining further another embodiment about the method concerning invention of the 2nd group. It is a work system diagram explaining the embodiment about the method concerning the invention of the 3rd group. It is an operation | work system diagram explaining other embodiment about the method which concerns on invention of the 3rd group. It is a work system diagram explaining further another embodiment about the method concerning invention of the 3rd group. It is a work system diagram explaining further another embodiment about the method concerning invention of the 3rd group.

Claims (5)

In a method for improving the characteristics of combustion residues generated in a combustion plant that burns fuel on a combustion grate and raises the temperature of the resulting combustion residues via appropriate combustion control,
The combustion residue is pre-sintered and / or melted in the fuel bed of the main combustion zone into main ash, and the residue that is not melted or sintered is extruded outside at the end of the combustion process and then returned to the combustion process again And activating the combustion control system. In a method of burning fuel on a combustion grate, quenching the resulting residue with a wet ashing device, and then processing the residue generated in a combustion plant that is conveyed externally from the wet ashing device,
The wet combustion residue removed from the wet ashing device is first separated into two classifications by a mechanical separation process,
The main classification consisting essentially of coarse classification and oversize classification is washed with water extracted from the wet ashing device to separate the fine particle portion adhering to the combustion residue,
The washing water is transported to the wet ashing device together with the fine particle parts detached during the washing step.
A method characterized by that. In a method of burning fuel on a combustion grate, quenching the resulting residue with a wet ashing device, and then processing the residue generated in a combustion plant that is conveyed externally from the wet ashing device,
The wet combustion residue removed from the wet ashing device is first separated into two classifications by a mechanical separation process,
The separated main classification consisting essentially of coarse classification and oversize classification is pulverized by a pulverization step, and then washed with water extracted from the wet ashing device, and adhered to the combustion residue. Parts are separated,
The washing water is transported to the wet ashing device together with the fine particle parts detached during the washing step.
A method characterized by that. In a method of treating residue generated in a combustion plant that burns fuel on a combustion grate and raises the temperature of the resulting combustion residue via appropriate combustion control,
Operate the combustion control system so that the combustion residue is pre-sintered and / or melted in the fuel bed of the main combustion zone into main ash,
Quench all of the generated residue in the wet ashing device, then take it out from the wet ashing device,
The wet combustion residue removed from the wet ashing device is first separated into two classifications by a mechanical separation process, and then the main classification consisting essentially of a coarse classification and an oversize classification is converted to the above. Wash with water extracted from the wet ashing device, and separate the fine particle part adhering to the combustion residue,
The washing water is transported to the wet ashing device together with the fine particle parts detached during the washing step.
A method characterized by that. In a method of treating residue generated in a combustion plant that burns fuel on a combustion grate and raises the temperature of the resulting combustion residue via appropriate combustion control,
Operate the combustion control system so that the combustion residue is pre-sintered and / or melted in the fuel bed of the main combustion zone into main ash,
Quench all of the generated residue in the wet ashing device, then take it out from the wet ashing device,
The wet combustion residue removed from the wet ashing device is first separated into two classifications by a mechanical separation process, and then separated into a main classification consisting essentially of a coarse classification and an oversize classification. Is pulverized by a pulverization step, and then washed with water extracted from the wet ashing device,
The washing water is transported to the wet ashing device together with the fine particle parts detached during the washing step.
A method characterized by that.

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