JPS60187398A - Thermal treatment of sludge - Google Patents

Abstract

PURPOSE:To utilize effectively the recovered oil and to save the fuel by blowing steam and compressed air into a reactor wherein preheated sludge is supplied to treat thermally the sludge, and dehumidifying and cooling the gas discharged from the reactor in a scrubber. CONSTITUTION:The sludge 2 which is hard to dehydrate is stored in a sludge storage vessel 1, then supplied to a heat exchanger 4 with a pump 3, preheated to about 120 deg.C therein, and supplied into the lower part of a reaction vessel 5. The sludge is heated to about 165 deg.C in the reaction vessel 5 by the steam 7 from a waste heat boiler 6 which is blown in from the lower part, pressurized by the compressed reaction air 8 at about 10kg/cm<2> pressure which is blown in from the lower part of the reactor 5, and thermally treated. The gas 11 discharged from the reactor 5 is introduced into a scrubber 10, dehumidified and cooled by the water 12, and then introduced into a deodorizing tower. The water 14 discharged from the bottom of the scrubber 10 is introduced into an oil recovery apparatus 15, and the contained oil component is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for heat treatment of sludge generated by treatment of sewage and wastewater.

In general, difficult-to-dewater sludge generated from the treatment of sewage and wastewater is stored in a sludge storage tank and then supplied to a heat exchanger for preheating before being supplied to a reactor where it is heated by steam blown into the reactor. At the same time, the sludge is heated and pressurized with compressed air blown into the reactor, and the heat treatment reaction improves dewatering performance and oxidizes and decomposes the malodorous components in the sludge.However, in conventional sludge heat treatment methods, Since the gas discharged from the reactor is dehumidified and cooled by a scrubber and then led directly to the water treatment equipment, the oil contained in the waste water from the scrubber causes the sediment to float, increasing the amount of floating sludge. This has the disadvantage that large quantities of scum may be generated during the process, which may have an adverse effect on water treatment.

The present invention was made in view of the above-mentioned conventional drawbacks, and involves blowing steam and compressed air into a reactor to which preheated sludge is supplied to perform heat treatment, and dehumidifying the gas discharged from the reactor with a scrubber. At the same time as cooling, the oil contained in the wastewater from the scrubber is recovered by an oil recovery device, the wastewater from which the oil has been removed is guided to a water treatment device, and steam is supplied to blow the recovered oil into the reactor. The sludge heat treatment method is structured so that the sludge is introduced into the fuel system of the boiler.In the sludge heat treatment process, the oil contained in the scrubber waste water is separated and the oil-free waste water is By introducing the present invention into a treatment device, water treatment is improved without oil being contained in wastewater, and fuel is saved by effectively utilizing the recovered oil.Examples of the present invention are as follows. will be explained with reference to the drawings.

In FIG. 1, 1 is a sludge storage tank, and sludge 2, which is difficult to dewater and is generated from the treatment of sewage and wastewater, is temporarily stored in the sludge storage tank 1 and then supplied to a heat exchanger 4 by a pump 3. After being preheated to about 120°C, it is supplied to the lower part of the reactor 5.

The sludge 2 supplied to the reactor 5 is heated to about 165°C by the steam 7 from the waste heat boiler 6 that is blown in from the lower part of the reactor 5, and 10 kg of sludge that is blown in from the lower part of the reactor 5 is heated. It is pressurized with compressed air 8 for reaction of about /crA and heat-treated.

The dehydration properties of the sludge 2 are improved by the heat treatment reaction in the reactor 5, and the malodorous components in the sludge 2 are also oxidized and decomposed, and the sludge is taken out from the reactor 5 as heat-treated sludge 9.

This heat-treated sludge 9 is led to a heat exchanger, where the heat is recovered, cooled to room temperature by a cooler, led to a thickening tank, and after being concentrated, it is dehydrated by a filter press. The illustration of the processing steps is omitted. The gas 11 discharged from the reactor 5 is led into the scrubber 10, dehumidified and cooled by water 12 sprayed from above, and then led to the deodorizing tower 13. The waste water 14 discharged from the tank is led to an oil recovery device 15 to remove oil contained in the waste water 14, and the waste water 16 from which the oil has been removed is led to a water treatment device 17.

Further, the oil 18 recovered by the oil recovery device 15 is led through a tank to the fuel system of the waste heat boiler 6 that supplies steam 7 to be blown into the reactor 5.

FIG. 2 shows an embodiment of an oil recovery device used in the process of the sludge heat treatment method shown in FIG. The baffle plates 20 are installed alternately to prevent the liquid level 21 from fluctuating due to the waste water 14 supplied into the oil recovery device 15. A chain 22 stretched between sprockets 23 and 23 is provided in this #15, and paddles 24 are attached at predetermined intervals on the circumference of the chain 22, and a chain 22 is connected through a motor 25 with a speed reducer. When the splot 23 is driven, the scraping plate 24 scrapes up the oil 18 floating on the liquid surface 21 along the tapered bottom surface 26 and removes the oil 18.
The oil component 18 is collected by scraping it into the tank 19.

In this case, the oil 18 attached to the surface of the scraper 1fi24 is
It may be scraped off by the swing plate 27. The oil 18 that has been pumped into the tank 19 is led to the fuel system of the waste heat boiler 6 via piping (not shown), and the waste water 16 from which the oil 1B has been removed is sent to the water treatment device 17 via piping (not shown).
It is designed to lead you to.

In the sludge heat treatment method of the present invention having the above-mentioned configuration, the sludge 2 preheated by the heat exchanger 4 is supplied to the reactor 5, and the steam 7 and the air 8 blown into the reactor 5 are It will be heat treated by

On the other hand, the waste water 14 discharged from the scrubber 10 that dehumidifies and cools the gas 11 discharged from the reactor 5 contains oil 18 concentrated by the heat treatment reaction in the reactor 5. The oil IB contained in the oil is scraped up by the scraping plate 24 of the oil recovery device [15] shown in FIG. 2, and is scraped into the tank 19 and recovered. Therefore, the discharged water 16 from which the oil 18 has been removed is led to the water treatment device 17, where the water is treated without any adverse effects of the oil, and the oil 18 is efficiently recovered.
8 is led to a fuel system such as a waste heat boiler 6 via a tank 19, and the oil 18 is effectively used as fuel. In addition to the oil recovery device 15 shown in FIG. 2, there are other types of oil recovery device 15 that utilize a centrifugal separation method, and the most suitable one may be selected in consideration of the oil properties, recovery amount, etc.

In addition, in order to confirm the effectiveness of the sludge heat treatment method of the present invention, sludge 2 with a concentration of about 2 was preheated and placed in the reactor 5 for 12 y.
When heat treatment was carried out by supplying &/h at a time, reactors 5 to 8
00 x/FF? /h of gas 11 is discharged, this gas 11 is dehumidified and cooled by spraying 30 d/b of water 12 with a scrubber 10, and the oil contained in the waste water 14 of the scrubber 10 is recovered with an oil recovery device 15. As a result, 1.1
It was demonstrated that the oil 18 with a high concentration of 1/h could be recovered, and that it could be introduced into the fuel system of the waste heat boiler 6 for sufficient practical use.

Since the sludge heat treatment method of the present invention is configured as described above, oil is not contained in the waste water from the scrubber that is led to the water treatment equipment, and unlike conventional methods, the oil causes the sediment to float, resulting in floating sludge. Since there is no fear that a large amount of scum will increase, water treatment can be carried out efficiently.

In addition, in the present invention, since the recovered oil is guided to the fuel system such as a boiler that supplies steam to be blown into the reactor, fuel can be saved, and the oil in the scrubber waste water can be effectively absorbed. You can plan to use it. Furthermore, since the oil content in the scrubber waste water is relatively concentrated by the heat treatment reaction in the reactor, it has many advantages such as being able to efficiently recover the oil content in the oil recovery equipment.
It is possible to provide a method for heat treatment of sludge that is easy to apply to existing equipment and is extremely effective in practice.

[Brief explanation of the drawing]

FIG. 1 is a process diagram of a sludge heat treatment method showing one embodiment of the present invention, and FIG. 2 is a sectional view showing one embodiment of an oil recovery apparatus. 1...Sludge storage tank 2...Sludge 3...
... Pump 4 ... Heat exchanger 5 ...
・Reactor 6... Waste heat boiler 7... Steam 8... Compressed air 9... Heat treated sludge 10... Scrubber 11... Gas 12... Water 13... Deodorizing tower 14... Drainage 15... Oil recovery device 16... Drainage from which oil was removed 17... Water treatment device 1B... Oil 19... Tank Patent applicant Kubota Iron Works Co., Ltd.

Claims (1)

[Claims] Heat treatment is performed by blowing steam and compressed air into the reactor into which preheated sludge is supplied, and the gas discharged from the reactor is dehumidified and cooled by a scrubber, and the oil contained in the discharge from the scrubber is removed. Collected by oil recovery equipment,
A heat treatment for sludge, characterized in that wastewater from which oil has been removed is led to a water treatment device, and the recovered oil is led to a fuel system 6 such as a waste heat boiler that supplies steam to be blown into a reactor. Method.