JP2010284589A - Waste disposal system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste disposal system which can shorten drying time under an adopted new deodorization by a drying method for inhibiting the diffusion of malodor to the surroundings. <P>SOLUTION: This waste disposal system includes at least, a pressure container 1 with a loading port 1a and a discharging port 1b for the waste, a stirring means 2 for stirring the waste inside the container 1, a high hot water vapor supply means 4 for supplying the high hot saturated water vapor into the container 1, a pressure adjusting means 5 for adjusting the internal pressure of the container 1 by means of an on-off valve, and a control means 9 for controlling the internal temperature and pressure of the container 1. In this system, after hydrolytic treatment of the waste, the internal pressure of the container 1 is lowered by the on-off valve of the pressure adjusting means 5 and then, superheated water vapor is injected into the container 1 and thus the waste is dried. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an efficient waste treatment system that does not affect the environment and is efficient by miniaturization and drying by hydrolysis of waste.

  Waste, especially organic waste, has been replaced by conventional incinerators and underground disposal, and recently, there is a waste treatment method in which water is hydrolyzed in a high-temperature, high-pressure environment. Attention has been paid. In addition, there are some waste treatment devices and systems that have been actually developed and manufactured and delivered to local governments.

  As the above-mentioned waste treatment method and apparatus, for example, in Patent Documents 1 and 2, mainly organic wastes are treated, and those wastes are placed in a sealed pressure-resistant container and then placed in the container. A waste treatment method in which high-temperature saturated steam is supplied and the waste is hydrolyzed while being stirred in a high-temperature and high-pressure environment while controlling the temperature and pressure in the container, and pyrolyzed and carbonized for treatment. A device has been proposed.

  Further, in Patent Documents 3 and 4, in order to reuse the waste, the waste as a raw material is put into a sealed pressure vessel or a processing vessel, and high-pressure steam is injected into the vessel. A method and apparatus for maintaining the pressure and temperature in the container in a predetermined range according to the properties of the raw material, and converting the properties of the waste by hydrolysis to obtain the desired exothermic molded body, fuel, and fertilizer. Proposed.

  Further, Patent Documents 5 and 6 describe that organic waste as a raw material is hydrolyzed while stirring in a high-temperature and high-pressure environment in a container or a treatment kettle, and then heated in another container or the same treatment kettle. Waste disposal methods and devices have been proposed for use in applications such as fertilizers, power generation raw materials, and fuels by decomposing, drying and carbonizing.

  In the waste treatment apparatus and the raw material conversion treatment system proposed in the above Patent Documents 1 to 6, it is necessary to take out the treated waste from the pressure vessel after the hydrolysis treatment, but the treated waste is fertilizer and fuel. A process for drying the treated waste is incorporated regardless of the molding material.

  In the drying process, after the hydrolysis is completed, the pressure is reduced by the on-off valve, and the remaining water is evaporated by the heat of the injected saturated steam, but the latent heat of evaporation is removed by the evaporation, and the temperature gradually decreases. As a result, there was a problem that drying did not proceed sufficiently. In order to prevent this temperature drop, in the treatment system proposed in Patent Document 2, high temperature steam is supplied to the gap between the outer wall and the inner wall of the pressure vessel having a double wall structure to prevent the temperature drop. Moreover, in the waste disposal apparatus proposed in Patent Document 5, the hydrolyzed waste is moved into a double-structure container for heating and drying, and then between the inner shell and outer shell of the container. Superheated steam is supplied to heat and dry the inside of the container.

  The drying process of the apparatus proposed in Patent Documents 2 and 5 is excellent because it can prevent the temperature in the container from decreasing. However, since it is indirect heating, it takes a long time to dry. There was room for further improvement in terms of shortening the. In order to shorten the drying time, there was a strong demand for improvement from the viewpoint of recovering the high cost required for installing the waste treatment apparatus and saving the cost of operating the apparatus. This is related to the rotation rate of the device, how much a large amount of waste can be processed per day, or how many times a day can be operated. If the drying time can be reduced, This is because the amount of waste that can be processed by increasing the turnover rate can be greatly increased, which can contribute to saving operating costs and cost recovery.

  Incidentally, in the conventional drying method, it took about 7 hours to sufficiently dry the treated waste so that it can be easily taken out, and it took about 4 to 5 hours when the container was heated. In this case, the apparatus can be operated only about 2 to 3 times a day, and there is a problem in terms of cost recovery and saving. If the pressure vessel is opened in a state where it has not been sufficiently dried in order to expedite the time, there is a problem in that the waste becomes muddy and it takes time to take out the work. Moreover, when the waste after hydrolysis is taken out in a state where it is not sufficiently dried, there is a problem that a bad odor is diffused to the surroundings as the water evaporates.

  Further, in the conventional waste treatment apparatus, when waste is hydrolyzed, a gas containing an odor component is generated. Therefore, the exhaust gas is exhausted after being deodorized by the deodorization apparatus before exhausting the generated gas. For example, in the apparatus proposed in Patent Document 5, exhaust gas containing an odor component is processed by a deodorization processing apparatus and then exhausted to the outside.

  However, as in the fuel production apparatus proposed in Patent Document 4, if the object to be treated is raw garbage, sewage sludge, fish residue, peat, livestock dung, squid liver, etc., the deodorization apparatus has sufficient odor components. There was a problem that could not be removed. In the fuel production device proposed in Patent Document 4, in the drying process, it takes time to evaporate moisture by leaving it at room temperature for about one day after the hydrolysis treatment, and malodor is diffused to the surroundings. There was a problem.

JP 2007-7622 A WO 2008/038361 A1 Japanese Patent No. 3832587 Japanese Patent No. 3613567 JP 2008-246300 A Japanese Patent No. 3898918

  The present invention is a waste treatment method and apparatus in which the conventional water vapor is hydrolyzed in a high-temperature and high-pressure environment, so that the drying process takes too much time, resulting in poor operation efficiency of the apparatus. Gases containing odorous components that are generated cannot be sufficiently deodorized by conventional deodorizing equipment, and some of the odorous components are contained in the water that evaporates when drying the hydrolyzed waste. In view of the problem of being dissipated in the environment, the problem is to provide a waste treatment system with a new deodorizing / drying method that reduces the drying time and does not disperse bad odors to the surroundings. It is.

  The structure of the present invention made for the purpose of solving the above problems is a pressure-resistant container provided with a waste inlet and outlet, a stirring means for stirring waste in the container, and high-temperature saturation in the container. In a waste treatment system comprising at least a high-temperature steam supply means for supplying steam, a pressure adjusting means for adjusting the pressure in the container by an on-off valve, and a control means for controlling the temperature and pressure in the container, After the decomposition treatment, after the pressure in the container is lowered by the on-off valve of the pressure adjusting means, superheated steam is injected into the container to dry the waste. .

  In the above configuration, the present invention adjusts the superheated steam injected into the pressure vessel so that the waste after hydrolysis is not carbonized so that the temperature of the waste becomes 100 to 200 ° C. You may make it the structure which dries a thing.

  Further, the present invention is the above-described configuration, wherein a gas containing an odor component that is partially generated in hydrolysis is washed with an acidic aqueous solution such as dilute sulfuric acid, and then washed with an alkaline aqueous solution such as caustic soda. Alternatively, gas cleaning may be performed by adding hypochlorous acid.

  In the waste treatment system of the present invention, the drying time can be greatly shortened by supplying superheated steam directly at a temperature at which the waste is not carbonized in the pressure vessel after hydrolysis. As a result, the amount of waste that can be processed per day can be greatly increased, so that the operating efficiency is improved and the cost recovery rate is high. Moreover, in the waste treatment system of this invention, since the gas containing the odor component which generate | occur | produces partially at the time of a hydrolysis can be processed effectively without a bromide, the effect that a bad odor is not dissipated to the surrounding environment is also acquired.

Schematic of an example waste disposal apparatus used for the system of the present invention.

  Next, the waste treatment system of the present invention will be described with reference to the schematic diagram of the example waste treatment apparatus shown in FIG. 1 used in the system.

  In FIG. 1, 1 is a pressure-resistant container for accommodating and processing waste, 1a is a waste inlet, and 1b is a treated waste outlet. The pressure vessel 1 has a sealed structure, and although not shown, the inlet 1a and outlet 1b can be opened and closed by valves. Reference numeral 2 denotes a stirring blade for transferring the waste introduced from the charging port 1a while stirring, 2a denotes a shaft of the stirring blade 2, and the shaft 2a is provided through the pressure-resistant vessel 1. Reference numeral 3 denotes a motor for rotating the shaft 2a. The motor 3 is controlled to rotate forward and backward, and the thrown-in waste is transferred back and forth in the pressure-resistant container 1. Although not shown in the drawings, the pressure vessel 1 for storing and processing waste may have a double wall structure and supply high-heat steam to the gap between the outer wall and the inner wall.

  4 is a boiler for supplying high-temperature steam into the pressure-resistant container 1, 4 a is a steam supply pipe for supplying high-temperature steam into the pressure-resistant container 1 during the agitation transfer of waste from the boiler 4, and 4 b is also from the boiler 4. It is a superheated steam injection pipe for supplying superheated steam into the pressure vessel 1 after waste hydrolysis. Note that the temperature and pressure of the steam supplied into the pressure vessel 1 and the superheated steam to be injected are adjusted according to the properties of the waste to be treated.

  Reference numeral 5 denotes a pressure adjusting device for adjusting the pressure in the pressure-resistant container 1 by an on-off valve (not shown) and maintaining the pressure at a predetermined pressure. 6 is a temperature detection line connected to a sensor for measuring the temperature in the pressure vessel 1, 7 is a pressure detection line connected to a sensor for measuring the pressure in the pressure vessel 1, and 8 is water vapor in the pressure vessel 1. This is a steam outlet for discharging to the outside of the container 1.

  9 is a control device for controlling the temperature and pressure in the pressure-resistant vessel 1, and the opening / closing operation of the on-off valve of the pressure adjusting device 5 based on the temperature and pressure in the pressure-resistant vessel 1 measured by the temperature detection line 6 and the pressure detection line 7. do. Further, the control device 9 controls the opening / closing of the inlet 1a and outlet 1b of the pressure vessel 1, the forward / reverse rotation of the stirring blade 2, the control of the rotational speed, the selection of the supply destination of the steam from the boiler 4, that is, the steam Switching of the supply pipe 4a and the superheated steam injection pipe 4b, control of the supply temperature and supply pressure of the steam, control of the injection temperature and injection pressure of the superheated steam, control of the exhaust steam from the steam outlet 8 and the like are also performed.

  Reference numeral 10 denotes a condenser connected to the steam discharge port 8, and 11 denotes a vacuum pump connected to the condenser 10. The vacuum pump 11 sucks the water vapor in the pressure-resistant container 1, and the condenser 10 cools the liquid. Reference numeral 12 denotes a pump connected to the condenser 10 for sucking waste liquid liquefied with water vapor.

  The gas that is not liquefied by the condenser 10 is cleaned by the acid cleaning absorption tower 13 and the alkali cleaning absorption tower 14 via the vacuum pump 11, de-bridged, and then exhausted 15 outside. The acid cleaning absorption tower 13 contains an acidic aqueous solution such as dilute sulfuric acid, and the alkali cleaning absorption tower 14 contains an alkaline aqueous solution such as caustic soda. In the process of passing through these aqueous solutions, the odor components in the gas are absorbed and removed. In some cases, hypochlorous acid is added to the alkaline aqueous solution for oxidative decomposition removal.

  Reference numeral 16 denotes a water evaporation can (vacuum dryer) in the waste liquid sucked by the pump 12 and neutralized in the neutralization tank 17, and in the waste liquid from the acid cleaning absorption tower 13 and the alkali cleaning absorption tower 14. Moisture is evaporated and part of the remaining odor component is adsorbed and removed by an activated carbon adsorption processor (not shown) attached to the moisture evaporator. In addition, a small amount of precipitates (inorganic salts) in the waste liquid discards sludge of evaporation residue. In the conventional waste treatment apparatus, the waste water liquefied by the condenser is treated by the waste water treatment facility. However, after the aeration treatment, it takes time to discharge and there is room for improvement. In the present invention, the effect that it can be dried in a short time by drying in a water evaporator 16 is obtained, and the advantage that drainage does not occur in a location where a drainage load is not increased in a densely populated area or the like. There is.

  Next, the operation content of the waste treatment system of the present invention will be described. The system of the present invention is characterized in that the waste after hydrolysis treatment is dried in a short time compared to the conventional one, and the waste to be treated is not particularly limited as long as it can be hydrolyzed. Further, in the system of the present invention, the waste after hydrolysis treatment is dried in a short time, but it can be reused as fuel, fertilizer, etc. without performing pyrolysis and carbonization.

  The conditions for hydrolyzing the waste are not particularly limited, but as an example, when the temperature in the pressure vessel is controlled to 230 ° C. or higher and the pressure is controlled to 3 MPa, the waste is stirred, and most of the organic waste is hydrolyzed. I know I can. Wastes include sludge, waste plastics, paper waste, wood waste, animal solid waste, animal and plant residues, animal manure, animal carcass, infectious specially controlled industrial waste, or business waste , Household waste, medical waste, infectious specially managed municipal waste, sorted garbage, food residues, etc.

  As a condition for hydrolyzing the waste, in addition to the above, for example, when the waste is raw garbage, the temperature in the pressure vessel is kept at about 220 ° C., and the pressure is kept at 2.06 MPa to 2.65 MPa or less. In the case of medical waste, the temperature in the pressure resistant container is maintained at 190 ° C. to 230 ° C. or lower, and the pressure is maintained at 1.96 MPa to 2.55 MPa or lower. When the waste is polyethylene, polypropylene, or ABS resin, The temperature in the container is maintained at about 225 ° C. and the pressure is maintained at 2.55 MPa to 2.65 MPa. When the waste is polystyrene, the temperature in the pressure resistant container is maintained at about 220 ° C. and the pressure is about 2 It may be a condition such as holding at 0.06 MPa.

  The waste hydrolyzed as described above has a high water content and cannot be taken out of the pressure vessel as it is. Therefore, in the system of the present invention, after the hydrolysis treatment, after the pressure in the container is lowered by the opening / closing valve of the pressure adjusting means, superheated steam is injected into the container and dried in a short time.

After putting medical waste into the pressure resistant container 1 having an internal capacity of 5 m ³ , high-temperature steam is supplied into the pressure resistant container 1 from the steam supply pipe 4a, the temperature in the container 1 is set to 230 ° C., and the pressure is set to 3 MPa. Hydrolysis was performed while rotating the stirring blade 2 while being held.
The introduced waste had a capacity of 3 m ³ , a weight of 350 kg (sludge content 280 kg, moisture 70 kg), a bulk density of 0.05 kg / l, and a water content of 20%.
The waste after hydrolysis had a water content of 80% and a water content of 1,120 kg.
With respect to this hydrolyzed waste, superheated steam is injected into the pressure vessel 1 from the superheated steam injection pipe 4b, and the stirring blade 2 is rotated while the pressure is maintained at 1 Mpa (10 atm) and the temperature is maintained at 200 ° C. Dried.
The drying was completed in about 3 to 4 hours when the water content of the waste immediately after hydrolysis was changed from 80% to 20%.

The medical waste was hydrolyzed under the same conditions as in Example 1.
Superheated steam is injected into the pressure-resistant container 1 from the superheated steam injection pipe 4b to the waste after hydrolysis, and the stirring blade 2 is rotated while maintaining the pressure at 0.1 Mpa (1 atm) and the temperature at 120 ° C. Dried while.
The drying was completed in about 2 to 3 hours when the water content of the waste immediately after hydrolysis was changed from 80% to 20%.

In both cases of Examples 1 and 2, the drying could be completed in a short time without remodeling the surrounding equipment by directly adding superheated steam without heating the pressure vessel from the outside. In particular, in the case of Example 2 where the pressure was reduced and drying was performed, speed drying was possible.
Further, in the case of Examples 1 and 2, since the water removal rate by superheated steam is high, the odor component remaining in the waste immediately after hydrolysis is absorbed and removed together, so malodor is diffused to the surroundings. There was hardly anything.

  According to the waste treatment system of the present invention, the conventional waste treatment apparatus or the equipment in the raw material conversion treatment system is used as it is, and the drying process is improved and the drying time is greatly shortened. Therefore, the daily rotation rate of the apparatus can be increased, and the cost can be greatly shortened. Moreover, since the odor component can be effectively removed at the stage of hydrolysis and the stage of the drying process, bad odor is not diffused to the surroundings and the environment is not adversely affected.

DESCRIPTION OF SYMBOLS 1 Pressure-resistant container 2 Stirring blade 3 Motor 4 Boiler 5 Pressure control device 6 Temperature detection line 7 Pressure detection line 8 Steam exhaust port 9 Control apparatus 10 Capacitor 11 Vacuum pump 12 Pump 13 Absorption tower for acid washing 14 Absorption tower for alkali washing 15 Exhaust 16 Moisture evaporator (vacuum dryer)
17 Neutralization tank

Claims (9)

  Pressure-resistant container provided with waste inlet and outlet, agitation means for agitating waste in the container, high-heat steam supply means for supplying high-heated saturated steam into the container, and pressure for opening and closing the pressure in the container In a waste treatment system comprising at least a pressure adjusting means for adjusting the temperature, and a control means for controlling the temperature and pressure in the container, after the hydrolysis treatment of the waste, the on-off valve of the pressure adjusting means A waste treatment system characterized in that after the pressure is reduced, superheated steam is injected into the container to dry the waste.   The waste treatment system according to claim 1, wherein the superheated steam injected into the pressure vessel after the hydrolysis treatment of the waste is adjusted so that the temperature of the waste is 100 to 200 ° C., and the waste is dried.   The waste treatment system according to claim 1 or 2, wherein a gas containing an odorous component partially generated in hydrolysis is washed with an acidic aqueous solution such as dilute sulfuric acid and then washed with an alkaline aqueous solution such as caustic soda.   The waste disposal system according to claim 3, wherein hypochlorous acid is added to the alkaline aqueous solution to perform gas cleaning.   The waste treatment system according to any one of claims 1 to 4, wherein condensed water containing oil generated by hydrolysis is evaporated by a water evaporator to prevent oil-containing wastewater from being produced.   The pressure vessel has a double wall structure, and supplies high-temperature steam to the gap between the outer wall and the inner wall, and after the waste is hydrolyzed, superheated steam is injected into the gap. Waste disposal system.   The waste treatment system according to any one of claims 1 to 6, wherein the stirring treatment of the input waste is performed by controlling the temperature in the pressure resistant container to 230 ° C or higher and the pressure to 3 MPa.   Waste is industrial waste of at least one of sludge, waste plastics, paper waste, wood waste, animal solid waste, animal and plant residues, animal manure, animal carcasses, infectious specially controlled industrial waste The waste disposal system according to any one of claims 1 to 7. The waste is a general waste of at least one of business-type general waste, household waste, medical waste, infectious special management general waste, sorted garbage, and food residue. Any waste treatment system.

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