JP2003275798A - Apparatus for heat-treating organic waste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-treating apparatus the pressure in which can be kept by a simple means without using a pressure reducing valve which is likely to be clogged. <P>SOLUTION: This heat-treating apparatus has a reaction tank 3 in which the organic waste 21 containing 1-20% solid can be heat-treated continuously under pressure. The tank 3 has a sludge supplying pump 2 for introducing the subject to be treated into the tank 3 and a pressure reducing pump 4 for discharging the pressurized and treated material from the tank 3. A volume pump is used as the pumps 2 and 4. The heat-treatment in the tank 3 can be performed at 100-200°C within 3 hours residence time. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus for organic waste, and more particularly to a treatment apparatus for thermally decomposing organic waste containing solid matter under pressure.

[0002]

2. Description of the Related Art Incineration treatment is widely used in the treatment of organic waste. Since the incineration process converts all the organic components in the waste into carbon dioxide gas, etc., it is an extremely excellent method for reducing the final disposal amount of the waste. However, in recent years, it has become difficult to construct a new incinerator due to problems such as dioxins, so various alternative technologies such as gasification and melting, methane fermentation, and composting have been proposed. Among them, methane fermentation is attracting attention because it can reduce the volume and, at the same time, it can recover energy as electric power by combining it with a power generation facility.

Among the organic waste generated in Japan,
About 1/100 of biological sludge generated in sewage treatment plants and septic tanks
Occupy four. As mentioned above, the merits of applying methane fermentation to these biologically treated sludges are great. However, the solid matter decomposition rate of biologically treated sludge in methane fermentation is 30 to 40%, which means that the effects of volume reduction and energy recovery are limited. Therefore, as a means for improving the solid matter decomposition rate, there is a method of performing pretreatment such as crushing, addition of chemicals, and heat treatment before the methane fermentation. In the heat treatment method among these, it is known that the sewage surplus sludge has a solid matter decomposition rate of 50% or more when treated at a temperature of 150 to 180 ° C. for 30 minutes. Other advantages of heat treatment are that recovered heat can be used for treatment, it is safe because no chemicals are used, pathogenic microorganisms contained in sludge can be reliably inactivated, and dehydration of treated sludge is For example, the dehydration coagulant can be saved because it is improved.

When the organic waste is heat-treated at a temperature of 100 ° C. or higher, in order to continuously process it, the pressure inside the reaction vessel is maintained at a high pressure of atmospheric pressure or higher. Need to be attached. In order to maintain the pressure inside the reaction tank above atmospheric pressure, install a pressure reducing valve etc. in the outflow pipe,
It is necessary to use it as a pressure holding means. However, this means, by the solid matter contained in the object to be treated, piping,
In particular, it is difficult to apply because the pressure reducing valve or the like may be blocked. In addition, in order to perform batch treatment, pressure, temperature, water level may be detected or frequent valves may be detected, which may damage the inside of the reaction tank by temporarily applying a large force during sludge or heating. Since it is necessary to open and close the device, complicated operation control is required and the initial cost of the device increases, which is a problem.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and, when heat-treating organic waste, does not use a pressure-reducing valve which may cause blockage, and uses a simple means for pressure control. An object of the present invention is to provide a heat treatment device that can be held.

[0006]

In order to solve the above problems, in the present invention, a heat treatment having a reaction vessel capable of continuously heat treating an organic waste containing a solid matter under pressure. An apparatus for heat treatment of organic waste, characterized in that the reaction tank has a mud feed pump for introducing an object to be treated and a decompression pump for discharging a pressurized substance to be treated. . In the heat treatment device,
The mud feed pump and the vacuum pump are preferably of a positive displacement type, and the heat treatment in the reaction tank is preferably performed at a reaction temperature of 100 ° C. to 200 ° C. and a residence time of 3 hours or less.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is directed to an organic waste containing 1 to 20% of solid matter, and in a device for performing heat treatment at 100 ° C. or higher, the pressure inside the reaction tank during the heat treatment is increased. It is an apparatus that maintains a high pressure of at least atmospheric pressure and continuously performs processing. In the present invention, since the object to be treated is continuously heat-treated under a high pressure equal to or higher than the atmospheric pressure, a decompression pump is arranged at the outflow portion of the reaction tank. The mud supply pump and decompression pump are, for example, positive displacement pumps such as single screw pumps, roots pumps, gear pumps, etc. The internal pressure can be maintained at a high pressure to prevent temperature drop due to pressure drop. Further, since the temperature of the object after the treatment is 100 ° C. or more and the pressure is atmospheric pressure or more, it is boiled when it is opened under normal pressure, and the temperature is lowered to around 100 ° C., while the surplus temperature energy is converted to steam. To be converted. Since this phenomenon occurs downstream of the decompression pump, a drainage tank is installed, and excess steam in the upper part of the drainage tank is returned to the raw material storage tank to be used for heating the raw material to save heating energy. be able to.
Furthermore, by providing a heat exchanger at the outflow portion of the sludge discharge tank and using the recovered heat to heat the boiler feed water, it is possible to further reuse the residual heat.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a flow configuration diagram showing an example of the processing apparatus of the present invention. In the figure, 1 is a raw material storage tank, 2 is a mud feed pump, 3 is a reaction tank, 4 is a decompression pump, 5 is a mud discharge tank, 6 is a mud pump, and 7 is a heat exchanger. The operation of the processing apparatus of the present invention will be described with reference to FIG. 1. After the raw material 21 is once stored in the raw material storage tank 1, it is sent to the reaction tank 3 by the mud feed pump 2. In the reaction tank 3, the raw material 21 is heated by the heating steam 22 and heat-treated at a temperature of 100 to 200 ° C. In order to set the temperature condition in the reaction tank 3 to a predetermined condition, the amount of steam is controlled by the steam supply valve 8 which is interlocked with the thermometer 11. The heat-treated raw material is the vacuum pump 4
And is discharged to the sludge tank 5. At that time, since the inside of the sludge discharge tank 5 communicates with the outside through the raw material storage tank 1 and the deodorizing duct 23, the pressure is close to the atmospheric pressure and 100
It cannot rise above ℃. Therefore, boiling occurs in the sludge tank 5, and excess energy becomes excess steam 12. The surplus steam is blown into the raw material storage tank 1 through a pipe connected to the raw material storage tank 1 and is used for preliminary heating of the raw material 21. The raw material thus treated is transferred from the sludge pump 6 to the fermenter 24 through the heat exchanger 7.

FIG. 2 is a flow diagram showing another example of the processing apparatus of the present invention. In FIG. 2, the raw material 21 is supplied from the raw material storage tank 1 to the reaction tank 3 by the mud supply pump 2. The reaction tank 3 is heated by the steam 22. Heating is a thermometer 1
This is performed by controlling the steam supply valve 8 with the indicated value of 1. The raw material after the heat treatment is supplied to the sludge tank 5 through the pressure reducing pump 4. The heat exchanger 7 is installed on the discharge pipe of the mud supply pump 2 and the suction side of the decompression pump 4 to reuse the heating energy. In the mud discharge tank 5, since the pressure drops, surplus steam 12 is generated. Therefore, the steam is supplied to the raw material storage tank 1 and used for heating the raw material 21.

FIG. 3 is a flow configuration diagram showing another example of the processing apparatus of the present invention. In FIG. 3, the raw material 21 is supplied from the raw material storage tank 1 to the reaction tank 3 by the mud supply pump 2. The reaction tank 3 is heated by the steam 22. Heating is a thermometer 1
This is performed by controlling the steam supply valve 8 with the indicated value of 1. The raw material after the heat treatment is supplied to the fermenter 24 through the vacuum pump 4. The heat exchanger 7 is installed on the discharge pipe of the mud supply pump 2 and the suction side of the decompression pump 4 to reuse the heating energy.

[0011]

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 Table 1 shows the result of heating cow's dung by a screw press dehydrator with a separated liquid for 30 minutes at 150 ° C., and the amount of gas generated after methane fermentation of treated and untreated juice. . The apparatus used the uniaxial screw pump for the mud supply pump 2 and the decompression pump 4. The effective capacity of the reaction tank 3 is 0.1 m ³ . As a result of the heat treatment, the polymer compound contained in the cow dung juice has a low molecular weight, thereby increasing the soluble COD and slightly reducing the solid content. When the untreated juice and the heat-treated juice were subjected to methane fermentation, the heat-treated juice was able to generate 1.5 times more methane than the untreated juice.

[0012]

[Table 1]

[0013]

INDUSTRIAL APPLICABILITY According to the present invention, in an apparatus for subjecting an organic waste containing a solid to a heat treatment at 100 ° C. or higher, the pressure inside the reaction vessel during the heat treatment is maintained at a high pressure of atmospheric pressure or higher. Moreover, it was possible to construct a simple device that can perform continuous processing and does not have complicated operation control.

[Brief description of drawings]

FIG. 1 is a flow configuration diagram showing an example of a heat treatment apparatus of the present invention.

FIG. 2 is a flow configuration diagram showing another example of the heat treatment apparatus of the present invention.

FIG. 3 is a flow configuration diagram showing another example of the heat treatment apparatus of the present invention.

[Explanation of symbols]

1: Raw material storage tank, 2: Mud supply pump, 3: Reaction tank, 4: Decompression pump, 5: Sludge discharge tank, 6: Sludge pump, 7: Heat exchanger, 8: Steam supply valve, 9: Water level meter 10, pressure gauge, 1
1: Thermometer, 12: Excess steam, 21: Raw material, 22: Heating steam, 23: Deodorizing duct, 24: Fermenter

Continued front page    F-term (reference) 4D004 AA01 CA13 CA22 CB04 CB31                       CB42 CB43 DA03 DA06 DA12                 4D059 AA00 BA21 BB03 EB06 EB16

Claims (3)

[Claims] 1. A heat treatment apparatus having a reaction vessel capable of continuously heat-treating an organic waste containing a solid matter under pressure, wherein the reaction vessel introduces an object to be treated. A heat treatment apparatus for organic waste, comprising a mud supply pump and a decompression pump for discharging a pressurized treatment product. 2. The types of the mud supply pump and the decompression pump are:
The heat treatment apparatus for organic waste according to claim 1, wherein the heat treatment apparatus is a positive displacement pump. 3. The heat treatment in the reaction vessel is performed at a reaction temperature of 1.
The heat treatment apparatus for organic waste according to claim 1 or 2, wherein the heat treatment apparatus is performed under the conditions of 00 ° C to 200 ° C and a residence time of 3 hours or less.