JPS60261695A - Sludge dehydrator - Google Patents

Abstract

PURPOSE:To decrease considerably the moisture content of dehydrated cake and to increase treating capacity by constituting a titled device of a preliminary dehydrating section, forming section and dehydrating section having a pair of endless filter cloths circulating through a low-pressure dehydrating section, middle-pressure dehydrating section and high-pressure dehydrating section. CONSTITUTION:Sludge is efficiently and preliminarily thickened in the preliminary dehydrating section 10 by which the volume of the sludge is decreased prior to pressure dehydration. The preliminarily thickened sludge is divided and ground in the sludge forming section 20 and is formed to a mince shape, etc. The sludge divided to small lump is introduced into the dehydrating section 30 in succession thereto and dehydrated cake is formed. The dehydrating mechanism of the belt press type consisting of the upper filter cloth 1 and the lower filter cloth 2 is adopted for the section 30 and the high-pressure dehydrating section consisting of a high-pressure belt 3 is provided to the rear stage thereof. The sludge is dehydrated by the gradually increased pressurizing force in the low- and middle-pressure dehydrating sections.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a sludge dewatering device for dewatering water-containing sludge such as sewage mixed raw sludge or sludge to facilitate disposal and incineration.

[Technical background of the invention and its problems] As this type of sludge dewatering apparatus, those shown in FIGS. 2 and 3 are conventionally known.

In the dewatering device shown in Fig. 2, an upper filter cloth 1 and a lower filter cloth 2 are each stretched between a plurality of rolls as shown in the figure, and water-containing sludge is supplied between these two filter cloths and compressed and dehydrated. Most of the conventionally used belt press type sludge dewatering devices are of this type. This type of sludge dewatering equipment has the following problems.

The first problem is that the dewatering efficiency is low because one type of filter cloth performs both gravity dewatering and pressure dewatering of sludge.

In other words, there are contradictory aspects in that a coarse filter cloth with a wide filtration area is suitable for gravity dehydration, while a fine filter cloth is suitable for pressure dehydration, and it is natural that one type of filter cloth can handle these problems. efficiency has to be sacrificed.

The second problem is that the efficiency of gravity dewatering is low, resulting in low processing capacity.

The third problem is that since the structure is simply a filter cloth wrapped around a roll, the compression pressure is about 2 kg/cm2 at maximum, and the moisture content of the cake does not decrease sufficiently.

Next, the sludge dewatering device shown in Fig. 3 will be explained. This device basically uses two sheets of m cloth 1.2 mm, similar to the device shown in Fig. 2.
Although it is a belt press type, a high pressure dehydration mechanism using a high pressure belt 3 is attached at the rear stage to increase the dehydration rate of the cake. In this dehydration equipment shown in Fig. 3, the second
The first and second problems described with respect to the device in the figure still remain unresolved, and the following other problems are included.

That is, although a high compression mechanism is provided in the latter stage, high pressure cannot be applied in the latter stage if the water content has not been sufficiently reduced in the previous stage. Forcibly applying high pressure may cause problems such as cake sticking out or leaking from the filter cloth.

[Purpose of the invention]

The present invention was made in view of the following two circumstances, and is a sludge dewatering device that can significantly reduce the water content of dehydrated cake and increase sweat treatment capacity compared to conventional dewatering devices. It provides:

1i [Summary of the Invention] The sludge dewatering apparatus according to the present invention comprises a preliminary dewatering section that receives water-containing sludge, a forming section that divides the predehydrated sludge into small lumps, a low pressure dewatering section, a medium pressure dewatering section, and a high pressure dewatering section. and a dewatering section having a pair of endless filter cloths that continuously circulate water.

To roughly explain the function of each part in the dewatering apparatus of the present invention, the pre-dewatering section efficiently pre-concentrates sludge to reduce the volume of sludge before pressurized dewatering and increase the actual processing capacity. Moreover, stable operation is possible even when the concentration of raw sludge fluctuates.

Next, the sludge pre-concentrated in this way is divided and crushed in a forming section to form minced pieces or the like. This makes it possible to efficiently discharge water inside the sludge, and also to increase the rate of filtrate discharge during the subsequent pressurized dehydration. Furthermore, by employing the sludge forming section, the thickness of the cake in the width direction and length direction of the filter cloth becomes uniform, making it possible to prevent wrinkles and meandering of the filter cloth.

Subsequently, the sludge divided into small lumps is introduced into a dewatering section to form a dewatering cake. In this case, the pressure is gradually increased in the low-pressure dehydration section and the medium-pressure dehydration section to perform dehydration, and the moisture content of the cake is sufficiently reduced to the extent that it can be treated in the high-pressure dehydration section. In addition, in the high-pressure dewatering section, water that has not been dehydrated in the low-pressure and medium-pressure dehydrating sections is squeezed from parent wood. Further, in the present invention, by providing the preliminary dehydration section and the forming section, dehydration in this high pressure dehydration section acts effectively,
This makes it possible to efficiently form a dehydrated cake with an overall low moisture content.

[Embodiments of the invention]

The present invention will be explained in detail below.

FIG. 1 is an explanatory diagram showing a sludge dewatering apparatus according to an embodiment of the present invention. In the figure, 1J is a preliminary dewatering section, A'' is a sludge forming section, and 1'' is a dewatering section.

In this embodiment, the preliminary dehydration section ↓J is configured as a pocket-type gravity dehydration mechanism as shown in the figure. but,
In addition to this, for example, a gravity dewatering mechanism using a flat filter cloth 11 as shown in FIG. 4(A) or a drum thickener as shown in FIG. 4(B) may be used. In addition, Figure 4 (
12 in A) is a cleaning spray, 13 in FIG. 4(B) is a sludge supply pipe, 14 is a sludge chute, 15 is a shaft, 16 is a screen, 17 is a screen cleaning pipe, 18
is a spiral vane for transportation.

Next, the sludge forming section 20 in the embodiment shown in FIG. 1 will be explained. In this embodiment, a roll-type forming machine having the configuration shown in FIG. 5(A) is employed. That is, pre-dehydrated sludge is received in a hopper 21, and this sludge is transferred to a pair of rolls 22.
．． ．． The continuous sludge is divided into minced small lumps by passing it through the meshing part of 222. In addition, as the sludge forming section 20, in addition to such a roll-type forming machine, for example, forming machines shown in FIGS. 5(B) to 5(D) can be used. Figure 5(B) shows an extrusion type forming machine.
The sludge is pushed out using a cylinder 23 using hydraulic power or the like to form minced sludge. FIG. 5(C) shows a forming machine using vibration dewatering, in which sludge is dropped onto an inclined punching metal or screen 24, and the sludge is formed into pellets by vibrating the apparatus. In addition, Fig. 5 CD) is a pressing and dewatering forming machine, which supplies sludge into a semi-cylinder 25 made of punched metal and forms the sludge into a noodle shape by pressing with a scraper 26 and a presser roller 27. be.

The dewatering section 30 in the embodiment of FIG.
This is the same as the conventional sludge dewatering device explained in the figure. That is,
A belt press type dewatering mechanism using an upper filter cloth 1 and a lower filter cloth 2 is adopted throughout, and a high pressure dewatering section using a high pressure belt 3 is provided at the rear stage. The area other than the high-pressure water extraction section is the low- and medium-pressure deicing section, which dehydrates by gradually increasing the pressure. In addition to the embodiment shown in FIG. 1, the high-pressure dewatering section may be constructed of a pressure filter cloth 31, 32 and a pressure plate 33, as shown in FIG. 6(A), for example. The pressure roller 34 may be used as shown in FIG. 6(B).

When sewage treatment mixed raw sludge was dehydrated using the sludge dewatering apparatus according to the embodiment shown in FIG. 1, and the manner in which the moisture content of the cake decreased at that time was investigated, the results shown in FIG. 7 were obtained. As is clear from the figure, the water content on one side of the preliminary dewatering section becomes approximately flat when it drops to about 90%. At this point, the sludge is transferred to the sludge-forming part where it is divided, and the water content is further reduced by 3-4%. Next, the sludge is introduced into the dewatering section - shadow, and the sludge is reduced to 65% in the bottom/medium pressure deicing section.
It was found that after the water content has been dehydrated to a certain level, a water content of about 60% is further achieved in the high-pressure dehydration section.

〔Effect of the invention〕

As detailed above, the sludge dewatering device of the present invention can form a dehydrated cake with a low water content that could not be achieved with conventional devices, and the processing capacity is also equivalent to or equal to that of conventional devices. It is possible to make it more than that, etc.
It is possible to obtain a remarkable effect.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the sludge dewatering device according to the present invention, FIGS. 2 and 3 are explanatory diagrams of a conventional sludge dewatering device, respectively, and FIG. 4 (A) and FIG. The preparation used in the sludge dewatering apparatus of the present invention! An explanatory diagram showing another example of a dehydrator,
FIG. 5(A) shows the sludge forming part 20 in the embodiment of FIG.
Fig. 6(B) to (D) are explanatory drawings showing other examples of the sludge forming machine, and Fig. 6(A) and Fig. 6(B) are explanatory drawings showing other examples of the sludge forming machine. Fig. 7 is an explanatory diagram showing another example of the sewage treatment mixed raw sludge using the sludge dewatering apparatus according to the embodiment shown in Fig. 1, and the decrease in cake moisture content was investigated. FIG. ■... Upper filter cloth, 2... Lower filter cloth, 3... High pressure belt, Upper J... Preliminary dewatering section, 11... Filter cloth, 12...
...Cleaning sled, 13...Sludge supply pipe, 14...Sludge chute, 15...Shaft, 16...Screen, 17...Screen cleaning pipe, 18...Transfer spiral vane, 20...Sludge forming part, 21...Hoe 2 par, 22. ．． 222...Roll pair, 23...Cylinder, 24...Punching metal (or net), 25...
... Semi-cylindrical container made of punched metal, 26... Scraper, 27... Press roller, 30-... Dewatering section, 3
1.32... Filter cloth, 33... Pressure roller

Claims (1)

[Claims] A pre-dewatering section that receives water-containing sludge, a forming section that divides the pre-dehydrated sludge into small lumps, and a pair of endless filter cloths that continuously circulate through a low-pressure dewatering section, a medium-pressure dewatering section, and a high-pressure drying section. 1. A sludge dewatering device comprising: a dewatering section.