JPH115100A - Sewage sludge treatment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To convert sewer sludge to combustion ash by dehydrating the sludge discharged by a sewage treatment with a sludge dehydrating machine and subjecting the dehydrated sludge to heating decomposition by a heating decomposition furnace, then burning the sludge by a boiler, thereby generating steam. SOLUTION: The sludge discharged from a sewage treatment plant 1 is dehydrated by a centrifugal separating and drying machine 2, by which the moisture included in the sewage sludge is wrung away. Next, the dehydrated concentrated sludge is subjected to the heating decomposition by the heating decomposition furnace 3 after the dehydrated sludge is pulverized. This heating decomposition furnace 3 is heated by the high-temp. steam formed in the boiler 4 or the waste gases discharged from the boiler 4 as a heating source. The org. matter included in the sewage sludge is decomposed and carbonized by such heating decomposition process. The volatile components are discharged outside. The sludge subjected to the heating decomposition is thereafter supplied as fuel to the boiler 4, where the sludge subjected to the heating decomposition is burned to form the high-temp. steam. The formed high-temp. steam is supplied as the heating source of the heating decomposition furnace 3 to the furnace and is supplied as a driving power source of an energy plant 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a sewage sludge treatment system for treating sludge discharged by sewage treatment, and more particularly to a sewage sludge treatment system capable of effectively utilizing energy contained in sewage sludge.

[0002]

2. Description of the Related Art Conventionally, as a sewage sludge treatment method for stably treating sewage sludge, a method of dewatering sewage sludge and then landfilling the dewatered concentrated sludge (first conventional method). There is also known a method (second conventional method) in which heavy oil or the like is mixed into concentrated sludge and incinerated.

In addition to these methods, a method of fermenting sewage sludge into fertilizer (third conventional method) and a method of melting and solidifying sewage sludge at a high temperature of about 1500 ° C. (fourth conventional method) Etc. are being studied.

[0004]

However, among the above-mentioned conventional sewage sludge treatment methods, the first conventional method for landfill disposal of concentrated sludge can easily perform landfill disposal. There is a problem that it is difficult to secure the location of the disposal site for such disposal, and there is a concern about the influence on the surrounding environment of the disposal site.

In the second conventional method in which heavy oil or the like is mixed into concentrated sludge and incinerated, it is difficult to effectively use heat during high-temperature combustion because of various contaminants peculiar to sludge contained in sewage sludge. Another problem is that most of the heat is wasted.

Further, the third conventional method of fermenting sewage sludge to produce fertilizer has a problem in that there is an anxiety in terms of safety and uniformity of sludge components in making fertilizer.

Further, in the fourth conventional method of melting and solidifying sewage sludge at a high temperature of about 1500 ° C., there is no concern about safety, but there is a problem that equipment costs and energy consumption are excessive. .

As described above, a large amount of sludge discharged daily from a sewage treatment plant has no safe and effective treatment method at present, and it is said that it is landfilled despite the difficulty of location of the disposal site. Is the actual situation.

The present invention has been made in view of the above points, and can effectively solve the problem of sludge treatment, and can effectively use energy contained in sewage sludge, which has been mostly discarded in the past. It is an object to provide a sewage sludge treatment system that can be utilized.

[0010]

SUMMARY OF THE INVENTION The present invention provides a sludge dewatering device for dewatering sludge discharged by sewage treatment, a pyrolysis furnace for thermally decomposing sludge dewatered by the sludge dewatering device, and a pyrolysis furnace. And a boiler that burns the sludge decomposed by heat to generate steam.

Further, the present invention is characterized by comprising a pyrolysis furnace for thermally decomposing the sludge subjected to the drying treatment, and a boiler for burning the sludge pyrolyzed by the pyrolysis furnace to generate steam. To provide a sewage sludge treatment system.

Further, the present invention, in the above-described sewage sludge treatment system, may further include means for supplying steam generated by the boiler or exhaust gas discharged from the boiler as a heating source of the pyrolysis furnace. . In addition, it is preferable to further include a power generation plant or a heat source plant that uses steam generated by the boiler as a power source.

According to the present invention, the sludge pyrolyzed by the pyrolysis furnace is burned by the boiler, so that the sewage sludge which has been difficult to treat conventionally can be changed to combustion ash which hardly needs to be treated. Therefore, the problem of sludge treatment can be effectively solved. In addition, by thermally decomposing sewage sludge in a pyrolysis furnace, flammable organic substances contained in large amounts in sewage sludge can be converted into fuels that can be easily handled. The included energy can be used effectively.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a sewage sludge treatment system according to the present invention.

As shown in FIG. 1, the sewage sludge treatment system treats sludge discharged from a sewage treatment plant 1. Here, the sewage treatment plant 1 is equipped with a back tank (not shown) for converting the organic matter dissolved in the sewage into the form of microorganisms by utilizing the digestion of the organic matter by microorganisms, and sand and mud flowing into the sewage. And a sedimentation tank 1a for precipitating and collecting microorganisms having taken up organic substances. In such a sewage treatment plant 1, sewage supplied from outside is purified through a back tank and a sedimentation tank 1a.
It is separated into purified treated water and solid component sludge and discharged.

Next, the configuration of the sewage sludge treatment system will be described. As shown in FIG. 1, the sewage sludge treatment system includes a centrifugal dryer (sludge dehydrator) 2 for dewatering sludge discharged from a sewage treatment plant 1, and sludge dewatered by the centrifugal dryer 2 (concentrated sludge). ), A boiler 4 for burning sludge thermally decomposed by the pyrolysis furnace 3 (pyrolysis sludge) to generate high-temperature steam, and a high-temperature steam generated by the boiler 4 as a power source. And an energy plant 5 for producing electricity and cold and hot water.

Here, the centrifugal dryer 2 is for dewatering sludge using centrifugal force. In order to reduce the water content of the concentrated sludge after dehydration as much as possible, the centrifugal dryer 2 is used as a power source for the centrifugal dryer 2. Uses a high frequency power supply including an inverter.

Further, the thermal decomposition furnace 3 has a temperature of 200 ° C. to 400 ° C.
The organic matter contained in the concentrated sludge is carbonized by thermally decomposing the concentrated sludge under a reducing atmosphere.
As the pyrolysis furnace 3, for example, a conventionally well-known kiln as shown in FIG. 2 can be used. As shown in FIG. 2, the kiln 3 as a pyrolysis furnace includes a cylindrical portion 31.
a and a rotation drive unit 31b for rotating the cylindrical portion 31a
And In FIG. 2, the concentrated sludge supplied from one side end (left side in the figure) of the kiln 3 is a cylindrical portion 31a.
Is heated and decomposed while moving toward the right side in the drawing, and is discharged as pyrolysis sludge from the other end (the right side in the drawing). In the kiln 3, a pipe or the like for passing high-temperature steam generated by the boiler 4 is arranged.

The pyrolysis process in the pyrolysis furnace 3 requires a lot of energy, and therefore, the pyrolysis furnace 3 is an important device that affects the efficiency of the entire system. FIG. 3 shows another example of the thermal decomposition furnace 3 having excellent energy efficiency. As shown in FIG. 3, the pyrolysis furnace 3 includes a container 32a in which concentrated sludge pulverized into granules is filled,
And a stirrer 6 arranged in the container 32a for stirring the concentrated sludge. The high temperature exhaust gas discharged from the boiler 4 is supplied from an opening 32b provided at a lower portion of the container 32a. In FIG.
The concentrated sludge filled in 2a is stirred by the stirrer 6, and is thermally decomposed at a high temperature while the exhaust gas discharged from the boiler 4 passes through the concentrated sludge. And container 3
The volatile components (mainly steam) in the concentrated sludge and the exhaust gas from the boiler 4 are exhausted from an outlet 32c provided at the upper part of the container 2a, and the outlet part 32 provided at the lower part of the container 32a.
The thermally decomposed sludge is taken out from d. According to the thermal decomposition furnace 3 shown in FIG. 3, the exhaust gas as the heating source and the concentrated sludge come into direct contact, so that high thermal efficiency can be realized. Note that in the pyrolysis furnace 3, a pipe or the like for passing high-temperature steam generated by the boiler 4 may be arranged as in FIG. 2.

The boiler 4 burns the pyrolysis sludge generated by the pyrolysis furnace 3 to generate high-temperature steam. The high-temperature steam generated by the boiler 4 is supplied not only to the energy plant 5 but also to the above-mentioned pipes and the like arranged in the pyrolysis furnace 3.

Further, the energy plant 5 produces electricity and cold / hot water using the high-temperature steam (including the steam discharged through the thermal cracking furnace 3) generated by the boiler 4 as a power source. As shown in FIG. 4, such an energy plant 5 includes, for example, a power generation plant 7 including a turbine generator and the like, and a heat source plant 8 including a heat pump and the like.

Next, the operation of the present embodiment having such a configuration will be described.

First, the sludge discharged from the sewage treatment plant 1 is dewatered by the centrifugal dryer 2. Sewage sludge usually contains as much as 99% of water, and if it is heated as it is, most of the supplied energy is taken away as latent heat of steam, and the energy cannot be used effectively.
Therefore, in the centrifugal dryer 2, most of the water contained in the sewage sludge is squeezed. In addition, when the ordinary centrifugal dryer 2 is used, the moisture content of the concentrated sludge after dehydration is about 80%. The water content of the concentrated sludge after dehydration is 70%.
It is about to be.

Next, the concentrated sludge thus dehydrated is pulverized into particles, and then the pulverized concentrated sludge is thermally decomposed in a pyrolysis furnace 3 in a reducing atmosphere. The pyrolysis furnace 3 is provided with the high-temperature steam generated by the boiler 4 or the boiler 4.
200 ° C to 400 ° C using the exhaust gas discharged from
It is heated to a temperature of about ° C. By such a thermal decomposition process, about half of the organic matter contained in the sewage sludge is decomposed and carbonized, and volatile components (mainly water vapor) are discharged to the outside. Finally, a carbon content of about 30% is obtained. Solid matter (pyrolysis sludge) is discharged from pyrolysis furnace 3.

Next, the pyrolysis sludge thus discharged is supplied to the boiler 4 as fuel. Here, the boiler 4 burns the supplied pyrolysis sludge to generate high-temperature steam, and supplies the generated high-temperature steam as a heating source of the pyrolysis furnace 3 and also as a power source of the energy plant 5. . Note that the thermally decomposed sludge burned in the boiler 4 is discharged as combustion ash that requires little treatment.

Finally, the high-temperature steam (including the steam discharged through the thermal cracking furnace 3) generated by the boiler 4 is supplied to the power plant 7 of the energy plant 5. Here, the power plant 7 guides the high-temperature steam generated by the boiler 4 to a steam turbine, generates power using the high-temperature steam as a power source, and supplies exhaust steam to the heat source plant 8. In addition, the heat source plant 8 is provided with the exhaust steam discharged from the power generation plant 7 and the exhaust gas from the pyrolysis furnace 3 (in the case of the pyrolysis furnace 3 shown in FIG. In the case of the furnace 3, the volatile components in the sludge and the exhaust gas from the boiler 4) are used as the power source, and the sewage treated water discharged from the sewage treatment plant 1 is used as the heat source water. Produces mainly hot water.

As described above, according to the present embodiment, the sludge thermally decomposed by the pyrolysis furnace 3 is burned by the boiler 4, so that the sewage sludge which has been difficult to treat conventionally can be burned with little need for treatment. It can be converted to ash, which effectively solves the problem of sludge treatment.

Further, by thermally decomposing the sewage sludge by the pyrolysis furnace 3, a large amount of combustible organic substances contained in the sewage sludge can be converted into fuels that can be easily handled. The energy contained in the sewage sludge can be effectively used as a power source of the energy plant 5 and the like.

Furthermore, by using the sewage treated water discharged from the sewage treatment plant 1 as the heat source water of the heat source plant 8, the sewage treated water is relatively cold in summer and relatively warm in winter, so that it can be efficiently used. Cold and hot water can be generated.

In the above-described embodiment, the sludge discharged from the sewage treatment plant 1 is dewatered by the centrifugal dryer 2, but the apparatus for dewatering the sewage sludge is not limited to this. Various sludge dehydrators such as a vacuum filter and a pressure filter can be used. When treating the sludge that has been subjected to the drying process, the centrifugal dryer 2
The sewage sludge treatment system of the present invention can be configured in a form excluding.

[0031]

As described above, according to the present invention, sewage sludge which has been difficult to treat conventionally can be changed to combustion ash which hardly needs to be treated, so that the problem of sludge treatment can be effectively solved. be able to. Further, since a large amount of combustible organic matter contained in the sewage sludge can be changed to a fuel that can be easily handled, the energy contained in the sewage sludge, which has been mostly discarded in the past, can be effectively used.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a sewage sludge treatment system according to the present invention.

FIG. 2 is a diagram showing an example of the thermal decomposition furnace shown in FIG.

FIG. 3 is a diagram showing another example of the thermal decomposition furnace shown in FIG.

FIG. 4 is a diagram showing an example of the energy plant shown in FIG.

[Explanation of symbols]

 Reference Signs List 1 sewage treatment plant 1a sedimentation tank 2 centrifugal dryer (sludge dewatering machine) 3 thermal decomposition furnace 4 boiler 5 energy plant 6 power plant 8 heat source plant

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masao Kaneko 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Fuchu plant of Toshiba Corporation

Claims (8)

[Claims] 1. A sludge dewatering device for dewatering sludge discharged by sewage treatment, a pyrolysis furnace for thermally decomposing sludge dewatered by the sludge dewatering device, and burning sludge thermally decomposed by the pyrolysis furnace. And a boiler for generating steam. 2. A sewage system comprising: a pyrolysis furnace for thermally decomposing sludge subjected to drying treatment; and a boiler for burning sludge thermally decomposed by the pyrolysis furnace to generate steam. Sludge treatment system. 3. The sewage sludge treatment system according to claim 1, further comprising means for supplying steam generated by said boiler as a heating source of said pyrolysis furnace. 4. The sewage sludge treatment system according to claim 1, further comprising means for supplying exhaust gas discharged from said boiler as a heating source of said pyrolysis furnace. 5. The sewage sludge treatment system according to claim 1, further comprising a power plant using steam generated by said boiler as a power source. 6. The sewage sludge treatment system according to claim 1, further comprising a heat source plant using steam generated by said boiler as a power source. 7. The sewage sludge treatment system according to claim 6, wherein the heat source plant uses, as a power source, exhaust gas discharged from the pyrolysis furnace in addition to steam generated by the boiler. 8. The sewage sludge treatment system according to claim 6, wherein said heat source plant uses treated sewage as heat source water.