Waste disposal methods

Abstract

To suppress consumption of biomass charcoal and to melt waste.SOLUTION: A waste treatment method of melting ash contents generated by thermal decomposition and gasification of at least waste in a melting furnace charges first biomass charcoal and second biomass charcoal whose consumption required for waste treatment goes beyond a consumption of the first biomass charcoal required for waste treatment in the melting furnace, forms a fire grate in the melting furnace with the first biomass charcoal to burn the first biomass charcoal, burns the second biomass charcoal in the fire grate or on an upper surface, melts the ash contents with heat caused by combustion of the first biomass charcoal and the second biomass charcoal, and makes a ratio of weight of the first biomass charcoal relative to a weight totalizing weight of the charged first biomass charcoal and weight of the charged second biomass charcoal 30% or higher.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a waste treatment method. [Background technology]

[0002] In a gasification melting furnace that processes waste, coke made from coal is fed along with the waste. This coke reaches the bottom of the furnace and burns, forming a grate through the gaps between the coke. The waste fed into the gasification melting furnace is pyrolyzed and gasified by the high heat and high-temperature gases produced by the combustion of the coke, and the ash resulting from pyrolysis and gasification reaches the bottom of the furnace. The ash that reaches the bottom of the furnace is melted by the heat from the combustion of the coke, producing molten slag and molten metal. The molten slag and molten metal then descend through the gaps in the grate formed by the coke and are discharged from the slag outlet.

[0003] In contrast to such processing methods that use coke, there is an invention that processes waste using biomass instead of coke in a gasification melting furnace in order to reduce carbon dioxide emissions during operation of the furnace. For example, the waste melting method disclosed in Patent Document 1 uses biomass molded products, which are formed by pressure molding biomass raw materials, and biomass charcoal, which is carbonized biomass raw materials, instead of coke. In this melting method, the biomass charcoal forms a grate and also functions as a heat source for melting the ash. Furthermore, in this melting method, the amount of biomass charcoal charged is limited to at least the minimum amount necessary to form the grate, and the heat required to melt the ash is compensated for by the heat generated by burning the biomass molded products. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6168287 Summary of the Invention [Problem to be solved by the invention]

[0005] When biomass charcoal is used in a gasification and melting furnace, a large amount of biomass charcoal is used. However, since it is difficult to secure large quantities of the same type of biomass charcoal, gasification and melting furnaces that process waste use products from multiple biomass charcoal plants. When products from multiple biomass charcoal plants are used, the properties of the biomass charcoal vary depending on the plant that produces it. The amount of biomass charcoal consumed to process waste varies greatly depending on the properties of the biomass charcoal, so consumption can increase significantly depending on the biomass charcoal used.

[0006] The present invention has been made in view of the above, and aims to melt waste while reducing the consumption of biomass charcoal. [Means for solving the problem]

[0007] A waste treatment method according to one aspect of the present invention is a waste treatment method in which ash produced by at least pyrolysis and gasification of waste in the melting furnace is melted in the melting furnace, the method comprising: charging first biomass charcoal and second biomass charcoal, the amount of which required to treat the waste exceeding the amount of first biomass charcoal required to treat the waste, forming a grate in the melting furnace using the first biomass charcoal to combust the first biomass charcoal, burning the second biomass charcoal in or on the grate, melting the ash with heat from the combustion of the first biomass charcoal and the second biomass charcoal, and setting the ratio of the weight of the first biomass charcoal to the combined weight of the first biomass charcoal charged and the second biomass charcoal charged to 30% or more.

[0008] In the waste treatment method according to the present invention, the first biomass charcoal may be made up of a plurality of types of biomass charcoal that differ in the amount consumed for treating the waste.

[0009] In the waste treatment method according to the present invention, the first biomass charcoal has an apparent density of 0.9 g / cm 3The weight per piece may be 60 g or more, the volatile content may be 7 dry wt % or less, and the lower heating value may be 26 MJ / kg or more.

[0010] In the waste treatment method according to the present invention, the second biomass charcoal may be made up of a plurality of types of biomass charcoal that differ in the amount consumed for treating the waste. [Effects of the Invention]

[0011] According to the present invention, it is possible to achieve the effect of melting waste while reducing the consumption of biomass charcoal. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing the configuration of a gasification and melting furnace 1 according to an embodiment of the present invention. [Figure 2] FIG. 2 is a graph showing the measurement results of the consumption of biomass charcoal. [Figure 3] FIG. 3 is a graph showing the measurement results of the consumption of biomass charcoal. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments described below. It should be noted that the drawings are schematic and that the dimensional relationships between elements may differ from the actual ones.

[0014] [Embodiment] Figure 1 is a diagram showing the configuration of a gasification and melting furnace 1 according to an embodiment of the present invention. The gasification and melting furnace 1 is a shaft furnace type. In this embodiment, two types of biomass charcoal are fed into the gasification and melting furnace 1 along with waste, and the heat generated by the combustion of the fed biomass charcoal is used to gasify and melt the waste.

[0015] A supply device is provided above the gasification and melting furnace 1 to supply waste 33 such as municipal solid waste, first biomass charcoal 31, second biomass charcoal 32, and limestone 34. The supply device is not shown in Figure 1. The limestone 34 is used as a composition adjuster for the slag produced in the gasification and melting furnace 1.

[0016] The gasification and melting furnace 1 has an inlet 2 at the top of the furnace. Waste 33, first biomass charcoal 31, second biomass charcoal 32, and limestone 34 are transported from a supply device by a transport conveyor and fed into the furnace through the inlet 2. Note that the transport conveyor is not shown in FIG. 1. The first biomass charcoal 31 and the second biomass charcoal 32 may be placed in separate hoppers, and a predetermined amount of each may be cut out and fed into the supply device. Alternatively, the first biomass charcoal 31 and the second biomass charcoal 32 may be mixed in advance and placed in a single hopper, and then cut out from one location and fed into the supply device.

[0017] A gas outlet 3 is provided on the side of the upper furnace of the gasification and melting furnace 1. The gas outlet 3 is an outlet for discharging gas generated in the furnace to a secondary combustion chamber 10. The secondary combustion chamber 10 is connected to the gas outlet 3. The secondary combustion chamber 10 is provided with an air outlet 11 for blowing in air for secondary combustion. In the secondary combustion chamber 10, combustible gases generated by the pyrolysis and gasification of the waste 33 in the gasification and melting furnace 1 are burned.

[0018] A boiler 12 is provided adjacent to the secondary combustion chamber 10. The boiler 12 recovers heat generated by burning combustible gas in the secondary combustion chamber 10. The exhaust gas from which heat has been recovered in the boiler 12 is sent to an exhaust gas treatment device connected to the boiler 12. Note that the exhaust gas treatment device is not shown in FIG. 1.

[0019] The internal space of the gasification and melting furnace 1 is roughly divided into three regions in the vertical direction. Specifically, the internal space is roughly divided into a lower shaft section 21, a middle shaft section 22, and a freeboard section 23 from the bottom.

[0020] The lower shaft section 21 is an area where the first biomass charcoal 31 and the second biomass charcoal 32 that have been introduced and piled up in the furnace are combusted to form a high-temperature combustion zone. Waste 33 introduced into the furnace is piled up on the high-temperature combustion zone formed in the lower shaft section 21 to form a waste layer. A main tuyere 5 is provided on the furnace wall of the lower shaft section 21. The main tuyere 5 is a tuyere through which oxygen-enriched air is blown in to form the high-temperature combustion zone. The lower shaft section 21 also has a slag discharge port 4. The slag discharge port 4 is a discharge port for discharging slag formed by melting the ash of the waste 33 and molten metal contained in the waste 33.

[0021] The middle shaft section 22 is located above the lower shaft section 21. The middle shaft section 22 is a region where waste 33 in the waste layer formed on the high-temperature combustion zone is pyrolyzed. Sub-tuyeres 6 are provided on the furnace wall of the middle shaft section 22. The sub-tuyeres 6 are tuyeres through which air is blown in to gently flow the charged and piled waste 33 while pyrolyzing and combusting it.

[0022] The freeboard section 23 is located above the middle shaft section 22. The freeboard section 23 is an area where a portion of the combustible gas produced by the combustion of the waste 33 is combusted. A three-stage tuyere 7 is provided on the furnace wall of the freeboard section 23. The three-stage tuyere 7 blows air into the furnace to combust a portion of the combustible gas produced by the thermal decomposition of the waste 33 and maintain the interior of the furnace at a predetermined temperature.

[0023] Next, we will explain the first biomass charcoal 31 and the second biomass charcoal 32 that are fed into the gasification and melting furnace 1 together with the waste 33. In the present invention, the first biomass charcoal 31 and the second biomass charcoal 32 are fed into the gasification and melting furnace 1 instead of coke.

[0024] In the present invention, the first biomass charcoal 31 and the second biomass charcoal 32, which are examples of biomass charcoal, are charcoal products obtained by pressurizing and carbonizing biomass. Examples of pressurizing methods include extrusion molding and pressurizing after filling a mold. While various raw materials exist for the first biomass charcoal 31 and the second biomass charcoal 32, the present invention does not place any particular restrictions on the biomass raw materials, and any type may be used. The biomass before carbonization may be cut to an appropriate size, or may be crushed and molded.

[0025] The first biomass charcoal 31 and the second biomass charcoal 32 function as a heat source for melting ash produced by the pyrolysis and gasification of the waste 33. The first biomass charcoal 31 and the second biomass charcoal 32 also form a grate in the lower part of the furnace. That is, in the present invention, by using the first biomass charcoal 31 and the second biomass charcoal 32, the function of the grate and the function of the heat source for melting ash are ensured, and the melting and gasification treatment of the waste 33 becomes possible without using coke.

[0026] For example, when the weight of coke consumed to process 1000 kg of waste 33 is taken as 100%, the weight of the first biomass charcoal 31 consumed to process 1000 kg of waste 33 is less than 100%. In other words, an example of the first biomass charcoal 31 is biomass charcoal that is consumed in an amount less than that of coke to process the waste 33. The shape of the first biomass charcoal 31 is, for example, cylindrical, but it may also be spherical or rectangular.

[0027] In order to replace the coke for forming the grate with the first biomass charcoal 31, it is preferable to use the first biomass charcoal 31 having the following properties. Specifically, the first biomass charcoal 31 has an apparent density of 0.9 g / cm 3 More preferably, the apparent density is 1.0 g / cm 3It is preferable that the weight of each piece of the first biomass charcoal 31 is 60 g or more, and more preferably 90 g or more. The first biomass charcoal 31 preferably has a volatile content of 7 dry wt% or less. The first biomass charcoal 31 preferably has a lower heating value of 26 MJ / kg or more. The first biomass charcoal 31 is produced by subjecting biomass to a long-term carbonization process, ultimately reaching a high temperature. It has a higher density and strength than charcoal produced under low-temperature and short-term conditions. The first biomass charcoal 31, which has a high apparent density and a heavy weight, quickly descends within the furnace to reach the lower part of the furnace, and only a small amount is burned during the process, allowing for the formation of a good grate. The first biomass charcoal 31 has a slow combustion rate and remains in the furnace for a long time, allowing for a reduced amount of material to be added to form a grate of the same volume. Therefore, the amount of the first biomass charcoal 31 fed per unit time can be reduced in order to maintain a region where the ash can be melted.

[0028] For example, if the weight of coke used to process 1,000 kg of waste 33 is taken as 100%, the second biomass charcoal 32 is biomass charcoal whose weight consumed to process 1,000 kg of waste 33 is 100% or more. In other words, an example of the second biomass charcoal 32 is biomass charcoal whose consumption amount to process the waste 33 is equal to or greater than that of coke. The shape of the second biomass charcoal 32 may be any of spherical, cylindrical, rectangular, etc. For example, the second biomass charcoal 32 may be biomass charcoal that does not have the properties required for the first biomass charcoal 31 described above. Such second biomass charcoal 32 burns together with the first biomass charcoal 31 and functions as a heat source to melt the ash. Note that the second biomass charcoal 32 does not need to be high in strength as long as it serves only as a heat source to reach the lower shaft portion 21 and melt the ash.

[0029] In the present invention, the first biomass charcoal 31 and the second biomass charcoal 32 are charged into the furnace at a predetermined ratio so that the total weight of the first biomass charcoal 31 and the second biomass charcoal 32 is less than the total weight of the coke alone. For example, when the first biomass charcoal 31 and the second biomass charcoal 32 are mixed and charged into the furnace, the mixing ratio of the first biomass charcoal 31 is 30% or more, preferably 40% or more, and more preferably 50%. Here, the mixing ratio of the first biomass charcoal 31 refers to the ratio of the weight of the first biomass charcoal 31 to the total weight of the first biomass charcoal 31 and the second biomass charcoal 32. Here, when the first biomass charcoal 31 and the second biomass charcoal 32 are used as a mixture, the total amount of biomass charcoal required to melt the ash is less than the simple average of the amounts of each biomass charcoal used individually, weighted by the mixing ratio. If the mixing ratio of the first biomass charcoal 31 is 50% or more, operation is possible with the same weight as when only the first biomass charcoal 31 is charged into the furnace. Note that if the mixing ratio of the first biomass charcoal 31 is 30% or more, multiple types of second biomass charcoal 32 with different properties may be mixed and charged into the gasification and melting furnace 1. Furthermore, with regard to the first biomass charcoal 31, if the mixing ratio is 30% or more, multiple types of first biomass charcoal 31 with different properties may be mixed and charged into the gasification and melting furnace 1.

[0030] Next, we will explain the gasification and melting process of waste 33 in the gasification and melting furnace 1. Predetermined amounts of waste 33, first biomass charcoal 31, second biomass charcoal 32, and limestone 34 supplied from a supply device are each charged into the furnace through the charging port 2. Oxygen-enriched air is blown into the furnace through the main tuyeres 5. Air is also blown into the furnace through the sub-tuyeres 6 and the third-stage tuyeres 7.

[0031] Waste 33 introduced through the inlet 2 is deposited in the middle shaft section 22 inside the furnace, forming a waste layer. This waste layer is dried by high-temperature gases rising from the high-temperature combustion zone in the lower shaft section 21 and air blown in through the sub-tuyeres 6, and then pyrolyzed. The combustible gases generated by the pyrolysis of the waste 33 are combusted in the freeboard section 23 by air blown in through the third-stage tuyeres 7, maintaining a temperature of 850°C or higher. The combustible gases are then decomposed and sent to the secondary combustion chamber 10 located outside the furnace. In the secondary combustion chamber 10, air is blown in through the air outlet 11, and combustible gases supplied through the gas outlet 3 are combusted. The heat generated by the combustion of the combustible gas in the secondary combustion chamber 10 is recovered in the boiler 12.

[0032] The first biomass charcoal 31 descends into the lower shaft section 21, and the gaps between the first biomass charcoal 31 form a grate through which air and liquid can pass. The second biomass charcoal 32 descends into the lower shaft section 21 and burns on the grate formed by the first biomass charcoal 31. The second biomass charcoal 32 has a weaker grate-forming ability than the first biomass charcoal 31, so it enters the grate but is consumed by combustion before reaching the bottom of the grate. The top surface of the grate layer formed by the first biomass charcoal 31 is located above the main tuyere 5. Oxygen-enriched air blown in from the main tuyere 5 rises through the gaps between the first biomass charcoal 31 and combusts the first biomass charcoal 31 and the second biomass charcoal 32. The combustion of the first biomass charcoal 31 and the second biomass charcoal 32 forms a high-temperature combustion zone that serves as a heat source for melting ash and incombustible materials in the waste 33.

[0033] Combustion gases generated by the combustion of the first biomass charcoal 31 and the second biomass charcoal 32 rise to the waste layer and pyrolyze and gasify the waste 33. Ash from the pyrolyzed and gasified waste 33 in the waste layer in the middle shaft section 22 descends and reaches the lower shaft section 21, where a high-temperature combustion zone is formed. In the lower shaft section 21, the first biomass charcoal 31 and the second biomass charcoal 32 combust, and the heat of this combustion turns the ash into molten slag and molten metal. The molten slag and molten metal then descend through the gaps between the first biomass charcoal 31 that form the grate and are discharged from the slag discharge port 4. The slag and metal discharged outside the furnace are supplied to a water granulation device installed outside the furnace, where they are cooled, solidified, and recovered.

[0034] [Example] The inventors of the present invention conducted an operational test using the gasification and melting furnace 1 shown in FIG. 1. During the operational test, the properties of biomass charcoals A to F charged into the gasification and melting furnace 1 were measured. Table 1 shows the properties of biomass charcoals A to F. In addition, in the operational test, for biomass charcoals A to F with the properties shown in Table 1, the consumption amount per 1000 kg of waste when only biomass charcoal was charged into the gasification and melting furnace 1 was measured. Note that the consumption amount per 1000 kg of waste when only biomass charcoal was charged is shown as a relative value to the weight of coke, where the weight of coke when only coke is charged into the gasification and melting furnace 1 is set to 100%.

[0035] [Table 1]

[0036] Biomass charcoal A, biomass charcoal B, and biomass charcoal C, which have the properties shown in Table 1, have a consumption rate of less than 100% per 1,000 kg of waste, and correspond to the first biomass charcoal 31. Furthermore, biomass charcoal A, biomass charcoal B, and biomass charcoal C match the properties of the first biomass charcoal 31 described above.

[0037] Biomass charcoal D and biomass charcoal E, whose properties are shown in Table 1, had a consumption rate of 100% or more per 1,000 kg of waste, and correspond to second biomass charcoal 32. As for biomass charcoal F, it was prone to collapse in the furnace and a high-temperature combustion zone was not sufficiently formed, so the molten slag was not discharged from the slag outlet 4, making it impossible to continue operating the gasification melting furnace 1, and therefore the consumption rate per 1,000 kg of waste could not be measured. Biomass charcoal F also corresponds to second biomass charcoal 32.

[0038] In addition, in the operational test, different ratios of the first biomass coal 31 and the second biomass coal 32 were charged into the gasification and melting furnace 1, and the total consumption of the first biomass coal 31 and the second biomass coal 32 was measured. FIG. 2 is a graph showing the measurement results of the total consumption of biomass coal B and biomass coal D when different ratios of biomass coal B corresponding to the first biomass coal 31 and biomass coal D corresponding to the second biomass coal 32 were charged into the gasification and melting furnace 1. Note that the measured consumption is shown as a relative value to the weight of coke when biomass coal B and biomass coal D are charged into the furnace, with the weight of coke being set to 100% when only coke is charged into the gasification and melting furnace 1. In the graph of FIG. 2, the horizontal axis represents the mixing ratio of biomass coal B charged, and the vertical axis represents the total consumption of biomass coal B and biomass coal D relative to the coke.

[0039] As shown in Figure 2, when the mixing ratio of biomass charcoal B, which is the first biomass charcoal 31, is 30% or more, the combined consumption of biomass charcoal B, which is the first biomass charcoal 31, and biomass charcoal D, which is the second biomass charcoal 32, is less than the consumption of coke when only coke is fed into the gasification and melting furnace 1. In other words, when the mixing ratio of first biomass charcoal 31 is 30% or more, the waste 33 can be treated with a smaller weight of the first biomass charcoal 31 and the second biomass charcoal 32 fed into the furnace than with coke. In addition, the combined consumption of biomass charcoal B, which is the first biomass charcoal 31, and biomass charcoal D, which is the second biomass charcoal 32, is located below the simple average, i.e., the line connecting the points where the mixing ratio of biomass charcoal B is 0% and 100% in Figure 2. When the mixing ratio of biomass charcoal B is 30%, the consumption amount when simply weighted by the mixing ratio is 87% × 0.3 + 130% × 0.7 = 117%, but according to Figure 2, it is 101%, showing a significant reduction effect of more than 10%. When the mixing ratio of biomass charcoal B (first biomass charcoal 31) is 50% or more, the combined consumption of biomass charcoal B (first biomass charcoal 31) and biomass charcoal D (second biomass charcoal 32) does not increase significantly from the consumption amount when only biomass charcoal B is fed into the gasification and melting furnace 1, increasing by less than 4%. When the mixing ratio of biomass charcoal B is 40%, the increase is 8%, and when it is 30%, the increase is 16%.

[0040] 3 is a graph showing the measurement results of the combined consumption of biomass coal C and biomass coal F when varying the mixing ratio of biomass coal C corresponding to the first biomass coal 31 and biomass coal F corresponding to the second biomass coal 32 and charging them into the gasification and melting furnace 1. The measured consumption is shown as a relative value to the weight of coke, where the weight of coke when only coke is charged into the gasification and melting furnace 1 is set to 100%, and the total weight of biomass coal C and biomass coal F when biomass coal C and biomass coal F are charged into the furnace. In the graph of FIG. 3, the horizontal axis represents the mixing ratio of charged biomass coal C, and the vertical axis represents the combined consumption of biomass coal C and biomass coal F relative to the coke. When the mixing ratio of biomass charcoal C, which is the first biomass charcoal 31, is 50% or more, the combined consumption of biomass charcoal C, which is the first biomass charcoal 31, and biomass charcoal F, which is the second biomass charcoal 32, does not increase significantly from the consumption when only biomass charcoal C is fed into the gasification and melting furnace 1, increasing by less than 10%. If the mixing ratio of biomass charcoal C is 40%, the increase is 22%, and if it is 30%, the increase is 39%, but continued operation was impossible in the range where the mixing ratio of biomass charcoal C is less than 30%.

[0041] 3, even if the mixing ratio of biomass coal C, which is the first biomass coal 31, is 30% or more, the combined consumption of biomass coal C, which is the first biomass coal 31, and biomass coal F, which is the second biomass coal 32, may be greater than the amount of coke consumed when only coke is fed into the gasification and melting furnace 1. In this case, as shown in FIG. 3, if the mixing ratio of biomass coal C, which is the first biomass coal 31, is 50% or more, the combined consumption of biomass coal C, which is the first biomass coal 31, and biomass coal F, which is the second biomass coal 32, will be less than the amount of coke consumed when only coke is fed into the gasification and melting furnace 1. Furthermore, even when biomass charcoal B and biomass charcoal D are mixed, as shown in Figure 2, if the mixing ratio of biomass charcoal B, which is the first biomass charcoal 31, is 50% or more, the combined consumption of biomass charcoal B, which is the first biomass charcoal 31, and biomass charcoal D, which is the second biomass charcoal 32, is less than the consumption of coke when only coke is fed into the gasification and melting furnace 1. In other words, even if the type of first biomass charcoal 31 and the type of second biomass charcoal 32 are changed, if the mixing ratio of first biomass charcoal 31 is 50% or more, waste 33 can be treated with less consumption than coke. Furthermore, if the first biomass charcoal 31 is mixed at 50% or more, the influence of second biomass charcoal 32 is less apparent, and operation at a consumption rate close to that of first biomass charcoal 31 becomes possible regardless of the type of second biomass charcoal 32.

[0042] As described above, in the present invention, by charging a mixture of the first biomass charcoal 31 and the second biomass charcoal 32, the consumption of the first biomass charcoal 31 used to form the grate can be reduced. Furthermore, in the present invention, the heat quantity that is insufficient in the first biomass charcoal 31 for melting the ash can be compensated for by the second biomass charcoal 32. That is, in the present invention, the first biomass charcoal 31 and the second biomass charcoal 32 ensure the heat quantity for melting the ash, while the consumption of the first biomass charcoal 31 can be reduced to form the grate. Furthermore, in the present invention, the first biomass charcoal 31 and the second biomass charcoal 32 can be used to melt the waste 33 with less consumption than coke, thereby reducing carbon dioxide emissions and the operating costs of the gasification and melting furnace 1, thereby enabling stable operation.

[0043] Furthermore, when only one type of biomass charcoal is fed into the gasification and melting furnace 1, changing the type of biomass charcoal causes fluctuations in consumption. For example, if only one type of biomass charcoal is fed into the gasification and melting furnace 1 during operation and the fed biomass charcoal is changed from biomass charcoal B to biomass charcoal E, the amount of biomass charcoal consumed will increase significantly. On the other hand, in the present invention, by mixing the first biomass charcoal 31 and the second biomass charcoal 32 in a predetermined ratio, consumption can be reduced compared to when only coke is fed into the furnace, even when the types of the first biomass charcoal 31 and the second biomass charcoal 32 are changed. Furthermore, because operation can be continued at a consumption rate close to that when only the first biomass charcoal 31 is used, fluctuations in consumption caused by feeding only one type of biomass charcoal and changing the type can be suppressed.

[0044] Furthermore, in the present invention, even when the first biomass charcoal 31 and the second biomass charcoal 32 are mixed and charged, the consumption amount is not simply the average of the consumption amount when only the first biomass charcoal 31 is used and the consumption amount when only the second biomass charcoal 32 is used, but it is possible to operate at a consumption amount close to the consumption amount when only the first biomass charcoal 31 is charged. As a result, even when the second biomass charcoal 32 is charged, an increase in fuel consumption can be suppressed, and it is possible to maximize the treatment amount of the waste 33 using the secured biomass charcoal. Furthermore, the second biomass charcoal 32, which is consumed in large amounts when used alone, can be used together with the first biomass charcoal 31, which is consumed in small amounts, to treat the waste 33 at a consumption amount close to that of the first biomass charcoal 31.

[0045] Furthermore, if only biomass charcoal with a high volatile content, such as biomass charcoal F, is fed into the furnace, a high-temperature combustion zone will not be formed sufficiently, and the molten slag will not be discharged from the slag outlet 4, making it impossible to operate the gasification melting furnace 1.However, in the present invention, waste 33 can be processed by mixing biomass charcoal F with the first biomass charcoal 31 and using it.

[0046] Furthermore, if only a large amount of the second biomass charcoal 32, which is consumed in a relatively large amount relative to coke for treating the waste 33, is charged, a heat amount greater than that required to melt the ash will be generated, resulting in a waste of valuable biomass energy. Furthermore, if only a large amount of the second biomass charcoal 32, which is consumed in a relatively large amount relative to coke for treating the waste 33, is charged, not all of it will be converted into heat by combustion, but will be gasified while absorbing heat through a reaction between high-temperature carbon dioxide and the biomass charcoal, resulting in a waste of biomass energy that is not used to melt the ash. In contrast, in the present invention, the first biomass charcoal 31, which is consumed in a relatively small amount relative to coke for treating the waste 33, is mixed and charged into the furnace. This eliminates the need to charge a large amount of the second biomass charcoal 32. Furthermore, by improving the consumption efficiency of the second biomass charcoal, a heat amount greater than that required to melt the ash will not be generated, resulting in no wasted heat.

[0047] The first biomass charcoal 31 is not limited to charcoal whose consumption for treating the waste 33 is less than that of coke, and may be charcoal whose consumption for treating the waste 33 is less than that of the second biomass charcoal 32. The second biomass charcoal 32 is also not limited to charcoal whose consumption for treating the waste 33 is greater than that of coke, and may be charcoal whose consumption for treating the waste 33 is greater than that of the first biomass charcoal 31, for example.

[0048] When three or more types of biomass charcoal are fed into the furnace, the biomass charcoal that consumes the least amount of waste 33 when used alone may be defined as the first biomass charcoal 31, and the other biomass charcoal may be defined as the second biomass charcoal 32.

[0049] In the present invention, a mixture of multiple types of biomass charcoal that meet certain standards may be specified as the first biomass charcoal 31 to be charged into the furnace. 3 A mixture of multiple types of biomass charcoal having an apparent density of 0.9 g / cm or more, a weight per piece of 60 g or more, a volatile content of 7 dry wt% or less, and a lower heating value of 26 MJ / kg or more may be specified as the first biomass charcoal 31 to be charged into the furnace. For example, a mixture of two of the above-mentioned biomass charcoal A, biomass charcoal B, and biomass charcoal C may be charged into the furnace as the first biomass charcoal 31, or a mixture of all three may be charged into the furnace as the first biomass charcoal 31. 3 The first biomass char 31 may also include chars that slightly deviate from the above characteristics, such as a weight per piece of 60 g or more, a volatile content of 7 dry wt% or less, and a lower heating value of 26 MJ / kg or more.

[0050] In the present invention, the apparent density is 0.9 g / cm 3A mixture of multiple types of biomass charcoal that do not satisfy the conditions of having a weight per piece of 60 g or more, a volatile content of 7 dry wt% or less, and a lower heating value of 26 MJ / kg or more may be specified as the second biomass charcoal 32 to be charged into the furnace. For example, a mixture of two of the above-mentioned biomass charcoal D, biomass charcoal E, and biomass charcoal F may be charged into the furnace as the second biomass charcoal 32, or a mixture of all three may be charged into the furnace as the second biomass charcoal 32.

[0051] In the above-described embodiment, the gasification and melting furnace 1 is configured to pyrolyze, combust, and gasify the waste 33, but is not limited to this configuration. For example, the gasification and melting furnace 1 may be configured with the waste layer lowered so that the sub-tuyeres 6 protrude above the waste layer. In this configuration, the waste layer is not fluidized by the air blown in through the sub-tuyeres 6, and the waste 33 is pyrolyzed and gasified by the high-temperature gas rising from the lower shaft 21, without combustion. A portion of the combustible gas generated by the pyrolysis of the waste 33 is combusted by the air blown in through the sub-tuyeres 6. Alternatively, instead of lowering the waste layer, the sub-tuyeres 6 may be omitted. In this configuration, the waste layer is not fluidized by the air blown in through the sub-tuyeres 6, and the waste 33 is pyrolyzed and gasified by the high-temperature gas rising from the lower shaft 21, without combustion. [Explanation of symbols]

[0052] 1. Gasification and melting furnace 2 Inlet 3 Gas outlet 4 Slag outlet 5 Main tuyere 6 Secondary tuyere 7 Three-stage tuyere 10 Secondary combustion chamber 11 Air vent 12 Boiler 21 Lower shaft part 22 Middle shaft 23 Freeboard section 31 First Biomass Coal 32 Secondary biomass coal 33 Waste 34 Limestone

Claims

1. A waste treatment method in which ash produced by at least thermal decomposition and gasification of waste in a melting furnace is melted in the melting furnace, A first biomass charcoal having an apparent density of 0.9 g / cm 3 or more, a weight per piece of 60 g or more, a volatile content of 7 dry wt % or less, and a lower heating value of 26 MJ / kg or more, and a second biomass charcoal whose consumption amount required for treating the waste exceeds the consumption amount of the first biomass charcoal required for treating the waste and whose volatile content is 8 dry wt % or more and 17 dry wt % or less are charged into the melting furnace; forming a grate in the melting furnace using the first biomass charcoal and burning the first biomass charcoal; burning the second biomass charcoal in or on the grate; The ash is melted by heat generated by combustion of the first biomass charcoal and the second biomass charcoal; The ratio of the weight of the first biomass charcoal to the total weight of the first biomass charcoal and the second biomass charcoal is 30% or more. Waste disposal methods.

2. The first biomass charcoal is made up of a plurality of types of biomass charcoal having different consumption amounts required for waste treatment. The waste treatment method according to claim 1.

3. The second biomass charcoal is made up of a plurality of types of biomass charcoal having different consumption amounts required for waste treatment.

3. The waste treatment method according to claim 1 or 2.

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