JPH0146239B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a high-pressure belt press type dehydrator used for dewatering sewage sludge and the like to obtain a dehydrated cake with low moisture content.

(Prior art) A belt press type dewatering machine that dewaters the workpiece while running it with the workpiece sandwiched between an upper belt and a lower belt that are passed between many rollers is suitable for dewatering pulp waste mud, etc. It has been known for a long time to be suitable. However, in conventional belt press type dehydrators, for example, as shown in Japanese Patent Application Laid-open No. 74656/1983, a pressure zone is immediately provided after an extremely short gravity dehydration zone and a wedge zone in which the distance between the upper and lower belts is gradually narrowed. In particular, in the case of sewage sludge, which contains a large amount of water and has a high organic content, water cannot be drained sufficiently in the gravity dewatering zone, and the pressure zone is used to pressurize the water. When compressed, sludge tends to flow laterally of the belt and escape, which is a so-called side leak. In addition, in such conventional belt press type dewatering machines, if the lower belt is made coarse in order to perform sufficient gravity dehydration, sludge will leak out during pressurization, so it is necessary to use a fine belt with relatively low air permeability. Furthermore, since the belt speed is determined based on the pressure zone as a standard, the effect of the gravity dehydration zone cannot help but be insufficient. In addition, in order to reduce the moisture content of the dehydrated cake, there is also a high-pressure belt press type dehydrator that applies high pressure from the outside of the upper and lower belts using pressure bands, as shown in Japanese Patent Publication No. 15292/1983. Although this is known, even if high pressure is applied to a dehydrated cake with high moisture content, only side leaks occur, so it has not been possible to obtain a sufficient effect in dewatering sewage sludge. In this way, in a high-pressure belt press type dehydrator, it is necessary to remove as much water as possible in the front stage to keep it in a non-flowing state, and draining the water in the front stage is even more important than in a normal belt type dehydrator. It is. Therefore, special public service was carried out in the 1980s.
As shown in Japanese Patent No. 36880, a belt press type dewatering machine has been proposed which has an extended gravity dewatering zone and is provided with a buff-full plate above the zone for scraping sludge. However, such a buttful plate has a structure that easily lifts from the belt surface when it comes into contact with fibrous lumps in the sludge, so the effect of exposing the belt surface and promoting water drainage is still insufficient. There were some unsatisfactory points in the dewatering of sewage sludge, which contains a lot of fiber such as lint and human hair.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems by thoroughly draining sewage sludge, which is highly fibrous and difficult to dewater, and then dewatering it under high pressure. It was completed with the aim of being a belt press type dehydrator that can produce dehydrated cakes with low moisture content.

(Means for Solving the Problems) The present invention is supported on the upper surface of an upper belt that drains sludge supplied to the surface by a sludge supply section, so as to be rotatable and vertically movable on a vertical axis, and is always attached to the belt surface by its own weight. A number of contacting cylindrical plows each having a truncated cone-shaped brim at the lower end are arranged in a staggered manner to form a draining zone, and the downstream side of the upper belt has a drained and concentrated plow. A wedge zone is formed by a belt for receiving sludge, the belt and the upper belt, and pressurizes the sludge while leveling it to a uniform thickness. It was developed for the purpose of being a belt press type dehydrator, which has a pressure zone for dewatering and a compression zone equipped with a pressure band with higher tension.

(Example) Next, the present invention will be explained in more detail with reference to illustrated examples.

In Fig. 1, 1 is an endless upper belt;
2 is a sludge supply chute that supplies sewage sludge, etc. to the upper surface thereof. Upper belt 1 is sludge supply chute 2
A sludge supply section 3 is formed by sloping upward with respect to the traveling direction of the belt, and a horizontal section following it and having a length of at least half the length of the main body is a drainage zone 4. On the upper surface of the upper belt 1 of this draining zone 4, as shown in an enlarged view in FIG. 2, a large number of cylindrical plows 5 made of synthetic resin or the like are arranged in a staggered manner. Each plow 5
is a vertical shaft 6 hanging from a frame (not shown)
It is supported so that it can rotate and move up and down,
Although the bottom surface is normally in contact with the belt surface due to its own weight, it is preferable to form a large diameter portion 7 at the lower end of the vertical shaft 6 so that it can be lifted together with the vertical shaft 6 when necessary. In addition, a truncated conical collar 8 is formed at the lower end of each plow 5, and the plows are arranged so that when the plow 5 pushes through the sludge, the plow 5 receives a downward force from the sludge and is pressed against the belt surface. By arranging multiple plows in one row in the width direction of the filter cloth, arranging them in multiple rows in the direction of travel of the filter cloth, and arranging even and odd rows alternately in a staggered manner, the entire sludge can be stirred uniformly. Water removal is promoted. In the embodiment, in order to further enhance the water removal effect, the plows 5 are installed alternately before and after the support rod 14 extending in the width direction of the upper belt 1, as shown in FIGS. 2 and 3. When viewed from the direction of movement of the plows 1, the plows 5 are arranged closely together without gaps. This has the effect of temporarily damming up the sludge and making the dammed sludge become lame. In particular, if the arrangement of the even-numbered rows and odd-numbered rows is changed and arranged alternately in a staggered manner as shown in the figure, the mud can be uniformly stirred and plowed back, and an excellent water drainage effect can be obtained.

9 is a guide chute that guides drained sludge falling from the rear end of the upper belt 1; 10 is a belt provided below the upper belt 1; belt 1
0 is also an endless belt, and these upper belts 1
A wedge zone 13 is formed by the belt 10 and the belt 10 . In the embodiment, in order to further enhance the dewatering effect in the wedge zone 13, a pressure mat 1 made of a rubber plate or the like is installed between the upper belt 1 and the belt 10.
1 is provided with its base end pivotally supported by a horizontal shaft 12 and its free end hanging down over the belt 10 by its own weight. This pressurizing mat 11 uses its own weight to pressurize the sludge transferred on the belt 10 to a uniform thickness, and the pressurizing effect can be increased by making the free end thicker or adding weight. . Next to the wedge zone 13 is a pressure zone 16 in which the belt 10 and the upper belt 1 are stretched between a number of rollers 5 arranged in a zigzag pattern, and the sludge is dewatered by the tension of the belt. There is. As shown in the figure, the diameter of these rollers 15 is gradually reduced to increase the contact pressure, and each roller 15 is made of a steel pipe with many holes or a cylindrical shape made by winding punched metal. It is preferable to enhance the dehydration effect. Reference numeral 17 denotes a pressure band having a tension greater than that of the upper belt 1 and the belt 10, which is stretched between three rollers 19 outside the large diameter roller 18 next to the pressure zone 16. This pressure band 17 is made of stainless steel, polyester resin, etc., and forms a compression zone 20 in which the sludge is pressed under high pressure by strongly pressing the belt 10 and the upper belt 1 against the surface of the large diameter roller 18. It is something to do. The large roller 18 is rotated by a drive device (not shown), and the pressure band 17 connects the belt 10 and the upper belt 1 to the large diameter roller 1.
8 and travels along with the rotation of the large diameter roller 18. Note that 21 is a resin or metal scraper for peeling the dehydrated cake from the belt 10 and the upper belt 1, and 22 is the upper belt 1 and the belt 10 after the dehydrated cake has been peeled off.
This is a cleaning nozzle installed across the entire width of the belt.

(Function) With this structure, if sludge that has been flocculated in advance with a polymer flocculant is supplied from the sludge supply section 3 to the surface of the upper belt 1, free water is dehydrated by gravity on the inclined belt surface. Only sludge is sent to drainage zone 4. Since the draining zone 4 is made long as mentioned above, the free water remaining in the sludge is further dehydrated, and the cylindrical plows 5 arranged in a staggered manner on the surface plow through the sludge. Since ridges are formed in the flow direction to expose the surface of the upper belt 1, dewatering is promoted, and the staggered arrangement uniformly agitates the entire sludge and drains water throughout. At this time, each plow 5 is supported by a vertical shaft 6 so that it can rotate and move up and down, so even if the fibrous material in the sludge becomes clogged, the plow rotates due to the resistance and moves the fibrous material stuck to the front side backward. Since each plow 5 is always in contact with the belt surface of the upper belt 1 due to its own weight, it is highly effective in exposing the belt surface.
is formed at the lower end, the plow 5 can be pressed against the belt surface using both sides of the sludge.
The best dehydration effect can be obtained. However, since the plow 5 is made of a light material such as synthetic resin and has a small coefficient of friction, it will not damage the belt surface.

The sludge, which has been sufficiently gravity-dewatered and concentrated in the draining zone 4, then falls onto the belt 10 via the guide chute 9, and is smoothed to a uniform thickness by the pressure mat 11 in the wedge zone 13, and is pressed into the mat. The weight of the water gradually pressurizes the water and dehydrates it. At this time, the sludge has already lost its fluidity, so side leaks will not occur. Next, the sludge is sandwiched between the belt 10 and the upper belt 1 in the pressurizing zone 16, and as it moves between the zigzag rollers 15, it is gradually pressurized and sufficiently dewatered. At this time, since the pressure against the surface of the roller 15 generated by the tension of the belt is inversely proportional to the diameter of the roller, it is advantageous to gradually reduce the diameter of the roller 15 as in the embodiment. The sludge is then pressed at a higher pressure by greater tension by the pressing band 17 of the pressing zone 20;
Scraper 21 as a dehydrated cake with extremely low moisture content
It will be taken out.

(Effects of the Invention) As is clear from the above description, the present invention forms a draining zone using an upper belt and a specially shaped plow, and in this zone, water is sufficiently drained to wedge the sludge that has lost its fluidity. Since the feed is sent sequentially to the zone, pressure zone, and compression zone, there is no side leak like in the conventional method, and even sewage sludge, which has a lot of fiber and is difficult to dewater, can be dehydrated under high pressure to create a dehydrated cake with a low moisture content. Obtainable.
Further, the present invention has the advantage that the amount of sludge supplied can be increased compared to the conventional method, and the throughput can be increased since there is no fear of side leaks. Therefore, the present invention greatly contributes to the development of industry as a belt press type dewatering machine that eliminates the problems of the prior art.

[Brief explanation of drawings]

FIG. 1 is a schematic vertical sectional view showing an embodiment of the present invention, FIG. 2 is a partially cutaway perspective view showing a draining zone, and FIG. 3 is a plan view showing the arrangement of plows in the draining zone. 1: Upper belt, 3: Sludge supply section, 4: Draining zone, 5: Plow, 6: Vertical shaft, 8: Collar section, 1
0: Belt, 13: Wedge zone, 15: Roller, 16: Pressure zone, 17: Pressure band, 2
0: Squeezing zone.

Claims (1)

[Claims] 1. On the upper surface of the upper belt 1 which drains the sludge supplied to the surface by the sludge supply section 3, there is a cylindrical shape with a conical lower end, which is supported rotatably and vertically on a vertical shaft 6 and is always in contact with the belt surface due to its own weight. A large number of plows 5 each having a platform-shaped brim 8 are arranged in a staggered manner to form a draining zone 4, and a belt 10 on the downstream side of the upper belt 1 receives drained and concentrated sludge. A wedge zone 13 is formed by the belt 10 and the upper belt 1 and pressurizes the sludge while smoothing the sludge to a uniform thickness. A belt press type dehydrator characterized in that a pressurizing zone 16 for dewatering sludge and a squeezing zone 20 equipped with a pressurizing band 17 having a higher tension are sequentially provided.