JP4045337B2 - Organic waste treatment method and equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic waste processing method and processing equipment. More specifically, the present invention relates to an apparatus in which combustion treatment is performed or provided with a combustion treatment facility, and particularly relates to an apparatus suitable when activated sludge treatment is performed or an activated sludge treatment facility is provided.
[0002]
[Prior art]
In recent years, various attempts have been made to effectively use energy in the treatment of organic wastes such as waste liquid and sewage sludge. One of them is that "organic waste is combusted under pressure, and the gas turbine is driven by the high-temperature and high-pressure exhaust gas generated by the combustion to recover energy". For example, as shown in FIG. 1, a combustion furnace 101 that burns organic waste P, and a gas turbine 114 that is driven by a high-temperature and high-pressure exhaust gas G generated in the combustion furnace 101 are used. And an air compressor 117 that is driven by the power recovered by the gas turbine 114. In this facility, after the air C is compressed by the air compressor 117, it is sent to the combustion furnace 101 as the combustion air A so as to circulate energy. Some of these facilities are further provided with a heat exchanger 115. Even after this facility is used to drive the gas turbine 114, the exhaust gas G still has thermal energy. Therefore, the thermal energy is recovered by the heat exchanger 115, and the previous compressed air is heated by the recovered energy. In this way, energy circulation is achieved.
[0003]
[Problems to be solved by the invention]
However, these facilities have the following problems.
That is, in these facilities mainly intended for the treatment of organic waste, unlike in power plants, etc., a general-purpose product that is small and inexpensive as a gas turbine is generally provided. In general, an air compressor is provided in a gas turbine. These are used as a single axis. This is because the energy recovery rate varies depending on the components and amount of organic waste in facilities that mainly handle organic waste, so the economic effect is appropriate for introducing large and expensive gas turbines. This is because it cannot be expected. The general-purpose products that are considered to be uniaxial are designed on the assumption that high-grade gas fuels such as LNG (liquefied natural gas) and liquid fuels such as light oil and kerosene are used, and enter the gas turbine. The amount of gas (m ³ N standard) and the amount of compressed air generated in the air compressor (m ³ N standard) are substantially equal. However, when organic waste is combusted, the amount of exhaust gas increases due to the vaporization of moisture. Therefore, it is necessary to select a gas turbine based on this increased amount of exhaust gas. According to the above, since the amount of compressed air becomes excessive, energy is lost correspondingly. Further, in such equipment, as described above, the heat energy of the exhaust gas is used for heating the compressed air, but the heat energy of the exhaust gas is not completely recovered by this heat use, so that much. It becomes a loss of energy.
[0004]
Then, the main subject of this invention is providing the processing method and processing apparatus of the organic waste which can utilize energy still more effectively.
[0005]
[Means for Solving the Problems]
The present invention that has solved the above problems is as follows.
[0006]
<Invention of Claim 1 >
An organic waste is burned under pressure, and a gas turbine is driven by exhaust gas generated by the combustion.
An organic waste treatment method, wherein the exhaust gas is used as a heat source in activated sludge treatment after the exhaust gas is used for driving the gas turbine.
[0007]
[0008]
<Invention of Claim 2 >
An activated sludge treatment facility for organic wastewater equipped with a heat utilization device, a combustion furnace for burning organic waste containing excess sludge generated in this activated sludge treatment facility under pressure, and an exhaust gas generated in this combustion furnace A combustion treatment facility equipped with a driving gas turbine, and an organic waste treatment facility comprising:
An organic waste treatment facility, wherein the exhaust gas is used as a heat source of the heat utilization device after being used for driving the gas turbine.
[0009]
<Invention of Claim 3 >
The activated sludge treatment facility comprises an aeration tank for aeration of organic waste water, a settling tank for separating the aerated organic waste water into treated liquid and precipitated sludge, and a part of the precipitated sludge as return sludge. A return means for returning to the aeration tank, and a digester for anaerobic digestion treatment with the remainder of the precipitated sludge as excess sludge,
The organic waste treatment facility according to claim 2 , wherein at least one of the aeration tank, the return means, and the digester is a heat utilization device.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments and reference embodiments of the present invention will be described below.
<Outline of this embodiment >
The organic waste processing method according to the present embodiment relates to a case where organic waste is burned under pressure, and a gas turbine is driven by high-temperature and high-pressure exhaust gas generated by the combustion. By effectively using “(1) pressure (expansion force)” or “(2) heat”, energy is effectively used.
The method of this embodiment as a method of effectively using the pressure ((1)) and heat ((2)) of the exhaust gas is generated by driving an air compressor by a gas turbine and driving the air compressor. A part of the compressed air is used for burning organic waste, and the remainder of the compressed air is used for aeration of organic waste water. By using the compressed air not only for burning organic waste but also for aeration of organic waste water, the problem of excess compressed air described in the prior art is solved.
[0011]
Further, the method of this embodiment as a method of effectively using the heat of exhaust gas ((2)) is characterized in that the exhaust gas is used as a heat source in activated sludge treatment after being used for driving a gas turbine. It is what. By using the exhaust gas as a heat source in the activated sludge treatment, the thermal energy of the exhaust gas remaining even after heat recovery by a heat exchanger or the like is effectively used.
[0012]
In these methods, the aeration process or the activated sludge process may be performed in the system of this embodiment of organic waste treatment or may be performed in a system different from this embodiment. . Hereinafter, in this embodiment, the case where these processes are performed in the system of this embodiment , that is, the case where the process of this embodiment includes “activated sludge treatment” and “combustion treatment” will be described.
[0013]
<Activated sludge treatment>
FIG. 2 shows an organic waste treatment facility according to this embodiment having an activated sludge treatment facility 60 and a combustion treatment facility 70.
In the activated sludge treatment facility 60 according to the present embodiment, the organic waste water H such as sewage, human waste, and industrial waste water can be configured from the storage tank 50 by a supply path (the supply path is, for example, a pipe). The same applies to other supply paths, return paths, and exhaust paths.) The gas is supplied to the aeration tank 51 directly through 31 or via a (first) sedimentation tank (not shown). In this aeration tank 51, the organic waste water H is brought into contact with activated sludge as an aerobic microorganism source under an aerobic condition and subjected to a biooxidation treatment. The aeration tank 51 is provided with an air blow means 51A for discharging air so that the inside of the tank can be kept aerobic.
[0014]
The organic waste water H that has been subjected to biological oxidation treatment in the aeration tank 51 is supplied to the precipitation tank 52 through the supply path 32. In the sedimentation tank 52, the organic waste water H is separated into a liquid to be treated W and a sedimentation sludge D.
[0015]
Among these, the liquid W to be treated is sent to the water quality adjustment tank 53 through the supply path 33, and after the water quality is adjusted in the water quality adjustment tank 53, it is discharged out of the system.
On the other hand, a part of the precipitated sludge D (return sludge B) is returned to the aeration tank 51 through a return path 34 as a return means. The returned sludge B is used as activated sludge in the aeration tank 51. The remainder of the sedimented sludge D (excess sludge Y, corresponding to the increased amount of activated sludge in the aeration tank 51) is supplied to the concentrating device 54 via the supply path 35 and concentrated. After the concentration treatment, the excess sludge Y is supplied to the anaerobic digester 55 via the supply path 36, digested, and stabilized and reduced in volume. Digestion gas S such as methane gas generated during the digestion process is collected and used as appropriate. The surplus sludge Y that has been digested is further supplied to the dehydrator 56 via the supply path 37 and dehydrated. The excess sludge Y that has been dehydrated is supplied to the storage tank 5 of the combustion treatment facility 70 via the supply path 39.
[0016]
<Combustion treatment>
Next, the combustion treatment facility 70 according to this embodiment will be described.
The combustion treatment facility 70 is provided with a combustion furnace 1. A plurality of organic waste P supply ports 2 provided with spray nozzles and the like are provided in the upper portion of the combustion furnace 1 (note that only one supply port 2 is shown in FIG. 1). .) These supply ports 2 are connected to a storage tank 5 for organic waste P through a supply pump 4 by an organic waste supply path 3. A supply path 6 for combustion air A is connected to the organic waste supply path 3. The organic waste P stored in the storage tank 5 such as waste liquid and surplus sludge Y supplied from the activated sludge treatment facility 60 described above is pressurized by the supply pump 4 and is combusted from the supply port 2 together with the combustion air A. 1 is supplied by spraying. The organic waste P supplied by spraying is burned in the combustion furnace 1.
[0017]
A plurality of auxiliary fuel R supply ports 7 provided with spray nozzles and the like are provided in the upper part of the combustion furnace 1 (note that only one supply port 7 is shown in FIG. 1). A supply path 9 for auxiliary fuel R is connected to these supply ports 7. A supply path 8 for combustion air A branched from the supply path 6 is connected to the supply path 9. The auxiliary fuel R is injected and supplied into the combustion furnace 1 together with the combustion air A and burned in the combustion furnace 1. As the auxiliary fuel R, for example, liquid fuel such as light oil and kerosene can be used.
[0018]
An ash content outlet 10 for discharging inorganic ash contained in the organic waste P is provided at the bottom of the combustion furnace 1. In addition, an exhaust port 11 is provided at the top of the combustion furnace 1 for exhausting the combustion exhaust gas G containing soot generated by the combustion of the organic waste P. The exhaust port 11 is connected to a dust collector 13 such as a bag filter through an exhaust path 12.
[0019]
The dust collector 13 is for removing the dust in the combustion exhaust gas G. If this dust collector 13 is not installed, the dust in the combustion exhaust gas G enters the gas turbine 14 to be described later, which may damage the turbine or adhere to the turbine and hinder stable operation. In the dust collector 13, the clean gas (combustion exhaust gas) G from which the dust is removed is sent to the auxiliary combustion furnace 19 via the exhaust passage 24.
[0020]
In addition to the supply path 24 for supplying the clean gas G, the auxiliary combustion furnace 19 is supplied with a supply path 26 branched from the supply path 6 for the combustion air A and a supply branched from the supply path 9 for the auxiliary fuel R. A passage 20 and an exhaust passage 21 connected to the gas turbine 14 are connected. The auxiliary fuel R and the clean gas G supplied to the auxiliary combustion furnace 19 are combusted by the combustion air A, and the combustion exhaust gas G generated by this combustion is sent to the gas turbine 14 through the exhaust passage 21, and thus the gas The turbine 14 is driven.
[0021]
When the pressure of the combustion exhaust gas G generated in the combustion furnace 1 is low, for example, when the pressure in the combustion furnace 1 is not sufficient because the combustion treatment facility 70 is initially operated, the auxiliary combustion furnace 19 The amount of auxiliary fuel R to be supplied is increased, and the amount of combustion exhaust gas G sent from the auxiliary combustion furnace 19 to the gas turbine 14 is increased. As a result, the air C can be pressurized to a sufficient pressure and supplied to the combustion furnace 1, and the high pressure state in the combustion furnace 1 can be stably maintained, or the rise time until the high pressure state is reached can be shortened. be able to.
[0022]
In this embodiment, the clean gas G from the dust collector 13 is sent to the auxiliary combustion furnace 19 via the supply path 24. However, the present invention is not limited to this embodiment. For example, the clean gas G from the dust collector 13 may be sent directly to the gas turbine 14.
[0023]
The combustion exhaust gas G used for driving the gas turbine 14 is further passed through the supply path 28 to the preheater 15 and used as a heat source. The combustion exhaust gas G used as a heat source is further provided with a heat utilization device 57 provided in the activated sludge treatment facility 60 (in FIG. 2, this heat utilization device 57 is shown in a place different from the activated sludge treatment facility 60. (This is for convenience of explanation.) And is used as a heat source.
[0024]
In the facility of the present embodiment, the heat utilization device 57 includes an aeration tank 51 (1 in the figure (maru 1)), a return path 34 (2 (in circle) in the figure) as a return means, and a digester 55 (3 (in the figure) in the figure). )). However, the present invention is not limited to this, and only one of the devices may be used as the heat utilization device 57 (in this case, a device that does not become the heat utilization device 57 is provided with another heat source or does not use heat). In addition, the heat utilization device 57 can be used as long as other devices utilize heat. Further, the exhaust gas G can be directly sent to the heat utilization device 57 without passing through the preheater 15.
[0025]
The exhaust gas G that has been heat-utilized in this way is sent to the exhaust gas treatment device 16 including an electric dust collector and the like through the supply path 29, and after being purified, is discharged into the atmosphere.
[0026]
Incidentally, in the present embodiment, a compressor 17 is connected to the gas turbine 14, and is driven as the gas turbine 14 is driven. Air C is supplied to the compressor 17. The air C supplied to the compressor 17 is compressed into compressed air, and then sent to the preheater 15 through the supply path 30. In the preheater 15, the compressed air C is heated by the heat of the combustion exhaust gas G, and then passes through the supply path 6 and the supply path 8 and the supply path 26 branched from the supply path 6 as high-temperature and high-pressure combustion air A. Is done. In this way, the combustion furnace 1 is supplied with the high-pressure combustion air A pressurized by the compressor 17, so that the organic waste P is burned in the combustion furnace 1 at a pressure higher than normal pressure. Will be.
[0027]
In this embodiment, the pressure in the combustion furnace 1 is set to be 0.2 to 1.0 MPa. When the pressure in the combustion furnace 1 falls below 0.2 MPa, the pressure of the combustion exhaust gas G exhausted from the exhaust port 11 and supplied to the gas turbine 14 through the exhaust path 12, the auxiliary combustion furnace 19, and the exhaust path 21 is small. Therefore, unless the amount of the auxiliary fuel R supplied into the auxiliary combustion furnace 19 is increased, the gas turbine 14 cannot be driven, and efficient energy recovery may be hindered. On the other hand, in order to increase the pressure in the combustion furnace 1 to exceed 1.0 MPa, the combustion furnace 1 must be made to have a higher pressure resistance structure, and in view of the fact that the energy recovery efficiency is improved. There is a risk of becoming economical.
[0028]
In the combustion treatment facility 70, it is also conceivable to connect a generator (not shown) to the gas turbine 14 via the compressor 17. However, depending on the amount of organic waste processed, there is a case where there is no advantage of collecting power by installing a generator.
[0029]
However, in this embodiment, a part of the combustion air A is sent to the aeration tank 51 via the supply path 40 and discharged from the air blowing means 51A. Thereby, effective use of compressed air is achieved.
[0030]
In this embodiment, a part of the combustion air A heated by the preheater 15 is sent to the aeration tank 51. However, the present invention is not limited to this. The air compressed by the air compressor 17 can be sent directly to the aeration tank 51 without passing through the preheater 15. However, when a part of the combustion air A heated by the preheater 15 is sent to the aeration tank 51, the inside of the aeration tank 51 is heated by the combustion air A. The need for the device 57 and the need to provide a unique heat source in the aeration tank 51 are eliminated, and the facility is simplified.
[0031]
Incidentally, in this embodiment, the compressor 17 and the preheater 15 are directly connected via the supply path 30, but the gas turbine 14 is interposed between the compressor 17 and the preheater 15 as indicated by a dotted line in FIG. 1. It is also possible to interpose an oxygen PSA device 22 driven by In this regard, the oxygen PSA device is for adsorbing nitrogen in pressurized air and increasing the oxygen concentration as is well known. Therefore, in this form (form in which the oxygen PSA device 22 is interposed), the oxygen concentration of the combustion air A increases, so that the organic waste when the combustion air A is supplied to the combustion furnace 1 The combustion efficiency of P is improved. Thereby, the usage-amount of the auxiliary fuel R is reduced and a more economical combustion process is implement | achieved.
[0032]
Further, the combustion exhaust gas G generated when the organic waste P and the auxiliary fuel R are combusted with the combustion air A having a high oxygen concentration mainly comprises water vapor and carbon dioxide. Therefore, if the combustion exhaust gas G is cooled, for example, in the exhaust gas treatment device 16, the water vapor is condensed, so that the combustion exhaust gas G is mainly composed of carbon dioxide. This makes it easier to collect and remove carbon dioxide than in the case of combustion exhaust gas G generated by the use of normal air, where nitrogen accounts for the majority. It is possible to provide a combustion treatment facility that can contribute to the reduction of the emission amount.
[0033]
【Example】
The effect of the organic waste treatment facility (combustion treatment facility 70) according to this embodiment shown in FIG. 2 was confirmed.
In this embodiment, the air C pressurized by the compressor 17 is supplied directly to the preheater 15 without going through the oxygen PSA device 22 and preheated, and then a part thereof is supplied to the combustion furnace 1 as combustion air A. The remainder is sent out of the system. As the organic waste P, surplus sludge Y was used. The excess sludge Y had a water content of 89% by mass, an organic content of 11% by mass, and an organic component heat generation amount of 27 MJ / kg. This surplus sludge Y was supplied to the combustion furnace 1 at 100 t / day by a supply pump 4 having a boosting capacity of 1.5 MPa and burned. At this time, kerosene as auxiliary fuel R for maintaining temperature was also supplied and burned. The amount of kerosene supplied was 850 l / h. The pressure in the combustion furnace 1 was 0.5 MPa, and the temperature was 850 ° C. Kerosene was also supplied to the auxiliary combustion furnace 19 for combustion. The amount of kerosene supplied was 50 l / h. All the combustion exhaust gas G discharged from the auxiliary combustion furnace 19 was supplied to the gas turbine 14, and the compressor 17 was driven to pressurize the air C. At this time, the flow rate of the exhaust gas at the inlet of the gas turbine 14 was 15000 m ³ N / h, and the amount of air discharged from the compressor 17 was about 11000 m ³ N / h. The temperature of the exhaust gas at the inlet of the gas turbine 14 was 880 ° C., and the pressure was 0.46 MPa.
[0034]
In operation under such conditions, in order to keep the pressure in the combustion furnace 1 at the initial pressure of 0.5 MPa, the combustion air A of about 6500 m ³ N / h is supplied into the combustion furnace 1. It was enough. That is, about 3900 m ³ N / h of combustion air A was surplus (use of about 600 m ³ N / h of combustion air A in the auxiliary combustion furnace). Thereby, it turned out that a part of combustion air A can fully be utilized for an aeration process. The exhaust gas G that passed through the preheater 15 had a temperature of 450 ° C. and a flow rate of 15000 m ³ N / h. From this, it was found that the thermal energy of the exhaust gas G can be sufficiently utilized in the activated sludge treatment.
[0035]
【The invention's effect】
As described above, according to the present invention, an organic waste processing method and processing apparatus that can make more effective use of energy can be obtained.
[Brief description of the drawings]
FIG. 1 is a flow diagram showing a conventional organic waste treatment facility.
FIG. 2 is a flow diagram showing an organic waste treatment facility of the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Combustion furnace, 13 ... Dust collector, 14 ... Gas turbine, 15 ... Preheater, 16 ... Exhaust gas treatment device, 17 ... Compressor, 19 ... Auxiliary combustion furnace, 22 ... Oxygen PSA device, 50 ... Storage tank, 51 ... Aeration tank, 52 ... Precipitation tank, 53 ... Water quality adjustment tank, 54 ... Concentration device, 55 ... Digestion device, 56 ... Dehydration device, 60 ... Activated sludge treatment facility, 70 ... Combustion treatment facility, A ... Combustion air, B ... Return sludge, C ... air, D ... precipitation sludge, G ... combustion exhaust gas, H ... organic waste water, P ... organic waste, R ... auxiliary fuel, S ... digestion gas, Y ... excess sludge.

Claims (3)

An organic waste is burned under pressure, and a gas turbine is driven by exhaust gas generated by the combustion.
An organic waste treatment method, wherein the exhaust gas is used as a heat source in activated sludge treatment after the exhaust gas is used for driving the gas turbine. An activated sludge treatment facility for organic wastewater equipped with a heat utilization device, a combustion furnace for burning organic waste containing excess sludge generated in this activated sludge treatment facility under pressure, and an exhaust gas generated in this combustion furnace A combustion treatment facility equipped with a driving gas turbine, and an organic waste treatment facility comprising:
An organic waste treatment facility, wherein the exhaust gas is used as a heat source of the heat utilization device after being used for driving the gas turbine. The activated sludge treatment facility comprises an aeration tank for aeration of organic waste water, a settling tank for separating the aerated organic waste water into treated liquid and precipitated sludge, and a part of the precipitated sludge as return sludge. A return means for returning to the aeration tank, and a digester for anaerobic digestion treatment with the remainder of the precipitated sludge as excess sludge,
The organic waste treatment facility according to claim 2 , wherein at least one of the aeration tank, the return means, and the digester is a heat utilization device.

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