JP2010149079A - Treatment method of waste containing highly hydrous waste and treatment device used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment method of waste containing highly hydrous waste collecting the heat of the waste without consuming it as evaporative latent heat of contained water, collecting energy that high-moisture waste has with high yield, and reducing a consumption amount of chemicals required for drainage treatment, and also to provide a treatment device used for the same. <P>SOLUTION: Organic biomass having high moisture content such as food waste or sludge is separated to methane gas, digested sludge and drain by methane fermentation treatment. The water content of the digestive sludge is reduced and then the digestive sludge is mixed with an organic waste so that the water content of the waste to be treated in a gasifying melted furnace is reduced. A whole amount or a part of the methane gas obtained from the methane fermentation is blown to the tuyere of the gasifying melted furnace together with oxygen, air added with oxygen, and combustible dust collected at the latter part of the gasifying melted furnace, and is used as a reducing agent in the furnace and a heat source for heating. So that a consumption amount of coke used as the fuel of the gasifying melted furnace, and a whole amount or a part of the drain generated as a by-product by the methane fermentation treatment is blown to a combustion furnace arranged at the latter part of the gasifying melted furnace and is detoxified. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a processing method and a processing apparatus for waste containing high water content waste.

  Specifically, the present invention relates to a processing method and a processing apparatus for waste having a moisture content of 70% or more, such as food waste, sludge, peat, and the like, and waste having a total water content exceeding 40%. .

  In recent years, with the ratification of the Kyoto Protocol, the demand for CO2 reduction is high, and the demand for the use of renewable energy such as biomass is increasing.

  In particular, some biomass, such as sewage sludge, contains a lot of moisture, and when these wastes are used as heat, there is a problem that heat cannot be sufficiently utilized due to sensible heat in the exhaust gas or latent heat of vaporization of moisture. there were.

  Utilizing these unused energy can greatly contribute to the reduction of CO2 emissions and the prevention of global warming.

  Various proposals have conventionally been made on methods for treating highly hydrous waste.

For example, in Japanese Patent No. 3758513 (Patent Document 1 below), a gas turbine is rotated with digestion gas, and exhaust heat of the gas turbine and gas engine is used as a heat source for thermal decomposition. However, the temperature of the exhaust gas from the gas turbine is low and sufficient thermal decomposition cannot be obtained, and the ash content of the waste cannot be melted by the method of Patent Document 1 and the recycling rate cannot be sufficiently obtained. was there.
Japanese Patent No. 3758513

  The present invention suppresses heat consumption due to the latent heat of evaporation of water contained in waste, which is necessary when gasifying and drying waste with high moisture content, and increases the energy of high moisture waste. It is an object of the present invention to provide a treatment method and a treatment apparatus for waste containing a highly water-containing waste that can be efficiently recovered and reduce the consumption of chemicals necessary for wastewater treatment.

The present invention has been made as a result of intensive studies in order to solve the above-mentioned problems, and the gist of the present invention is the following contents as described in the claims.
(1) In a waste treatment method in which organic waste including general waste is treated in a gasification melting furnace, organic biomass with a high water content such as food waste and sludge is separated from other waste. The organic biomass with a high water content is separated into methane gas, digested sludge and wastewater by methane fermentation treatment, and the digested sludge is mixed with other organic waste after reducing moisture in a gasification melting furnace. Reduce the amount of water in the waste to be treated, and add all or part of the methane gas obtained by the methane fermentation together with oxygen or oxygenated air and combustible dust collected after the gasification melting furnace. In addition to blowing into the tuyere, all or part of the wastewater produced as a by-product of the methane effecting treatment is blown into a combustion furnace installed downstream of the gasification melting furnace to make it harmless. And the processing method of waste containing a high water content waste.
(2) The gasification melting furnace is a shaft type gasification furnace, and the methane gas obtained by the methane fermentation is blown into the tuyere together with the combustible gas, and the surplus is generated by the gas engine or the gasification melting furnace is discarded. The method for treating waste containing high water content waste according to (1), characterized in that it is used as a heat source for an external superheater associated with a thermal boiler power generation system.
(3) The gasification and melting furnace is a shaft type gasification furnace, and the amount of water charged into the gasification furnace is adjusted to 10 to 40%. The high value according to (1) or (2) A method for treating waste containing hydrous waste.
(4) Aerobic fermentation is used as a method for reducing the moisture content of the digested sludge, and the treatment of the waste containing the highly water-containing waste according to any one of (1) to (3) Method.
(5) Among the highly water-containing wastes, methane fermentation is performed with a high methane gas generation rate, and either sewage sludge, human waste sludge, or methane fermentation residue with a low methane gas generation rate is dried with heat from aerobic fermentation. The processing method of the waste containing the highly water-containing waste as described in any one of (1)-(4) characterized by the above-mentioned.
(6) The waste sewage staying at the bottom of the waste pit is used as a raw material for methane fermentation or as additional water necessary for methane fermentation treatment, as described in any one of (1) to (5) A method for treating waste containing highly water-containing waste.
(7) The highly water-containing waste according to any one of (1) to (6) is used, characterized in that wastewater discharged from the gasification melting furnace is used as additive water necessary for methane fermentation. Waste disposal method.
(8) Any one of (1) to (7), characterized in that the wastewater generated in the methane fermentation treatment is subjected to primary treatment and mixed with wastewater generated from a gasification melting furnace to perform wastewater treatment. The disposal method of the waste containing the high water content waste as described in a term.
(9) The highly water-containing waste according to any one of (1) to (8), wherein the heat source necessary for the methane fermentation is obtained using exhaust heat of a gasification melting furnace. Waste disposal methods.
(10) The method for treating waste containing high water content waste according to (9), wherein the exhaust heat is steam turbine exhaust.
(11) A high water content waste characterized by having a gasification melting furnace and a methane fermentation treatment device used in the method for processing a high water content waste according to any one of (1) to (10). Waste disposal equipment.
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In facilities where waste is treated by incineration or other heat treatment, the heat obtained is recovered by a boiler, etc., and heat is used by power generation or other methods, heat generated by incineration when the moisture content of the object to be treated is high Is consumed by the evaporation of water contained in the waste and is difficult to recover as heat.
According to the invention of (1), coke is used as a reducing agent in the shaft type gasification melting furnace. However, when there is a lot of moisture, energy is consumed for drying, and the amount of coke used may increase. Moisture separation can be achieved by subjecting waste with high water content to methane fermentation, and water supplied to the gasifier can be suppressed. Further, the amount of coke used can be reduced by blowing the obtained methane gas into the tuyere. In addition, because the separated water is organic wastewater, wastewater treatment is required for discharge, but wastewater treatment requires a huge amount of chemicals, which is economically undesirable and consumes chemicals. The load on is also high. However, by blowing wastewater into the combustion furnace, it becomes possible to treat organic wastewater without affecting coke in the gasification melting furnace. Even in gasification melting furnaces other than the shaft, moisture bypass processing in the melting furnace is possible, and consumption of auxiliary fuel such as kerosene and heavy oil can be reduced. In addition, when methane gas is blown into the tuyere, the effect is increased by blowing it together with dust collected at the subsequent stage of the melting furnace.
According to the invention of (2), high power generation efficiency can be obtained by performing gas engine power generation using surplus methane gas. Compared to the case where all gas engine power is generated by blowing into the tuyere, it is used as primary energy, so the energy utilization efficiency is high. Further, since methane gas does not generate corrosive gas even if it is burned, the efficiency of waste power generation that does not increase the temperature due to the problem of conventional corrosion and does not increase efficiency can be improved.
According to invention of (3), the ratio of the water | moisture content thrown into a gasification melting furnace can be adjusted by adjusting the fraction of organic waste. Moreover, the odor generated by aerobic fermentation can be decomposed by blowing it into the combustion chamber as combustion air.
According to the invention of (4), it becomes possible to remove moisture without newly consuming energy by using the fermentation heat of aerobic fermentation.
According to the invention of (5), the fermentation equipment can be made compact by carrying out methane fermentation treatment limited to waste with high fermentation efficiency, and by drying sewage sludge with secondary fermentation heat. The energy of sewage sludge can be used for waste power generation without being consumed for water evaporation.
According to the invention of (6), the water discharged from the trash is recovered from the pit, but since it is organic wastewater, drainage is costly. By processing at the same time as methane fermentation, low cost name processing becomes possible.
According to invention of (7), it becomes possible to reduce the usage-amount of clean water by using miscellaneous wastewater etc. as additional water of a methane fermentation process.
According to the invention of (8), when wastewater treatment is carried out, the wastewater treatment facility can be made compact by mixing and treating the same treatment process with wastewater from the melting treatment and wastewater generated by the methane fermentation treatment. Can do.
According to the invention of (9), it is possible to improve the overall thermal efficiency by utilizing the exhaust heat of the gasification melting furnace as a heat source necessary for methane fermentation.
According to the invention of (10), since the turbine exhaust cannot be used elsewhere, the use of the turbine exhaust heat is effective for increasing the thermal efficiency of the entire plant.
According to the invention of (11), a processing apparatus for realizing the waste processing method including the highly water-containing waste described in (1) to (10) by having a gasification melting furnace and a methane fermentation processing apparatus. Can be provided.

  According to the present invention, it is possible to recover the latent heat of evaporation of water contained in food waste, sludge, peat and other high water content waste, and to recover the energy of high moisture waste with high efficiency. It is possible to provide a processing method and a processing apparatus for waste containing high water content waste that can reduce the consumption of chemicals necessary for wastewater treatment, and the present invention has significant industrially useful effects.

  The best mode for carrying out the present invention will be described in detail with reference to FIGS.

  1 to 7, 1 is a high water content biomass, 2 is a pretreatment device, 3 is a methane fermentation device, 4 is a dehydration device, 5 is a drying device, 6 is an organic wastewater treatment, 7 is a gas treatment, and 8 is a waste product. , 9 is a gasification melting furnace, 9 'is a gasification furnace, 10 is a combustion furnace, 10' is a secondary combustion furnace, 11 is a boiler, 12 is a economizer, 13 is a temperature reducing tower, and 14 is a deaerator. 5 is a bag filter, 16 is an induction fan, 17 is a catalytic reaction tower, 18 is a chimney, 19 is a superheater, 19 'is an independent superheater, 20 is a steam turbine, 21 is a condenser, and 22 is a condensate tank. In order to avoid duplication of explanation, the same symbols are used for the same elements.

  FIG. 1 is a diagram illustrating a combination of a gasification melting furnace and methane fermentation in a method for treating waste containing high water content waste according to the present invention.

  As a method for melting the waste, for example, a shaft furnace type waste melting furnace is used. As shown in FIG. 1, the waste material 8 is charged from the upper part of the gasification melting furnace 9 with the waste 8 to be treated, coke as auxiliary fuel, limestone as the basicity adjusting agent, and the like. 8 is melt-processed from the upper layer of the melting furnace 9 through a dry / pre-tropical zone (about 300 to 400 ° C.), a thermal decomposition zone (about 300 to 1000 ° C.), and a combustion / melting zone (about 1700 to 1800 ° C.). The

  Further, the high-temperature combustion exhaust gas rises as a counterflow through the waste packed bed in the gasification melting furnace 9, is introduced into the combustion furnace 10 as a combustible gas from the exhaust gas pipe at the upper part of the melting furnace, and is combusted. Then, after being introduced into the boiler 11 through the exhaust gas pipe and heat exchanged by the economizer 12, the waste heat is recovered, the temperature is adjusted by the temperature reducing tower 13, and the dust is removed by the bag filter 15, After the pollutant is removed in the catalytic reaction tower 17, it is discharged from the chimney 18.

  In addition, as shown in FIG. 1, the electric power generated by using the heat | fever collect | recovered by the boiler 11 as motive power of the steam turbine 20 can be used as auxiliary power and electric power for sale.

  However, in a conventional general waste melting furnace, the waste is melted and moisture contained in the waste is also treated. At this time, there is a problem that the combustion heat is consumed for drying the moisture and cannot be recovered and used as heat.

  Therefore, the present invention is a waste treatment method in which organic waste 8 containing general waste is treated in the gasification melting furnace 9, and the water content of food waste, sludge, etc. is as high as 70% or higher. Biomass 1 is separated into methane gas and digested sludge by a methane fermentation device 3, and the digested sludge is gas-reduced by reducing moisture with a dehydrating device 4 and further reducing moisture with a drying device 5 and mixing with organic waste. The amount of water in the waste to be treated in the gasification and melting furnace is reduced, and all or part of the methane gas obtained by the methane fermentation apparatus 3 is combusted by oxygen or oxygen-added air and after the gasification and melting furnace. By blowing into the tuyere of the gasification and melting furnace together with dust and using it as a reducing agent in the furnace and a heat source for heating, the consumption of coke used as fuel for the gasification and melting furnace is suppressed. The amount of chemicals required for wastewater treatment can be reduced by blowing all of the wastewater produced as a by-product of the methane fermentation treatment into a combustion furnace installed downstream of the gasification melting furnace to make it harmless. Features.

  That is, in the present invention, coke is used as a reducing agent in the shaft type gasification melting furnace. However, when there is a lot of moisture, energy is consumed for drying, and the amount of coke used may increase. Moisture separation can be achieved by subjecting waste with high water content to methane fermentation, and water supplied to the gasifier can be suppressed.

  In addition, after the gas treatment 7 is applied to the obtained methane gas to adjust the components, the amount of coke used can be reduced by blowing into the tuyere of the gasification melting furnace 9. In addition, because the separated water is organic wastewater, wastewater treatment is required for discharge, but wastewater treatment requires a huge amount of chemicals, which is economically undesirable and consumes chemicals. The load on is also high. However, by blowing the waste water into the combustion furnace 10, it becomes possible to treat organic waste water without affecting the coke in the gasification melting furnace 9. Even in gasification melting furnaces other than the shaft, moisture bypass processing in the melting furnace is possible, and consumption of auxiliary fuel such as kerosene and heavy oil can be reduced.

  Even when the entire amount of waste water is not blown into the combustion furnace, the optimum amount for operation is blown, the remaining waste water is treated and discharged, and the cost of waste water treatment can be suppressed. If the amount blown into the combustion furnace is excessively large, stable operation of the furnace may be affected.

  In the present invention, the highly water-containing waste means one having a water content of 70% or more.

  In addition, a fluidized bed, kiln aerobic fermentation, or the like can be used as a drying device. When drying waste, it is desirable to use an enclosed drying furnace to prevent odor diffusion.

  In addition, when discharging the condensed water after drying, it is preferable to provide a sewerage treatment plant or an organic wastewater treatment 6 according to the conditions such as the drainage standard, detoxify so as to satisfy the drainage standard, and then discharge the sewage.

  FIG. 2 is a diagram exemplifying a method of using methane gas and the like in the method for treating waste containing high water content waste according to the present invention.

  The methane gas obtained by the methane fermentation is blown into the tuyere of the gasification melting furnace 9, and surplus methane gas is generated by generating a surplus with a gas engine or as a heat source for an external superheater of the gasification melting furnace 9. A high power generation efficiency can be obtained by generating a gas engine using the power. Compared to the case where all gas engine power is generated by blowing into the tuyere, it is used as primary energy, so the energy utilization efficiency is high. Further, since methane gas does not generate corrosive gas even if it is burned, the efficiency of waste power generation that does not increase the temperature due to the problem of conventional corrosion and does not increase efficiency can be improved.

  FIG. 3 is a diagram exemplifying the separation treatment of sewage sludge in the waste treatment method including a highly water-containing waste according to the present invention.

  Among the highly water-containing wastes, methane fermentation is performed on moss with high methane gas generation rate, and waste with high fermentation efficiency is obtained by drying sewage sludge, human waste sludge, etc. with low methane gas generation rate with heat from aerobic fermentation. It is possible to reduce the size of the fermentation equipment by performing the methane fermentation treatment only, and to use the energy of the sewage sludge for waste power generation by drying the sewage sludge with the secondary fermentation heat. It becomes possible.

  FIG. 4 is a diagram illustrating the use of wastewater in the method for treating waste containing high water content waste according to the present invention.

  By using waste sewage accumulated at the bottom of the waste pit as a raw material for methane fermentation or as additional water required for methane fermentation treatment, moisture from the pit is recovered, but because it is organic wastewater, Drainage is costly. Processing at the same time as methane fermentation enables low-cost processing.

  In addition, by using wastewater from the gasification melting furnace as additional water necessary for methane fermentation, it is possible to reduce the amount of water used by using miscellaneous wastewater as additional water for methane fermentation treatment. It becomes.

  FIG. 5 is a diagram illustrating common use of wastewater treatment in the method for treating waste containing high water content waste according to the present invention.

  When the wastewater generated in the methane fermentation treatment apparatus 3 is subjected to primary treatment and mixed with wastewater generated from the gasification melting furnace 9 for wastewater treatment, wastewater discharged from the melt treatment and methane The wastewater treatment facility can be made compact by mixing the same treatment process with the wastewater generated in the fermentation treatment apparatus 3.

  FIG. 6 is a diagram illustrating the use of residual heat in the method for treating waste containing high water content waste according to the present invention.

  By obtaining the heat source necessary for the methane fermentation using the exhaust heat of the gasification melting furnace 9, the overall thermal efficiency can be improved. The residual heat includes boiler exhaust gas sensible heat, turbine extraction, turbine exhaust, and the like.

  Since turbine exhaust cannot be used elsewhere, use of turbine exhaust is effective in increasing the thermal efficiency of the entire plant.

  Moreover, the process which implement | achieves the processing method of the waste containing the high water content waste of this invention by having the gasification melting furnace 9 and the methane fermentation processing apparatus 3 used for the processing method of the high water content waste of this invention An apparatus can be provided.

  The shaft furnace waste gasification and melting furnace 9 shown in Fig. 1 is mixed with dry waste obtained by drying biomass 1 with a moisture content of 70% by mass to 30% by mass and other wastes 8, and then formed with coke and limestone. The waste was melted by blowing air from the upper tuyere and oxygen-enriched air from the lower vent. In all cases, the upper air flow rate (air) 350Nm3 / h, the lower air flow rate (air) 250Nm3 / h, and the oxygen content in the lower air flow (pure oxygen) 60Nm3 / h to enrich the oxygen. Constant conditions with an oxygen concentration of 36.3%, and the amount of blast furnace coke and hollow cylindrical carbide used were 40 kg / waste t. As waste, general municipal waste discharged in K city was used.

  As a result of the test, according to the method for treating a waste containing a high water content waste according to the present invention, the latent heat of evaporation of water contained in a high water content waste such as food waste, sludge, peat and the like having a moisture content of 70% by mass It was confirmed that the energy of high-moisture waste can be recovered with high efficiency and the consumption of chemicals necessary for wastewater treatment can be reduced.

  In this embodiment, the packed bed type waste melting furnace has been described. However, the present invention can be applied to a fluid type coke bed type melting furnace and a melting furnace using coke such as a cupola. Further, application to a furnace that uses fuel other than coke (LPG, natural gas, kerosene, etc.) as a melting heat source is not hindered.

It is a figure which illustrates the combination of the gasification melting furnace and methane fermentation in the processing method of the waste containing the highly water-containing waste of this invention. It is a figure which illustrates the other utilization method of the methane gas in the processing method of the waste containing the highly water-containing waste of this invention. It is a figure which illustrates the separation process of the sewage sludge in the processing method of the waste containing the highly water-containing waste of this invention. It is a figure which illustrates utilization of the waste_water | drain in the processing method of the waste containing the highly water-containing waste of this invention. It is a figure which illustrates sharing of the waste_water | drain process in the processing method of the waste containing the highly water-containing waste of this invention. It is a figure which illustrates the utilization of the residual heat in the processing method of the waste containing the highly water-containing waste of this invention.

Explanation of symbols

1 High water content biomass
2 Pre-treatment device 3 Methane fermentation device 4 Dehydration device 5 Drying device 6 Organic wastewater treatment 7 Gas treatment 8 Waste 9 Gasification melting furnace 9 'Gasification furnace 10 Combustion furnace 10' Secondary combustion furnace 11 Boiler 12 Carbon-saving device 13 Decooler 14 Deaerator 15 Bag filter 16 Induction fan 17 Catalytic reactor 18 Chimney 19 Superheater 19 ′ Independent superheater 20 Steam turbine 21 Condenser 22 Condensate tank

Claims (11)

In a waste processing method of processing organic waste including general waste in a gasification melting furnace,
Separate organic biomass with high water content such as food waste and sludge from other waste, separate organic biomass with high water content into methane gas, digested sludge and wastewater by methane fermentation treatment,
The digested sludge reduces the moisture content of the waste to be treated in the gasification melting furnace by mixing with other organic waste after reducing the moisture,
The whole or part of the methane gas obtained by the methane fermentation is blown into the tuyere of the gasification melting furnace together with oxygen or oxygen-added air and combustible dust collected after the gasification melting furnace, and by the methane effecting treatment A method for treating waste containing highly water-containing waste, characterized in that all or part of the wastewater produced as a by-product is blown into a combustion furnace installed downstream of the gasification melting furnace to make it harmless.   The gasification melting furnace is a shaft type gasification furnace, and the methane gas obtained by the methane fermentation is blown into the tuyere together with the combustible gas, and the surplus is generated by a gas engine, or the waste heat boiler power generation of the gasification melting furnace 2. The method for treating waste containing highly water-containing waste according to claim 1, wherein the waste is used as a heat source of an external superheater attached to the system.   The highly water-containing waste according to claim 1 or 2, wherein the gasification melting furnace is a shaft type gasification furnace, and the amount of water input to the gasification furnace is adjusted to 10 to 40%. Waste disposal method.   An aerobic fermentation is used as a method for reducing the moisture content of the digested sludge. The method for treating waste containing a highly water-containing waste according to any one of claims 1 to 3.   Among the high water-containing wastes, methane fermentation is performed on moss having a high methane gas generation rate, and any one of sewage sludge, human waste sludge and methane fermentation residue having a low methane gas generation rate is dried by heat from aerobic fermentation. The processing method of the waste containing the highly water-containing waste as described in any one of Claims 1-4.   The highly water-containing waste according to any one of claims 1 to 5, wherein the waste sewage staying at the bottom of the waste pit is used as a raw material for methane fermentation or as additional water necessary for methane fermentation treatment. Disposal method of included waste.   The wastewater discharged from the gasification melting furnace is used as an additional water necessary for methane fermentation, The method for treating waste containing highly water-containing waste according to any one of claims 1 to 6, .       The effluent generated in the methane fermentation treatment is subjected to a primary treatment, mixed with the effluent generated from a gasification melting furnace, and treated as a effluent. A method for treating waste containing hydrous waste.   The treatment of waste containing high water content waste according to any one of claims 1 to 8, wherein a heat source necessary for the methane fermentation is obtained by using exhaust heat of a gasification melting furnace. Method.   10. The method for treating waste containing highly water-containing waste according to claim 9, wherein the exhaust heat is steam turbine exhaust.   It has a gasification melting furnace used for the processing method of the highly water-containing waste as described in any one of Claims 1-10, and a methane fermentation processing apparatus, The processing of the waste containing the high water-containing waste characterized by the above-mentioned. apparatus.

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