JP2004089777A - Treatment method for organic waste and treatment equipment therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment method for organic waste capable of more effectively utilizing energy. <P>SOLUTION: Organic waste P is burnt under pressure and a gas turbine 14 is driven by the exhaust gas G generated by this combustion. At this time, organic waste is fermented and at least a part of a combustible product produced by fermentation is burnt at a temperature higher than the combustion temperature of the waste P. The high temperature gas T generated by this high temperature combustion is mixed with the exhaust gas G to raise the temperature of the exhaust gas G at the supply to the gas turbine 14. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and a facility for treating organic waste. More particularly, the present invention relates to an apparatus in which a combustion process is performed under pressure or a pressure furnace is provided.
[0002]
[Prior art]
Conventional treatment methods for organic waste (waste containing organic matter) such as waste liquid and sewage sludge simply incinerate organic waste, and there is little consideration for effective use of energy. Had not been done.
[0003]
On the other hand, in a power plant or the like, power is recovered by a facility 100 as shown in FIG. In this facility 100, CWM, which is a liquefied fuel obtained by mixing and dispersing pulverized coal in water and stabilized, is burned in a combustion furnace 101, and the high-temperature and high-pressure exhaust gas G1 generated by the combustion causes gas turbine 114 and power generation. Device 118 is driven to recover power. At the same time, the water is heated in the boiler device 115 by the thermal energy of the high-temperature exhaust gas G2 discharged from the gas turbine 114, and further heated in the combustion furnace 101 to collect steam J. The steam turbine 117 and the generator 119 are driven by J to recover electric power.
[0004]
Therefore, at the time of the treatment of organic waste, the treatment in accordance with the treatment in the facility 100 has been performed, and the effective use of energy has been started. In other words, in the current treatment of organic waste, organic waste is burned in a fluidized-bed furnace or the like, which is considered preferable for burning organic waste. Driving loads such as gas turbines and generators, as well as recovering steam in boilers and the like using the thermal energy of high-temperature exhaust gas discharged from gas turbines, and driving loads such as steam turbines and generators with this steam With this, energy such as electric power is recovered.
[0005]
[Problems to be solved by the invention]
However, this processing method has the following problems.
That is, first, the combustion temperature of the organic waste is stabilized by melting the inorganic substances contained in the organic waste and sintering the fluidized medium (when the combustion furnace is a fluidized bed furnace). From the viewpoint of preventing the operation from being hindered, the temperature is generally set to about 800 to 900 ° C. Therefore, there is a problem that the temperature of the exhaust gas entering the gas turbine is relatively low, and the turbine efficiency deteriorates.
[0006]
In addition, since organic waste is waste such as waste liquid and sewage sludge, the calorific value naturally changes. Therefore, there is a problem that energy such as recovered electric power is not stable and cannot be used systematically.
[0007]
Further, due to the unstable energy recovery rate, even when the steam turbine is driven, energy such as electric power cannot be effectively recovered. On the contrary, there is a problem that it is not economical due to an increase in equipment costs.
[0008]
Therefore, a main object of the present invention is to provide a method and an apparatus for treating organic waste, which can utilize energy more effectively.
[0009]
[Means for Solving the Problems]
The present invention which has solved the above-mentioned problems is as follows.
<Invention according to claim 1>
A method for treating organic waste by burning organic waste under pressure and driving a gas turbine by exhaust gas generated by the combustion,
Fermenting the organic waste, burning at least a portion of the combustible products generated by the fermentation at a high temperature compared to the combustion temperature of the organic waste,
A method for treating organic waste, wherein the temperature of the exhaust gas when supplied to the gas turbine is increased by mixing the high-temperature gas generated by the high-temperature combustion into the exhaust gas.
[0010]
<Invention according to claim 2>
The method for treating organic waste according to claim 1, wherein the fermentation residue of organic waste is burned alone or together with other organic waste.
[0011]
<Invention of Claim 3>
The organic waste treatment method according to claim 1 or 2, wherein the organic waste to be fermented is heated by thermal energy of the exhaust gas after being used for driving the gas turbine.
[0012]
<Invention of Claim 4>
A combustion furnace for burning organic waste, and a gas turbine driven by exhaust gas generated in the combustion furnace, an organic waste treatment facility having:
An auxiliary combustion furnace that burns at least a portion of the combustible products generated by fermentation of the organic waste at a temperature higher than the combustion temperature in the combustion furnace is provided.
The high-temperature gas generated in the auxiliary combustion furnace is mixed into the exhaust gas to increase the temperature of the exhaust gas when supplied to the gas turbine. Facility.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
<Overview of the present invention>
The method for treating organic waste according to the present invention is a method of burning organic waste under pressure and driving a gas turbine by exhaust gas generated by the combustion, and fermenting the organic waste. At least a part of combustible products such as combustible gas and liquid generated in fermentation is burned at a high temperature compared to the combustion temperature of organic waste, and the high-temperature gas generated by this high-temperature combustion is contained in exhaust gas. The mixing increases the temperature of the exhaust gas when supplied to the gas turbine.
[0014]
In this regard, a combustion furnace other than a fluidized bed furnace can be used for combustion of “combustible products generated by fermentation of organic waste”. Therefore, the sintering problem described above can be avoided. In addition, in the combustion of “combustible products generated by fermentation of organic waste”, there is naturally no fear of melting inorganic substances. Therefore, the "flammable products generated by fermentation of organic wastes" can be burned at high temperatures without any adverse effects. On the other hand, if "combustible products generated by fermentation of organic waste" is burned at a higher temperature than the combustion temperature of organic waste, the exhaust gas will also be hot, so this high-temperature gas is When mixed with the exhaust gas generated by the combustion of waste, the temperature of the exhaust gas increases. The higher the temperature of the supplied gas, the higher the turbine efficiency of the gas turbine. Therefore, according to the method of the present invention, there is provided a method for treating organic waste, which can utilize energy more effectively without causing inconveniences such as operation failure of a combustion furnace.
[0015]
Further, according to the method of the present invention, even if the amount of exhaust gas generated by combustion of organic waste is unstable, high-temperature gas generated by combustion of combustible products generated by fermentation of organic waste is used. To adjust the amount of gas supplied to the gas turbine. Therefore, stable energy recovery can be achieved.
[0016]
The method for fermenting the organic waste is not particularly limited. Known methods can be used.
[0017]
The organic waste to be fermented is not particularly limited. The same can be applied to the same organic waste to be burned, such as waste liquid and sewage sludge. However, it is preferable to burn the fermentation residue of the organic waste alone or together with other organic waste. In this way, the energy of organic matter can be fully utilized.
[0018]
Furthermore, when fermenting the organic waste, it is preferable to heat the organic waste to be fermented by the thermal energy of the exhaust gas used for driving the gas turbine. In this regard, in the organic waste treatment facility, unlike a power plant or the like, even if a steam turbine is driven by thermal energy of exhaust gas, energy such as electric power cannot be effectively recovered. This is the same even if the energy recovery rate is stabilized by the method of the present invention. This is because the uneconomicity caused by capital investment is remarkable. However, if the thermal energy of the exhaust gas is used to heat the organic waste to be fermented as in the present invention, the facility cost is hardly increased (because of the waste treatment facility). , Heat energy can be used effectively.
[0019]
<Processing equipment>
Next, an example of the present embodiment that embodies the above processing method will be described with reference to FIG.
The processing facility 70 includes the combustion furnace 1. At the upper part of the combustion furnace 1, a plurality of supply ports 2 for organic waste P provided with a spray nozzle and the like are provided (note that FIG. 1 shows only one supply port 2). .). These supply ports 2 are supplied by an organic waste supply path (the supply path can be constituted by a pipe, for example. The same applies to other supply paths and exhaust paths described below). The organic waste P is connected to a storage tank 5 via a pump 4. 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 sewage sludge is pressurized by the supply pump 4 and sprayed and supplied into the combustion furnace 1 from the supply port 2 together with the combustion air A. The organic waste P supplied by spraying is burned under pressure in the combustion furnace 1.
[0020]
A plurality of supply ports 7 for the auxiliary fuel R provided with a spray nozzle and the like are provided at the upper part of the combustion furnace 1 (only one supply port 7 is shown in FIG. 1). A supply path 9 for the auxiliary fuel R is connected to these supply ports 7. The supply path 9 is connected to the supply path 8 of the combustion air A branched from the supply path 6. The auxiliary fuel R is injected and supplied into the combustion furnace 1 together with the combustion air A, and is burned in the combustion furnace 1.
[0021]
As the auxiliary fuel R, for example, a liquid fuel such as light oil or kerosene, a solid fuel such as pulverized coal, a gas fuel such as LNG, and the like can be used. Instead, a combustible gas or liquid S (hereinafter, also simply referred to as a combustible product S) supplied from the fermentation treatment apparatus 57 via the supply path 38 is used. Thereby, effective use of energy is achieved. In the present embodiment, the flammable product S is transported through the supply path 38. However, for example, the flammable product S is packed in a container, and the container is transported and used. It can also be.
[0022]
At the furnace bottom of the combustion furnace 1, an ash outlet 10 for discharging inorganic ash contained in the organic waste P is provided. Further, at the furnace top of the combustion furnace 1, an exhaust port 11 for exhausting a combustion exhaust gas G containing dust generated by the combustion of the organic waste P is provided. The exhaust port 11 is connected to a dust collector 13 including a bag filter and the like via an exhaust path 12.
[0023]
The dust collector 13 is for removing dust in the combustion exhaust gas G. If the dust collecting device 13 is not installed, dust in the combustion exhaust gas G may enter the gas turbine 14 described below and damage the turbine or adhere to the turbine, which may hinder stable operation. In the dust collector 13, the clean gas (combustion exhaust gas) G from which the dust has been removed is supplied to the gas turbine 14 via the exhaust path 21.
[0024]
An exhaust path 24 for exhausting the high-temperature gas T generated in the auxiliary combustion furnace 19 is connected to the exhaust path 21. In addition to the exhaust path 24, a supply path 20 for the auxiliary fuel R ′ and a supply path 26 branched from the supply path 6 for the combustion air A are connected to the auxiliary combustion furnace 19. The auxiliary fuel R ′ supplied to the auxiliary combustion furnace 19 is burned by the combustion air A. The high-temperature gas T generated by this combustion is exhausted through the exhaust path 24 and mixed into the combustion exhaust gas G.
[0025]
The mixing of the high temperature gas T is for increasing the temperature of the combustion exhaust gas G. Therefore, the combustion in the auxiliary combustion furnace 19 needs to be performed at a higher temperature than the combustion temperature of the organic waste P in the combustion furnace 1. In the present embodiment, the combustion temperature is 900 to 1200 ° C., although it depends on the amount of gas generated in the auxiliary combustion furnace 19.
[0026]
As the auxiliary fuel R ′, for example, a liquid fuel of kerosene grade or higher, a gaseous fuel such as LNG, or the like can be used, but the combustible product S supplied from the fermentation treatment apparatus 57 via the supply path 38 is used. It is preferred to use
[0027]
When a liquid fuel of kerosene grade or higher or a gaseous fuel such as LNG is used as the auxiliary fuel R, the supply passage 20 is branched from the supply passage 9 to supply the auxiliary fuel R to the auxiliary combustion furnace 19. It can also be configured to be performed.
[0028]
When the pressure of the combustion exhaust gas G generated in the combustion furnace 1 is low, for example, when the inside of the combustion furnace 1 is not at a sufficient pressure due to, for example, the beginning of the operation of the processing equipment 70, the gas is supplied to the auxiliary combustion furnace 19. The amount of the high-temperature gas T exhausted from the auxiliary combustion furnace 19 is increased by increasing the amount of the auxiliary fuel R ′. Thereby, 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 is stably maintained, or the rise time until the high-pressure state is reached is reduced. be able to.
[0029]
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 sent to the fermentation treatment device 57 and used as a heat source for heating the organic waste P. In the present embodiment, the combustion exhaust gas G is supplied to the fermentation treatment device 57 after passing through the preheater 15, but may be directly sent to the fermentation treatment device 57 without passing through the preheater 15. it can.
[0030]
The fermentation treatment device 57 is a device for fermenting the organic waste P, and a known device can be used. The supply path 38 is connected to the fermentation treatment apparatus 57, and the flammable product S can be transported by the supply path 38 as described above.
[0031]
The combustion exhaust gas G used as a heat source in this way is sent to the exhaust gas treatment device 16 including an electric dust collector or the like via the supply path 29, and after being cleaned, is discharged into the atmosphere.
[0032]
By the way, in the present embodiment, a compressor 17 is connected to the gas turbine 14, and is driven in accordance with the driving of the gas turbine 14. 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 via 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 paths 8 and 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 is generated in the combustion furnace 1 at a pressure higher than normal pressure (under pressure). P will be burned.
[0033]
In the present 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 via the exhaust passages 12 and 21 becomes small. The gas turbine 14 cannot be driven unless the amount of the auxiliary fuel R supplied to the inside is increased, which may hinder efficient energy recovery. On the other hand, in order to increase the pressure in the combustion furnace 1 to more than 1.0 MPa, the combustion furnace 1 must be provided with a higher-strength pressure-resistant structure. It may be economical.
[0034]
It should be noted that a generator (not shown) may be connected to the combustion processing facility 70 via the compressor 17 to the gas turbine 14. However, depending on the amount of the organic waste P to be treated, there is a case in which there is no advantage of installing a generator to recover power, and therefore, it is not provided in the present embodiment.
[0035]
By the way, in the present embodiment, the compressor 17 and the preheater 15 are directly connected via the supply path 30. However, as shown by a dotted line in FIG. An oxygen PSA device 22 driven by the turbine 14 may be interposed. In this respect, the oxygen PSA device is for adsorbing nitrogen in pressurized air to increase the oxygen concentration, as is well known. Therefore, in such a configuration (a configuration in which the oxygen PSA 22 is interposed), the oxygen concentration of the combustion air A increases, so that the organic waste P when the combustion air A is supplied to the combustion furnace 1 is removed. The combustion efficiency will be improved. Thereby, the usage amount of the auxiliary fuel R is reduced, and more economical combustion processing is realized.
[0036]
Further, most of the composition of the combustion exhaust gas G generated when the organic waste P is burned by the combustion air A having a high oxygen concentration is 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 facilitates the recovery and removal of carbon dioxide as compared with the case of flue gas G generated by the use of ordinary air in which the majority of nitrogen is used. It is possible to provide a combustion treatment facility that can contribute to a reduction in emissions.
[0037]
【The invention's effect】
As described above, according to the present invention, there are provided a method and an apparatus for treating organic waste, which can utilize energy more effectively.
[Brief description of the drawings]
FIG. 1 is a flowchart showing equipment for effectively performing power recovery.
FIG. 2 is a flowchart showing an organic waste treatment facility of the present embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Combustion furnace, 13 ... Dust collection device, 14 ... Gas turbine, 15 ... Preheater, 16 ... Exhaust gas treatment device, 17 ... Compressor, 19 ... Auxiliary combustion furnace, 22 ... Oxygen PSA device, 57 ... Fermentation treatment device, 70 ... Organic waste treatment equipment, A ... Combustion air, C ... Air, G ... Combustion exhaust gas, P ... Organic waste, R, R '... Auxiliary fuel, S ... Combustible products, T ... High temperature gas .

Claims (4)

A method for treating organic waste by burning organic waste under pressure and driving a gas turbine by exhaust gas generated by the combustion,
Fermenting the organic waste, burning at least a portion of the combustible products generated by the fermentation at a high temperature compared to the combustion temperature of the organic waste,
A method for treating organic waste, wherein the temperature of the exhaust gas when supplied to the gas turbine is increased by mixing the high-temperature gas generated by the high-temperature combustion into the exhaust gas. The method for treating organic waste according to claim 1, wherein the fermentation residue of the organic waste is burned alone or together with another organic waste. The organic waste treatment method according to claim 1 or 2, wherein the organic waste to be fermented is heated by thermal energy of the exhaust gas used for driving the gas turbine. A combustion furnace for burning organic waste, and a gas turbine driven by exhaust gas generated in the combustion furnace, an organic waste treatment facility having:
An auxiliary combustion furnace that burns at least a portion of the combustible products generated by fermentation of the organic waste at a temperature higher than the combustion temperature in the combustion furnace is provided.
The high-temperature gas generated in the auxiliary combustion furnace is mixed into the exhaust gas to increase the temperature of the exhaust gas when supplied to the gas turbine. Facility.

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