JP2014234968A - Waste melting treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste melting method in which the bulk or whole quantity of coal coke conventionally used in a waste melting furnace can be replaced with a biomass material.SOLUTION: In a waste melting treatment method, waste is charged into a waste melting furnace 1 together with biomass to be thermally decomposed and burnt, and residue after thermal decomposition and burning is melted in a lower part of the furnace. The biomass includes a biomass molding obtained by pressure-molding a biomass material, and a biomass carbide obtained by carbonizing the biomass material. A high-temperature grate is formed from the biomass carbide in the lower part of the melting furnace 1. The biomass carbide and the biomass molding are burnt to be used as a melting heat source.

Description

  The present invention relates to a waste melting method for thermally decomposing and burning waste in a shaft furnace type gasification melting furnace to melt ash.

  As a technique for treating waste such as municipal waste and shredder dust, a waste melting process is known in which waste is pyrolyzed and burned to melt ash to form slag.

  This treatment method is capable of recovering the combustion heat by pyrolyzing and gasifying the waste and burning the combustible gas, and by melting and discharging the ash after the pyrolysis and combustion as slag. It has the advantage that the volume to be finally disposed of in landfill disposal can be reduced. There are several methods for such melting treatment, and one of them is a method using a shaft furnace type waste gasification melting furnace having a vertical shape.

  This shaft furnace type waste gasification melting furnace, for example, burns coke deposited in the lower part of the furnace, throws the waste on this high-temperature coke, pyrolyzes and partially oxidizes it, gasifies and ash Is a furnace that performs a process of melting slag into slag (see Patent Document 1).

  In the shaft furnace type waste gasification and melting furnace of Patent Document 1, the functions of a vertical cylindrical furnace body are roughly divided into three regions in the vertical (up and down) direction. That is, a high-temperature combustion zone having a coke bed with coke deposited at the lower part of the furnace is formed, a waste layer is formed on the high-temperature combustion zone, and a large space above the waste layer at the upper part of the furnace body. The free board part is made.

  In such a gasification melting furnace, oxygen-containing gas is blown into the furnace in each of the three regions. A main tuyere is provided in the high-temperature combustion zone in the lower part of the furnace to burn the coke of the coke bed that has been charged and deposited, and to obtain a melting heat source that melts the residue (ash) after pyrolysis of waste Oxygen-enriched air is blown into. Further, the waste layer is provided with a sub tuyere, and air is blown in order to cause the waste that has been input and deposited to flow gently and to thermally decompose and partially oxidize the waste. In addition, the freeboard section is provided with a third stage tuyere, in order to maintain the inside of the furnace at a predetermined temperature by partially burning part of the pyrolysis gas (combustible gas) generated by pyrolyzing the waste Air is blown into.

  As described above, the shaft furnace type waste gasification and melting furnace is a facility capable of performing both pyrolysis gasification treatment and melting treatment in one furnace as the waste falls in the furnace. The input waste is pyrolyzed to produce gas and residue. Coke on the coke floor is combusted by blowing oxygen-enriched air from the main tuyere to form a high-temperature combustion zone, and the residue after pyrolysis of the waste is melted and discharged as molten slag and molten metal. In the coke floor, a high-temperature grate is formed by the gap generated between the cokes, and the oxygen-enriched air blown from the main tuyere and the high-temperature gas generated by the combustion of the coke are ventilated to raise and vent the above-mentioned gap. Ensuring and ensuring the liquid flow through which the molten slag and the molten metal flow downward through the gap are performed. The high-temperature gas generated by coke combustion in the high-temperature combustion zone heats the waste in the waste layer formed on the high-temperature combustion zone, and the waste is thermally decomposed by blowing air from the sub tuyere. The gas generated by the gas rises in the waste layer, passes through the free board part, and is discharged from the exhaust flue provided in the upper part of the furnace to the secondary combustion chamber outside the furnace. The pyrolysis gas contains a large amount of flammable gas, and part of it is burned by the air blown from the third stage tuyere at the free board part, and further burned in the secondary combustion chamber and recovered by the boiler. Steam is generated and used for power generation and the like. Exhaust gas treatment, such as removing relatively coarse dust with a cyclone, cooling with a temperature reducing device, removing harmful gas by reaction with a hazardous substance remover, and removing dust with a dust collector And then released from the chimney to the atmosphere.

  In such a waste gasification melting furnace, a coke bed in which coke is deposited on the bottom of the furnace forms a high-temperature grate, and the coke forming this high-temperature grate burns to become a heat source for melting the residue after pyrolysis. However, in recent years, there has been a demand for reducing carbon dioxide emissions by reducing the amount of coal coke derived from fossil fuels. A waste melting method has been proposed in which the amount of coke used is reduced by using massive biomass carbides such as charcoal and charcoal obtained by heat-compression-molding sawdust from building waste as an alternative fuel for coal coke (see Patent Document 2). .

JP 09-060830 A JP-A-2005-249310

  In order to reduce the amount of carbon dioxide emitted, in order to reduce the amount of coke used in the waste melting furnace, even if bulk biomass carbide is used as an alternative to coke as in Patent Document 2, biomass carbide is compared with coal coke. Therefore, there is a problem that the cost required for reducing the amount of coal coke used increases and the operating cost of the waste melting furnace increases.

  As described above, even when biomass carbide is used as a substitute for coke, there is a problem in that the operating cost increases, and it has been impossible to reduce the amount of coke used by replacing most or all of the coke with biomass.

  In view of such circumstances, an object of the present invention is to provide a waste melting method capable of reducing the amount of coke used by replacing most or all of the conventionally used coal coke with biomass.

  In the waste melting method according to the present invention, waste is introduced into a waste melting furnace together with biomass, the waste is pyrolyzed and burned, and the ash content after pyrolytic combustion is melted in the lower part of the furnace.

  In such a waste melting treatment method, in the present invention, the biomass includes a biomass molded product obtained by pressure-molding a biomass raw material and a biomass carbide obtained by carbonizing the biomass raw material. It is characterized by burning biomass charcoal and biomass molding to form a heat source for melting ash.

  Biomass is categorized by FAO (International Food and Agriculture Organization). As biomass, woody biomass such as wood chips, forest residue, thinned wood, unused trees, sawn timber, construction waste, rice straw, rice husk, herbaceous Examples of the biomass include papermaking biomass, agricultural residues, livestock manure, and unused biomass resources such as food waste. In the present invention, a pressure-molded product using these biomasses as raw materials (referred to as biomass raw materials) is used as a biomass molded product, and a carbonized product is used as biomass carbide.

  Coal coke that has been used in the past has the function of forming a high-temperature grate that ensures air flow and liquid flow through the gaps formed between the coke due to its bulk shape, and melts ash It has a function as a heat source. On the other hand, in the present invention, the biomass carbide forms a high-temperature grate, and the biomass molded product can be used even if its high-temperature strength is low, and burns with the biomass carbide to function as a heat source for melting ash.

  According to the present invention having such a configuration, by using both the biomass charcoal obtained from the biomass raw material and the biomass molded product, most or all of the conventionally used coal coke is replaced with biomass, and the required energy is obtained from the biomass. While ensuring, a stable operation of melting waste ash can be performed by forming a high-temperature grate with biomass carbide in the lower part of the furnace.

  In the present invention, the supply of biomass carbide and biomass molding is performed by setting the input amount of biomass carbide to 1 to 3 wt% with respect to the waste input amount, and setting the input amount of biomass molding to 3 to 10 wt% with respect to the waste input amount. % Is desirable. By making the biomass carbide and the biomass molding into such an input amount, in an optimum state, the biomass carbide and the biomass molding are burned while forming a good high temperature grate with the biomass carbide at the lower part of the furnace. An ash melting heat source can be secured by the amount of heat generated.

In the present invention, it is preferable that the biomass carbide has a drum strength DI ₁₅ ³⁰ of 50% or more and a post-hot reaction strength index CSR (10 mm) of 10% or more.

  Moreover, in this invention, it is preferable that the intensity | strength index CSR (10 mm) after hot reaction of a biomass molded product is 5% or less.

  Furthermore, in the present invention, it is preferable that the biomass molded product is a molded product obtained by pressure molding while heating to a temperature lower than the carbonization temperature.

  As described above, the present invention uses both the biomass carbide and the biomass molded product, and generates the biomass carbide and the biomass molded product by burning the biomass carbide and the biomass molded product while forming a high-temperature grate by the biomass carbide in the lower part of the furnace. As the ash melting heat source can be secured by the amount of heat, the operation cost can be suppressed by using a cheap biomass molding compared with the expensive biomass carbide, and most or all of the coke that has been used can be replaced with biomass. The amount of carbon dioxide generated can be reduced by significantly reducing or eliminating coke usage.

It is a figure which shows schematic structure of the one Embodiment apparatus of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1 of the accompanying drawings. The present embodiment is characterized in that biomass is introduced into the shaft furnace type waste gasification melting furnace together with waste, and the biomass includes biomass carbide and biomass molded product. Prior to explanation of these features, A schematic configuration of the shaft furnace type waste gasification melting furnace will be described.

  The shaft furnace type waste gasification and melting furnace of one embodiment of the present invention shown in FIG. 1 includes a waste as a processing object, a biomass molding as a fuel, and a biomass at the top of the gasification melting furnace 1. An inlet 2 for introducing limestone as a component adjusting material for carbide and slag into the furnace is provided, and a gas outlet 3 for exhausting the gas in the furnace to the outside of the furnace is provided on the upper side. It has been. In addition, an outlet 4 for discharging molten slag and molten metal is provided in the lower part of the gasification melting furnace 1.

  In the shaft furnace type waste gasification and melting furnace, the internal space of the gasification and melting furnace 1 is roughly divided into three regions in the vertical direction. This is a region having a middle shaft portion II located at the top and a free board portion III formed at the top. Each of these parts I, II, and III is an area having the following functions. That is, the lower shaft portion I is a region where the deposited biomass molded product and biomass carbide are burned to form a high temperature combustion zone, and the middle shaft portion II is formed by the accumulation of wastes put on the high temperature combustion zone. The region where the waste in the generated waste layer is thermally decomposed, the free board part III, is a region where a part of the generated combustible gas is combusted.

  Disposed above the waste gasification and melting furnace 1 is a supply device (not shown) for supplying waste such as municipal waste, biomass charcoal, biomass molding, and limestone used as a component adjusting material for the generated slag. The waste, biomass charcoal, biomass molding, and limestone supplied from this supply device are conveyed by a conveyer (not shown) and charged into the furnace through the inlet 2 at the top of the furnace.

  A tuyere for blowing oxygen-containing gas is provided on the furnace wall for each of the lower shaft portion I, the middle shaft portion II, and the freeboard portion III formed in the waste gasification melting furnace. That is, the main tuyere 5 that blows oxygen-enriched air for melting the pyrolysis residue (ash) into the lower shaft portion I to form a high-temperature combustion zone by burning the deposited biomass carbide and biomass molded product. The middle shaft portion II is provided with a sub tuyere 6 for blowing air for pyrolyzing and burning while gently flowing the waste deposited and deposited, and the free board portion III A three-stage tuyere 7 for blowing air for burning a part of the combustible gas generated by thermal decomposition of the waste and maintaining the inside of the furnace at a predetermined temperature is provided.

  A secondary combustion chamber 10 is connected to the gas discharge port 3, and combustible gas generated by pyrolyzing waste is combusted in the secondary combustion chamber 10. The secondary combustion chamber is provided with an air blowing port 11 for blowing air for secondary combustion. Further, the secondary combustion chamber 10 is provided with a boiler 12 adjacent to which heat is recovered from the combustion gas obtained by burning the combustible gas in the secondary combustion chamber 10.

  Next, a description will be given of biomass charcoal and biomass molded product that are put into the furnace in place of the previously used coal coke together with waste in the gasification melting furnace 1 described above.

  The waste thrown into the gasification melting furnace is pyrolyzed and gasified in the upper part of the waste layer in the middle shaft part II, and the pyrolysis residue (ash content) reaches the lower part of the furnace. Conventionally, coal coke that was introduced at the same time as waste reaches the lower part of the furnace without being consumed in the waste layer, burns with oxygen-enriched air blown from the main tuyere, generates high temperature, and waste To melt the ash.

  Coal coke conventionally used in a waste gasification and melting furnace has two functions of “high temperature grate formation in the lower part of the furnace” and “ash melting heat source”. Coal coke is in the form of a lump from the beginning of charging into the furnace, and a high-temperature grate is formed in the high-temperature combustion zone of the lower shaft portion I by a gap between the coal cokes. The upper surface of this high-temperature grate layer is located above the main tuyere 5, and the oxygen-enriched air blown from the main tuyere 5 rises and ventilates the gaps, so that coal coke burns well. The sufficiently high temperature combustion gas rises and reaches the waste layer. On the other hand, in the high-temperature combustion zone, the ash content of the waste is sufficiently melted by the amount of heat generated by the combustion of coal coke, resulting in molten slag and molten metal. The molten slag and the molten metal flow down well through the gap between the high-temperature grate and reach the taphole 4.

  In the present invention, for the purpose of replacing most or all of the coal coke with biomass, biomass carbide is used for “high temperature grate formation in the lower part of the furnace” and biomass molded product (for ash melting heat source) ( Non-carbonized biomass) is put into the furnace instead of coal coke. In this way, it is possible to ensure two functions of coal coke that has been conventionally used by using biomass, and thereby it is possible to perform melting and gasification treatment of waste without using coal coke.

  In the present invention, a pressure-molded product using biomass as a raw material (referred to as biomass raw material) is used as a biomass molded product. As the pressure molding method, a method such as extrusion molding, filling a mold, and pressure molding is used. Moreover, you may use what was pressure-molded as a biomass molded product, heating to temperature lower than carbonization temperature. Here, the carbonization temperature refers to the temperature at which the volatile matter of the biomass raw material starts to volatilize, and is also the temperature at which dry distillation begins. Since the biomass molded product that is pressure-molded while heating the biomass raw material to a temperature lower than the carbonization temperature contains volatile components, this biomass molded product is charged and burned at the bottom of the melting furnace to become a melting heat source. Thus, the combustion heat of the volatile matter of the biomass material can be used effectively.

  In this invention, it is preferable that the input amount of biomass shall be 1-3 wt% of biomass charcoal and 3-10 wt% of biomass molding with respect to the amount of waste treated. If the amount of biomass carbide input is less than 1 wt% of the waste treatment amount, a high-temperature grate cannot be sufficiently formed, and if it exceeds 3 wt%, the effect on the formation status of the high-temperature grate will not change, but rather expensive biomass carbide The upper limit is set to 3 wt% because the operation cost cannot be suppressed because a large amount of is used. If the amount of biomass molding input is less than 3 wt% of the waste treatment amount, it will be insufficient as a melting heat source, and if it exceeds 10 wt%, the effect on ash melting will not change, so there is no need to add excessively and the upper limit is 10 wt %.

  Hereinafter, the biomass molded product and biomass carbide will be described in more detail. In addition, although various biomass raw materials exist, in the present invention, there is no particular limitation on the biomass raw material, and any type may be used.

<Biomass molded product>
The biomass molded product has an apparent density of 1.2 g / cm ³ or more, desirably 1.3 g / cm ³ or more. The weight of the biomass molded product is preferably 100 g or more, desirably 200 g or more per piece. It is preferable that the biomass molding has such a high density and high weight because it can reach the lower part of the furnace in a short time after being put into the furnace and is not consumed in the process of descending. Further, the moisture content of the biomass molded product is preferably 15 wt% or less, and desirably 10 wt% or less. The shape may be any of a spherical shape, a cylindrical shape, a rectangular parallelepiped shape, and the like. By introducing such a biomass molded product, coal coke can be substituted as an “ash melting heat source” in operation without using coal coke.

  As the biomass molded product, it is preferable to use a molded product while being heated to a temperature lower than the carbonization temperature. Such a biomass molded product has not only fixed carbon but also a calorific value including a volatile component, and the volatile component calorie can contribute to melting of ash. Biomass molded products have a large amount of the above volatile components, and carbides carbonized from biomass molded products in the furnace are also highly reactive. Consumed as a melting heat source.

Compared to the fact that coal coke descends and reaches the lower part of the furnace, there is a part that is consumed, and the biomass molding has a high density and high weight (preferably an apparent density of 1.3 g as described above) / Cm ³ or more, weight 200 g or more), it reaches the lower part of the furnace in a shorter time than coal coke, so a high-density, high-weight biomass molded product consumes less in the process of reaching the lower part of the furnace. . As a result, the amount of heat supplied by the coal coke of the supply amount that was conventionally supplied as the melting heat source and the supply amount less than the calculated value of the supply amount of biomass molding required to supply the same amount of heat, In the lower part, the ash melting state equivalent to that when using coal coke, that is, the ash melting slag can be raised to the same temperature. As described above, the high-density and high-weight biomass molded product can contribute to the supply of the melting heat source at the lower part of the furnace more efficiently.

  On the other hand, biomass carbide used for high-temperature grate formation burns faster than coal coke, so the time during which high-temperature grate can be formed may be shorter than that of coal coke. It is preferable to burn more rapidly on the high-temperature grate layer that the carbide forms in the lower part of the furnace.

  In addition, if combustion residues of biomass moldings on the high-temperature grate and fragments of carbides that could not be burned after the biomass molding was gasified and burned on the high-temperature grate, mixed into the high-temperature grate layer, Molten slag dripping and gas flow are impeded. Therefore, it is preferable that the biomass molded product has a low hot strength and quickly becomes finer and burns and disappears on the high-temperature grate. Therefore, the hot strength of the biomass molded product is preferably 5% or less, preferably 0%, after the hot reaction strength index (CSR) (opening: 10 mm).

  Hereinafter, the hot reaction intensity index will be specifically described. The strength index after hot reaction (CSR) is generally used as one of coke quality indicators.

As a method for evaluating the strength including reactivity in consideration of the behavior of coke after charging in the furnace, there is strength after hot reaction (strength after CO ₂ reaction, CSR). This measures strength after reacting with CO ₂ under specified conditions, and is considered to be an important indicator of coke quality.

This hot reaction strength CSR is measured by reacting a coke sample adjusted to a predetermined particle size range with CO ₂ gas at a temperature of 1100 ° C. for a certain period of time, and charging the coke sample after reaction into a specific test device. Then, after rotating at a constant number of revolutions (for example, 600 revolutions), sieving with a sieve having a mesh opening of 10 mm, the ratio of the coke weight remaining on the sieve to the weight of the coke sample after the reaction charged in the test apparatus is This is the strength after inter-reaction (strength after CO ₂ reaction, CSR). That is, hot strength after reaction CSR is coke after reaction with CO ₂ gas, it shows the percentage of remaining Without being destroyed by the rotation of a particular test device, CO ₂ after the reaction It is used as an index indicating the strength of coke. The higher the CSR, the higher the coke strength. In other words, when the post-hot reaction strength index (CSR) is low, it means that the amount of coke destroyed and powdered after the CO ₂ reaction increases.

  With such a post-hot reaction strength index (CSR), the hot strength of the biomass molded product is evaluated as follows.

The biomass molded product was reacted with CO ₂ gas at a temperature of 1100 ° C. for 2 hours, sized to 20 mm, rotated only 600 times with a type I drum tester, sieved with a sieve having an opening of 10 mm, and sieved The ratio of the remaining weight to the weight of the sample put in the test apparatus was defined as a strength index CSR (10 mm) after hot reaction. Since the hot strength of the biomass molding is low and it is preferable that the biomass molding quickly becomes fine and burns and disappears on the high temperature grate, the hot strength of the biomass molding is the strength index after hot reaction (CSR) (opening) 10 mm) is 5% or less, desirably 0%. When the biomass molded product has a strength index after hot reaction (CSR) of 5% or less, the biomass molded product easily collapses when burned on a high-temperature grate, and can be burned even after gasification combustion. The missing carbide fragments are preferred because they do not cause a problem that the molten slag dripping and the gas flow are hindered by mixing in the high-temperature grate layer. In addition, for economical operation, it is desirable to maximize the amount of low-cost biomass molding used within a range that does not allow carbide fragments from the biomass molding carbonized in the furnace to enter the high-temperature grate at the bottom of the furnace. .

<Biomass carbide>
In the case of operation using only conventional coal coke, about 20 to 40% of coal coke contributes to the formation of a high-temperature grate at the lower part of the furnace. In order to replace the coal coke for forming the high-temperature grate with biomass carbide, it is preferable to use biomass carbide having the following properties. That is, the fuel ratio (fixed carbon / volatile content) is 10 or more, desirably 15 or more, the apparent density is 0.9 g / cm ³ or more, desirably 1.0 g / cm ³ or more, and the weight per piece is 20 g or more, Desirably, 50 g or more of biomass carbide is used. If the fuel ratio of the biomass carbide is 10 or more, desirably 15 or more, the ratio of fixed carbon is high and a high-temperature grate can be formed satisfactorily. Further, if the apparent density of the biomass carbide is 0.9 g / cm ³ or more, preferably 1.0 g / cm ³ or more, or if the weight per piece is 20 g or more, preferably 50 g or more, the biomass After the carbide is introduced, it quickly descends in the furnace, reaches the lower part of the furnace, and can form a high-temperature grate well. The biomass carbide may have any shape such as a spherical shape, a cylindrical shape, and a rectangular parallelepiped shape. The biomass raw material before carbonization may be one obtained by cutting biomass into an appropriate size or one obtained by molding crushed material. Biomass carbides with the above properties are produced by subjecting biomass to high temperature and controlled carbonization for a long time, and are denser and stronger than carbides produced under low temperature and short time conditions. high.

The required strength of the biomass carbide may be that the cold strength is a drum strength DI ₁₅ ³⁰ of 50% or more and a post-hot reaction strength index CSR (10 mm) of 10% or more. Biomass carbide having such strength reaches the lower part of the furnace without being collapsed by being put into the furnace, and can maintain a high-temperature grate.

Here, the drum strength is evaluated by a coke drum strength (DI) test method defined in JISK2151. The sample is put in a specified drum, and after rotating 30 times at a predetermined number of revolutions, the weight% remaining on the 15 mm sieve is expressed as drum strength. If, for example, 60% remains on the sieve, it is expressed as DI ₁₅ ³⁰ = 60.

  In the present embodiment configured as described above, the waste gasification and melting treatment is performed as follows.

  Waste from the supply device, biomass charcoal and biomass molding, and limestone are introduced into the furnace by a predetermined amount through the inlet 2 provided in the upper part of the gasification melting furnace 1, respectively. Oxygen-enriched air or air is blown into the furnace from the mouth 6 and the three-stage tuyere 7, respectively. The waste introduced from the inlet 2 is deposited on the middle shaft part II in the furnace to form a waste layer, and from the high temperature gas and sub tuyere rising from the high temperature combustion zone of the lower shaft part I. It is dried by blown air and then pyrolyzed. A part of the combustible gas generated by pyrolysis is burned in the freeboard section III by the air blown from the three-stage tuyere and maintained at a temperature of 850 ° C. or higher, and decomposes harmful gas and tar content. After being treated, it is sent to a secondary combustion chamber provided outside the furnace, where it is burned and the combustion gas is heat recovered by a boiler. The biomass carbide descends to the lower shaft portion I to form a high-temperature grate, and the biomass molded product descends to the lower shaft portion I and is suppressed on the high-temperature grate while the volatile components are prevented from being pyrolyzed and burned on the way. Thus, a high temperature combustion zone is formed in which the biomass carbonized material and the biomass molded product burn. Residue resulting from thermal decomposition of the waste in the waste layer of the middle shaft part II descends and reaches the lower shaft part I where the high temperature combustion zone is formed. In the lower shaft part I, the volatile matter in the biomass molded product Then, the carbonized biomass and the fixed carbon in the biomass molded product are combusted, and the incombustible and ash are melted by the heat of combustion to form molten slag and molten metal. The molten slag and molten metal are discharged from the tap 4 and supplied to a water granulating device provided outside the furnace, cooled and solidified, and the cooled and solidified granulated slag and granulated metal are recovered.

  Waste carbonization melting furnace is charged with biomass charcoal and biomass molding, high temperature grate is formed with biomass charcoal at the bottom of gasification melting furnace 1, biomass charcoal and biomass molding are burned, and heat of waste A melting heat source that melts decomposition residues (ash) and incombustibles. The amount of biomass carbide to be charged into the furnace is an amount necessary for forming a high-temperature grate, and the amount of heat necessary as a melting heat source is supplemented by the biomass molded product, and a predetermined amount is respectively charged.

  In such a process of gasification and melting of waste, among the biomass charcoal and the biomass molded product as fuel, the biomass charcoal is in the form of a lump from the beginning of charging into the furnace, and in the high temperature combustion zone of the lower shaft portion I. A high-temperature grate is formed by gaps between biomass carbides. The upper surface of this high-temperature grate layer is located above the main tuyere 5, and oxygen-enriched air from the main tuyere 5 rises through the gaps and burns biomass carbide and biomass moldings. Is performed well, and the sufficient combustion gas rises to the waste layer to thermally decompose and partially burn the waste. On the other hand, in the high temperature combustion zone, the waste ash is sufficiently melted by the combustion heat of the biomass carbonized product and the biomass molded product to produce molten slag and molten metal. The molten slag and the molten metal flow down well through the gap between the high-temperature grate and reach the taphole 4.

  According to such a gasification and melting treatment method for waste, the biomass carbide forming the high-temperature grate has an agglomerate shape, and the air passage between the biomass carbides and the passage of liquid can be secured. It functions as a high-temperature grate that is reliably performed and as a heat source for melting ash. On the other hand, high-temperature strength is not necessary for the biomass molded product, and the amount of heat generated by combustion with the biomass carbide is used as a melting heat source. Therefore, the amount of biomass carbide required for forming the high-temperature grate is sufficient, and the shortage as a heat source for melting can be compensated for by the above-mentioned biomass molded product. This enables the formation of high-temperature grate with biomass carbide. As long as the biomass molded product only serves as a source of melting heat, that is, as a melting heat source, high-temperature strength is not required. Therefore, a low-cost biomass molded product can be used, the amount of expensive biomass carbide used can be reduced, and the operating cost of the waste melting furnace can be reduced.

  As described above, in the high-temperature grate, the biomass carbide and the biomass molded product are combusted while maintaining the upward flow of the combustion gas and the downward flow of the molten slag and the molten metal. Thus, the amount of biomass carbide used is minimal, while the biomass molded product does not require high-temperature strength, and low-cost biomass molded products can be used as fuel. Furthermore, by burning the biomass molded product on the high-temperature grate, the combustion heat of the volatile component of the biomass raw material can be effectively used as a melting heat source. In this way, waste gasification and melting treatment without using coal coke can be performed using biomass charcoal and biomass molding, thus reducing carbon dioxide emissions and operating the waste gasification and melting furnace. Costs can be reduced and waste can be melted for stable operation.

  As long as it is a condition that allows the volatile matter of the biomass raw material to remain effectively as the biomass molded product, it may be heat-press molded under other conditions instead of the conditions described above.

<Example>
An operation test was conducted using the waste gasification melting furnace of FIG. The molten slag temperature at the bottom of the furnace is measured as an indicator of the operating state, and the molten slag is smoothly discharged in the operation where only coal coke is added to maintain the molten slag temperature at 1400 ° C, which is a standard for stable operating state. As described above, the operation test was performed by changing the input amounts of biomass carbide and biomass molding. Table 1 shows the properties of the biomass carbide (wood chip molding carbide) and the biomass molding (wood chip molding) used. Table 2 shows the results of the operation test (Examples 1 and 2). Here, the weight ratio of the input amounts of the biomass charcoal and the biomass molded product to the waste treatment amount is expressed as the input rate (%).

  As shown in Table 2, it was confirmed that the operation of becoming a continuous continuous dumping state can be performed at the input rate of the biomass carbides and biomass molded products of Examples 1 and 2, and that the operation without using coal coke can be realized. .

  1 Gasification melting furnace

Claims (5)

  In a waste melting treatment method in which waste is introduced into a waste melting furnace together with biomass, the waste is pyrolyzed and burned, and the ash content after pyrolytic combustion is melted in the lower part of the furnace. And a biomass carbide obtained by molding and carbonizing a biomass raw material, forming a high-temperature grate with the biomass carbide in the lower part of the melting furnace, and burning the biomass carbide and the biomass molding to produce a heat source for melting ash And a waste melting method.   The waste according to claim 1, wherein the input amount of biomass carbide is 1 to 3 wt% with respect to the input amount of waste, and the input amount of biomass molding is 3 to 10 wt% with respect to the input amount of waste. Melt processing method. 3. The waste melting method according to claim 1 or 2, wherein the biomass carbide has a drum strength DI ₁₅ ³⁰ of 50% or more and a post-hot reaction strength index CSR (10 mm) of 10% or more.   The waste melting method according to any one of claims 1 to 3, wherein a strength index CSR (10 mm) after hot reaction of the biomass molded product is 5% or less.   The method for melt treatment of waste according to any one of claims 1 to 4, wherein the biomass molded product is a molded product that is pressure-molded while being heated to a temperature lower than the carbonization temperature.

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