JPH11319898A - Liquefying treatment of sewer sludge and its apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the continuous forcing of sewer thickened sludge into a reaction chamber by directly forcing the sewer thickened sludge into the reaction chamber under high-temp. and high-pressure conditions, separating the sludge to waste gases, steam and the liquefied sludge at temp. above vapor generation temp., lowering the temp. to the vapor generation temp., separating only the waste gases and executing a waste gas treatment. SOLUTION: The thickened sludge 1 is forced into the reaction chamber 3 under the high-temp. and high-pressure conditions by a forcing piston 2 without dehydration, where the org. components in the thickened sludge are made low polymeric. The internal pressure for migrating the steam to a gas side by a pressure reducing device 4 is regulated to the prescribed positive pressure above atm. pressure and the thickened sludge is separated to the (waste gases + steam) 5 and the liquefied sludge 10. The pressure of the (waste gases + steam) 5 and the liquefied sludge 10 is reduced by a pressure reducing device 6 and a pressure reducing device 11. The (waste gases + steam) 5 is lowered to the temp. below the vapor generating temp. by a heat exchanger 7 and is separated to the waste gases and the steam and thereafter only the waste gases are treated by a treating device 8 and are released as treated gases 9. As a result, the continuous forcing of the sludge into the reaction chamber is made easier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and apparatus for liquefying sewage sludge.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional sewage sludge liquefaction treatment method. In the conventional sewage sludge liquefaction treatment method, a concentrated sludge 15 having a water content of 98% is dewatered by a centrifugal separator 16 to obtain a solid dewatered sludge 17 having a water content of 80%.
7 by the press-fitting piston 18 under high temperature and high pressure conditions (200
To 250 DEG C., 50 to 70 atm). After liquefaction of the dewatered sludge 17 by the reaction tank 19,
The heat is recovered by the heat exchanger 20 and used as a heat source for the reaction tank 19 in the preceding stage. If the recovered heat alone is not sufficient as a heat source for the reaction tank 19, the heating medium is heated by the heater 21 to supply necessary heat to the reaction tank 19.

Next, the reaction product cooled by the heat exchanger 20 is depressurized to a normal temperature by a decompression device 22, and then the exhaust gas 2 is cooled.
5 and liquefied sludge 23, and the exhaust gas 25 is treated by an exhaust gas treatment device 26 and discharged to the atmosphere as a treatment gas 27, and the produced liquefied sludge 23 is stored in a storage tank 24.

[0004]

Although the liquefied sludge 23 is produced by the above-mentioned treatment method, it is difficult to continuously press the solid dehydrated sludge 17 into the reaction tank 19, Problems such as clogging also occurred. The present invention, in view of the drawbacks of the prior art, provides a method and apparatus for liquefying sewage sludge which facilitates continuous press-fitting into a reaction tank and eliminates problems such as clogging of the reaction tank. The purpose is to:

[0005]

According to the first aspect of the present invention,
To achieve this task, concentrated sewage sludge is directly heated to high temperatures.
After pressurized into the reaction tank under high pressure conditions and liquefied in the reaction tank, first, at a temperature equal to or higher than the steam generation temperature, the exhaust gas and steam are separated into liquefied sludge, and then the separated exhaust gas and The present invention proposes a sewage sludge liquefaction treatment method characterized in that steam is reduced to a temperature equal to or lower than a steam generation temperature by heat recovery, and only exhaust gas is separated and subjected to exhaust gas treatment. In this case, it is preferable that the recovered heat obtained when separating the exhaust gas and the steam be used as a heating source for the reaction tank.

A third aspect of the present invention relates to an apparatus for effectively implementing the first aspect of the present invention.
A reaction tank for reacting the concentrated sewage sludge under high temperature and high pressure conditions, press-fitting means for injecting the concentrated sewage sludge into the reaction tank, and sludge connected to the reaction tank and liquefied by the reaction in the reaction tank At a temperature equal to or higher than the steam generation temperature, into a waste gas and water vapor, and a liquefied sludge; and a heat recovery of the waste gas and steam separated by the first separation device to a temperature below the steam generation temperature by heat recovery. It is characterized by comprising a second separation device for lowering and separating only exhaust gas, and an exhaust gas treatment device for treating the exhaust gas separated by the second separation device.

In the embodiment described below, the internal pressure is reduced to a first pressure (normal pressure or higher), the reaction temperature is reduced to a temperature equal to or higher than the steam generation temperature, and the first pressure is further reduced to normal pressure. Since the temperature is reduced to a temperature equal to or lower than the steam generation temperature by the heat recovery, the first and second separation devices are configured by combining the pressure reducing device and the heat exchanger, but the invention is not limited thereto.

According to this invention, since the feedstock to the reaction tank is changed from solid dehydrated sludge to slurry-type concentrated sludge, the centrifugal separator can be omitted, and slurry-like concentrated sludge can be removed from the dehydrated sludge. By changing to, the supply sample can be easily supplied to the reaction tank. Further, in the first separation device, the sludge liquefied by the reaction in the reaction tank is transferred to the gas side by adjusting the temperature by decompression or the like, and liquefied sludge can be obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the drawings. However, unless otherwise specified, dimensions, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the invention, but are merely illustrative examples. FIG. 1 is a configuration diagram relating to a sewage sludge liquefaction treatment method according to an embodiment of the present invention. In the figure, the concentrated sludge 1 is not dewatered and is directly used by the press-in piston 2 under high temperature and high pressure conditions (200 to
250 ° C., 50 to 70 atm).
Reduce the molecular weight of organic components in concentrated sludge.

Next, in order to transfer water vapor to the gas side by the decompression device <1> 4, the internal temperature of the decompression device <1> 4 is set to 120.
The internal pressure of the pressure reducing device <1> 4 is adjusted to a predetermined positive pressure equal to or higher than the normal pressure so that the temperature is reduced to 150 ° C.
Then, the liquefied sludge 10 and the liquefied sludge 10 are each depressurized to normal pressure by the decompression device <2> 6 and the decompression device <3> 11.

The (exhaust gas + steam) 5 is recovered by the heat exchanger 7 to reduce the temperature to below the steam generation temperature to separate the exhaust gas from the steam (the steam is recovered as water). And released as a processing gas 9. The liquefied sludge 10 also recovers heat in the same manner as the (exhaust gas + steam) 5 and stores it in the storage tank 12. The heat recovered from each product in heat exchangers 7 and 13 is transferred to reaction tank 3
Use as a heat source.

If the recovered heat alone is not sufficient as a heat source for the reaction tank 3, the heating medium is heated by the heater 14 to supply necessary heat to the reaction tank 3.

According to this embodiment, the sludge supplied to the reaction tank 3 for performing the liquefaction treatment is changed from the conventional solid-state dehydrated sludge 17 to the slurry-like concentrated sludge 1 so that the centrifugal separator 16 can be used. This can be omitted, and not only can the initial cost and running cost of the centrifuge 16 be reduced, but also the supply of raw materials becomes easy even when the inside of the reaction tank 3 is at a high pressure, and continuous treatment can be performed for liquefaction of sewage sludge. is there.

Particularly, when the concentrated sludge 1 in the form of slurry is used as a raw material, since the sludge is originally in a liquefied state, the organic component in the concentrated sludge 1 is reduced in the reaction tank 3 rather than in the liquefaction treatment. Liquefaction sludge 10 is generated only when (steam + exhaust gas) 5 and liquefaction sludge 10 are separated in device <1> 4.

Further, (steam + exhaust gas) 5 and liquefied sludge 1
If the pressure is reduced to normal pressure by the decompression device <1> 4, the reaction product becomes normal temperature, and water in the reaction product exists as a liquid. Water mixes. Therefore, the pressure reducing device <1> 4 does not reduce the pressure to the normal pressure, but raises the internal temperature of the pressure reducing device <1> 4 to 120 to
By adjusting the internal pressure of the pressure reducing device <1> 4 to 150 ° C., water is easily transferred to the gas side as gas (steam), and (exhaust gas + steam) 5 and liquefied sludge 10
Can be separated.

In this embodiment, the number of decompression devices is increased by two compared to the conventional one. However, since the decompression device has less power and has a simple structure, it is better to omit the centrifugal separator in both initial cost and running cost. Can be reduced.

[0017]

As described above, according to the first and third aspects of the present invention, continuous press-fitting into the reaction tank can be facilitated, and problems such as clogging of the reaction tank can be solved. According to the second aspect of the present invention, the heat recovered at the time of the respective separations is supplied to the reaction tank, so that the heat energy can be effectively used.

[Brief description of the drawings]

FIG. 1 is a configuration diagram relating to a sewage sludge liquefaction treatment method according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a conventional sewage sludge liquefaction treatment method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 concentrated sludge 2 press-in piston 3 reaction tank 4 decompression device <1> 5 exhaust gas + steam 6 decompression device <2> 7, 13 heat exchanger 8 exhaust gas treatment device 9 process gas 10 liquefied sludge 11 decompression device <3> 12 storage Vessel 14 heater

Claims (3)

[Claims] Claims: 1. Sewage concentrated sludge is directly injected into a reaction tank under high-temperature and high-pressure conditions and liquefied in the reaction tank. At first, at a temperature higher than the steam generation temperature, exhaust gas and steam are converted into liquefied sludge. A method for liquefaction treatment of sewage sludge, comprising separating the exhaust gas and water vapor to a temperature equal to or lower than the steam generation temperature by heat recovery to separate only the exhaust gas, and then subjecting the exhaust gas to waste gas treatment. 2. A sewage sludge liquefaction treatment method according to claim 1, wherein recovered heat obtained when the exhaust gas and steam are separated is used as a heating source for the reaction tank. 3. A reaction tank for reacting concentrated sewage sludge under high-temperature and high-pressure conditions, press-fitting means for injecting concentrated sewage sludge into the reaction tank, and a reaction tank connected to the reaction tank and reacting in the reaction tank. A first separation device that separates liquefied sludge into exhaust gas and water vapor and liquefied sludge at a temperature equal to or higher than the steam generation temperature, and generates steam by heat recovery of the exhaust gas and steam separated by the first separation device. Liquefaction treatment of sewage sludge, comprising: a second separation device that separates only exhaust gas by lowering the temperature to below the temperature, and an exhaust gas treatment device that treats the exhaust gas separated by the second separation device. apparatus.